Irish last names: 140+ Irish surnames and second names, with meanings
174 names · Updated · By The Nomezo Editors · Save to Pinterest
The most common Irish last names, or Irish second names as surnames are often called in Ireland, are Murphy and Kelly, followed by names such as O'Sullivan, Walsh and O'Brien, and most began as Gaelic family names built with Ó, meaning descendant of, or Mac, meaning son of. Under English rule many families dropped the Ó and Mac, and during the Gaelic Revival of the late 1800s and early 1900s many took them back, which is why both Connor and O'Connor exist today.
This page lists 140+ real Irish surnames with their Gaelic form and meaning: the most common names in Ireland, Ó surnames, Mac surnames, Irish second names by county, names honoring saints and trades, Norman-Irish families, surnames grouped by meaning, and surnames in Irish with a simple pronunciation guide. Pronunciations are approximate, since Irish dialects differ.
Can't decide? Shuffle 6 random picks
Ward
Mac an Bhaird, son of the bard; hereditary poets
Galvin
Ó Gealbháin, from geal, bright or white
Flynn
Ó Floinn, descendant of Flann, ruddy or red
Breen
Ó Braoin, from braon, a drop of rain or moisture
McGillycuddy
Mac Giolla Mochuda, son of the servant of Saint Mochuda
O'Mahony
Ó Mathghamhna, descendant of Mathghamhain, bear; a Cork family
Irish name tools
See an Irish surname the way a man, his daughter and his wife write it, hear how Irish first names are said, and build a traditional name chain or byname.
A surname for him, her and his wife
In English: O'Brien
Ó, descendant, becomes Ní for a daughter and Uí for a wife, and the next word takes an h where it can (lenition).
In Ulster, a woman who takes her husband's surname often just uses Ní or Nic with it.
How to say it
- Saoirse SEER-shuh/ˈsˠiːɾˠ.ʃə/ · freedom · source
Name chain and byname
Most common Irish last names
Ireland's most widespread surnames, led by Murphy. Each note gives the original Gaelic form and its meaning or home ground.
- Kelly US #80: Ó Ceallaigh, descendant of Ceallach, an early Irish first name
- O'Sullivan US #2,941: Ó Súilleabháin, a name built on súil, eye; strongest in Cork and Kerry
- Walsh US #302: Breathnach in Irish, meaning Welshman or Briton
- O'Brien US #261: Ó Briain, descendant of Brian Boru, High King of Ireland
- Byrne US #1,198: Ó Broin, descendant of Bran, raven; a Wicklow family
- Ryan US #201: Ó Riain, descendant of Rian, or a short form of Ó Maoilriain (Mulryan); strongest in Tipperary and Limerick
- O'Connor US #416: Ó Conchobhair, descendant of Conchobhar, lover of hounds
- O'Neill US #673: Ó Néill, descendant of Niall; the great royal family of Ulster
- O'Reilly US #2,913: Ó Raghallaigh, descendant of Raghallach; rulers of east Breifne in Cavan
- McCarthy US #395: Mac Cárthaigh, son of Cárthach, loving; kings of Desmond
- Gallagher US #488: Ó Gallchobhair, descendant of Gallchobhar; long rooted in Donegal
- Doherty US #1,280: Ó Dochartaigh, descendant of Dochartach; from Inishowen in Donegal
- Lynch US #269: Ó Loingsigh, mariner; also a Norman family of Galway
- Daly US #1,128: Ó Dálaigh, from dáil, assembly; a family of famous poets
- Brennan US #697: Ó Braonáin, descendant of Braonán; a Kilkenny family
- O'Connell US #986: Ó Conaill, descendant of Conall; the Kerry family of the Liberator
- Moore US #18: Ó Mórdha, from mórdha, stately or majestic; a Laois clan. Also a common English name
Irish Ó surnames (O' names)
Ó means grandson or descendant. In English it became O', and many families dropped it entirely before reclaiming it.
- O'Donnell US #784: Ó Domhnaill, descendant of Domhnall, world ruler; lords of Tír Chonaill
- O'Mahony: Ó Mathghamhna, descendant of Mathghamhain, bear; a Cork family
- O'Callaghan: Ó Ceallacháin, descendant of Ceallachán, a king of Munster
- O'Shea US #3,366: Ó Séaghdha, descendant of Séaghdha; an old Kerry family
- O'Leary US #1,607: Ó Laoghaire, descendant of Laoghaire, calf herder
- O'Rourke US #2,197: Ó Ruairc, from the Norse name Hrøríkr; kings of Breifne
- O'Dwyer: Ó Duibhidhir, from dubh odhar, dark and dun-colored
- O'Keeffe: Ó Caoimh, from caomh, gentle or kind; a Cork family
- O'Farrell: Ó Fearghail, descendant of Fearghal, man of valor; Longford lords
- O'Carroll: Ó Cearbhaill, descendant of Cearbhall; lords of Éile in Offaly
- O'Hara US #1,671: Ó hEaghra, descendant of Eaghra, a lord in County Sligo
- O'Malley US #2,045: Ó Máille, the seafaring Mayo clan of the pirate queen Gráinne
- O'Driscoll: Ó hEidirsceoil, from eidirsceol, go-between or bearer of news
- O'Toole US #3,297: Ó Tuathail, descendant of Tuathal, ruler of the people
- Hogan US #546: Ó hÓgáin, from óg, young; Tipperary and Clare
- Sheehan US #1,331: Ó Síodhacháin, from síodhach, peaceful
- Hennessy US #3,821: Ó hAonghusa, descendant of Aonghus, one strength
- Finnegan US #3,428: Ó Fionnagáin, from fionn, fair-haired
- Moran US #358: Ó Móráin, descendant of Mórán, from mór, great
- Regan US #1,678: Ó Riagáin, descendant of Riagán
Irish Mac and Mc surnames
Mac means son of. In Ireland it usually names a medieval ancestor, and Mc is simply a shortened spelling of Mac.
- McMahon US #893: Mac Mathghamhna, son of the bear; lords of Oriel and Clare
- McNamara US #1,334: Mac Conmara, son of the hound of the sea; a Clare clan
- McGrath US #1,019: Mac Craith, son of Craith; hereditary poets in Thomond
- McLoughlin: Mac Lochlainn, son of Lochlann, a name for a Norseman
- McDermott US #1,157: Mac Diarmada, son of Diarmaid; lords of Moylurg in Roscommon
- Maguire US #2,216: Mag Uidhir, son of the dun-colored one; lords of Fermanagh
- McKenna US #1,311: Mac Cionaoith, son of Cionaodh; a Monaghan family
- McDonnell US #2,546: Mac Domhnaill, son of Domhnall; Scottish-descended lords of the Glens of Antrim
- Brady US #465: Mac Brádaigh, son of Brádach; a Cavan family
- McCann US #1,009: Mac Cana, son of Cana, wolf cub; an Armagh family
- McGovern US #2,164: Mag Shamhradháin, from samhradh, summer; a Cavan family
- McCormack US #2,095: Mac Cormaic, son of Cormac, an old royal first name
- McKeown US #4,837: Mac Eoghain, son of Eoghan; say mik-OH-in
- McNally US #2,263: Mac an Fhailghigh, son of the poor man
- MacMurrough: Mac Murchadha, son of Murchadh; kings of Leinster
- Keogh: Mac Eochaidh, son of Eochaidh, horseman; say KEE-oh
- McSweeney: Mac Suibhne, son of Suibhne, pleasant; galloglass from Scotland
- McElroy US #1,479: Mac Giolla Rua, son of the red-haired lad
Irish second names by county
In Ireland, people often say second name for surname (in Irish, sloinne). These family names are still linked to the county or region where they began.
- Boyle US #905: Ó Baoighill; Donegal chiefs who gave their name to Boylagh
- Donnelly US #1,138: Ó Donnghaile, brown valor; an old Tyrone family
- McGuinness: Mag Aonghuis, son of Aonghus; lords of Iveagh in County Down
- McManus US #1,546: Mac Maghnuis, son of Magnus; a Fermanagh family of annalists
- Buckley US #840: Ó Buachalla, from buachaill, cowherd or boy; very common in Cork
- Crowley US #1,149: Ó Cruadhlaoich, hardy hero; a west Cork family
- Riordan US #4,565: Ó Ríoghbhardáin, descendant of the royal poet; a Cork name
- Foley US #667: Ó Foghladha, from a word for plunderer; rooted in Waterford
- Hickey US #1,253: Ó hÍcidhe, the healer; physicians to the O'Briens in Clare
- Moloney: Ó Maol Dhomhnaigh, servant of the church; a Clare family
- O'Meara: Ó Meadhra, from meadhar, merry; Toomyvara in Tipperary
- Molloy US #4,891: Ó Maolmhuaidh, proud chief; lords of Fir Cell in Offaly
- Fallon US #3,085: Ó Fallamháin, leader; an old Roscommon family
- Madden US #1,006: Ó Madaidhín, from madadh, hound; east Galway
Irish surnames from saints and trades
Giolla (servant), Maol (devotee) and Mac an (son of the) produced surnames honoring saints and hereditary professions.
- McGowan US #1,080: Mac Gabhann, son of the smith
- McAteer: Mac an tSaoir, son of the craftsman or carpenter
- McEntee: Mac an tSaoi, son of the scholar or wise man
- McNulty US #2,653: Mac an Ultaigh, son of the Ulsterman
- McInerney: Mac an Airchinnigh, son of the erenagh, a church steward
- Cleary US #2,306: Ó Cléirigh, from cléireach, clerk or cleric
- Fitzpatrick US #867: Mac Giolla Phádraig, son of the servant of Saint Patrick
- Gilmartin: Mac Giolla Mhártain, son of the servant of Saint Martin
- Kilbride: Mac Giolla Bhríde, son of the servant of Saint Brigid
- Gillespie US #836: Mac Giolla Easpaig, son of the bishop's servant
- McAleese: Mac Giolla Íosa, son of the servant of Jesus
- McGillycuddy: Mac Giolla Mochuda, son of the servant of Saint Mochuda
- Malone US #489: Ó Maoil Eoin, descendant of the devotee of Saint John
- Kavanagh: Caomhánach, follower of Saint Caomhán; a Leinster royal line
- Gilmore US #721: Mac Giolla Mhuire, son of the servant of Mary
- Monahan US #2,435: Ó Manacháin, from manach: the little monk
- Mullen US #971: Ó Maoláin, from maol, a devotee or tonsured monk
Norman and Anglo-Irish surnames
The Normans arrived in 1169. Many of their families adopted Irish language and customs, and their surnames are now thoroughly Irish.
- Burke US #256: From Norman de Burgh, a fortified place; Irish de Búrca
- Fitzgerald US #442: Son of Gerald; the Geraldine earls of Kildare and Desmond
- Power US #2,430: Norman le Poer, the poor man, or from Poix in France; a great Waterford family
- Roche US #1,924: Norman family named for a rock or rocky fort; Cork and Wexford
- Joyce US #1,052: From the Breton first name Josse; one of the Tribes of Galway
- Butler US #112: Wine steward of a royal household; the Ormond family of Kilkenny Castle
- Costello US #1,121: Mac Oisdealbhaigh, a Gaelicized branch of the Norman de Angulo family
- Nugent US #2,257: From Nogent in France; barons of Delvin in Westmeath
- Purcell US #1,620: Old French pourcel, piglet, a Norman nickname; Tipperary
- Prendergast: From a place in Pembrokeshire, Wales
- Fitzsimons: Son of Simon, with Norman fitz, son
- Fitzmaurice: Son of Maurice; lords of Kerry
- Fleming US #350: For someone from Flanders
- Devereux: From Évreux in Normandy; a Wexford family
- Tobin US #2,012: From Saint-Aubin in France; Kilkenny and Tipperary
- Cusack: From Cussac in southwest France; Meath landholders
- Lacy US #1,591: From Lassy in Normandy; the family built Trim Castle
Irish surnames by meaning
Gaelic names often described hair, character or an admired animal. Here are surnames meaning dark, ruddy, wolf, holly, fox and more.
- Duffy US #915: Ó Dubhthaigh, from dubh, black or dark
- Dunne US #3,941: Ó Duinn, from donn, brown
- Flanagan US #1,166: Ó Flannagáin, from flann, ruddy or red
- Duggan US #2,960: Ó Dubhagáin, from dubh, dark
- Dowd US #2,686: Ó Dubhda, from dubh, dark; a Sligo family
- Gorman US #1,145: Ó Gormáin, from gorm, blue
- Galvin US #3,032: Ó Gealbháin, from geal, bright or white
- Corcoran US #2,056: Ó Corcráin, from corcair, purple
- Whelan US #3,162: Ó Faoláin, from faol, wolf
- Cullen US #1,790: Ó Cuilinn, from cuileann, holly
- Keane US #3,304: Ó Catháin, from cath, battle
- Cahill US #1,738: Ó Cathail, descendant of Cathal, battle ruler
- Garvey US #3,185: Ó Gairbhith, from garbh, rough
- Treacy: Ó Treasaigh, descendant of Treasach, warlike or fierce
- Mooney US #1,082: Ó Maonaigh, descendant of Maonach, wealthy
- Murtagh: Ó Muircheartaigh, descendant of Muircheartach, sea navigator
- Coughlan: Ó Cochláin, from cochall, cape or hood
- Breen US #2,799: Ó Braoin, from braon, a drop of rain or moisture
- Connolly US #1,205: Ó Conghalaigh, from conghalach, valiant
- Kearney US #1,805: Ó Ceithearnaigh, warrior; the root of kern, an Irish foot soldier
- Markey: Ó Marcaigh, from marcach, horse rider
- Halloran: Ó hAllmhuráin, a stranger from across the sea
- Quinlan US #3,509: Ó Caoindealbháin, handsome form or shape
- Rafferty US #3,851: Ó Rabhartaigh, from rabharta, flood tide
- Durnin: Ó Doirnáin, from dorn, fist: the little fist
- McCabe US #1,167: Mac Cába, son of Cába, a byname meaning cape or cloak
- Fox US #180: Ó Sionnaigh, from sionnach, fox; rulers of Tethbae in the Midlands
Surnames in Irish: how to write and say them
Many people use the Irish form of their surname. These are modern standard spellings; the notes above often give the older form, such as Ó Murchadha for Ó Murchú. Women use Ní instead of Ó and Nic instead of Mac, and the next sound often softens.
- Ó Murchú: Murphy in Irish; say oh MUR-uh-khoo
- Ó Ceallaigh: Kelly in Irish; say oh KYAL-ee
- Ó Súilleabháin: O'Sullivan in Irish; say oh SOOL-uh-vawn
- Breathnach: Walsh in Irish, meaning Welshman; say BRAN-ukh
- Ó Briain: O'Brien in Irish; say oh BREE-in
- Ní Bhriain: A woman's form of Ó Briain; say nee VREE-in
- Ó Broin: Byrne in Irish; say oh BRIN
- Ó Riain: Ryan in Irish; say oh REE-in
- Ó Néill US #673: O'Neill in Irish; say oh NAYL
- Mac Cárthaigh: McCarthy in Irish; say mok KAR-hee
- Nic Cárthaigh: A woman's form of Mac Cárthaigh; say nik KAR-hee
- Ó Dónaill: O'Donnell in Irish; say oh DOH-nil
- Mac Mathúna: McMahon in Irish; say mok MAH-hoo-nuh
- de Búrca: Burke in Irish; say deh BOOR-kuh
- Mac Gearailt: Fitzgerald in Irish; say mok GAR-ilt
- Ó Dochartaigh: Doherty in Irish; say oh DOKH-ar-tee
- Ó Loingsigh: Lynch in Irish; say oh LING-shee
- Ó Dubhghaill: Doyle in Irish; say oh DOO-ill
- Ó Sé: O'Shea in Irish; say oh SHAY
- Ó Conchúir: O'Connor in Irish; say oh KUN-uh-khoor
- Ó Raghallaigh: O'Reilly in Irish; say oh RYE-lee
- Ó Dálaigh: Daly in Irish; say oh DAW-lee
- Ó Cinnéide: Kennedy in Irish; say oh kin-AY-deh
- Ó Floinn: Flynn in Irish; say oh FLIN
- Ó Tuathail: O'Toole in Irish; say oh TOO-uh-hil
- Ó hAodha: Hayes in Irish; say oh HAY
- Ó Cathasaigh: Casey in Irish; say oh KA-ha-see
- Mac Conmara: McNamara in Irish; say mok kun-MAR-uh
- Mac Giolla Phádraig: Fitzpatrick in Irish; say mok GIL-uh FAW-drig
- Ní Mhurchú: A woman's form of Ó Murchú; say nee VUR-uh-khoo
How to pick the right name
Know the Gaelic form
Most Irish surnames are English spellings of Gaelic names. Knowing that Murphy is Ó Murchú or Walsh is Breathnach helps with family history and with characters who speak Irish.
Let the county guide you
Many surnames are tied to a home ground: O'Sullivan to Cork and Kerry, Gallagher and Doherty to Donegal, Byrne to Wicklow. A surname can quietly place a character on the map.
Use the right form for women in Irish
In Irish, a daughter is Ní or Nic rather than Ó or Mac, so Máire Ó Briain is wrong and Máire Ní Bhriain is right. In English, the surname stays the same for everyone.
Keep the apostrophe
Write O'Brien and O'Neill with an apostrophe in English. Some families never restored the O, so plain Brien or Neill spellings can be authentic too.
Save this list for later
Pin it to a naming board, or tap the heart next to any name to keep it in your favorites on this device.
Irish last names: what ranks in Ireland and the US, and how the O' and Mac came and went
By The Nomezo Editors · Updated October 25, 2026 · How we research names
Murphy and Kelly have led Ireland's surnames for well over a century: they top both Matheson's count of births in 1890 and the births registered in 2020. In the US the same families often lost their prefix along the way, so Sullivan outnumbers O'Sullivan almost 18 to 1.
In Irish, a surname also changes with who carries it: the son of Ó Briain is Ó Briain, his sister is Ní Bhriain and his wife can be Bean Uí Bhriain. The tools above build those forms and show how to say them.
Ireland's most common surnames, 1890 and 2020
| Rank | 1890 (Matheson) | 2020 (CSO) |
|---|---|---|
| 1 | Murphy | Murphy |
| 2 | Kelly | Kelly |
| 3 | O'Sullivan | O'Brien |
| 4 | Walsh | Ryan |
| 5 | Smith | Byrne |
| 6 | O'Brien | O'Connor |
| 7 | Byrne | Walsh |
| 8 | Ryan | O'Sullivan |
| 9 | O'Connor | McCarthy |
| 10 | O'Neill | Doyle |
Source: Irish Genealogy Toolkit, quoting Robert Matheson's report on births registered in 1890 and the Central Statistics Office's count of surnames of babies registered in the Republic in 2020. Both count births, not the whole population.
Irish surnames in the US
- Mc or Mac says nothing about Ireland or Scotland. McCarthy outnumbers MacCarthy about 157 to 1 in the US, and even the Scottish McDonald (172,700) far outnumbers MacDonald (45,126).
| Surname | People in 2020 | Other spelling | People in 2020 |
|---|---|---|---|
| Sullivan | 212,701 | O'Sullivan | 11,971 |
| Carroll | 129,163 | O'Carroll | 686 |
| Reilly | 39,645 | O'Reilly | 12,063 |
| O'Brien | 115,547 | Brien | 2,637 |
| McCarthy | 80,108 | MacCarthy | 509 |
| McMahon | 38,378 | MacMahon | 540 |
Source: US Census Bureau, 2020 surnames. Murphy is the most common Irish surname in the US at No. 65 (298,047 people), and O'Brien (No. 261) the most common O' name. Older Census files drop the apostrophe, so search records for OBRIEN as well as O'Brien.
How Irish surnames work
- Ó and Mac. Ó (older Ua) means descendant or grandson, and Mac means son; Mag replaces Mac before a vowel, as in Mag Uidhir, Maguire (Wikipedia).
- Women's forms. A daughter takes Ní or Nic, and a married woman Bean Uí or Bean Mhic, or simply Uí or Mhic. The next sound softens, except that Nic and Mhic do not soften a c or g, as in Nic Cárthaigh (Wikipedia).
- The Normans. The first Normans landed at Bannow Bay, County Wexford, on 1 May 1169, led by Robert FitzStephen and Maurice de Prendergast (Wikipedia). Prendergast and the Fitz names are among the oldest Norman-Irish surnames.
- Fox is Irish too. In Ireland the surname Fox mainly comes from Ó Sionnaigh, a Midlands family who ruled Tethbae (Wikipedia)).
Sources
Frequently asked questions
What is the most common Irish last name?
Murphy is the most common surname in Ireland. It comes from Ó Murchadha, descendant of Murchadh, a name meaning sea warrior. Kelly, O'Sullivan, Walsh and O'Brien are also among the most common.
What do O' and Mac mean in Irish last names?
Ó, written O' in English, means grandson or descendant, and Mac means son. So O'Brien is descendant of Brian, and McCarthy is son of Cárthach.
Why do some Irish surnames have O' or Mac and others do not?
Under English rule many families dropped the prefix to fit in. During the Gaelic Revival of the late 1800s and early 1900s many restored it, while others, like most Murphys and Kellys, kept the shorter form.
What are Irish second names?
In Ireland, people often say second name for a surname, so Irish second names are family names like Murphy, Kelly and Walsh. The Irish word for surname is sloinne. In the Irish language they are written Ó Murchú, Ó Ceallaigh and Breathnach, and women use Ní or Nic in place of Ó or Mac.
Is Mc Irish and Mac Scottish?
No. Mc is simply a shortened spelling of Mac, and both are used in Ireland and Scotland. Which one a family uses usually came down to a clerk's habit or family preference.
What is the most common Irish surname in the US?
Murphy, No. 65 in the 2020 US Census with 298,047 people, followed by Kelly at No. 80 and Sullivan at No. 107. O'Brien is the most common surname that kept its O'.
What is a married woman's surname in Irish?
She can use Bean Uí or Bean Mhic before her husband's surname, or the short Uí or Mhic, with the next sound softened: the wife of Seán Ó Briain is Bean Uí Bhriain. A daughter uses Ní or Nic: Ní Bhriain.
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