Common Irish Surnames
Mc, Mac = son of
O = can signify either grandson, or earlier ancestor
Fitz, from French fils = son of
Ní, Nic = girl's use before her father's name
Ban = wife's use before her married name
The Counties and places listed are where the names are/were (most) prominent.
Ahearne — (AY-hern) only Irish name spelled with the first letter of the alphabet. Originally Ó hEachtighearna, meaning "lord of the horse". Also, Aheron, and changed in the 18th C. by emigrants to Canada, the USA, and Australia to Herne, Hearne. Heron.
Barrett — Báróid. Ancestors came with the Norman invasion circa 1169. Cork, Galway, Mayo.
Barry — from Wales with the Anglo-Norman invasion of 1170 and soon possessed a vast area of County Cork. To distinguish from all the different Barrys, they were known as Barry Mór (the Senior), Barry Óg (the Younger), Barry Roe (the Red), Barry Maol (the Bald), and Barry Liadir (the Strong). Barrymore probably derived from Barry Mór (the Senior). De Barra, Barrymore. Cork.
Beirne — Ó Beirne. With or without the Ó, is not to be confused with Byrne, although they sound alike. Beirne is thought to originate from Norse Bjorn. The Beirnes settled in County Roscommon and formed an important sept. O'Birn.
Blake — They came with the Normans through Wales with the name Caddell. A dark-hued member of the family was nicknamed "Le Blaca" (the Black), and it evolved to Blake. They settled in Galway city and county and became rich landowners and merchants, and part of the 14 Tribes of Galway. In the west of Ireland there are Blake families of Gaelic origin whose name Ó Blathmhaic was anglicized to Blowick, and then to Blake. Blowick, O'Blathmhaic, Caddell.
Boland — Ó Beolláin. Their name comes from a Norwegian who came to Ireland long ago. In Irish it is Ó Beolláin, in English it used to be O'Bolan. One branch claims to descent from Mahon, one of King Brian Boru's brothers, who went to Clare where they lived around Lough Derg. Ballybolan perpetuates their name. The other family settled in Sligo with their headquarters in Doonalton. Bolan.
Boyle — Ó Baoighill, Ó Baoill, possibly means "having profitable pledges". In recent years, use of the "O" prefix has resumed. O'Boyle. Cork, Derry.
Brady — MacBrádaigh, "spirited". Sometimes confused with the O'Gradys of Limerick. Matthew Brady (1823-1896) was one of the first war photographers during the American Civil War. Cavan, Leinster, Ulster.
Breen — O Braoin, "sadness, sorrow". MacBreen, Brawney. Kilkenny, Westmeath, Wexford.
Brennan — O Braonáin, "little drop" or "sorrow". Louis Brennan invented the torpedo used in WWI; Maire Brennan and her twin brothers are part of the music group Clannad, and their sister Enya is also well known. Kerry, Kilkenny, Westmeath.
Brody — MacBruaideadha. Attached to the O'Briens of Thomond. Clare.
Brown — came with the Normans in the 12th C., and known as le Brun, settling in Galway and marrying into the leading families and joined the 14 Tribes of Galway. Browne, Broun, le Brun.
Buckley — O Buachalla, "boy". Many were outlawed after Kings James II was defeated. Cork, Kerry.
Burke — originally de Burgo or de Burca, both mean "of the borough". The Burkes descend from William the Conqueror, and are the most numerous and integrated of the Normans who came to Ireland in the 12th C. Bourke, de Burgh, de Burgo.
Butler — one of the most outstanding of Norman-Irish families, with Anne Boleyn and William Butler Yeats among kinsman. The family name came about when Theobald Fitzwalter was created Chief Butler of Ireland by Henry II in 1177. Butler is very common in England and Ireland, lacking an authentic pedigree and almost impossible for one to trace their ancestry to the Ormonds or any other branch of the family.
Byrne — see O'Byrne.
Cahill — one of the earliest recorded surnames; originally MacCathail, Cathail is the Irish form of Charles, "manly" or "valour". Cahill remains most numerous in Munster; but the "O" prefix seems to have been dropped completely. Clare, Galway, Tipperary.
Carey — O Ciardha. O'Kerry, Kerry, Carew. Kerry, Kildare.
Carroll — Ó Cearbhaill, from Cearbhal, "warlike champion", one of King Brian Boru's leadind swordsman at the Battle of Clontarf in 1014. MacCarvill.
Cassidy — O Caiside, originated from a personal name of the head of a family who were teachers and physicians to the Maguire chieftains of Fermanagh for 300 years. Fermanagh originally, now widespread.
Clancy — MacFhlannchaidh, "ruddy warrior". Clanchy, Glanchy, MacClancy. Clare, Leitrim.
Clarke — Cleireach, "clerk". Clerys changed their name to Clarke after Gaelic Irish names were outlawed by English conquerors. O'Cleirigh, O'Clery, Macalary, MacClery. Ulster.
Clery — Ó Cleirigh; cléireach is the Irish word for "clerk". Cleary dates from an early 9th C. Cléureach of the lineage of King Guaire of Connacht, reknowned for his hospitality. Julie, Queen of Spain, and Desiree, Queen of Norway and Sweden, were daughters of a Clery in Marseilles in Napoleonic times. Cleary, Clarke.
Coghlan — MacCochlain or O Cochlain, "cape or hood". Coughlin, O'Coughlan, Coughlan, Cohalan, MacCoughlan. Cork, Offaly.
Collins — anglicization of Irish Ó Cioleáin, "young whelp or young creature". The hero of the family is Michael Collins, "The Big Fellow", whose promising political life was cut short in the civil war in 1922. West Cork.
Conaghan — Ó Connacháin, usually found anglicized as Cunningham. Ulster.
Connolly — Ó Conghaile, the original Gaelic Conghaile means "valorous". An ancient sept of Connacht, which separated and dispersed as three distinct families. At one time they were one of the Four Tribes of Tara. "Little Mo" the USA tennis star of the 1950's was a Connolly; as was patriot James Connolly (born in Scotland), who was an Irish trade union pioneer and commanded the Republican army in Dublin. Before his execution, he signed the Proclamation of the Irish Republic. Connely, Connolley. Connacht, Cork, Monaghan, Ulster.
Conroy — O Conratha, "hound of prosperity". O'Mulconry, Mulconry, Conary, Conree, Conry. Clare, Roscommon.
Conway — MacConnmhaigh. "hound or wolf of the plains" or "head-smashing". Thomas Count Conway (d. 1800) fought in the American Revolutionary War. O'Conway. Clare, Kerry, County Dublin.
Cooney — O Cuanaic, "handsome, elegant". Conan, Coonan, O'Cuana, Counihan. Clare, Galway, West Cork.
Corcoran — O Corcrain, "ruddy". Brigadier General Michale Corcoran took parting the Battle of Bull Run in the American Civil War. O'Corcoran. Fermanagh, Kerry, Mayo, Offaly.
Costello — MacOisdealbh, "son of Oistealb". A Norman name beginning in Connacht as de Angulos. Paul Costello (b. 1945) is a top designer whose clientele included Princess Diana. Nangle, Costelloe. Connacht, but widespread.
Costelloe — A a separate clan from Costello (the Norman de Nangles) and the one anglicised as Costelloe (Dalcassians). The modern Irish village of Costelloe has been regaelicised as CASLA and means "inlet from the sea". The original form of the tribal/clan name was probably Caisle (or gCaisle) — a seafaring tribe, hence the use of the "E" at the end of the anglicised name to differentiate the two septs, one Norman, one Celtic who had the misfortune to meet the English. The modern regaelicisation of the Costello sept is MacCoisdela, which has no equivalent for the Costelloe sept. They never used O', Ui, Mc or Mac: the tribal signifier was gCais (= Dalcais).
Crowley — O Cruadhlaoich, "hunchbacked" or "strong hero". Thady Crawley was chaplain to King James II. Crawley. Cork, Roscommon.
Cuif — French version of the surname O'Keeffe. O'Keefe.
Cullen — Ó Cuillin, "holly tree". Settled and founded Kilcullen in County Kildare. Possibly connected with a Scottish clan. An Australian shrub, eucalyptus cullenii, is named after a Cullen horticulturist there. Cullion, Culhoun, MacCullen, Cullinane. Kildare, Wexford.
Cummins — O Comáin, "a hurley". Geraldine Cummins was a novelist and biographer; her sister Ashely was an international hockey player. Commons, Comyns, Hurley. Kerry, Limerick, Mayo.
Curran — O Corráin, "a descendant of O'Corrain". Galway, Kerry, Ulster, Waterford.
Curtin — Mac Cuirtin, at one time in Irish it was Cruitín "hunchback". The MacCurtin family was prominent in France during the Revolution; and a Cork man, Tomás MacCurtain commanded the Cork Brigade during the war of independence and later Lord Mayor of Cork, was brutally murdered by misguided militia in 1920. MacCuirtin, MacCruitin, MacCurtin, Curtayne. Cork, Dublin, Limerick.
Cusack — Cíomhsóg. Cusacks came from the French province of Guienne in 1211 in the wake of the Anglo-Norman invasion. Known in County Mayo as MacIosóg. Notable Cusacks are Cyril Cusack, of stage and screen, along with his kids Anne, Joan, and John; Michael Cusack of Clare, helped found the Gaelic Athletic Association in 1884. Kildare, Meath.
Daly — Ó Dálaigh was the word for "a meeting place", as in Dail Eireann. Ancestry goes back to the 14th C., to Niall of the Nine Hostages, the High King who had his palace at Tara, County Meath, and from whom descend also the O'Neills and the O'Donnells. Dawley.
Delany — O Dubhshlaine, "of the river Slaney". From dubh "black" + Slaine "the river Slaney". Delane, Delaney. Dublin, Leix.
Dempsey — O Diomasaigh, "proud". Claim descent from Ros Railghe, eldest son of Cathaoir Mor, 2nd C. king of Ireland. Jack Dempsey was a famous boxer in the US. Leix, Offaly.
Devine — O Daimhin, "poet, bard". Davin, Devane, Devin, Downes. Cavan, Dublin, Fermanagh, Louth, Tyrone.
Devlin — O Doibhlin. Sligo, Tyrone.
Dillon — Arrived from Brittany as de Leon 800 years ago, and they are a widespread and well-recorded family that has merged indistinguishable with the Irish.
Doherty — Ó Dochartaigh, "obstructive". Doherty is the most common variant of O'Doherty. Descended from the powerful 14th C. King Niall of the Nine Hostages. Dougharty, Dougherty, MacDevitt, O'Dogherty. Ulster.
Dolan — O Dobhailen, "black defiance, challenge". Doolan, Dowling, Doelan, O'Doelan. Galway, Roscommon.
Donoghue — Ó Donnchadha, comes from the personal name Donnchadh (Donogh). A 12th C. O'Donoghue founded the Jerpoint Abbey in County Kilkenny. Donohue, Donohoe, O'Donoghue, O'Donagh, Donaghue, Dunphy, Donju (Spanish).
Doran — O Deoradháin, "exile or stranger". Armagh, Down, Kerry, Leix, Wexford.
Dowling — O Dunlaing. Carlow, Dublin, Kilkenney, Leix, Wicklow.
Doyle — Ó Dubhghaill, from dubh-ghall "dark foreigner", when Norsemen came to Ireland circa 9th C. Of this family were Sir Arthur Conan Doyle, author of Sherlock Holmes novels; and Jack Doyle, "The Gorgeous Gael" of boxing. Doyelle, Doyley, MacDowell. Wexford.
Driscoll — see O'Driscoll.
Duffy — Ó Dubthaigh, meaning unknown, but dubh means "black"; little is recorded of their origins except for their prominence at the church in Monaghan in the 7th C. Doohey, Dowey, Duhig, O'Duffy. Roscommon, Ulster.
Duggan — O Dubhagain, "black head". Doogan, Dougan. Cork, Donegal, Galway, Tipperary.
Dunne — Ó Duinn, "brown". The Dunnes were very active in the Jacobite wars, and emigrated to the USA afterwards, serving in the church, law, and army. In recent years Dunne's Stores, a countrywide chain store group, has become a household word. Dunn.
Egan — Mac Aodhagáin, "son of Aodh", anglicized to Hugh. The name has become Egan in modern times, seldom using their Mac prefix. Their origins are in Galway, Roscommon and Leitrim, and have scattered to Tipperary, Kilkenny and Offaly. Keegan, MacEgan.
Fagan — O Faodhagain, "little Hugh". O'Hagan, Fegan, O'Hogan. Dublin, Kerry.
Fahy — O Fathaigh, "field green". Fahey, Faghy, Green. Galway, Tipperary.
Fallon — O Fallamhain, "ruler". Falloon. Cork, Donegal, Galway, Kerry Wexford.
Farin — Mac Fearachàin, Mac Mhearain, possible form of Ferran.
FitzGerald — fitz means "son", and Maurice, son of Gerald, came with the Norman invaders in 1170. The FitzGeralds became one of the most powerful families. F. Scott Fitzgerald wrote novels, including The Great Gatsby.
Fitzpatrick — MacGiolla Padraig, "servant of St. Patrick". The only Fitz surname that is Irish and not Norman in origin. Kilpatrick, MacGillapatrick. Leix, widespread.
Flanagan — O Flannagain, "red". O'Flannagan. Fermanagh, Offaly, Roscommon.
Flynn — O Floinn, "red, ruddy". Errol Flynn was a Hollywood film star. Flinn, O'Loinn, O'Lynn. Antrim, Cork, Roscommon.
Fogarty — cognate with Gogarty; O Fogartaigh, "exiled, banished". Tipperary.
Foley — O Foghladha, "plunderer". Mostly Munster, Waterford.
Friel — Ó Frighil, "man of valor"; form of Fearghal (Farrell).
Gaffney — O Gamhna, "calf". Could also be O'Caibheanaigh, MacConghamhna, MacCarrghamhna, or Mag Fhachtna. Caulfield. Connacht.
Gallagher — Ó Gallchobhair. One of the principal septs of Donegal. The translation of their Irish name gallchobhair, "foreign help", was possibly acquired in the 300 years when they were marshals in the armies of the O'Donnells. Frank Gallagher was a journalist who fought in the civil war and was the first editor of De Valera's newspaper, the Irish Press.
Galvin, Gallivan — Ó Gealbháin, "bright white". Kerry, Roscommon.
Garvey — O Gairbith or Mac Gairbhith, "rough peace". Armagh, Donegal, Down, Kilkenny.
Geraghty — Mag Oireachtaigh, "court or assembly". Garrity, Gerity, but there are more than 17 variants on the name. Galway, Roscommon.
Gilday — Mac Giolla Dhé, meaning "the son of the devotee of God." Originally from County Tirconnell and now found in Connacht and Clare. Gildea.
Griffin — Ó Gríobhtha, Ó Gríofa (modern Irish spelling). There are two Gaelic Griffin surnames native to Ireland, and also those who descend from Welsh-Norman planters of the name Griffith/Griffiths/Griffis whom have changed there name to Griffin since first arriving in Ireland. With respect to the Gaelic families, there are the Ó Grifín and the Ó Gríobhtha/Ó Gríofa. The Ó Grifín are from County Kerry (Dingle) and the other family, the Ó Gríobhtha, "Griffin-like", are from County Clare. In Kerry, Griffin was used as a nickname for a brave warrior and later when surnames came into vogue, the descendants of these warriors called themselves Ó Grifín, "descendants of the Griffin". Because of this, Kerry Griffins are not necessarily related - different towns in Kerry had different "Griffin" warriors - as it was a nickname. In Clare, the Griffins descend from Angus, son of Dal (4th century chieftain of Thomond - Co. Clare today). The Dalcassians (descendants of Dal) invented the surname (the first people on the planet to use surnames), and Brian Boru - a Dalcassian himself, made surnames compulsory for all Irish people 1000 years ago.
Guinness — MagAonghusa, "son of Aonghus" (one choice). Ancestry goes back to a 5th C. chief of Dal Araidhe. Most notable is the Guinness brand of ale, established in 1759 on the River Liffy in Dublin by Arthur Guinness In 1894, there were sixteen different versions of this Ulster surname. McGennis, MacGinnis, Magennis, MacGuinness, MacInnis.
Hagan — see O'Hagan.
Healy — Ó hÉildhe, modern Healy/Hely is an amalgam of two distinct septs, Ó hÉildhe, éildhe "claimaint", and Ó hÉilaighthe, éiladhach "ingenious". O'Healy, Hely, O'Healihy. Cork, Sligo, Tipperary.
Hennessey — Ó hAonghusa, from personal name Aonghus or Angus. Branches of this family have completely dropped the "O" prefix, gradually transforming their name to Hennessey, Hensey, Henchy. Cork, Limerick, Tipperary.
Hickey — O hIcidhe, "healer". Clare, Limerick, Tipperary.
Higgins — Ó hUigin, an ancient name in Ireland from the Irish Ó hUigín, uigín "knowledge". Earlier, they were a branch of the Westmeath O'Neills.
Hogan — Ó hOgáin, Óg is Irish for "young". An Ó hOgáin sept descends from the celebrated 10th C. King of Ireland, Brian Boru. They were of the Dalcassian people who inhabited Thomond, around Clare and Limerick. They divided to spread across Tipperary, where their chieftain has his fortress at Nenagh. Clare, Limerick, Thomond, Tipperary.
Jennings — MacSheóinín, "son of little John"; John, originally Burkes. Connacht.
Jorden — in Ireland, Jordan is an anglicization of the surname Mac Siurtáin. As a first name, it's a Hebrew place name (River Jordan), meaning "flowing down".
Joyce — from the French personal name Joie, Joy; Gaelic version Seoigh. The name is deeply embedded in Connacht since their arrival by sea after the Norman invasion. A Joyce who was captured in the Middle East learned the art of gold and silver smithing, and it is he who is creditied with the origins of the Claddagh ring. James Joyce was a playwright, poet, musician, and author of Ulysses. William Joyce broadcast Nazi propaganda from Germany in WWII, because of his American background he was hanged for treason after the war. Connacht, Galway, Ross.
Kavanagh — Caomhánach, direct descendants of Diarmuid MacMurrough, a 12th C. King of Leinster, who started the Anglo-Norman invasion. Cavanagh, MacMurrough.
Keane — Ó Cathain, originally Mac Cathain of West Clare, Ó Cahain of Ulster and Ó Céin of Munster, and derives from the personal name Cian. Kane, O'Cahan, MacCloskey. Munster, Ulster, West Clare.
Kelleher — O Céileachair, "loving spouse". Keller. Clare, Cork, Kerry.
Kelly — see O'Kelly.
Kennedy — see O'Kennedy.
Keogh — (KEE-oh) anglicization of Irish MacEochaidh, Eochaidh is a personal name, but adopted by a family with three distinct septs. John Keogh of Dublin was an early pioneer of Catholic Emancipation. In some cases Keogh was anglicized to O'Hoey or Hoy, septs that descended from the early kings of Ulster. Kehoe, Hoey, Hoy, K'Eogh, O'Hoey, Haughey, MacKehoe. Leinster, Wexford.
Killoran — "servant of Saint Luairean". From Mac Giolla Luairinn and Mac Giolla Luaithrinn. Luairinn derives from Saint Luairean (also Luaran/Loran). Cloren, Cloran, Killoran, Killoren, Kiloran, Kiloren, Killorn, Killorne, Killorin, Killaurin. Sligo.
Kinsella — O Cinnsealach, originally Mac Murrough. Wexford, Wicklow.
Kirwan — Ó Ciardubháin, "black"; origins back to Heremon of Milesians, probably from Spain. When they moved to Galway from Louth, with the Darcys, they were the only native family accepted into the 14 Tribes of Galway.
Lacy — de Léis, the de Lacys took their name from Lascy in Normandy, from which they came to conquer England and then Ireland. Founder of the family was Hugh de Lacy. Lacey, de Lacy.
Lalor — O Leathlobhair, "half-leper". Lawlor. Leix.
Lee — O Laoidhigh, "poetic"; or Mac an Leagha, "son of a physician". Cork, Galway, Limerick, Tipperary.
Lennon — Ó Leannáin. A number of western O’Leanáins (one ‘n’) eventually became Leonards. Lennan, Lennon, Lannan, Lannon, Linnane. Fermanagh, Mayo and Galway.
Lynch — Ó Loingsigh, one of the most numerous and distinguished Irish surnames and a fusion of two different races. One was de Lynch, who came with the Normans; two was Labradh Longseach ("mariner"), a 6th C. B.C. King of Ireland. These Lynches settled in Clare, Sligo and Limerick, with a branch in Donegal. Leaders of the 14 Tribes of Galway. Lynches have gone to Australia, Argentina, and Chile. Patrick Lynch is known as the "foremost Chilean naval hero"; Elizabeth Lynch and Paraguayan dictator Francisco Lopez II held sway there for 12 years; plantation owner Thomas Lynch signed the American Declaration of Independence; and Jack Lynch of Cork won six All-Ireland medals for hurling and Gaelic football.
Lyons — O Laighin or Ó Liathain. They are quite distinct from the Scottish and English families with the same name. Lehane, Lane, Leyne, O'Lyne, Lyne. Galway.
MacAuley — MacAmhlaoibh. Catherine McAuley (1778-1842) founded the Sisters of Mercy. McAuley MacAwley, McAwley, Cawley, Magawley. Cork, Fermanagh, Westmeath.
MacAuliffe — MacAmlaoibh, from Norse name "Olaf". Cork. McAuliffe.
MacBride — MacGiolla Brighde, "devotee of St. Brigid" or "son of the servant of St. Brigid". Donegal, Ulster. McBride.
MacCabe — Mac Cába. Many were mercenaries (known as gallowglasses) imported from Scotland by Irish chieftains in the middle ages who came from Inis Gall in the Hebrides. They served the O'Reillys and the O'Rourkes of Leitrim and Cavan. It is thought their name comes from the peculiar hats they were; caba means "hat or cap". McCabe
MacCann — MacAnnadh, originally spelled MacCana. Ambhlaith MacCanna claimed descent from the O'Neills of Ulster. Canny, McCann, Maccanna, MacCanna. Armagh.
MacCarthy — MacCarthaigh, "loving one". One of the most ancient and numerous surnames in Ireland, back to the 3rd C. King of Munster; derives from Carthac, a 12th C. descendant. MacCartney is the Scottish form of this surname; Paul MacCartney of the Beatles (b. 1942, Liverpool, England). McCarthy.
MacCormack — MacCormaic, "son of Cormac". Wright McCormick started the movement in 1920 for an annual St. Patrick's Day celebration in Boston. MacCormick, McCormick, McCormack. All over Ireland.
MacCulloch — Mac Cú Uladh, Mac Con Uladh. "Hound of Ulster". McCullagh, McCollough.
MacDermot — MacDiarmada, "free man". From a 12th C. descendant, Dermot, King of Moylurgh, that they adopted the surname Dermot. MacDermott, McDermmot, Kermode. Roscommon, Sligo.
McElrath — Mac Giolla Riabhaigh, "son of the brindled lad". MacIlrea, Kilrea (County Sligo) MacIlwraith, MacIlrath (Ulster and Scotland) MacElrath.
MacElroy — MacGiolla Rua, "redhaired youth". Fermanagh, Leitrim. McElroy.
MacEvoy — MacGuiollabhuidhe, "woodsman"; a variant is Mac A Buidhe, "yellow lad". MacAvoy, McAvoy, McEvoy. Leix, Louth.
MacFrederick — Mac Feardorcha (possibly); "son of Frederick". N. Ireland via Scotland.
MacGee — Mag Aodha, "son of Hugh". Magee, MacKee, McGee, McKee. Antrim, Armagh, Down.
MacGill — Mac An Ghaill, "son of the foreigner". Magill (East Ulster).
MacGovern — Mag Samhrain, "summer"; derived from Samhradh, who lived circa 1000. Magauran, MacGowran, McGovern, McGowran. Cavan, Fermanagh, Leitrim.
MacGrath — MacRaith or Mag Raith, "son of Raith"; raith "prosperity". Joseph McGrath, a veteran of the Rising and a government minister, helped found the Irish Hospitals Sweepstakes and revive the old Waterford crystal industry. Magraith, Magraw, MacGraw, Magrath, McGrath, McGraw. Clare, Donegal, Fermanagh, Limerick.
MacHugh — MacAoda, "son of Hugh". Eason, Hewson, MacCoy, McKee, Hughes, MacKay, McHugh. Donegal, Fermanagh, Galway, Leitrim, Mayo.
MacInerney — Mac An Airchinnigh, "steward of church lands"; originated in Connacht. Macnairney, Mcnerney, McInerney. Connacht.
MacKenna — Mac Cionaoith, Irish MacCionaoda "son of Cionaoid". Little is recorded or known of the MacKennas until recently. An Ulster family, they were lords of Truagh, the present Trough in County Monaghan. McKenna. Ulster.
MacLoughlin — O Maoilsheachlain, "follower of St. Secundinas". Also spelled MacLochlainn in Gaelic. O'Loghlen, MacLaughlin, McLaughlin, McLoughlin, O'Melaghlin. Clare, Derry, Donegal, Meath.
MacMahon — Mac Mathghamhna or MacMathuna, "son of a bear"; represents two distinct septs. Mac dropped from MacMahon, it indicates a completely different name, one which can also be Mohan, which at some time was also transformed to Vaughn. Mahon, McMahon, Mohan, Vaughn.
MacManus — MacMaghnuis, Gaelic adaption of the Norse-Viking name Magnus. McManus. Connacht, Fermanagh.
MacNally — Mac an Fhailghigh, "poor man". Macannally, McNally, Nally. Armagh, Mayo, Monaghan.
MacNamara — "son of the hound of the sea"; there were two septs, MacNamara Fion "fair" of the West, and MacNamara Reagh "swarthy" of the East. Caitlin MacNamara, wife of Dylan Thomas, and her father, Francis, were born at Ennistymon, now Falls Hotel. McNamara. Clare.
MacNulty — Mac An Ultaigh, "ulidian", "of Ulster". McNulty, Nulty. Ulster, Mayo.
MacQuaid — Mac Uaid, "son of Walter". McQuaid, MacQuaide, McQuaide, MacQuoid, McQuoid, MacWade, McWade. Ulster.
MacQuillan — MacCoilin or MacUighlilin, "son of little Hugh"; from Welsh-Norman Hugeli de Mandeville in the 12th C. McQuillan. Ulster.
MacSweeney — MacSuibhne, "pleasant". The Donegal MacSweeneys were descendants of Suibhne O'Neill, a chieftain of Scotland. Scottish mercenaries. McSweeney, MacSwiney, Sweeney, Sweeny. Cork, Donegal.
McKowen — MacEoghain (Connacht); MacEoin (east Ulster). Eoghan is ancient and possibly means "yew tree". Eoin is a common form of John. McKown, MacKeon, MacKeown.
McGinn — Mag Fhinn surnames. MacGinn and its composite form Maginn are approximately equally numerous and are now found respectively in Counties Tyrone and Down. MacGinn, or MacGinne, is listed in the 1659 "census" as a principal Irish name in the barony of Oneilland, Co. Armagh, i.e. the territory which lies between Tyrone and Down. Maginn, MacGinn, MacGinne.
Madden — O Madáin, "small dog". Galway, Limerick, Longford, Offaly.
Maguire — MagUidhir, comes from the Irish MagUidhir "pale colored". First recorded in 956, but not prominent until the 14th C. as a sept of the Fermanagh. Also kinsmen of the kingly O'Neills and O'Connells of Ulster. Many Maguires went to the US and became distinguished in their careers. The chief surgeon to Stonewall Jackson and professor at Virginia Medical College among them. MacGuire, McGuire.
Maher — O Meachair, "hospitable". Meagher. Kilkenny, Tipperary.
Mahoney — see O'Mahony.
Mallaghan — may be translated in two ways : "the gentle chief" or "the small bald man". Mallaghans were supposed to have been the wise men and advisers to the clan.
Malone — Ó Maoileoin, from Maoileoin "one who served St. John". Kinsmen of the O'Conors. Malones who supported James II had to flee to Europe, and can be traced to the armies and records of France and Spain. Offaly.
Martin — Ó Martain, MacGiolla Martain, MacMartain, kinsmen of the O'Neills of Tyrone, and one of the 14 Tribes of Galway. MacGiolla Martin was anglicized to Gilmartin. The Martins of Connacht, the most prominent family of the Martin name, claim descent from Olyver Martin, a Norman Crusader. Martyn, Kilmartin, Gilmartin.
Molloy — O Maolmhudaidh, "noble chief". Maloy, Miley, Millea, Mulloy. Offaly, widespread.
Moloney — O Maoldhomhnaigh, "descendant of a church servant". Musician Paddy Moloney is part of The Chieftains. Maloney, Malony, Molony. Clare, Tipperary.
Monaghan — O Manacháin, "monk". Listed as lords of Roscommon in1287. Minogue, Monahan, Monk. Roscommon.
Mooney — O Maonaigh, either "wealthy" or "dumb". Mainey, Meany, Meeney, Moony. Offaly, Sligo, Ulster.
Moore — Ó Mórdha, "noble"; descend from Conal Cearnach, a chieftain of the legendary Knights of the Red Branch. Thomas Moore was a poet and musician. Leix.
Moran — O Móráin, "big, great". Murrin. Connacht.
Moriarty — O Muircheartaigh, "expert navigator"; originated in the Dingle peninsula. Murdoch, Murtagh. Kerry.
Morrissey — O Muirgheasa, "sea choice". Cork, Limerick, Sligo, Waterford.
Mulcahy — O Maol Chathaigh, "battle chief". Dr. Risteard Mulcahy is a leading Dublin heart surgeon; Russell Mulcahy directed the film "Highlander", starring Christopher Lambert. Munster.
Mulrooney — Maelranaidh, an ancestor of the MacDermot clan.
Mulligan — Ó Maolagáin. Donegal, Mayo, Monaghan.
Murphy — Ó Morchoe, "sea warrior". Dermot MacMurrough, the most famous Murphy, invited the Normans into Ireland. Murphey, MacCamore, MacMurrough, O'Morchoe, O'Murchadha. Leinster, Sligo, Tyrone, Wexford.
Murray — Ó Muireadhaigh; anglisiced to Murray in the 17th century.
Nolan — O Nuaillain, "noble, famous". Mowlan. Carlow, West Cork.
Nugent — Nuinseann, originated in the 10th C. in the French town of Nogent, and moved to Ireland in the 12th C. Gilsenan. Westmeath.
O'Brien — take their name from the 10th C. Brian Boru, High King of Ireland. Clare, Limerick, Munster.
O'Byrne — Ó Broin, Byrne, with or without the "O" prefix is a common Irish name. Ó Broin comes from Branach "raven", a son of Maolmordha, 11th C. King of Leinster. Byrne. Wicklow.
O'Callaghan — Ó Ceallacháin, "strife". Probably from Ceallachan, 10th C. King of Munster and chieftain of the Eoghanact, a consortium of the leading families of Munster, and who plundered surrounding counties. He is also famed for killing Cinneide, father of the future king Brian Boru. Callaghan, Callahan. Kilkenny, Munster.
O'Casey — O Cathasaigh, "vigilant, watchful". Thomas Lincoln Casey built the Washington Monument in the US. Casey. Munster.
O'Connell — Ó Conaill, claim to a pedigree dating back to a circa 280 BC High King. The name probably evolved from the ancient British or Celtic first name Cunovalos. Sir Maurice O'Connell married the daughter of Captain Bligh of The Bounty. Derry, Galway, Munster.
O'Connor — Ó Conchobhair, "hero, champion"; pedigree going back to the 2nd C.; and took their name from the 10th C. King Conchobhair of Connacht. O'Conor, Conner, Connor. Clare, Munster, Offaly, Roscommon, Ulster.
O'Dea — O Deaghaidh. Cork, Dublin, Limerick, Tipperary.
O'Donnell — Ó Domhnaill, "world mighty"; a forefather was Niall of the Nine Hostages. Their base was Tirconnell (now Donegal) "Connell's territory", and their chieftains were inaugurated on the Rock of Doon near Letterkenny. Donegal.
O'Donovan — Ó Donnabhain, donn "brown" and dubhann "black"; pedigree goes back to Callaghan, a 10th C. King of Munster, whose son was Donnabhainn. Cork, Kilkenny.
O'Dowd — O Dubhda, "black". Dodd, Doody, Duddy. Galway, Mayo, Sligo.
O'Driscoll — O hEidersceoil, "intermediary, interpreter". Driscoll. Predominantly Cork.
O'Dwyer — O Dubhuidir, "black shirt". Mayo, Sligo.
O'Farrell — Ó Fearghaill, "man of great valour". Multiplied and divided into two septs: O'Farrel Boy, buidh means "yellow"; and O'Farrell Bán, bán means "white". They married into the Moore family, creating the sept More O'Ferrall. More, O'Ferrall.
O'Flaherty — Ó Flaithbheartaigh. A sear-faring people of Connacht and enemies of the 14 Tribes of Galway. They boast genealogy back 3,000 years. Flaherty, O'Flaverty. O'Laverty (in Ulster, where Irish is slightly different).
O'Flanagan — O Flannagain, "red". Flanagan. Connacht.
O'Gara — O Gadhra, "a mastiff " (dog). Mayo, Sligo.
O'Gorman — O Gormain, from the word for "blue". MacGorman, Gorman, Grimes. Clare, Leix, Monaghan.
O'Grady — Ó Grádaigh, "illustrious"; pedigree shows them to be of Dalcassian sept, kinsmen of the O'Briens. An O'Grady married to a black American woman, was the great-grandfather of Cassius O'Grady Clay (Muhammed Ali). Clare, Limerick.
O'Hagan — O hAodhagain or Ó hAgain, "young". Hagan, Aiken, Hogg. Tyrone, Ulster.
O'Halloran — O hAllmhurain, "stranger beyond the sea". Clare, Galway.
O'Hara — O hEaghra. Scarlett O'Hara is a well-known fictional character from the novel Gone With The Wind. Antrim, Sligo.
O'Hegarty — O hEigceartaigh, "unjust". Haggerty, Hagerty. Cork, Derry, Donegal.
O'Higgins — O hUigin, "knowledge, ingenuity". Leinster, Munster, Sligo.
O'Keeffe — Ó Caoinmh. Fionghuine's, a King of Munster, son Art O Caom gave his name to the O'Keeffes whose territory was around Glanmore and Fermoy in Cork. When uprooted by the Normans, they moved south to the Duhallow country where their surroundings came to be called Pobble O Keeffe "O'Keeffe country". Caom means "noble" or "gentle". Georgia O'Keeffe was a famous painter. O'Keefe.
O'Kelly — Ó Ceallaigh, derive their name from Ceallach, a 9th C. chieftain, meaning "war" or "contention". Kelly. Galway, Roscommon.
O'Kennedy — Ó Cinneide, kinsmen of King Brian Boru, whose brother, Dunchad, the O'Kennedys descend. Cean Éidig, "ugly head", was the father of Brian Boru and Dunchad and where the name originated. There is also a Kennedy clan in Scotland who long ago may have been related to the Irish Kennedys. Kennedys of the 19th and 20th Centuries have been distinguished in the church, medicine, law, and the navy. Most notably the Kennedys of Boston, including President John F. Kennedy, Robert F. Kennedy, Ted Kennedy, JFK, Jr., etc. Kennedy. Clare, Kilkenny, Tipperary.
O'Leary — O Laoghaire, "calf keeper". Cork.
O'Mahony — Ó Mahúna, from Mathghamhan, son of Cian Mac Mael Muda, a 10th C. prince and his wife Sadbh, daughter of Brian Boru. Mahony, Mahoney, O'Mahoney. Cork, Munster.
O'Malley — Ó Máille, a very old Mayo family whose name is said to derive from the Celtic word for chief, maglios. Melia.
O'Meara — O Meadhra, "mirth". Tipperary.
O'Neill — one of the most prestigious Irish families of the last 1,000 years. Niall means "champion". Creagh, Neill, Nihill. Antrim, Down, Tyrone, Ulster.
O'Reilly — Ó Raghailligh, took their name from Ragheallach "gregarious race", great-grandson of Maolmordha (Myles). Thought to be kinsmen of the O'Conor kings of Connacht through Maolmordha. Reilly, O'Rahilly, Riley. Cavan.
O'Riordan — O Riordáin, "royal bard". Riordan, Reardon. Cork, Tipperary.
O'Rourke — Ó Ruairc, thought to come from the Norse-Viking name Hrothrekr, who came and integrated, producing three kings of Connacht. Roark, Rooke, Rourke, Rorke. Cavan, Leitrim.
O'Shaughnessy — O Seachnsaigh. Shaughnessy, Sandys. Clare, Galway, Limerick.
O'Shea — O Seaghada, Ó Séaghdha (SHAY), Ó Sé (modern). "Hawk-like" or "stately"; possibly "majestic, courteous" or "dauntless". This family was a member of the Ten Tribes of Kilkenny. Shea, Shee. Kerry, Kilkenny.
O'Sullivan — Ó Súileabháin, "one" or maybe "hawk-eyed". Ancestry from Olioll Olum, 3rd C. King of Munster. Sir Arthur O Sullivan was the musical half of Gilbert & Sullivan operas. Cork, Kerry, Tipperary.
O'Toole — Ó Tuathail, from Tuathal, a 10th C. King of Leinster. Scholars say tuathal means "mighty people" or "prosperous". Originated from Kildare, and associated with Wicklow. Toal, Tool, Toole, Toohill, Twohill. Connacht, Kildare, Ulster, Wicklow.
Phelan — O Faoláin or O hAoileain, "joyful". Whelan, Heelan, Hyland. Carlow, Kilkenny, Waterford, Wexford.
Plunkett — from a French word for "white" or "blonde". An aristocratic family who came to Ireland from Denmark before the Normans. Plunketts fought for the Catholic Stuarts, fleeing to France with them to join the Irish regiments, but returned to Ireland and their original faith to save their lands in the 18th C. Plunket. Louth, Meath.
Power — came with the Normans, known as le Poer "poor". de Paor. Waterford, Wicklow.
Quigley — O Coigligh, "untidy hair". Cogley, Coigley. Derry, Donegal, Galway, Mayo, Sligo.
Quinlan — O Caoindealbháin, "gracefully shaped". Kindellan, Quinlevan. Munster.
Quinn — O Cuinn, "intelligent". Quin. Antrim, Clare, Longford.
Rafferty — O Reachtaire, or O Raithbheartaigh, "prosperity wielder"; or O Robhartaigh, "flood tide". O'Rafferty, O'Raverty (in records of 1663). Connacht.
Redmond — Réamonn, a Norman surname adopted into the Irish Gaelic and originated with Raymond le Gros, a Norman leader of the invasion in 1169. Wexford, Wicklow.
Regan — (said Reegan) Ó Reagáin or Ó Riagain, a widespread name which came from several ancestors. The Ó Riagáin were important because they were of the Four Tribes of Tara. Dublin, Leix, Meath.
Rice — from Welsh Rhys. Dublin, Kerry, Louth, Ulster.
Riggs — possibly "wealthy, rich"; or the name may be local, and denoting a steep elevation, a range of hills, or the upper part of such a range.
Roche — de Róiste, thought that the Roches originated in Flanders, certainly arriving in Ireland with the Normans from Roch Castle, the Pembrokeshire fortress, from which their name comes. There are five different branches that this family multiplied into. The first viscount Fermoy in 1570 was David Roche, an ancestor of Princess Diana.
Rooney — O Ruanaidh, "hero". Down, widespread.
Ryan — Ó Riain or Ó Maoilriain, "follower of Riain"; Ryan formed from an old personal name meaning either "administrator" or "water". They separated into two main branches: the Ó Riains of Idrone in Carlow; and the Ó Maoilriains, chiefs in Owney around Limerick and Tipperary. Mulryan. Carlow, Leinster, Limerick, Tipperary.
Scanlan — O Scannláin or MacScannlain. Scanlon. Connacht, Cork, Kerry, Limerick.
Scully — O Scolaidhe, "crier". Leinster, Tipperary.
Shannon — O Seanacháin, "old, wise". Clare, Ulster.
Sheehan — O Siodhacáin, "peaceful". Sheahan.Munster.
Sheehy — Mas Sithigh. Munster.
Sheridan — Ó Sirideáin, origin ambiguous, at first a personal name. General Philip Sheridan, distinguished at the battle for the Shenandoah Valley in the American Civil War, had roots were in Cavan. Sheriden. Cavan.
Taaffe — family came from Wales in 1196 to settle in Louth, and David is the Welsh equivalent.
Táilliúir — (TAWLL-yur) Gaelic version of Taylor, brought by the English to mostly Dublin and Ulster.
Tierney — O Tighearnaigh, "lordly". Tiernan. Donegal, Mayo, Tipperary.
Tobin — Tóibín, originally de St. Aubyn. Toibin. Brittany, Munster.
Treacy — O Treasigh, "fighter". Cork, Galway, Leix.
Tuite — Mac Confhiaclaigh (IG) and de Tiúit (Norman-Irish). The former were prominent in the above areas prior to the Norman invasion. The latter, lead by Richard de Tuit, came in with Strongbow in the Norman invasion of 1172. De Tuit means "of the clearing" (in a wooded area) and there are at least five such places in Normandy today called La Thuit. All of them are located in the Eure department of Normandy. Meath, Westmeath, Louth Longford.
Tully — O Taicligh or Mac an Tuile, "flood". The family changed their name to Flood when the English outlawed the Gaelic language. Flood, MacAtilla. Cavan, Connacht, Longford, Westmeath.
Twomey — O Tuama. Toomey. Clare, Cork, Kerry, Limerick.
Wall, de Valle — du Val, original Norman name was de Bhal. Carlow, Cork, Kilkenny, Limerick, Waterford.
Walsh — Breathnach, "Welshman"; name used to designate the hundreds of Welshmen who came with the Normans to Ireland, so there is no common Walsh ancestor for this family. Walshe, Welsh. Dublin, Kilkenny, Leix, Waterford, Wicklow.
Ward — Mac an Bháird, "bard". Connacht, Ulster.
Woulfe — de Bhulbh, "son of Ulf". Name brought by French Norman invaders. Wolfe, Wooley, Woolfe. Cork, Kildare, Limerick.