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Have you ever wondered about the history behind your Irish last name? Where did your earliest ancestors come from? What was their profession? How did their name change over the centuries?

The following is a comprehensive list of the 300 most common Irish surnames.


Ahern, O’Ahern, Hearne – This surname was first found in Co. Clare, where they held a family seat as a Dalcassian sept from before the year 1000. With the disruptions of the Strongbow invasion of 1172, they migrated southward to Cork and Waterford. In Waterford, the name is predominantly Hearn/Hearne.

(Mac)Auliffe – The name MacAuliffe is particular to Co. Cork and is scarcely found outside Munster. The MacAuliffes are a branch of the MacCarthys.

MacAleese – MacGiolla (son of the devotee of Jesus). The name of a prominent Derry sept. There are many variants of the name such as MacIliese, MacLeese, MacLice, MacLise, etc. The best known by this spelling, the painter Daniel MacLise, was from a family of the Scottish highlands, known as MacLeish, which settled in Cork.

Allen – This is usually of Scottish or English origin but sometimes in Offaly and Tipperary Ó hAillín has been anglicized Allen as well as Hallion. Allen is found as a synonym of Hallinan. As Alleyn it occurs frequently in medieval Anglo Irish records. The English name Allen is derived from that of a Welsh saint.



Barrett – The surname Barrett came to Ireland with the Anglo-Norman invaders at the end of the twelfth century. To this day, the surname is most frequently found in Co. Cork.

Barry – de Barra – The majority of these names are of Norman origin, i.e. de Barr (a place in Wales); they became completely hibernicized. Though still more numerous in Munster than elsewhere the name is widespread throughout Ireland. Barry is also the anglicized form of Ó Báire and Ó Beargha (meaning spear-like according to Woulfe), a small sept of Co. Limerick.

O’Beirne – Although the pronunciation of this name is very similar to O’Byrne, there is no connection between the septs. O’Beirne belongs almost exclusively to the Connacht.

Bodkin – This non-Irish sounding name is intimately connected with Galway, with the Bodkins being one of the fourteen “tribes” of the city. The name was originally spelled Boudakyn, then Bodekin, before eventually finalizing at Bodkin.

O’Boland – The old form of this name, Bolan or O’Bolan, is almost obsolete, though occasionally found around Ireland. There are two distinct septs of the name, both of which come from County Sligo.

O’Boylan – The O’Boylan sept of Oriel, which sprang originally from the same stock as the O’Flanagans of Fermanagh, were, in medieval times, located in a widespread territory stretching from Fermanagh to Louth.

O’Boyle – Boyle is O Baoighill in modern Irish, the derivation of which is possibly from the Old Irish word baigell, i.e. having profitable pledges. Modern scholars reject the derivation baoith-geall. It is thus, of course, a true Irish surname.

(Mac)Brady – In Irish, the name is Mac Bradaigh, so it should correctly be MacBrady in the anglicized form. The prefix Mac, however, is seldom used in modern times; the modern use of the prefix O instead of Mac with this name is erroneous. The MacBradys were once a powerful sept belonging to Breffny.

O’Brallaghan – Few Irish surnames have been more barbarously maltreated by the introduction of the English language into Ireland than O Brollachain. For some extraordinary reason, it was generally given as its anglicized form, the common English name Bradley. Though in a few places, notably County Derry, it is quite rationally still O’ Brallghan.

O’Breen, MacBreen – Presently the Breens are widely distributed around Ireland. They are usually called simply Breen, though originally there were both MacBreens and O’Breens. The Mac Braoins (Irish form of the name) were an Ossory sept seated near Knock-topher in County Kilkenny; after the Anglo-Norman invasion they were dispersed by the Walshes and sank in importance.

Brennan – Ó Braonáin – (The word braon has several meanings, possibly sorrow in this case). The name of four unrelated septs, located in Ossory, east Galway, Kerry and Westmeath. The county Fermanagh sept of Ó Branáin was also anglicized Brennan as well as Brannan.

O’Brien – The Old Gaelic name used by the O’Brien family in Ireland was O Briain, which means descendant of Brian. It was first found in Thomond, a territory comprised mostly of Co. Clare with adjacent parts of Limerick and Tipperary. Before the 10th Century, the sept was a Dalcassian Clan known was the Ui Toirdealbhaigh, which achieved prominence with the rise of their ancestor Brian

Boru, the High King of Ireland.MacBride, Kilbride – MacBride is Mac Giolla Brighde in Irish, i.e. son of the follower or devotee of St. Brigid. The name is found most frequently in Ulster, particularly in Co. Donegal and Co. Down.

O’Broder, Broderick, Brothers – Broderick is a fairly common indigenous surname in England. However, very few Irish Brodericks are of English extraction, with the surname also deriving from the Gaelic “O’ Bruadair.” Broderick affords a good example of how names evolved and were Anglicized over the course of two centuries of English domination in Ireland.

Butler: Anglo Norman name later Earl of Ormond. Lord FitzWalter later Butler accompanied British forces to Ireland in 1169 to secure Anglo Norman lands. Family recieved Irish titles for their service. Later connected to Ormond line in the Kilkenny, Tipperary area O’Byrne – This name in Irish is O Broin, i.e. descendant of Bran (earlier form Broen), King of Leinster, who died in 1052. With the O’Tooles, the O’Byrnes were driven from their original territory in modern Co. Kildare at the time of the Anglo-Norman invasion, and settled in the wilder country of South Wicklow in roughly 1200.



MacCabe – Mac Cába – An anglicized form of the Gaelic MacCába, which comes from cába, meaning cape or hat. In the Middle Ages the Irish O’Reilly and O’Rourke families of Leitrim and Cavan brought fighters from Scotland to build their forces. Many of these gallowglass men were MacCabes rom Inis Gall in the Hebrides. They are believed to have worn distinctive hats. Having regards to their origin it is more likely to be from a non-Gaelic personal name.

(Mac)Caffrey – The MacCaffreys are a branch of the MacGuires of Fermanagh. The townland of Ballymacaffrey near Fivemiletown on the Tyrone border marks their homeland. The great majority of people with this name today belong to families in Fermanagh and Tyrone.

O’Cahill – In early medieval times the most important sept of O’Cahill was that located in County Galway near the Clare border. The head of which was Chief of Kinelea, but by the middle of the thirteenth century their former position as the leading family in Kilmacdaugh had been taken by the O’Shaughnessys.

Callaghan – Ó Ceallacháin – The eponymous ancestor in this case was Ceallacháin, King of Munster (d. 952). The sept was important in the present Co. Cork until the seventeenth century and the name is still very numerous there. The chief family was transplanted under the Cromwellian regime to east Clare, where the village of O’Callghan’s Mills is called after them.

MacCann, Canny – In Irish Mac Anna (son of Annadh) it has become, by the attraction of the C of Mac, Mac Canna in Irish and MacCann in English. The MacCanns occupied a district of Co. Armagh which was originally ran by the O’Graveys.

O’Cannon – Cannon is a common English surname derived from the ecclesiastical word canon. It is also the anglicized form of the name of two quite distinct Irish septs, one stemming from Galway and the other from Donegal. The original Gaelic form of the name is O Canain, from the word ‘cano,’ which means wolf cub.

Carey – The O’Kearys (Irish: O Ciardha), later used the anglicized form Carey. They belonged to the southern Ui Niell and were lords of Carbury (Co. Kildare) until dispersed by the invasion of the Anglo-Normans.

O’Carolan – The Irish name O’Carolan claims descent from the O’Connors, Kings of Connaught, in Donegal, where Carlan (from the Irish ‘carla’ and ‘an,’ meaning ‘one who combs wool’). The name O’Caloran was first found in Co. Limerick.

Carroll – The name Carroll was first found in counties Tipperary, Offaly, Monaghan and Louth. It has undergone many variations since its genesis. In Gaelic it appeared as Cearbhaill, derived from the name of Cearbhal, the lord of Ely who helped Brian Boru lead the Irish to victory in the Battle of Clontarf.

MacCartan (Carton) – The Irish surname MacArtain became, in English, MacCartan, or sometimes Carton. This is an example of the error often found with Mac names beginning with a vowel, where the letter C of Mac was carried forward to form the start of the name proper (i.e. – MacCann, MacCoy etc.). The name is derived from the common Christian name Art, of which Artan is a diminutive.

MacCarthy – No Irish Mac name comes near MacCarthy in numerical strength. The abbreviated form Carthy is also very common, but MacCArthy is a name which has generally retained the prefix. It is among the dozen most common names in Ireland as a whole, due to the very large number of MacCarthys from Co. Cork, which accounts for some 60% of them. From the earliest times, the name has been associated with South Munster or Desmond.

O’Casey (MacCasey) – There were originally at least 6 six distinct and unrelated septs of O Cathasaigh, the most important of these in early times were found in Co. Dublin. However, O’Caseys were also found in Fermanagh, Limerick, Cork and Roscommon. In its ancient Gaelic form, the name is O Cathasaigh, from the word ‘cathasach’ which means ‘watchful.’

(Mac)Clancy – Clancy is a Mac name: the initial C of Clancy, is in fact the last letter of the prefix Mac, so it would have been MacLancy. Clancy also happens to be an alternative form of the name ‘Glanchy,’ which was common in the seventieth century and is still occasionally found.

O’Coffey – This name is O Cobhthaigh in Irish, pronounced O’Coffey in English: it is likely derived from the word cobhthach, meaning victorious. Coffey is one of those surnames that has not often retained the “O” prefix. Coffey has several distinct septs that date back to the medieval times, two of which are still well represented in their original homeland. These are the Coffeys in Co. Cork and Co. Roscommon.

(Mac)Coghlan, O’Coughlan – There are two quite distinct septs of Coughlan, one being MacCoughlan of Offaly and the other O’Coughlan of Co. Cork. In Gaelic it has appeared as Mac Cochlain or O Cochlain.

O’Connor – Associated with the areas of Derry, Connacht, and Munster. An anglicized form of Gaelic Ó Conchobhair. Many claim descent from a 10th century king of Connacht of this name. In Irish legend, Conchobhar was a king of Ulster who lived at around the time of Christ and who adopted the youthful Cú Chulainn.

MacColgan – In early medieval times, Colgan had the prefixes O and Mac. There are two distinct septs of this name – one originating in Co. Derry and the other stemming from Offaly. Those in Derry claim descent from the O’Connors.

Collins, Colin – In Ireland, often the anglicized form of Coileain, prefixed by Mac or O, and found mainly in the western part of the country. In this case the name translates as “the young hound.” Also derived from the Greco-Roman name Nicholas.

O’Colman – Though families called Coleman are known to have settled in Ireland in as early as the thirteenth century, having come from England, where the name is common, Coleman in Ireland almost always denotes a Gaelic origin. The main sept of Coleman, O Colmain, originated in Co. Sligo.

O’Concannon – The name Concannon is rarely found outside the territory of its origin, which is Galway. All 21 recorded births registered for this name in the last available statistical return took place in Co. Galway or in contiguous areas of adjacent counties.

Condon – The northeastern division of Co. Cork, close to the adjoining counties of Limerick and Tipperary, is called the barony of Condons. This was named after the family of Condon that was in control of most of the area, with their principal stronghold being the Castle of Clogleagh near Kilworth. They may indeed be described as a sept rather than a family.

MacCormack – Cormick, Mac Cormaic – Formed from the forename Cormac. This name is numerous
throughout all the provinces, the spelling MacCormick being more usual in Ulster. For the most part it originated as a simple patronymic; the only recognized sept of the name was of the Fermanagh-Longford area. Many of the MacCormac(k) families of Ulster are of Scottish origin, being a branch of the clan Buchanan-MacCormick of MacLaine.



Dalton – Though this name is not Irish in origin, it is on record in Dublin and Meath as early as the beginning of the thirteenth century, the family having been established in Ireland following the Anglo-Norman invasion. Its Norman origin is more apparent in the alternative spelling, still sometimes used – D’Alton, or, of Alton, a place in England.

O’Daly – O’Daly is said to be the greatest name in Gaelic literature. Other septs may have produced one or two more famous individuals, but the O’Dalys have a continuous record of literary achievement from the twelfth to the seventeenth century and, indeed, even to the nineteenth. There have been no less than thirty O’Dalys distinguished as writers between 1139 and 1680.

Darcy, O’Dorcey, MacDarcy – This name is often spelled D’Arcy. This is historically correct in the case of the families who descend from Sir John D’Arcy, Chief Justice of Ireland in the fourteenth century. There are the Darcys of Hyde Park, Co. Westmeath and it is reasonable to assume that the D’Arcys of the east midlands of Ireland are of that stock.

O’Dargan, Dorgan – The Gaelic name Ó Deargáin, the root of which is dearg (red), has taken the anglicized form Dargan in Leinster, and Dorgan in Munster. The latter is almost confined to Co. Cork (Ballydorgan) while respectable families of Durgan have long been living in the midland counties. As a Gaelic sept they were of little importance so they seldom appear in the Annals, the “Book of Rights,” the Fiants, the “Topographical Poems,” “An Leabhar Muimhneach,” or any of the usual sources of genealogical information.

O’Davoren – Formerly a flourishing Thomond sept, the O’Davorens have dwindled to small numbers but are still found in Clare and the adjoining county of Tipperary. They are described as the formerly learned Breton family seated at Lisdoonvarna, where they had a literary and legal school, among the pupils of which was Dald MacFirbis, the most distinguished of the celebrated family of Irish antiquaries.

O’Dea – O’Dea is a name associated (in the past and present alike) almost exclusively with County Clare and areas like Limerick City and North Tipperary, which immediately adjoin it. It is not a common name elsewhere – even in County Clare it appears infrequently outside the part of the county where it originated.

O’Delany, Delaney – Delany is a surname rarely seen today with the prefix O, with which it belongs. It is Ó Dubhshláinte in Irish, Delany being a phonetic rendering of this – the A of Delany was formerly pronounced broad. An earlier anglicized form was O’Delany, as in Felix O’Delany, Bishop of Ossory from 1178 to 1202, who built St. Canice’s Cathedral in Kilkenny.

O’Dempsey, Dempsey – The O’Dempseys are of the same stock as the O’Connors of Offaly and were a powerful sept in the territory on the borders of Leix and Offaly known as Clanmalier, which lays on both sides of the River Barrow. They were Clanmalier’s traditional chiefs. The name O’Dempsey originally appeared in Gaelic as O Diomasaigh, from the word ‘diomasach,’ which means ‘proud.’

McDermott – the McDermots are one of the few septs whose head is recognized by the Irish Genealogical Office as an authentic chieftain, that is to say he is entitled in popular parlance to be called The McDermott; and in this case this is enhanced by the further title of Prince of Coolavin, though of course titles are not recognized under the Irish Constitution the designation is only used by courtesy.

O’Devine, Davin, Devane – The name Devine is chiefly found today in the counties of Tyrone and Fermanagh. Up to the fifteenth century, the chief of this sept was Lord of Tirkennedy in Co. Fermanagh. Though the etymology of the name has been questioned, we may accept the view of so eminent a scholar as O’Donovan that it is in Irish Ó Daimhín.

O’Devlin – There was once a not unimportant sept of Ó Doibhilin, anglice O’Devlin, in what is now the barony of Corran, Co. Sligo. As late as 1316 one of these, Gillananaev O’Devlin, who was standard bearer to O’Connor, was slain in battle. Their descendants have either died out or have been dispersed. The principal sept of the name belongs to Co. Tyrone.

Dillon – Although not native Gaelic in origin, the name Dillon may now be regarded as hundred percent Irish: when met outside Ireland it will most always be found belonging to a person of Irish origin. The Dillons came to Ireland at the time of the Anglo-Norman invasion. Dillon has been an important name in Irish history and modern politics.

O’Dineen, Dinan, Downing – Today, the great majority of Dineens, who rarely if ever have the prefix O in English, belong to Co. Cork families, especially to the southwestern part once known as Corca Laoidhe. It was there that the sept originated.

Disney – Derived from a French place-name and originally written D’Isigny etc., the name Disney occurs quite frequently in the records of several Irish counties in the south and midlands since the first half of the seventeenth century.

O’Doherty – Doherty is an example of a surname in which the resumption of its prefix O during the recent century has been very marked. Comparing the statistics of 1890 with 1955, we find that in the former year in Ireland out of 465 births registered, fewer than two percent were O’Doherty. Alternative spellings such as Dogherty and Dougherty are rarely met with nowadays as well.

O’Dolan, Doolan – The name Dolan is fairly common today in Ulster, in the Catholic areas of Counties Cavan and Fermanagh, and in the Counties of Roscommon and Galway in Connacht. The latter is the place of origin of this sept which is a branch of the Ui Máine (Hy Many). In the census of 1659 the name appears principally in Counties Roscommon and Fermanagh (the portion dealing with Co. Galway is missing).

MacDonlevy, Dunleavy, Leavy – Dunleavy, to give its most usual modern form, may be regarded as a Mac surname (Mac Duinnshléibhe in Irish) though in some early manuscripts, e.g. the “Topographical Poems” of O’Dugan and O’Heerin, the prefix O is used. In the “Annals of Loch Cé” the O prefix appears in the sixteenth century, but all of those mentioned before that are Mac.

McDonnell – Today the McDonnells are found widely distributed all over Ireland, and without, including the cognate McDonald in the count, the McDonnells in Ireland amount to nearly 10,000 persons with three separate, distinct origins. The Dalriadan clans of ancient Scotland spawned the ancestors of the McDonnell family.

O’Donnell – The O’Donnells have always been numerous and eminent in Irish life. They are of course chiefly associated with Tirconnaill (Donegal), the home of the largest and best known O’Donnell sept. But as the present distribution of persons of the name implies, there were quite distinct O’Donnell septs in other parts of the country, two of which require special mention: Corcabaskin in West Clare, and another, a branch of the Ui Main (Hy Many, in Co. Galway).

O’Donnellan, Donlon – the O’Donnellans were a sept of the Ui Máine. They belong, therefore, by origin, to the southeastern part of Co. Galway where the place name Ballydonnellan perpetuates their connection with the district between Ballinasloe and Loughrea. They claim descent from Domhallán, lord of Clan Breasail.

O’Donnelly – According to the latest statistics there are just short of 10,000 persons of the name Donnelly in Ireland today, which places this name among the sixty-five most popular in the country. Practically all of these may be regarded as belonging to the Ulster Donnelly sept – Ó Donnghaile of Cinel Eoghan.

MacDonogh, Dinghy – Like so many well known Irish surnames, especially MacDonagh (Irish Mac Donnchadha, i.e. son of Donnchadh, or Donagh) the MacDonoghs are formed from a common Christian or personal name. MacDonagh is one that came to usage in two widely separated parts of the country.

O’Donoghue, Donohoe, Dunphy – Donoghue or Donohoe, more properly O’Donoghue, is one of the most important as well as the most common names in Ireland. In Irish, Ó Donnchadha denotes descendant of Donnchadh, anglice Donogh, a personal name. Several distinct septs of the name existed in early times.The original Gaelic form of the name Dunphy is O Donnchaidh as well.

O’Donovan – There are few families about which we have more information than the O’Donovans. The Genealogical Office has a verified pedigree of the eldest branch from Gaelic times, when they held a semi-royal position, up to the present day, and also the notes of Dr. John O’Donovan, one of Ireland’s most distinguished antiquarians and a member of a junior branch of the same sept. All of these are available to the general public.

O’Dooley – The modern form of this name in Irish is Ó Dubhlaoich. The Four Masters write it Ó Dughlaich when describing their chiefs in the eleventh and twelfth centuries as Lords of Fertullagh, the southeastern end of Co. Westmeath. They were driven thence by the O’Melaghlins and the Tyrrells and migrated to the Ely O’Carroll country where they acquired a footing on the western slopes of Slieve Bloom.

O’Doral, Dorrian – The O’Dorians have been justly described as “the great Breton family of Leinster,” but they are probably better known as traditional antiquarians who kept in their possession from generation to generation the three manuscript copies of the “Tripartite Life of St. Patrick.”

O’Dowd, Dowda, Doody, Duddy – This is one of the O names with which the prefix has been widely retained, O’Dowd being more usual than Dowd. Other modern variants are O’Dowdy and Dowds, with Doody, another synonym, found around Killarney. O’Dowd, which comes from O Dubhda, which means black or dark complexioned, was first found in county Mayo.

O’Dowling – The Dowlings are one of the “Seven Septs of Leix,” the leading members of which were transplanted to Tarbet on the border of north Kerry and west Limerick in 1609. This transplantation did not affect the rank and file of the sept, who multiplied in their original territory.

O’Downey, MachEldowney, Doheny, Muldowney – The O’Downeys were of some importance in early medieval times, when there were two distinct septs of Ó Dúnadhaigh. That of Sil Anmchadha, of the same stock as the O’Maddens, several of whom are described in the “Annals of Innisfallen” and “Four Masters” as lords of Sil Anmchadha, who became submerged as early as the twelfth century. Their descendants are still found in quite considerable numbers in that county.

Doyle, MacDowell – Doyle, rarely found as O’Doyle in modern times, stands high on the list of Irish surnames arranged in order of numerical strength, holding twelfth place with approximately 21,000 people out of a population of something less than 4 million. Though now widely distributed, it was once most closely associated with the counties of southeast Leinster (Wicklow, Wexford and Carlow) in which it is chiefly found today, and in the records of fifteenth, sixteenth and seventeenth centuries.

O’Driscoll – Few families have been so continuously and exclusively associated with the territory of their origin as the Driscolls or O’Driscolls. They belong to Co. Cork. At first they were concentrated in south Kerry, but pressure from the O’Sullivans drove them eastwards and they then settled around Baltimore in southwest Cork.

O’Duff, Duhig, Dowey – The name Duffy or O’Duffy is widespread in Ireland: it is among the fifty most common surnames, standing first in the list for Co. Monaghan. it is also very common in north Connacht. It is found in Munster to some extent, but there it often takes the form Duhig, while in parts of Donegal it has become Doohey and Dowey.

O’Duggan, O’Dugan – Dugan, in Irish Ó Dubhagain, is in some places given in English speech the Irish pronunciation of Doogan. The prefix O, dropped in the seventeenth century, has not been continued. Outside of Dublin, the name is almost entirely confined to Munster, especially Counties Cork and Tipperary, and Wexford. In the seventeenth century it was very common in Co. Tipperary.

O’Dunn, Dunn – In Irish Ó Duinn or Ó Doinn – doin is the genitive case of the adjective donn, which means brown. It is more often written Dunne than Dunn in English. The form O’Doyne, common in the seventeenth century, is now almost obsolete.

O’Dwyer – The O’Dwyers (in Irish Ó Duibhir, descendant of Duibhir) were an important sept in Co. Tipperary, though incomparable in power or extent of territory to the neighboring great septs. Their lands were Kilnamanagh, the mountainous area lying between the town of Thurles, and the county of Limerick.



Egan, Keegan – In Irish Egan is MacAodhagáin (from the Christian name Aodh, anglice Hugh), and the surname is really MacEgan, though the prefix Mac is rarely used in modern times except by the family who claims to be head of the sept.

McElroy, (Mac)Gilroy, Kilroy – This name is Mac Giolla Rua in Irish, i.e. son of the red (haired) youth. The sept originated in Co. Fermanagh where the place name Ballymackilroy was found: their territory was on the east side of Lough Erne.

MacEnchroe, Crowe – The very English-seeming name Crowe disguised the genuinely Irish surname MacEnchroe, which in its original form is Mac Conchradha. The form MacEnchroe is still in use but all of the members of this sept who live in its original territory, Thomond, are certainly called simply Crowe.

McEvoy, MacElwee, MacGilloway, MacVeagh – The MacEvoys were on of the “Seven Septs of Leix,” the leading members of which were transplanted to Co. Kerry in 1609. The lesser clansmen remained in their own territory and Leix is one of the areas in which the name is found fairly frequently today.



Fagan – In spite of its very Irish appearance (-gan is one of the most common terminations of Irish surnames) Fagan must be regarded as a family name of Norman origin. At the same time it must be pointed out that it is not an English name. It is derived from the Latin word Paguns. For many centuries it has been associated with Counties Dublin and Meath.

O’Fahy – Fahy (also spelt Fahey) is almost exclusively a Co. Galway name, though of course it is also found in the bordering areas, such as north Tipperary, and in Dublin. A sept of the Ui Máine, the center of their patrimony, which they held as proprietors up to the time of the Cromwellian upheaval (and where most of them still dwell) is Loughrea. Their territory was known as Pobal Mhuintir ui Fhathlaigh, i.e. the country inhabited by the Fahys.

O’Fallon, Falloone – The name Fallon or, as it is also written O’Fallon, has been closely associated with the counties of Galway and Roscommon. They held a family seat in Galway in very ancient times. The Gaelic form is O Fallamhain.

O’Farrell, O’Ferrell – Farrell, with and without the prefix O, is a well known name in many parts of the country and it stands thirty-fifth in the statistical returns showing the hundred most common names in Ireland. It is estimated that there are over 13,000 pepole with the name in Ireland; the great majority of these were born in Leinster, mainly in Co. Longford and the surrounding areas.

O’Farrelly, Farley – O’Farrelly – Ó Faircheallaigh in Irish – is the name of a Breffny sept associated in both early and modern times principally with Counties Cavan and Meath. The Gaelic poet Feardorcha O’Farrelly (d. 1746) was born in Co. Cavan.

O’Feeny – Apart from the quite definite fact that it is essentially a Connacht name, it is difficult to be precise in dealing with the surname Feeney. The reason for this is that in Connacht there are two different septs – Ó Fiannaidhe in Sligo and Mayo and Ó Fidhne in Galway and Roscommon.

O’Finn, Magian – The name Finn – it seldom has the prefix O in modern times – is chiefly found in Co. Cork today and this was equally true in the seventeenth century, as Petty’s census shows. This is curious because it is usually a fact that names are still most numerous in the part of Ireland in which they originated.

O’Finnegan – There are two distinct septs of Finnegan or Finegan whose name is Ó Fionnagáin in Irish, which means the descendants of Fionnagán, an old Irish personal name derived from the word fionn, i.e. fairheaded. One of these septs was located on the border of Galway and Roscommon, where there are two places called Ballyfinnegan – one in the barony of Ballymore and the second in the barony of Castlereagh.

Fitzgerald – The Ftizgeralds of Ireland, who are now very numerous, are said to all have descended from the famous Maurice, son of Gerald, who accompanied Strongbow in the Anglo-Norman invasion. Gerald was constable of Pembroke in Wales and was married to Nesta, Princess of Wales.

Fitzgibbon, Gibbons – In treating of the surname Gibbons in Ireland it must first be mentioned that this is a very common indigenous name in England and in the course of the several plantations of English settlers in this country from 1600 onwards, as well as a result of business infiltration, it is inevitable that at least a small proportion of our Gibbonses must be of English stock.

Fitzpatrick, Kilpatrick – This is the only surname with the prefix Fitz which is of native Irish origin, the others being Norman. The Fitzpatricks are Macgilpatricks – Mac Giolla Phádraig in Irish, meaning son of the servant or devotee of St. Patrick. First found in Kilkenny (which was then called Ossory).

O’Flaherty, Laverty – The O’Flahertys possessed the territory on the east side of Lough Corrib until the thirteenth century when, under pressure from the Anglo-Norman invasion into Connacht, they moved westwards to the other side of the lake and became established there. The head of the sept was known as Lord of Moycullen and as Lord of Iar-Connacht, which, at its largest, extended from Killary Harbour to the Bay of Galway and included the Aran Islands.

O’Flanagan – This surname is practically the same in both its Irish and anglicized forms, being in the former Ó Flannagáin, which is probably derived from the adjective flann meaning reddish or ruddy. It belongs to Connacht both by origin and location (i.e. present distribution of population).

O’Flannery – The name O’Flannery – or rather Flannery for the prefix O has been almost entirely discarded – is identified with two different areas. One sept of Ó Flannabrah was of the Ui Fiachrach, located at Killala, Co. Mayo; the other of the Ui Fidhgheinte was one of the main families of the barony of Connelloe, Co. Limerick.

Fleming – Fleming, as the word implies, denotes an inhabitant of Flanders, and this surname originated about the year 1200 when many Flemings emigrated to Britain, settling chiefly on the Scottish border and in Wales. Since then it has mostly been associated with Scotland. Nevertheless it is fairly common in Ireland.

O’Flynn, O’Lynn – The surname O’Flynn is derived from the Gaelic personal name Flann; the adjective flann denotes a dull red color and means ruddy when applied to persons. Ó Floinn is the form of the surname in Irish.

O’Fogarty – The sept O’Fogarty was of sufficient importance to give its name to a large territory – Eliogarty, i.e. the southern part of Eile or Ely, the northern being Ely O’Carroll. Eloigarty is now the name of the barony of Co. Tipperary in which the town of Thurles is situated.

O’Foley, MacSharry – Foley is an old Irish surname about which some confusion has arisen because there is an important family of Worcestershire called Foley, which is usually regarded as English, though some think it was originally Irish. For example it is the arms of this English family which are often ascribed to Gaelic Foleys.

Forde – It is impossible for any Irishman called Forde or Ford to know the origin of his people unless there can be a firm family tradition to aid him, or alternatively he knows that they have long been located in a certain part of the country. The reason for this is that at least three Irish septs with entirely different surnames in Irish became known in English as Forde or Ford.

Fox – In this note we may disregard English settlers of the name Fox, one family of whom became extensive landowners in Co. Limerick and are perpetuated there in the place name Mountfox, near

French, de Freyne – Originally Norman, the name was de Freeness, from Latin fracinus – an ash tree. When the Anglo-Normans began to settle in Ireland, they brought the tradition of local surnames to an island which already had a Gaelic naming system of hereditary surnames established. The Anglo-Normans had an affinity for local surnames (like French) which were formed from the names of the place where the person lived or was born.

O’Friel – O’Friel is a Donegal name. In Irish it is Ó Firghil (from Feargal); it is pronounced, and often written, Ó Fright, i.e. in English, phonetics O’Freel. This sept has a distinguished origins, descended from Eoghan, brother of St. Columcille.



Gaffney (Caulfield, O’Growney, Keveney, MacCarron, Carew) – Gaffney is one of those quite common Irish surnames about which much confusion arises. Not only is it used as the anglicized form of four distinct Gaelic names, but Gaffney itself has for some obscure reason become Caulfield in many places. It never appears today with either Mac or O as prefix: of the four patronymics referred to above two are O names and two are Mac.

O’Gallagher – The name of this sept, Ó Gallchobhair in Irish, signifies descendant of Gallchobhar or Gallagher, who was himself descended from the King of Ireland who reigned from 642-654. The O’Gallaghers claim to be the senior and most loyal family of the Cineal Connaill. Their territory extended over a wide area in the modern baronies of Raphoe and Tirhugh, Co. Donegal, and their chiefs were notable as marshals of O’Donnell’s military forces from the fourteenth to sixteenth centuries.

O’Galvin – The O’Galvins are a sept of Thomond and are mentioned among the Co. Clare septs which took part in the Battle of Loughraska, otherwise called the Battle of Corcomroe Abbey, in 1317. They haven’t appeared prominently in any branch of Irish public life since that time, but representatives of the sept have remained continuously in their original homeland and are still found in Co. Clare, and in greater numbers today, in Co. Kerry.

MacGannon – The name of the old Erris (Co. Mayo) family of Mag Fhionnáub is usually anglicized Gannon, without the Mac: in the spoken language in Irish it is often called Ó Geanáin but the equivalent O’Gannon is not used in English. Gannons are still more numerous in their original homeland in Co. Mayo than elsewhere.

O’Gara, Geary – The sept of O’Gara, Ó Gadhra in Irish, is closely associated with that of O’Hara. They have a common descendant down to the tenth century, Gadhra, the eponymous ancestor of the O’Garas, being nephew of Eadhra (a quo the O’haras). From then on they established separate chieftainries, O’Gara taking the territory to the south of the barony now known as Leyney, Co. Sligo, with the O’Haras being to the north of them.

MacGarry, Garrihy, O’Hehir, Hare – MacGarry is one of those names which in the anglicized form takes its initial letter from the end of the prefix – in this case Mag (a variant of Mac often used with the names beginning with a vowel or fh). In Irish MacGarry is Mag Fhearadhaigh.

O’Garvey, MacGarvey, Garvin – Garvey is one of those surnames which in Irish have both the Gaelic prefixes, Mac and O. Mac Gairbhith belongs to Co. Donegal where it is common: it is Mac Garvey in English, the prefix being retained. The O, on the other hand, has been almost entirely discarded.

MacGee – MacGee is an Ulster name which is more usually written Magee (cf. MacGuire, Maguire, MacGuinness, Magennis, etc.). In Irish it is Mag Aodha, i.e. son of Aodh or Hugh, the Mac, as is often the case when the prefix is followed by a vowel, becoming Mag. It has been stated that our Ulster MacGees are of Scottish descent, having come to Ireland during the Plantation of Ulster in the early seventeenth century.

MacGenis, Guinness, Magennis – The modern spelling of this name is usually MacGuinness or MacGenis but in the historical records in English they are called as a rule Magennis, a form still to be found in some places today. In Irish the name is MagAonghusa,which means ‘son of Angus.’ The name was first found on Co. Down in the province of Ulster – they held a family seat there from ancient times.

MacGeoghagan – Geoghegan, usually nowadays without the prefix Mac, is a name which no non-Irish person will attempt to pronounce at sight; it has many synonyms, and one of these, Gehegan, is a phonetic approximation of the longer and common form. In Irish it is Mag Eochagáin, from Eochaidh, from the now almost obsolete, but once common Christian name, Oghy. It will be observed that the initial “G” of Geoghegan comes from the prefix Mag, a variant of Mac – the anglicized form of Mageoghegan was formerly commonly used.

MacGeraghty, Gerty – Geraghty is a Mac name, being Mag Oireachtaigh in Irish. Mac usually becomes Mag before a vowel so the initial G of Geraghty is really the last letter of the prefix Mac or Mag. There are no less than seventeen different synonyms of Geraghty in English, including MacGerity, Gearty and even Jerety. The Gaelic form derives from the word ‘oireachtach,’ which refers to a member of an assembly.

MacGilfoyle, Powell – Guilfoyle is Mac Giolla Phóil in Irish, which means son of the follower or devotee of St. Paul. It is sometimes disguised under the form Powell, an English surname adopted in its stead during the period of Gaelic depression. The prefix Mac, which properly belongs to it, is very seldom used here in modern times.

MacGillycuddy, Archdeacon, Cody – This name is well known to everyone who has made a visit to Killarney or even studied a map with the idea of doing so, because the picturesque MacGillycuddy’s Reeks are the highest mountains in Ireland and are named from the Kerry sept who dwelled at their western base.

O’Glissane, Gleeson – In spite of its English appearance in its anglicized form, the name Gleeson, never found with the prefix O in English, is that of a genuine Gaelic Irish family. In modern Irish it is Ó Gliasáin, earlier Ó Glasáin and originally Ó Glesáin. They belong to the Aradh and their original habitat was mac Ui Bhriain Aradh’s country, that is the area in Co. Tipperary between Nenagh and Lough Derg. But it should be emphasized that the Gleesons are not Dalcassians – they are of the same stock as the O’Donegans, of the barony of Ara, Co. Tipperary, who were originally of Muskerry, Co. Cork.

MacGorman, O’Gorman – This name is of particular interest philologically because although it is (with rare exceptions) really a Mac name it is almost always found today – when not plain Gorman – as O’Gorman. This can be accounted for by the fact that in the eighteenth and early nineteenth centuries, when the native Irish were in complete subjection, the Gaelic prefixes Mac and O were universally allowed to fall into disuse, particularly in the case of some names like Gorman. Derived from Gaelic word ‘gorm,’ which means blue.

O’Gormley, Grehan, Grimes – Like many of the similar independent septs of northwest Ulster, the O’Gormleys sank into obscurity after the Plantation of Ulster around 1609. In the fourteenth century they were driven by the O’Donnells from their original territory, known as Cinel Moen (their tribe name), which was in the modern barony of Raphoe, Co. Donegal; but their survival in their new country on the other side of the Foyle, between Derry and Strabane, from whence they continued to fight the O’Donnells, is evidenced by the frequent mention of their chiefs in the “Annals of the Four Masters” up top the end of the sixteenth century.

MacGovern, Magauran – The MacGoverns are better known in history as Magauran. Both forms are phonetic approximations of the Irish mag Shamhradhain, since MH is pronounced V in some places and W in others. The G of Govern thus comes from the last letter of the prefix Mag, which is used before vowels and aspirates instead of the usual Mac. The Gaelic form derives from the word ‘samhra,’ which means summer.

MacGowan, O’Gowan, Smith, MacGuane – The Irish surname MacGowan (not to be confused with the Scottish MacGoun) is more often than not hidden under the synonym Smith. In Irish it is Mac and Ghabhain, which means son of the smith, and its translation to Smith (most common of all surnames in England) was very widespread, particularly in Co. Cavan where the MacGowan sept originated. – for instance ‘The Pogues’ Shane McGowan.

MacGuire, Maguire – These are spelling variants of Irish Maguidhir. Uidhir is the genitive case of odhar meaning dun-colored; mag is a form of mac used before vowels. This is one of those names definitely associated with one county. The Maguires belong to Co. Fermanagh.

O’Grady – The O’Grady sept originated in Co. Clare and may be classed as Dalcassian, though the seat and territory of the Chief of the name has for several centuries been at Killballyowen, Co. Limerick, as well as Galway. The name in Irish is Ó Grádaigh or more shortly Ó Gráda, so that the anglicized form approximates closely to the original. They were descendants of Olioll Olum, King of Munster.

MacGrath – Like several other names beginning with McG, Macgrath is often written Magrath (cf. MacGee, Magee, MacGennis, Magennis, etc.). In Irish it is Mac Craith, the earlier form of which is Mac Raith or Mag Raith. Other synonyms still in use, especially in Ulster, are MacGraw, Magraw, MacGra etc. while the same Gaelic surname is found in Scotland as MacCrea, MacRae and Rae. First found in County Clare, where they held a family seat from ancient times.

O’Griffy, Griffin, Griffith – Ó Gríobhta (pronounced O Greefa) is one of the many Gaelic surnames which have assumed in their anglicized forms those of British families of somewhat similar sound: in this case the earlier O’Griffy has been almost entirely superseded by Griffin. Here some confusion arises because a Welsh family of Griffin did actually settle in Ireland soon after the Anglo-Norman invasion. There is no doubt, however, that the great majority of Irish Griffins are really O’Griffys of Gaelic stock and not descendants of the Welsh settlers.



Hackett – The surname Hackett is of Norman origin, Haket being a common Norman personal name. The Hacketts came to Ireland at the time of the Anglo-Norman invasion at the end of the twelfth century, and people of that name were soon thereafter settled in several places in the area covered by the modern counties of Kilkenny, Carlow and Kildare.

O’Hagan, Aiken – This is one of the Gaelic names which was less affected than most by the widespread dropping of the prefix O during the centuries of Gaelic depression and submergence, for the form O’Hagan is much more common than Hagan. In Irish it is Ó hAodhagán (diminutive of Aodh or Hugh). There are many variants of the name in English such as Hegan, Aiken etc.

MacHale – Few names are more exclusively associated with one Irish county than MacHale of Mayo. Those of the Gaelic sept Mac Céile were erenaghs (lay parish administrators) of Killala. The surname MacHale was also adopted by a Welsh family who settled in the barony of Tirawley, Co. Mayo, in the thirteenth century: it derives from the forename Howell. Being located in the same county the descendants of these cannot now be distinguished from their namesakes of Gaelic origin: in any case, centuries of Connacht inter-marriages have made the one just as Irish in blood as the other.

O’Halloran – O’Halloran, in Irish Ó hAllmhurain, is the name of two distinct septs. These were located in adjoining counties, Clare and Galway, where their present day descendants are common, though seldom found in Leinster or Ulster. The propinquity of these two counties makes it a matter of doubt as to which sept dwellers on their border belong, except in cases where a pedigree or family tradition exists.

O’Hanlon – O’Hanlon is a name which is always associated with Co. Armagh. The sept was located in the baronies of Oneilland and Orior. For centuries their chiefs were known as lords of Orior.

O’Hanly, Henly – The surname Hanley or Hanly is the anglicized form of the Irish Ó hAinle, which is possibly derived from the Gaelic word áluinn, meaning beautiful (we may also note that in modern Irish, ainle means a swallow). It is found today principally in (and is almost confined to) two areas – Counties Roscommon and Galway, where it is usually spelled Hanly. In Co. Cork and adjacent districts the spelling is usually Hanley.

O’Hannon, Hanneen – Although there are many substantial families of Hannon in Munster and Connacht, the Annals and other sources of information regarding the septs of medieval Ireland seldom mention the name O’Hannon. The death of Maelisa O’Hannen, prior of Roscommon, in 1266 is one of the few.

O’Hanrahan, Hourihane – The O’Hanrahans are a Dalcassian sept: for the most part they are still found in their original location – Counties Clare and Limerick. Their name in Irish is Ó hAnracháin. This is stated to be a variant of Ó hAnradháain which has been anglicized O’Hourihane in Co. Cork, where a sept of the name were erenaghs of Ross.

O’Hanraghty, Enright, Hanvey – O’Hanraghty is an earlier, and now obsolete form of Ó hAnrachtaigh – the modern anglicized form being Hanratty. The name is rarely found outside its original locations of Louth and Armagh. The sept, a comparatively small one descended from lonrachtach, a scion of the great Maguires, was of Oriel. The latest available statistics show that apart from the city of Dublin, in which there are migrant families from all parts of Ireland, nearly all of the births registered for the name took place in the Counties Louth, Armagh and Monaghan.

O’Hara – The O’Haras are an important sept of distinguished origin. They are descended from Eaghra (pronounced Ara), who was chief of Leyny in Co. Sligo, a scion of the family of Olioll Ollum, King of Munster. In Irish the name is Ó hEaghra, of which the anglicized form O’Hara is a phonetic rendering.

Harrington, O’Harraghton – Harrington itself is a well-known English name, common in England, but very few of our Irish Harringtons are of English stock. This name is an example of that slavish tendency, much in evidence during the centuries of Gaelic submergence, whereby good old Gaelic Irish surnames were transmogrified into common English ones having more or less the same sound. The name is O’Airchdain in Gaelic.

O’Hart – Hart is a native English name; but in Ireland the Harts (usually spelled Harte in Connacht) are nearly all from the sept O’Hart. Some families have always retained, and others have recently resumed, the prefix O. In Irish the name is Ó hAirt, i.e. descendant of Art, who was son of King Conn of the Hundred Battles.

O’Hartigan – The O’Hartagans, or O’Hartigans, are a Calcassian sept located in Thomond and are still well known around Limerick, though nowhere are they very common. The name is Ó hArtagáin in Irish, probably derived from the well-known Christian name Art. Dunlaing O’Hartigan was one of the heroes of Clontarf. The best known of all the sept was born in Ulster far from the home of his ancestors, viz. Cineth O’Hartagan, the Gaelic poet who died in 975.

O’Hea, Hayes, Hughes – O’Hea is one of the anglicized forms of the very common Gaelic surname Ó hAodha, which has at least a dozen different and distinct origins in Ireland and is usually anglicized as Hayes, except in Ulster where it has become Hughes. Ó hAodha simply means descendant of Aodh, anglice Hugh.

O’Healy, Hely, Kerrisk – Though a genuine Gaelic name, Healy is very rarely found nowadays with its proper prefix O; there is no entry in current directories under O’Healy, O’Hely or O’Haly, forms which were common up to the end of the seventeenth century. Healy, however, is one of the most common names in Ireland taking forty-seventh place in the list of the hundred most common surnames, with a total number of persons of nearly 13,000. First found in Sligo, where the O’Healys held an ancient family seat.

O’Heffernan – The sept of Heffernan originally inhabited a territory near Corofin, Co. Clare, called Muintirfernáin after them. They established themselves in eastern Limerick on the Tipperary border, and were chiefs there of Owneybeg. They were then displaced by the Ryans. The principal families of the name did not migrate very far – they were among the most important in the barony of Clanwilliam in 1600.

O’Hegarty – Hegarty, sometimes O’Hegarty but seldom Haggerty in Ireland (a form of the name found among Irish-Americans), is in Irish Ó hÉigceartaigh (éigceartach means unjust). Though now associated principally with Co. Cork, the Hegartys of Munster are in fact a branch of the main O’Hegarty sept of the Cinel Eoghan, which was located on the borders of the present counties Donegal and Derry. In the fourteenth century the barony of Loughinsholin (Co. Derry) was their principal location.

O’Hennessy, Henchy – Hennessy is a name from which the prefix O has been entirely dropped in modern times, though O’Hennessy was still widely used in the seventeenth century. In Irish it is Ó hAonghusa, i.e. descendant of Aonghus or Angus. The principal sept of this name was located near the town of Kilbeggan and the hill of Croghan, their territory being chiefly in the northern part of Co. Offaly, where they shared with O’Holohan the lordship of Clan Cholgain.

(Mac)Henry, O’Henry, Fitzhenry – There are some 5,000 persons in Ireland today bearing the surname Henry – without O or Mac. The majority of these are Ulstermen formerly called O’Henry, the Irish form being Ó hInneirghe.

O’Heyne, Hynes – The rather commonplace surname Hines or Hynes is a modern form in English of the very distinguished name O’Heyne, in Irish Ó hEidhin. Descended from Guaire the Hospitable, King of Connacht. From the seventh century to the destruction of the Gaelic order nearly a thousand years later the head of the O’Heynes was chief of a territory in south Galway, barony of Kiltartan.

O’Hickey – Hickey, also spelled Hickie, is the anglicized form of the Irish Ó hIcidhe (pronounced O Hickee), iceadh, from which it is derived, means physician or healer. The Hickeys are closely identified with Co. Clare and north Tipperary, being Dalcassian in origin and hereditary physicians to the ruling O’Briens of Thomond. In the course of time they have spread to adjoining counties and at present are as numerous in Limerick as in Clare and Tipperary.

O’Higgin, O’Higgins – Despite the very English appearance of the surname Higgins, as it is usually anglicized, it is in fact a purely native Irish Gaelic name which should normally have been O’Higgins in English, the Irish form being Ó hUigín, pronounced O’Higgeen. The name, according to modern scholarship, is derived from the old Gaelic word uiging, akin to the Norse Viking, not from the word uige.

O’Hogan – The Hogans are a Dalcassian family, their eponymous ancestor being Ógan who was descended from an uncle of Brian Boru, the most celebrated of all the Kings of Ireland. The Dalcassian territory extended well beyond the boundaries of Co. Clare which was the heart of Thomond, their area.

O’Holohan, Holland, Holian, Mullholland, Hyland – O’Holohan – Ó hUallacháin in Irish – is the name of at least two septs originally located in Offaly and in Thomond. In the course of time they spread southwards in both cases, but in the census of 1659 the great majority of the name were living in Co. Kilkenny: at the present time it is chiefly found there with the spelling Holohan, and in the western part of Munster with the spelling Houlihan.

O’Horan, Haren – The true sept of O’Horan (Ó hOdráin in Irish) originated in Co. Galway whence they spread into Co. Mayo and are now fairly numerous in those Connacht counties. Another Gaelic surname, Ó hArracháin, which is a corruption of Ó Hannradhain (anglice Hanrahan) is commonly anglicized Horan, though in Thomond (Co. Clare), where this minor Dalcassian sept originated, it is usually pronounced and sometimes written, more phonetically Harhan.

O’Houneen, MacGlashan, Greene – Although Green is one of the most common indigenous surnames in England and no doubt many of our Irish Greenes are of English extraction, nevertheless the majority of those who hail from Connacht and west Munster are native Irish in origin. There the name is almost always spelled with a final E.

MacHugh – The Gaelic surname MacAodha, signifying the son of Aodh, i.e. Hugh, has acquired in the process of anglicization a great number of variants. These include MacKay, MacKee, MacCoy, Huges, Hewson, Eason, etc., and also MacHugh. MacHugh is the form used by the Connacht sept which is one of the same stock as the O’Flahertys: they were chiefs of the territory known as the barony of Clare in Co. Galway.

O’Hurley, O’Murhila, Murrily, O’Herlihy – The well known surname Hurley is used as the anglicized form of two distinct Gaelic patronymics. The Thomond sept of Ó hUirthile descends from one Uirthile or Urley (an obsolete Christian name) who was of the race of Blod, son of Cas, the progenitor of the Dalcassians. O’Hurley was one of the principal chiefs of Thomond in 1309, but after that they’ve have mainly been found in Co. Limerick, in the Kilmallock area, and in north Tipperary where there is a place-name Rathurley in the parish of Kilraune.

McInerney, Nerney, Kinnerk – In Irish this name is Mac an Airchinnigh, meaning son of Erenagh. The word erenagh deontes steward of church lands, originally an ecclesiastical office but later in the hands of laymen and hereditary. As might be expected, therefore, the surname in question came into existence in a number of unrelated families in different parts of the country. The Erenaghs of St. Patricks, Elphin, and of Tuam thus acquired the surname Mac an Airchinnigh.



Jennings – The name Jennings is the modern anglicized form of Mac Sheoinín, pronounced MacKeoneen, and written MacIonyn, MacJonine etc. in the records up to the middle of the seventeenth century. It is not, however, of true Gaelic origin being a surname adopted by a branch of the Burkes of Connacht, descended from Seoinín or Little John Burke. Jennings, of course, is itself a common indigenous English surname and some people in Ireland may well be of English origin, but it is safe to say that in Connacht, where the name is chiefly found today, they are of the Burke stock.

Jordan – Though Jordan is quite a common English name very few of Irish Jordans are of English descent. Mac Siurtáin was a surname of the Gaelic type adopted by one of the hibernicized Norman families which acquired extensive territory in Connacht after the invasion of 1172. It signifies descendants of Jordan, i.e. Jordan d’Exeter, and this sept in due course became associated with the phrase “wild Irish.”

Joyce – Though not Gaelic and sometimes found in England of non-Irish origin, Joyce may certainly be regarded as a true Irish name, and more particularly a Connacht one. The first Joyce to come to Ireland of whom there is authentic record was Thomas de Jorse or Joyce, stated by Macfirbis to be a Welshman, who in 1283 married the daughter of O’Briend, Prince of Thomond and went with her by sea to Co. Galway.



Kavanagh, Keevan – Kavanagh is one of the very few ancient Gaelic Irish surnames which has neither the prefix Mac or O: it is wrong to call it Ó Caomhánach in Irish. In Irish it is simply Caomhánach which is an adjective denoting association with Caomhán, in this case St. Caomhán, the first Kavanagh having been fostered by a successor of this saint. First found in Co. Carlow.

Keane, O’Kane, O’Cahan, MacCloskey, MacEvenney – There were two great septs of Ó Catháin. The earlier anglicized form of this name was O’Cahan, and even as late as the beginning of the present century, O’Cahans were still found in Co. Derry, but in modern times the forms Keane, Kane, and sometimes O’Kane, are almost universally used, Keane in Munster and Connacht, and Kane in Ulster.

O’Kearney, Carney – The name Kearney is evenly distributed throughout the four provinces of Ireland; the alternative spelling Carney, however, is almost confined to Connacht, particularly Co. Mayo. The latter are Ó Cearnaigh in Irish (presumably from cearnach, victorious) and are a branch of the Ui Fiachrach whose territory was name Moynulla and Balla in Co. Mayo. The Dalcassian O’Kearneys, who migrated to Cashel in early times, are also Ó Cearnaigh.

Keating, Keaty – Though it is still found indigenous in England, Keating is a name which may be regarded as hibernicized. The Keatings of Norman origin themselves first came to Ireland with the Anglo-Norman invaders at the end of the twelfth century, when they settled in Co. Wexford, with which they are most prominently associated.

O’Keeffe – The O’Keeffes not only originated in Co. Cork, but they also stayed there. It is still and out-and-out Co. Cork name, judging by birth registrations, voter lists, directories and the like. It is true that, like so many powerful native Irish septs, they were forced out of their original territory by the invading Normans, but in their case it was only a trek westwards within the bounds of what is now Co. Cork. It derives from the Gaelic word ‘caomh,’ which means ‘gentle.’

O’Keenan – The sept of O’Keenan – Ó Cianáin in Irish – is chiefly remarkable for the number of distinguished ecclesiastics and historians it produced in the middle ages. Between 1345 and 1508 no less than eight are mentioned by the Four Masters as historians to the Maguires of Fermanagh. The most famous of these was Adam Ó Cianáin, Canon of Lisgool, while one Rory O’Keenan was chief scribe of the “Book of Magauran.”

O’Kelleher – The Kellehers are a Dalcassian family, in Irish Ó Céileachair, i.e. descendent of Céileachar or Kelleher, who was a nephew of the famous Brian Boru. They left their original dwelling in Co. Clare in the fourteenth century and migrated to Co. Cork. The name is now seldom found outside of this part of Munster: of 148 births recorded in one year for the name, 92 were in Co. Cork and 23 in Co. Kerry.

O’Kelly, Queally, O’Keily – There are approximately 50,000 Kellys and O’Kellys in Ireland today. It is the second most common Irish surname, not far behind Murphy in numerical strength. This name presents a remarkable example of the extent to which the prefixes O and Mac, so widely dropped during the period of Gaelic submergence, have been resumed. The personal name may derive from the Gaelic word ‘ceallagh,’ which means ‘strife.’

MacKenna – MacKenna is one of the few names from which the old Gaelic prefixes of Mac and O were not generally dropped in the dark period of the eighteenth and nineteenth centuries. Though almost always written MacKenna, in the spoken language, Kenna is quite common and in some places, notably Clare and Kerry, the emphasis is on the final A, with the results that births have been from time to time registered under many synonyms.

O’Kennedy, Minnagh – The eponymous ancestor of the O’Kennedys was Kennedy, nephew of Brian Boru, or Cinnéide in Irish, the resultant surname being Ó Cinnéide (Brian Boru’s father was Cinnéide). They are thus a Dalcassian sept, and at first their territory was around Glenomra near Killaloe, and their occupation is perpetuated by the name of the civil parish comprising that area, viz. Killokennedy, but pressure from the powerful O’Briens and MacNamaras caused them to cross the Shannon and settle in Upper and Lower Ormond.

O’Kenny – The name Kenny is common in Ireland: it has seventy-sixth place in the list of commonest surnames. The majority of the people so called belong to families located in Counties Galway and Roscommon. This is the homeland in early times, as well as today, of the O’Kenny sept which in Irish is Ó Cionnaotih: it is of the Uí Máine (Hy Many) and the same stock as the O’Maddens.

MacKeogh, Kehoe, O’Hoey, Hoy, Haughey, Haugh, Hough – Keogh, including Kehoe and MacKeogh, almost equally common forms of the same Irish surname Mac Eochaidh – just misses a place in the hundred most common names in Ireland. It is chiefly found in the province of Leinster, the spelling Kehoe being usual in Co. Wexford. It derives from common personal name “Eachaidh,” meaning horseman.

MacKeon, MacKewon, Owens, Hone – Though it originated in Co. Sligo the sept of MacKeon may be regarded as belonging to the adjacent county of Leitrim, as it is there they are found both in medieval and modern times. The name, in Irish Mac Eoghain, simply means son of John or Owen (in the Tuam area it is sometimes anglicized as Johnson). This sept had an important branch in Co. Galway: the sixteenth century “Composition Book of Connacht” refers to lands in the barony of Kiltartan then called Termon Brian MacOwen.

O’Kieran, O’Kerin, Kearns, Kerrane – The sept known in Irish as Ó Céirín was in early times in possession of the greater part of the present barony of Costello, Co. Mayo, of which their chiefs were paramount. During the medieval period they gradually became reduced in importance, though they remained in their native habitat in a more or less subordinate position and also spread into the neighbouring counties.

O’Kinneally, Quinelly – The original Gaelic form of this name is Ó Cinnfhaelidhl – there are several anglicized forms of it – Kinneally, Kennelly, etc. Kennelly is also used as a synonym for Quinnelly, a west Cork surname, so that confusion may arise in this case. The name now under consideration is that of a sept living in the territory known today as the barony of Connello in Co. Limerick.

Kinsella – This is one of the few genuine native Gaelic surnames without the prefix Mac or O. It is true that the form O’Kinsellagh is sometimes found in old documents, and a few present-day Kinsellas have “resumed” an O, but to do so is incorrect, as Kinsella, or Cinnsealach in Irish, is, like Kavanagh, an agnomen which has supplanted the original name. Kinsellas and Kavanaghs descend from Dermot MacMurrough, ill-famed King of Leinster from 1134-1171.

O’Kirwan – The Kirwans – the O is never used with this name nowadays – are best known as one of the “Tribes of Galway.” They are second only to the Lynches as a leading family of the county. Like the Darcys and unlike the other twelve “tribes,” they are of Gaelic origin. They are first recorded in history as erenaghs in Co. Louth, and were not connected with Galway until the fifteenth century.



Lacy, de Lacy – The De Lacys of Ireland, more commonly now called Lacy or Lacey, came to the country at the time of the Anglo-Norman invasion, having gone to England from Lascy in Normandy in the previous century with William the Conqueror. In the Annals the name is written de Léis in Irish.

Lally, O’Mulally – The name Lally is a contraction of O’Mullally, which was formerly the normal form in English of the Gaelic Ó Maolalaidh. This sept, a branch of the Uí Máine of the same stock as the O’Naghtens, was of some importance in Connacht, where, after the coming of the Anglo-Normans, they were at constant feud with the deBurgos or Burkes. Through this, and other causes, they were obliged to move northwards, but only a short distance, as they remained in the area subsequently formed into Co. Galway.

O’Lalor, Lawlor – This name in modern times is spelled in three ways – Lawlor, Lalor, and Lawler. The first of these being slightly more common than the others. In Irish it is Ó Leathlaobhair, which would appear to denote descendant of the half leper, no doubt a nickname arising from physical defect and not to be taken literally. The prefix O, it may be noted, which was discarded during the period of Gaelic submergence, has not been resumed in modern times.

O’Leary – O’Leary is an always has been essentially a Co. Cork surname. Like many Gaelic septs they were driven from their original dwelling at the time of the Anglo-Norman invasion at the end of the twelfth century, but they did not migrate far – only from Corca county, a remote territory with the lofty Kerry mountains in sight to the west of them. Here they long ruled as chiefs under the Muskerry MacCarthys.

O’Lee, MacAlee – Lee is a fairly widespread name in Ireland, but as it is also a very common indigenous surname in England it is impossible to say in the absence of a pedigree, or at least a well-established tradition, whether a family of the name in Ireland is Gaelic in origin or of planter stock. The latter were well established in Co. Tipperary and elsewhere at the beginning of the seventeenth century.

O’Lenaghan, Linehan – A Roscommon family of this name, in Irish Ó Léanacháin, appears in early records, the most notable of whom was Maelciaran O’Lenechan of Tuamna, in Boyle barony, a priest very highly praised in the “Annals of Loch C” and by the Four Masters for his many good qualities: he died in 1249. Little is heard of them in modern times.

O’Lennon, Linnane, Leonard, Linnegar, MacAlinion – The normal form of Lennon in Irish is Ó Leannáin, or Ó Lionnáin, but confusion arises because these Gaelic names have been anglicized Leonard and Linnane, while the Irish surnames Ó Lonináin (Lenane) and even Ó Luinín (Lineen) are also sometimes Lennon or Leonard in English. Of these Lennane, or Linane, belongs to the Corca Laoidhe group and was situated near Glandore Harbour.

O’Lonergan – In pre-Norman times the O’Lonergans inhabited northeast Thomond, i.e. the part of Tipperary which lies on the east side of Lough Derg, but the pressure exerted by the Anglo-Norman Butlers forced them southwards to the country around Cashel and Cahir, where they have remained in considerable numbers up to the present day. The name, in Irish Ó Longargain, is usually anglicized Lonergan, without the prefix O, but sometimes takes the form Londrigan.

O’Lorcan, Larking – The prefix O has been entirely dropped from this old and distinguished Gaelic surname. It was born by a number of distinct and unrelated septs. The most important of these was Ó Lorcáin of Leinster, of royal blood in that province but dispossessed of their patrimony in the barony of Forth by the Anglo-Norman invaders.

O’Loughlin, Loughnane – The sept of O’Loughlin is entirely distinct from those of MacLoughlin, though some confusion arises outside of Munster due to the dropping of the prefixes Mac and O in the eighteenth and nineteenth centuries. It should also be remembered that the MacLoughlins of Cineal Eoghan or Kinel Owen, in the days when they were a royal family, were first called O’Loughlin, but about the year 1200 they became MacLoughlin.

MacLoughlin – The surname MacLoughlin, also spelled MacLaughlin, is used in modern Ireland as the anglicized form of that of two entirely distinct Gaelic septs, both of considerable importance. One indeed which was of royal status, is not a Mac name at all but an O name, being Ó Maoilsheachlainn in Irish, and up to the end of the seventeenth century always anglicized O’Melaghlin (with some slight variants).

O’Lowry, Lavery – The Irish surname Ó Labhradha is rendered in English as either Lowry or Lavery, both these forms found in almost equal numbers in northeast Ulster where the sept originated. Their territory in medieval times was in the neighborhood of Moira, Co. Down. Branches of the sept were called Baun-Lavery, Roe-Lavery and Trin-Lavery, these epithets being the Gaelic adjectives bán (white, rua (red) and tréan (strong)).

Lynch – It must be emphasized at once that the name Lynch, which is among the hundred most common surnames in Ireland, is of dual origin. Lynch is used as the anglicized form of the native Gaelic names Ó Loingsigh, and also of the Norman de Lench. First found in Galway.

O’Lyne, Lyons, Lehane, Lane – The four surnames given above are the anglicized forms of two distinct Gaelic surnames. Lehane is particular to Co. Cork, while Lyne today is found chiefly in Co. Kerry, though formerly well known in Co. Galway where Lyons has superseded it. Lyons is the most common.



O’Madden, MacAvaddy, Madigan – Madden is one of the Gaelic Irish surnames from which the prefix O was dropped during the centuries of Gaelic eclipse, but which did not share in the widespread resumption of Os and Macs since the Gaelic revival. In Irish it is Ó Madáin, the earlier form being Ó Madadháin. This sept was a branch of the Ui Máine (Hy Many) living in this part of Co. Galway which lies beside the Shannon, extending over that river into Offaly.

MacMahon, Mohan, Vaughan – MacMahon is one of the best known and most distinguished names in Ireland. In Irish Mac Mathghamha, or in ultra-modern spelling MacMahúna, it is said to be derived from the Irish word for a bear (mathghamhan). It is borne by two quite distinct septs. One of these belongs to Co. Clare, in which county it is now the most common name.

O’Mahony – There are a great many O’Mahonys in Ireland – the name is included, usually without the prefix O, in the hundred most common surnames. It belongs almost exclusively to West Munster, the great majority of Mahony and O’Mahony births being registered in Co. Cork, particularly in the area associated historically with the O’Mahony sept.

O’Malley – O’Malley may be referred to as the Irish of the Irish. It is one of the few O names from which the prefix was never widely dropped. It is not especially common, but it is very well known. It belonged exclusively in the past to Co. Mayo, and this is almost equally true of the present day: over 80 percent of the births recorded are in Connacht and most of these are in Co. Mayo.

O’Malone – Although Malone is a genuine O name, being in Irish Ó Maoileoin (meaning descendant of the follower of St. John), it is never met with in English with its prefix. The Malones are an ancient sept, associated with the O’Connors of Connacht, and for centuries their principal family was associated with the Abbey of Clonmacnois, to which they furnished many abbots and bishops. For a time Clonmacnois was an independent see before being united with Ardagh.

O’Mangan, Mongan – The normal form of Mangan in Irish is Ó Mangáin, which is more phonetically anglicized as Mongan in parts of Connacht. But even in Mayo, the original homeland of one of the septs, it is usually Mangan nowadays. The Munster Mangans, originally from co. Cork, are now found more frequently in Co. Limerick.

Mannion, O’Mannin, Manning – The sept of Ó Mainnín was located in the barony of Tiaquin, Co. Galway, their chief’s residence being the castle of Clogher. They were an important sept in the Hy-Many country but were not of that group by descent, as their ancestors were the ancient pre-Gaelic Pictish rulers of that area. Their territory was much reduced by the O’Kellys, and their estates were largely lost in the seventeenth century confiscations, but the Mannions remained in their homeland where they are common today.

Mannix, O’Manahan, MacNeice – Mannix is the usual form in English of the Gaelic surname Ó Mainichín (derived from manach – a monk), a minor sept of Corca Laoidhe in the southwest of Co. Cork: it is placed in the “Book of Lecan” and other medieval manuscripts in the O’Hennessy territory at the head of Rossy Bay. The name was never numerous and is now scarce, rarely found outside the counties of southwest Munster.

MacManus – This name is often stated to be Norse in origin, but in fact it is as thoroughly Irish as any ancient Gaelic name. MacManus is Mac Maghnuis in modern Irish, meaning the son of Magnus. Magnus (Latin: great) as a Christian name came to Ireland from northern Europe, but its combination with Mac as a surname originated in Ireland.

Martin, MacGilmartin, Kilmartin – Martin is among the fifty most numerous surnames in Ireland; in fact, it is in thirty-eighth place. The 13,000 persons of the name in Ireland are widely distributed over the country, being found most frequently in East Ulster and, of course, Dublin which, being the metropolis, contains families from all provinces. Martis is also a common name in Great Britain.

O’Meagher, Maher – Maher, also written Meagher (Ó Meachair in Irish) is derived from the word meachar, meaning hospitable. Maher is a word of two syllables, not pronounced Marr. Of the same stock as the O’Carrolls of Ely it belongs to the barony of Ikerrin in Co. Tipperary. In fact 50 percent of the 8,000 people of the name come from Co. Tipperary.

O’Meara, O’Mara – In Irish this name is Ó Meadhra and both the spellings given above are used as the ordinary anglicized form, O’Meara being slightly more numerous than O’Mara. It is of interest to note that while 60 years ago the records show that less than one third of the people of the name used the prefix O, today it is very rare in Ireland to find plain Mara or Meara without it.

O’Meehan, Meighan – O’Meehan (in Irish Ó Miadhacháin) is the name of a sept belonging to Co. Leitrim. This sept (also called Meighan) is of the same stock as the MacCarthys of south Munster, but by the end of the eleventh century they had migrated and established themselves in their new country. Their association therewith being perpetuated by the place name Ballaghmeehin, or Ballymeighan, in the parish of Rossinver, Co. Leitrim.

O’Molloy, Miley, Millea, Slowey – The O’Molloys, now always simply Molloy or occasionally Mulloy, are of very distinguished origin. They are of the southern Ui Neill, traditionally descended from the famous Niall of the Nine Hostages, King of Ireland A.D. 371. The head of this important sept was O’Molloy chief or lord of Fércal, a district covering several baronies of the county of Offaly (alias King’s County).

O’Molony, Maloghney – Molony or Moloney is Ó Maoldhomhnaigh in Irish, which denotes descendant of a servant of the church. It is seldom if ever found today with the original prefix O, though it is 100 percent Gaelic with no similar name to be found in England. Molony is a Dalcassian sept belonging to Kiltanon near Tulla in East Clare, where they are very numerous today, although it is also found in equal numbers in the adjoining counties of Limerick and Tipperary.

O’Monahan, Monkes – The name Monohan or Monaghan (the latter is the more usual spelling in Ireland) is chiefly found in the counties of Galway, Mayo and Fermanagh, all of which are not far from the original dwelling of the O’Monaghans, viz. the part of the Co. Roscommon which lies between Elphin and Jamestown. The Four Master record O Monaghan (Ó Manacháin in Irish) as Lord of the Three Tuathas of Roscommon in 1287, about the time they were displaced from lordship by the O’Hanlys.

O’Mooney, Meeny, Mainey – This name, Ó Maonaigh in modern Irish, is derived from the Old Irish word ‘moenach’ meaning ‘dumb,’ or ‘maonach,’ meaning ‘wealthy.’ It is a surname adopted by several unrelated septs. The eponymous ancestor of the O’Mooneys of Ulster was Monach, son of Ailioll Mór. First commonly found in Offaly.

O’Moran, Morrin – Though common enough to be included among the 60 most common names in Ireland and now to be found in every county, Moran is essentially a Connacht name and the majority of the population belong to the Connacht counties of Mayo, Galway, Roscommon and Leitrim. This might be expected, because the two quite distinct septs Ó Móráin and Ó Móghráin, now both anglicized Moran, held their territory in that province.

O’More, Moore – Moore is a very common name in Ireland: with some 16,500 of the population it holds twentieth place in the list of most common names. The great majority of these (apart from the metropolitan area) are in Munster and Ulster. It is practically impossible to say what proportion of these are of Gaelic Irish origin and what proportion of English extraction, for Moore is also indigenous in England and very common there.

O’Moriarty, Murtagh – Moriarty is Ó Muircheartaigh in Irish, but nowadays the prefix is never attached to this name, though the form O’Moriarty (and indeed occasionally MacMoriarty) is found in old records. The sept, which is of the same stock as the O’Donoghues and the O’Mahonys, has always been associated with Co. Kerry. Their original territory lay on both sides of Castlemaine Harbour, but after the Anglo-Norman invasion their influence was reduced by the rise of the Fitzgeralds, despite an early alliance by marriage. O’Moriarty, Chief of the Name, married the daughter of a leading Fitzgerald around the year 1210.

O’Moroney, Mulrooney – The Irish surname Ó Maolruanaidh (descendant or follower of Ruanaidh or Rooney) was that of several septs in mediaeval times. That of Fermanagh, where they were powerful before the rise of the MacGuires, survives today in small numbers under the name of Mulrooney. West of the Shannon the name has become Moroney.

Morris, Fitzmaurice, Morrison – though the name Morris is essentially English, it has been used, as well as Morrison, as an anglicized form of Ó Muirgheasa, a sept of the Ui Fiachrach (Co. Sligo), where the regular form Morrissey is now rarely met with. Ó Muirghis is an abbreviation of this. Morris is also used as an abbreviation of Fitzmaurice (in Irish Mac Muiris), the Fitzmaurices being celebrated as a branch of the Geraldines and lords of Lixnaw in Kerry.

Morrissey – As in the case of Morris, the bearer of the name Morrissey anxious about his forebears, is faced with many problems, unless he has a reliable pedigree of, or at least a well recognized tradition, about his own family. The only native Gaelic Irish sept whose name has been anglicized as Morrissey is Ó Muirgheasa, a branch of the Ui Fiachra: their territory was at the southern side of Sligo Bay.

Moynihan – Although there was a small sept of this name, sometimes changed to Munster in Mayo, families so called belong almost exclusively to south-west Munster, Moynihan being very numerous on the borders of two counties. Minihan, another form of the name, is mainly found in Cork. Ó Muimhneacháin can translate into Munsterman.

O’Mulcahy, Muckley – This is Ó Maolchathaigh in Irish – cathach means warlike. The prefix O is seldom if ever used here nowadays. Mulcahy is a fairly common name in south Munster but not elsewhere. It is said to have originated in south Tipperary. The census of 1659 shows that it was common in Counties Waterford and south Tipperary, and also Limerick and Cork in the seventeenth century.

O’Mullan, O’Mellan, Mullen – The name Mullen originated from several very distinct sources. It can be an abbreviation of MacMullen, a Scottish surname borne by many of the seventeenth century settlers in Ulster; it can be one of the anglicized forms of the Irish Ó Maoláin, which is possibly derived from the Gaelic word maol (bald). Other forms besides Mullen are Mullin and Mullan in Connacht, and Mullane and Mullins in Cork, Limerick and Clare.

O’Mulligan, Molohan, Mulqueen – The name Mulligan has in our day acquired a comic connotation on account of Jimmy O’Dea the Irish comedian’s inimitable sketches of “Mrs. Mulligan the Pride of the Coombe,” as well as the famous folk song. The sept of O’Mulligan (in Irish Ó Maolagáin), however, is of distinguished origin, its chiefs being lords of a territory called Tír MacCarthain. They were dispossessed in the Ulster Plantation of the early seventeenth century.

O’Mulvihil, Melville, Mitchell – O’Mulvihil is the anglicized form of Ó Maoil Mhicil, the eponymous ancestor being so called on account of his devotion to St. Michael. The sept was of some importance in medieval times, being of the same stock as the MacBrannans, and located with them on the west bank of the Shannon in the modern county of Roscommon; both were styled chiefs of Corca Sheachlainn, or Corcachlann.

O’Murphy, O’Morochoe – Murphy is the most common surname in Ireland: birth registration statistics indicate that of a population of 4 million, more than 55,000 are Murphys. The name, with which the prefix O is never used nowadays, may be either Ó Murchadha or Mac Murchadha in Irish. It arose independently in several parts of Ireland, but was first found in Wexford, Roscommon and Cork. In Gaelic, it means ‘sea battler, translating into Gaelic as MacMurchadh and O’Murchadh. The name was first anglicized to MacMurphy and then to Murphy in the early 19th century.

MacMurrough – The name Macmurrough is one of the most illustrious in Ireland. It is, of course, best known as that of the royal house of Leinster – not too happily in the case of Dermot MacMurrough (1110-1171), King of Leinster, the abductor of Dervorgilla, the wife of O’Rourke, Prince of Breffny. It was MacMurrough who sought help from Henry II and thus was the immediate cause of the Anglo-Norman invasion.

O’Murry, MacMurry, Murray, MacMorrow, Gilmore – A considerable proportion of the Murrays now living in Ireland are of Scottish extraction, particularly in Ulster, where they are more numerous than in the other provinces. The old Irish surname Ó Muireadhaigh, formerly anglicized O’Murry, is now almost always Murray.



O’Naghten, MacNaughton, MacCracken – There are a great many synonyms for O’Maghten (Ó Neachtain in Irish) in modern Ireland, including Naughtan, Naughton, Nochtin, Nocton, Knockton and even sometimes Connaughton (which is actually a different surname); while very strangely, some families of Naughton in Kerry have become Behane. The English name Norton is also used; the Nortons of Athlone, for example, are descended from feradach O’Naghten.

Nagle, Nangle – Nagle, or Neagle, is the form used by the Cork branch of the de Angulos who are called Nangle in North Connacht where, after the invasion at the end of the twelfth century, that famous Norman family became possessed of vast estates. The leading de Angulos adopted the surname MacCostello.

MacNally, Macanally – The usual form of this name in Irish is Mac an Fhailghigh, the derivation of which is obscure (in modern Irish failgheach means a poor man). These words are pronounced approximately MacAnally and this is quite a common alternative form of the name in English. In Connacht, where the name is found in Mayo and Roscommon, the prefix Mac is usually dropped, the simple form Nally being in use.

MacNamara – In Co. Clare, the homeland of the MacNamaras, the name is very common. In fact in everyday speech it is usually abbreviated to simple Mac: this is interesting because another Mac name, MacMahon, comes first in the numerical list of Co. Clare names, considerably ahead of MacNamara, which has second place, yet the abbreviation is never applied to MacMahon.

O’Neill – One of the proudest Irish names. Means descended from Niall, one of the great early Irish chieftains, Niall of the Nine Hostages. Niall can mean passionate or champion. Hugh O’Neill was one of the great irish chieftains. Eugene O’Neill was America’s greatest dramatist.

O’Neilan, Neylan, Nyland – This name is seldom found with the O nowadays. It is usually spelled Neilan in Connacht and Neylan in Co. Clare – the O’Neilans being the original owners of Ballyally Castle. It originated in Thomond (Co. Clare): three of the names are listed as persons of importance in Co. Clare in the “Composition Book of Connacht” in 1585, though they are not described as chiefs.

O’Nolan – Nolan, seldom found nowadays with its prefix O, is the name of a sept of great antiquity which has always been associated with that part of Ireland which lies around the barony of Forth in Co. Carlow (not to be confused with the better known Forth in Co. Wexford). In pre-Norman days their chiefs, who held high hereditary office under the Kings of Leinster, were known as Princes of Foharta (modern Forth).

Nugent, Gilsenan – Though not an indigenous Irish surname, Nugent may be regarded as completely Irish today, since the Nugents have been important people in Ireland since the twelfth century when they came at the time of the Anglo-Norman invasion, their home country being France. They were then called de Nogent, i.e. of a place called Nogent in France, where they can trace their descent back to A.D. 930.

MacNulty – the derivation of many Irish surnames is open to doubt, but there is none about that of Macnulty: in Irish it is Mac an Ultaigh, i.e. son of the Ulsterman. An older anglicized form of the name, now rare, is MacAnulty. the MacNultys belong today, as they have done since the inception of surnames, to Donegal, which claims to be the most Irish part of Ireland.

O’Nunan, Noonan, Neenan – The name Noonan, which is also, but less frequently, spelled Nunan (the prefix O has not been resumed), belongs almost exclusively to the province of Munster and particularly to Co. Cork, where it originated. In modern Irish it is Ó Nuanáin: this is a corrupt or contracted form of the older Ó h-Ion-mhaineáin, of which the anglicized form of O’Hinunane, now obsolete, is approximately a phonetic rendering.



O’Phelan, Whelan – The name Whelan must be dealt with in conjunction with Phelan, as they are anglicized variants of the same Gaelic surname, viz. Ó Failáin, which itself has variant forms such as Ó Faoiláin and Ó hAoláin. Whelan is more common than Phelan: it stands seventy-ninth in the list of the hundred commonest names in Ireland. With Phelan added, the name takes forty-fourth place, with an estimated population of about twelve thousand persons. O’Phelan comes from the word faol, which means wolf.

Plunkett – The name Plunkett or Plunket is of French origin, not danish as often stated: it is a corruption of blanchet, derived from blanc, white. Though not an indigenous Gaelic surname it is one of those introduced into Ireland at the time of the Anglo-Norman invasion which has become exclusively Irish, for Plunkett is not found elsewhere except in the case of exiles of Irish stock.

Power – Though not Gaelic in origin, Power is one of the class of hibernicized names (like Burke and Walsh) which may be regarded as one hundred percent Irish. The name is now one of the most common in Ireland – it is estimated that there about eleven thousand Powers in the country today. The name came with the Normans in Strongbow’s twelfth century invasion. It comes from a nickname of ‘poor man’ or ‘pauper.’

Prendergast, Pender – Maurice de Prendergast, whose name was taken from a village in Pembrokeshire, came to Ireland with Strongbow and was one of the leading Anglo-Norman invaders who obtained extensive grants of land in various parts of the south and west of the country. His descendants were seated near Waterford and in south Mayo, districts in which the name has always subsequently been found.

Purcell – Purcell is usually regarded as an Irish name, though the most famous man so called, composer Henry Purcell, was an Englishman. Both English and Irish Purcells are of Norman descent, the latter being found mostly in the contiguous counties of Kilkenny and Tipperary. The picturesque ruined castle of Loughmoe, the seat of the head of the family, is a well-known landmark near Thurles, to be seen from a main line railway between Dublin and Cork.



MacQuaid – The origin of the name MacQuaid, of which Mac Uaid is the form used in Irish, is obscure. It has long been well known in Co. Monaghan which is its principal location today. As MacQuaid, Mac Quade and MacQuoad it appears frequently in the Hearth Money Rolls for Co. Monaghan and for Co. Armagh (1664-1667). In Irish it is MacUaid (son of Wat). It has been borne by two notable churchmen – Bernard John MacQuaid (1823-1909), first bishop of Rochester, USA, whose parents, Irish emigrants, were murdered; and Most Rev. John Charles MacQuaid.

MacQuillan – Though MacQuillan is not a name of Gaelic origin it came into existence in Ireland and is not found elsewhere except among emigrants from Ireland. The MacQuillans are of Norman-Welsh descent: they settled soon after the invasion in the territory called the Route (Co. Antrim), and were known as Lords of the Route with their chief residence at the Castle of Dunluce until their major defeat at the battle of Ora in 1563 and again in 1580 by Sorley Boy MacDonnell, when they were dispersed by the Macdonnells.

MacQuilly, Cox – Although Cox is a common English name the great majority of our Irish Coxes are of native Irish stock, Cox (Cocks) being derived by translation the Gaelic Mac an Choiligh (son of the cock or rooster), the alternative form in English being the phonetic MacQuilly. This sept is still more common in the county of its origin, which is Roscommon. They were coarbs of St. Barry at Kilbarry in that country.

O’Quinlan, Quinlevan, Kindellan – Quinlan is the Munster form of the Gaelic Ó Caoindealbháin which, in Leinster, where the sept originated, was usually anglicized as Kindellan, and in modern times as Conlan and Connellan. They were of distinguished origin, being of the southern Ui Neill, and the senior line of the descendants of Laoghaire, King of Ireland in St. Patrick’s Day. The sept, originally located in north Meath, was much reduced by the Anglo-Norman invasion, but they remained there until the defeat of James II.

O’Quinn – Quinn is one of the most numerous Irish surnames, the number of people in Ireland so called at the present day being estimated at seventeen thousand: in the list of commonest surnames it occupies twentieth place in the country as a whole and first place in Co. Tyrone, though widespread in many counties. Tyrone is the place of origin of one of the five distinct septs of this name. The Gaelic form is O Cuinn, which means descendant of Conn.



O’Rafferty, Roarty, Raferty – Originally belonging to the adjacent counties of Donegal and Sligo, the O’Raffertys are now found in many parts of Ireland, though nowhere in large numbers. They are still associated with Co. Donegal where they were coarbs of St. Columcille in Tory Island. The name derives from Gaelic ‘rath bheartach,’ meaning ‘propserity wielder.’

MacRannall, Reynolds, Grannell – In Reynolds we have an example of a fine old Gaelic Irish surname which has been given as its usual anglicized form a common English one. In Irish it is Mac Raghnaill, Raghnall being the Gaelic equivalent of Randal or Reginald. The forms MacRannall and Grannell, also used in English, are of course, nearer to the original.

Redmond – Redmond is a name of Norman origin: the first in Ireland was Alexander Raymond, who was of the same stock as Raymond le Gros, one of the best known of the Anglo-Norman invaders. The name soon became Redmond. The family obtained considerable grants of land in Co. Wexford, and throughout the 780 years since they settled in Ireland they have always been associated with Wexford and prominent in its affairs.

O’Regan – Regan is listed among the hundred most numerous Irish surnames: it holds sixty-eighth place with a total estimated population of nine thousand two hundred and fifty persons at the present time. Fifty years ago few bearers of the name made use of their prefix O, but it has been resumed by many families, and the voter lists and directories now indicate that nearly forty percent are listed as O’Regan.

O’Reilly (O’Rahilly) – O’Reilly, in Irish Ó Raghailligh (descendant of Raghallach) was until recently much more commonly found without the prefix O. Reilly and O’Reilly constitute one of the most common names in Ireland, being among the first dozen in the list. The bulk of these come from Cavan and adjoining counties, the area to which they belong by origin, for they were for centuries the most powerful sept in Breffny, their head being chief of Breffny -O’Reilly and for a long time in the middle ages his influence extended well into Meath and Westmeath.

O’Rourke, O’Rorke, McRoric (also Drouke, Groarke, Roarke) – The name, which translates to “The descendant of Ruairc,” is an old and established one. Ruairc was a Norse-Viking personal name dating to before the year 800. The Ruairc family held large estates in Breffny, now Cavan and West Leitrim. A strong military clan that sent many of its leaders abroad.

Rice, O’Mulcreevy – The name Rice in Ireland is of two very different origins. The Rices of Oriel, now found chiefly in Louth and Armagh – counties comprised in that area – are Gaelic, and are called Ó Maolcraoibhe in Irish. The anglicizing of this surname as Rice is curious: the word craobh from which the name is derived means a branch. In Co. Down in O’Donovan’s time families of the name were known both as Mulcreevy and Rice, not as expected.

O’Riordan, Rearden – The sept of O’Riordan originated in Co. Tipperary, but they migrated to Co. Cork at such an early date that they can be regarded as belonging to that county, where they are now far more numerous than anywhere else. The vital statistics are indeed quite remarkable in this respect: of 170 births recorded for a given year, 100 were in Co. Cork and 54 in the counties (Kerry and Limerick) adjoining their territory in northwest Cork, where they were “followers of the Lords of Muskerry.”

Roche, Rochfort – Although Roche is not an indigenous Gaelic Irish surname it can nevertheless be regarded as exclusively Irish today, being found in England only in Irish, and more rarely French, emigrant families. It is French in origin – de la roche (of the rock) – and came to Ireland at the time of the Anglo-Norman invasion in the twelfth century.

O’Rooney – In modern Ireland this name is seldom if ever found with the prefix O to which it is entitled, since it is Ó Ruanaidh in Irish. The O’Rooneys were a sept of Dromore (Co. Down) and today they are principally to be found in Ulster and the neighbouring county of Leitrim. Several notable ecclesiastics of the name appear in the history of the diocese of Dromore.

MacRory, Rogers, MacCrory – In the sixteenth and seventeenth centuries, as evidenced by the Tudor Fiants, by the census of 1659 and other records, the name MacRory was both numerous and ubiquitous; now it is rare. This is no doubt partly due to the fact that in the southern half of the country it has been turned into the common English name Rodgers or Rogers. MacRory was first found in Tyrone, where the family held an ancient seat from the middle ages.

Ryan, O’Mulrian – Ryan is amongst the ten most common surnames in Ireland with an estimated population of 27,500. Only a very small proportion of these use the prefix O. Subject to one exception, to be noticed later in this section, it is safe to say that the great majority of the twenty-seven thousand five hundred Ryans are really O’Mulryans – this earlier form of the name is, however, now almost obsolete. First found in Tipperary.


Tipperary Ryan Nicknames



Sarsfield – This name is dear to all Irishmen on account of the picturesque career of one of our national heroes, Patrick Sarsfield (1650-1693). Highlights of the distinguished military career include the destruction of the Williamite siege train at Ballyneety, the defense of Limerick, and his death from wounds at Landen. The year before, he had been made a general in the French army. The name was first found in County Cork.

O’Scanlan, O’Scannell – There are at least two quite distinct septs whose descendants are now known as Scanlan. One is Ó Scannláin of Muster and the other Mac Scannláin of Oriel (Louth), neither of which has retained the prefix O or Mac in modern times. The latter are perpetuated in the place name Ballymascanlon near Dundalk.

O’Scully, Scullion – Though originally a Westmeath sept, as early as the twelfth century the Scullys were driven by Anglo-Norman pressure to co. Tipperary and may be regarded as belonging to Munster – birth statistics place them chiefly in Co. Cork today. A branch of the family retained its lands in Co. Dublin up to 1256 when the property of Willaim O’Scully passed into ecclesiastical possession.

O’Shannon, O Shanahan, Gilshenan, Giltenan – The Gaelic name of three distinct Irish families became anglicized as Shannon or O’Shannon. First there is Ó Seanáin (descendant of Senan, a personal name) of which we know little beyond the fact that it was associated with Counties Carlow and Wexford, where the name is now rare. Originally, Shannon was a nickname for someone ‘possessing great wisdom,’ or an elderly person.

MacShanly – The prefix Mac was dropped as early as the middle of the seventeenth century. Occasionally, since that time, O has been prefixed to it, but quite erroneously, as it is truly a Mac name: Mac Seanlaoich in Irish. In modern Irish seanlaoch means old hero. The sept is of Co. Leitrim, the chief being known as MacShanly of Dromod.

O’Shaughnessy – The O’Shaughnessys (in Irish Ó Seachnasaigh) were a sept of considerable importance in the part of Co. Galway known as the barony of Kiltartan, where people with this name are still concentrated. The original Gaelic name is O Seachnasaigh.

O’Shea – O’Shea is included in the list of fifty most common surnames in Ireland with an estimated number of nearly twelve thousand persons. If we include Shea, Shee, and O’Shee (variants of the same name) in the total. In Irish it is Ó Séaghdha, meaning descendant of Séaghdha: this word means hawk-like and dauntless. The O’Sheas are primarily a Kerry sept.

O’Sheehan, Sheahan – Sheehan is one of Ireland’s very common surnames: combining the alternative spelling Sheehan (eight percent) and Sheahan (twenty percent), it holds the seventy-fifth place in the list thereof, with an estimated total population in Ireland today of about eight thousand five hundred persons of the name. Of these the great majority were born in Co. Cork or on its borders. The Gaelic form is O Siodhachain, deriving from the word ‘siodhach’ which means peaceful.

MacSheehy – This name is now particular to Munster, though it is was not found there before 1420 when the first of the family came to Co. Limerick, when they took service with the Earl of Desmond and established themselves near the town of Rathkeale. They are first heard of in Ireland as gallowglasses, and as such they fought with distinction in many battles, having come to Ireland in the fourteenth century from Scotland (where they were a branch of the MacDonnell clan). It is derived from the word ‘sithigh’ which means ‘peace.’

O’Sheridan – The Sheridan family originated in Co. Longford, being Erenaghs of Granard, but later moved to the next county – Cavan – where they became devoted followers of the powerful O’Reillys. The name Ó Siirideáin in Irish, i.e. descendant of Siridean, a personal name.The Sheridans are now dispersed widely throughout every province, though less in Munster than elsewhere.

O’Shiel, Shields – By origin and by the test of present-day distribution of population, O’Shiel is an Ulster name. In Irish Ó Siadhail, it is usually anglicized as Shiels, Sheils, Shields or Sheilds rather than O’Shiel, and these forms are chiefly found in Counties Donegal, Derry, Antrim and Down. Though claiming descent from Niall of the Nine Hostages, the O’Shiels were known as a medical family, rather than as a territorial sept.

Skerrett – The Skerretts of Ballinduff, Co. Galway, and Finvarra, Co. Clare, have now died out in the make line – the last representative being Rev. Hyacinth Heffernan Skerrett, a priest. They were extensive landowners in both those counties eighty years ago. Some junior lines survive elsewhere, but the name is now rare.

O’Sullivan – In Irish O’Sullivan is Ó Súileabháin. The derivation of the name is in dispute among scholars. There is no doubt that the root word is súil (eye), but whether it is to be taken as one-eyed or hawk-eyed is left an open question. While not quite as numerous as Murphy and Kelly, Sullivan, which is by far the commonest surname in Munster, comes third in the list for all of Ireland.

MacSweeney – The statement that the MacSweenyes are of the same line as O’Neill is somewhat misleading because, though it is true that their eponymous ancestor was Suibhne O’Neill, this man was a chieftain in Argyle, and the MacSweenyes who later established themselves as three great septs in tirconnell (Donegal) did not do so until the fourteenth century. The name does derive from the Gaelic word “suibhne” which means pleasant. However there is no mention of them in the Annals before 1267, when both the Four Masters and the “Annals of Connacht” record the death of Murrough MacSweeney, who was grandson of Suibhne.



Taaffe – Taaffe was originally a Welsh name signifying David (the modern pet name Taffy). In Irish it is rendered Táth, pronounced Taa. Settling in Co. Louth soon after the Anglo-Norman invasion, the Taaffes, rapidly attained a position of considerable importance in the country and, though they never became numerous like so many of the Norman immigrants, they continued to be one of the most influential families in Ireland.

MacTiernan, MacKiernan – No less than thirty-three MacTiernans are mentioned in the “Annals of the Four Masters,” practically all of them Chiefs of Teallach Donnchadha (modern Tullyhunco, in the county of Cavan) or relatives. Though not much information is given about their exploits, the mere recording of so many obituaries indicates the importance of the sept throughout the three centuries from 1250 to 1550. The Gaelic form is “Tighearnain,” deriving from ‘tighearna’ which means ‘lord’

O’Tierney, Tiernan – The most important of the original O’Tierney septs was that of Co. Mayo, where their chiefs were lords of Carra. The name is now very scattered, found in every county of Munster and Connacht, while it is rare in Ulster, outside Donegal. In Mayo, Tierney and Tiernan have been used as synonyms and cases of this are also reported from Co. Clare. This name also derives from the Gaelic word for ‘lord.’

Tobin – Though Tobin is not an indigenous Gaelic Irish name, the family may be regarded as completely hibernicized. Originally of Aubyn in France, they were first called de St. Aubyn. They came to Ireland in the wake of the Norman invasion and by 1200 they were settled in Counties Tipperary and Kilkenny, whence they spread in course of time to the neighbouring counties of Waterford and Cork.

O’Toole, Toal – the O’Tooles are remarkable for their unremitting resistance to English attempts to conquer Ireland from the late twelfth century, when the Anglo-Norman invasion took place, down to the end of the seventeenth century, when the country was finally subdued. Nor is the name absent from the Roll of Honour in 1798. Their territory, though near Dublin, the seat of government, was admirably suited to resistance on account of its wooded and mountainous nature. Derived from ‘tuathal,’ meaning ‘people mighty.’

O’Tracy – It is easy to be misled with the surname Tracy, for it is borne by an ancient and noble English family (Barons Sudeley), who are descended from Saxon ancestry. Their surname, however is not Saxon, having been acquired from a female Norman line named after Traci, a place in France.  The Irish name is derived from the native Irish O’Treasaigh Septs. The name is taken from the Irish word “treasach” meaning “war-like” or “fighter”. It is also translated as “higher”, “more powerful” or “superior”. It may also be derived from the Irish word for three, with an association to the Tuatha Dé Danann.

Tracey Clan

MacTraynor – The Gaelic Ulster surname Mac Thréinfhir – son of the strong man, or champion – is anglicized Traynor, also spelled Treanor and Trainor, without the Mac, though the prefix is retained in the variant MacCrainor, which is phonetically more correct, since the T is aspirated in the Irish form of the name.

O’Trehy, Troy – Though not numerous in Ireland the name Troy is not uncommon in Co. Tipperary and surrounding areas. The location of this small sept (which originated in Co. Clare but did not remain there) was in the Clogheen district of Co. Tipperary: their association with that part of the country is perpetuated in the placename.

Tully, MacAtilla, Flood – This name is fairly common in Counties Galway and Cavan but is rare elsewhere (except in the city of Dublin where, of course, names from all parts of Ireland are found). It was formerly MacTully, and the form MacAtilla is used today in some places which suggests that the name in Irish was MacTuile or Mac a’tuile, meaning ‘son of the flood.’

O’Twomey – The name Twomey, usually without the prefix O, is now, as always, predominantly associated with Co. Cork. When found elsewhere it is often spelled Toomey. In the census of 1659 ’Twomy appears as the second most numerous surname in the barony of Barretts, Co. Cork, Murphy being then the most common there.



Wall – The name Wall is found in considerable numbers in the part of Munster that lies between Limerick and Waterford, and in the adjoining counties of Leinster. The name is common in England also. It is of Norman origin: its earliest form is duVal, i.e. of the valley, hence the form de Bhál in Irish.

Walsh, Brannagh – Only three surnames (Murphy, Kelly and Sullivan) exceed Walsh in numerical strength among the population of Ireland. It is found in every county and is particularly strong in Mayo, where it has first place, and also in Galway, Cork, Wexford, Waterford and Kilkenny.

MacWard, Ward – Although Ward is a very common English name, the great majority of Irish Wards are native Irish in origin, the Gaelic form being Mac and Bháird, which means son of the bard – the pronunciation of these words is closely reproduced in the alternative form in English, viz. Macanward, also written MacAward and McWard. The Wards, as their name implies, were professional and hereditary bards.

Whelan, Ó Faoláin – From faol, meaning wolf. A variant form of Phelan found in the country between Co. Tipperary and Co. Wexford. Whelan is also sometimes an abbreviation of Whelehan and occasionally a synonym of Hyland. Whelan is rare in Ulster.

Woulfe – The Woulfes, or Wolfes, are a family of Norman origin who first came to Ireland at the time of the invasion at the end of the twelfth century. In Irish the name is usually written de Bhulbh, but le would be more fitting than de since the Norman form is Le Woulf (the wolf).