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 overt 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.
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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 Kilmallock.
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.
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.
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.
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