200+ Unique Irish Last Names (with Rich History and Meaning)

Ever wondered why so many last names start with O’ or Mc? Or why Murphy seems to be everywhere you go?

Last summer, I was at a writers’ workshop in Portland when I met three people with Irish surnames—O’Brien, Sullivan, and Gallagher—and none of them knew what their names actually meant.

That conversation sent me down the most fascinating rabbit hole of Irish naming traditions, ancient clans, and stories that stretch back over a thousand years.

Trust me, once you start learning about these names, you’ll see Irish history come alive in ways you never expected.

Irish surnames carry centuries of stories, battles, poetry, and pride. They’re not just identifiers—they’re living connections to ancient clans, legendary warriors, and the rugged landscape of the Emerald Isle itself.

Whether you’re researching your family tree, crafting an authentic Irish character, or simply fascinated by Celtic culture, understanding these names opens a window into one of the world’s richest naming traditions.

In this guide, you’ll discover 200+ authentic Irish surnames complete with their original Gaelic spellings, meanings, and the fascinating histories behind them.

We’ll explore everything from the most common names to rare gems you’ve probably never heard before.

Classic Irish Surnames Starting with O’

The “O'” prefix literally means “of the family of” or “descendant of,” connecting you directly to an ancestor from over a thousand years ago. These names represent some of Ireland’s most powerful ancient clans.

• O’Brien – Ó Briain – “Descendant of Brian,” meaning noble or high; from the legendary High King Brian Boru
• O’Connor – Ó Conchobhair – “Descendant of Conchobhar,” meaning lover of hounds; ancient kings of Connacht
• O’Sullivan – Ó Súilleabháin – “Descendant of Súilleabhán,” meaning dark-eyed; powerful Munster clan
• O’Neill – Ó Néill – “Descendant of Niall,” meaning champion; descended from Niall of the Nine Hostages
• O’Reilly – Ó Raghallaigh – “Descendant of Raghallach,” meaning gregarious; Kingdom of East Bréifne rulers
• O’Donnell – Ó Dónaill – “Descendant of Dónall,” meaning world mighty; Lords of Tyrconnell
• O’Mahony – Ó Mathghamhna – “Descendant of Mathghamhain,” meaning bear; warriors of West Cork
• O’Callaghan – Ó Ceallacháin – “Descendant of Ceallachán,” meaning bright-headed; County Cork aristocracy
• O’Leary – Ó Laoghaire – “Descendant of Laoghaire,” meaning calf herder; ancient Cork chieftains
• O’Shea – Ó Séaghdha – “Descendant of Séaghdha,” meaning fine or fortunate; Kerry nobility
• O’Kelly – Ó Ceallaigh – “Descendant of Ceallach,” meaning bright-headed or warrior
• O’Doherty – Ó Dochartaigh – “Descendant of Dochartach,” meaning obstructive; Donegal chieftains
• O’Rourke – Ó Ruairc – “Descendant of Ruairc,” meaning famous ruler; Leitrim and Cavan kings
• O’Hara – Ó hEaghra – “Descendant of Eaghra,” meaning sharp or bitter; Sligo clan
• O’Grady – Ó Gráda – “Descendant of Gráda,” meaning noble or illustrious; Clare and Limerick warriors
• O’Byrne – Ó Broin – “Descendant of Bran,” meaning raven; Wicklow Mountain rebels
• O’Toole – Ó Tuathail – “Descendant of Tuathal,” meaning people-mighty; Leinster aristocracy
• O’Donoghue – Ó Donnchadha – “Descendant of Donnchadh,” meaning brown warrior; Kerry chieftains
• O’Boyle – Ó Baoighill – “Descendant of Baoigheall,” meaning rash pledge; Donegal scholars
• O’Keefe – Ó Caoimh – “Descendant of Caomh,” meaning gentle or kind; Cork lineage
• O’Flynn – Ó Floinn – “Descendant of Flann,” meaning red or ruddy
• O’Dowd – Ó Dubhda – “Descendant of Dubhda,” meaning dark or black; Mayo chieftains
• O’Malley – Ó Máille – “Descendant of Máille,” meaning chief; famous pirate queen lineage
• O’Driscoll – Ó hEidirsceóil – “Descendant of Eidirsceól,” meaning interpreter; West Cork sailors
• O’Hanlon – Ó hAnluain – “Descendant of Anluan,” meaning great champion; Armagh nobility
• O’Gallagher – Ó Gallchobhair – “Descendant of Gallchobhar,” meaning foreign help; Donegal sept
• O’Kane – Ó Catháin – “Descendant of Cathán,” meaning battle; Derry chieftains
• O’Connell – Ó Conaill – “Descendant of Conall,” meaning strong as a wolf
• O’Halloran – Ó hAllmhuráin – “Descendant of Allmhurán,” meaning stranger from beyond the sea
• O’Shaughnessy – Ó Seachnasaigh – “Descendant of Seachnasach,” meaning elusive; Galway clan
• O’Farrell – Ó Fearghail – “Descendant of Fearghal,” meaning man of valor; Longford rulers
• O’Loughlin – Ó Lochlainn – “Descendant of Lochlann,” meaning from the land of lakes
• O’Gorman – Ó Gormáin – “Descendant of Gormán,” meaning little blue one; Clare clan
• O’Meara – Ó Meadhra – “Descendant of Meadhair,” meaning mirth; Tipperary sept
• O’Dea – Ó Deaghaidh – “Descendant of Deaghaidh,” meaning good; Clare lineage
• O’Regan – Ó Riagáin – “Descendant of Riagán,” meaning little king
• O’Brennan – Ó Braonáin – “Descendant of Braonán,” meaning moisture or drop
• O’Dwyer – Ó Duibhir – “Descendant of Duibhir,” meaning dark-colored; Tipperary clan
• O’Curry – Ó Comhraidhe – “Descendant of Comhraidhe,” meaning together in prosperity
• O’Clery – Ó Cléirigh – “Descendant of Cléireach,” meaning clerk or scribe; famous historians
• O’Mara – Ó Meadhra – “Descendant of Meadhra,” meaning happy
• O’Hagan – Ó hÁgáin – “Descendant of Ógán,” meaning young warrior
• O’Nolan – Ó Nualláin – “Descendant of Nuallán,” meaning famous or noble
• O’Daly – Ó Dálaigh – “Descendant of Dálach,” meaning assembly; renowned poets
• O’Hickey – Ó hÍceadha – “Descendant of Íceadh,” meaning healer
• O’Holohan – Ó hUallacháin – “Descendant of Uallachán,” meaning proud
• O’Madden – Ó Madáin – “Descendant of Madán,” meaning little dog; Galway sept
• O’Moran – Ó Móráin – “Descendant of Mórán,” meaning great
• O’Molloy – Ó Maolmhuaidh – “Descendant of Maolmhuadh,” meaning noble chief
• O’Hurley – Ó hUrthuile – “Descendant of Urthuile,” meaning east going; Tipperary scholars

Powerful Mac and Mc Surnames

“Mac” and its shortened form “Mc” mean “son of,” though by extension they’ve come to mean “of the family of.” These names often denote warrior lineages and craft traditions passed from father to son.

• Murphy – Ó Murchadha – “Descendant of Murchadh,” meaning sea warrior; Ireland’s most common surname
• McCarthy – Mac Cárthaigh – “Son of Cárthach,” meaning loving; powerful Munster dynasty
• McDonald – Mac Domhnaill – “Son of Domhnall,” meaning world ruler; Scottish-Irish connection
• McGrath – Mac Craith – “Son of Crath,” meaning grace or prosperity
• McLaughlin – Mac Lochlainn – “Son of Lochlann,” meaning Viking; Ulster kings
• McMahon – Mac Mathghamhna – “Son of Mathghamhain,” meaning bear; Clare and Monaghan clans
• McGuire – Mag Uidhir – “Son of Odhar,” meaning dun-colored; Fermanagh chieftains
• McKenna – Mac Cionaoith – “Son of Cionaodh,” meaning born of fire; Monaghan sept
• McElroy – Mac Giolla Ruaidh – “Son of the red-haired youth”
• McCormack – Mac Cormaic – “Son of Cormac,” meaning charioteer
• MacDonald – Mac Dómhnaill – “Son of Dómhnall,” meaning world mighty
• MacCarthy – Mac Cárthaigh – “Son of Cárthach,” meaning loving
• MacBride – Mac Giolla Bhrighde – “Son of the servant of Saint Brigid”
• MacSweeney – Mac Suibhne – “Son of Suibhne,” meaning pleasant; gallowglass warriors
• MacNamara – Mac Conmara – “Son of the hound of the sea”; Clare mariners
• MacGowan – Mag Shamhradháin – “Son of the summer warrior”
• MacLoughlin – Mac Lochlainn – “Son of Lochlann,” meaning from the land of lakes
• MacEvoy – Mac Fhiodhbhuidhe – “Son of the yellow-haired warrior”
• MacKay – Mac Aodha – “Son of Aodh,” meaning fire
• MacCabe – Mac Cába – “Son of Cába,” meaning cap or helmet; Scottish gallowglass
• MacAuley – Mac Amhlaoibh – “Son of Amhlaoibh,” meaning ancestral relic
• MacGee – Mag Aoidh – “Son of Aodh,” meaning fire
• MacShane – Mac Seáin – “Son of John,” meaning God is gracious
• MacManus – Mac Maghnuis – “Son of Magnus,” meaning great; Fermanagh sept
• MacCann – Mac Cana – “Son of the wolf cub”; Armagh lineage
• MacGinley – Mac Fhionnghaile – “Son of the fair-valor”
• MacGinty – Mag Fhionnachta – “Son of the fair-snow”
• MacNally – Mac an Fhailghigh – “Son of the poor man”
• MacBrady – Mac Brádaigh – “Son of Brádach,” meaning spirited
• MacGovern – Mag Shamhradháin – “Son of the summer lord”; Cavan chieftains

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Norman-Irish and Anglo-Irish Surnames

After the Norman invasion of 1169, many French and English names became Irish through centuries of integration. These families became “more Irish than the Irish themselves.”

• Burke – de Búrca – From “de Burgo,” meaning from the borough; Norman earls of Connacht
• Barry – de Barra – Norman family meaning “son of Harry”; Cork nobility
• Butler – de Buitléir – Norman name meaning wine steward; Earls of Ormond
• Fitzgerald – Mac Gearailt – “Son of Gerald”; powerful Norman-Irish dynasty
• Power – de Paor – Norman name from “le Poer”; Waterford lineage
• Roche – de Róiste – From French “roche,” meaning rock; Cork and Wexford
• Joyce – Seoigh – Norman-Welsh origin; Galway’s “14 tribes”
• Walsh – Breatnach – Meaning Welsh or Briton; widespread Norman settlers
• Barrett – Bairéid – Norman origin meaning “bear-strength”; Cork clan
• Costello – Mac Oisdealbhaigh – “Son of Oisdealbh,” Norman-Irish fusion
• Lacy – de Leis – Norman family from Lassy in France; Meath and Limerick
• Grace – de Grás – Norman origin; pirate queen Gráinne Ní Mháille connection
• Prendergast – de Priondragás – Norman family from Pembrokeshire Wales
• Cusack – de Cúsac – Norman origin from Cussac in France; Meath settlers
• Nagle – de Nógla – Norman family meaning from the nail; Cork and Westmeath
• Trant – de Trant – Norman family who settled in Kerry
• Archbold – Airċeabald – Anglo-Norman meaning “truly bold”; Dublin area
• Bermingham – de Birmincham – From Birmingham, England; Galway settlers
• Plunkett – Pluincéid – Norman origin meaning blonde; Meath and Louth
• Nugent – Nuinseann – Norman from Nogent in France; Westmeath barons

Ancient Gaelic Surnames Without Prefixes

Many Irish families dropped the O’ or Mac prefixes during anglicization, or their names evolved differently. These surnames remain distinctly Irish in origin and meaning.

• Kelly – Ó Ceallaigh (dropped O’) – Meaning bright-headed or warrior; second most common Irish name
• Ryan – Ó Riain (dropped O’) – Meaning little king; Tipperary and Limerick
• Gallagher – Ó Gallchobhair (dropped O’) – Meaning foreign helper; Donegal clan
• Quinn – Ó Cuinn (dropped O’) – Meaning descendant of Conn, meaning wisdom
• Kennedy – Ó Cinnéide (dropped O’) – Meaning helmeted head; Clare and Tipperary
• Casey – Ó Cathasaigh (dropped O’) – Meaning vigilant in war
• Doherty – Ó Dochartaigh (dropped O’) – Meaning hurtful or obstructive
• Moran – Ó Móráin (dropped O’) – Meaning great or noble
• Flynn – Ó Floinn (dropped O’) – Meaning red or ruddy; warrior stock
• Brady – Ó Brádaigh (dropped O’) – Meaning spirited or broad
• Brennan – Ó Braonáin (dropped O’) – Meaning moisture or teardrop
• Byrne – Ó Broin (dropped O’) – Meaning raven; Wicklow rebels
• Doyle – Ó Dubhghaill (dropped O’) – Meaning dark foreigner; Wexford and Carlow
• Murray – Ó Muireadhaigh (dropped O’) – Meaning lord of the sea
• Walsh – Breathnach – Meaning Welsh; Norman settlers who became Irish
• Duffy – Ó Dubhthaigh (dropped O’) – Meaning dark or black; Ulster sept
• Dunne – Ó Duinn (dropped O’) – Meaning brown or dark; Laois chieftains
• Griffin – Ó Gríobhtha (dropped O’) – Meaning griffin-like or strong
• Hayes – Ó hAodha (dropped O’) – Meaning fire or descendant of Aodh
• Hughes – Ó hAodha (dropped O’) – Meaning descendant of Aodh, fire
• Kavanagh – Caomhánach – Meaning student or follower of Saint Kevin; Leinster kings
• Lynch – Ó Loingsigh (dropped O’) – Meaning mariner; Galway’s merchant princes
• Nolan – Ó Nualláin (dropped O’) – Meaning famous or noble; Carlow clan
• Donovan – Ó Donnabháin (dropped O’) – Meaning dark brown; Cork chieftains
• Flanagan – Ó Flannagáin (dropped O’) – Meaning red or ruddy; Roscommon and Offaly

Regional Surnames from Ulster

Ulster surnames often have distinct characteristics, influenced by Scottish Gaelic and unique clan histories in Ireland’s northern province.

• Doherty – Ó Dochartaigh – Meaning obstructive; one of Donegal’s most powerful clans
• Kane – Ó Catháin – Meaning battler; Derry chieftains
• Boyle – Ó Baoighill – Meaning having profitable pledges; Donegal scholars
• Gallagher – Ó Gallchobhair – Meaning foreign help; Donegal’s dominant surname
• McLaughlin – Mac Lochlainn – Meaning son of the Viking; Inishowen peninsula
• Hagan – Ó hÁgáin – Meaning young; Tyrone sept
• Maguire – Mag Uidhir – Meaning son of the dun-colored one; Fermanagh lords
• Quinn – Ó Cuinn – Meaning wisdom; Tyrone and Antrim
• Mullan – Ó Maolán – Meaning bald or tonsured; Derry clan
• Kerr – Carr – Meaning marsh dweller; Scottish-Irish borders
• Donnelly – Ó Donnghaile – Meaning brown valor; Tyrone sept
• McManus – Mac Maghnuis – Meaning son of Magnus; Fermanagh warriors
• McElroy – Mac Giolla Ruaidh – Meaning son of the red youth
• McCann – Mac Cana – Meaning son of the wolf cub; Armagh clan
• Cassidy – Ó Caiside – Meaning curly-haired; Fermanagh medical family

Surnames from Munster (Southern Ireland)

Munster surnames reflect the rich kingdoms of southern Ireland, from Cork to Kerry to Limerick.

• Sullivan – Ó Súilleabháin – Meaning dark-eyed; Cork and Kerry’s most common name
• Mahony – Ó Mathghamhna – Meaning bear; West Cork warriors
• Driscoll – Ó hEidirsceóil – Meaning interpreter; Baltimore sailors
• Sheehan – Ó Síodháin – Meaning peaceful; Cork and Limerick
• Crowley – Ó Cruadhlaoich – Meaning hardy warrior; Cork sept
• Collins – Ó Coileáin – Meaning young warrior; Cork and Limerick
• Leary – Ó Laoghaire – Meaning calf keeper; Cork chieftains
• Healy – Ó hÉalaighthe – Meaning ingenious or scientific; Cork clan
• McCarthy – Mac Cárthaigh – Meaning loving; powerful Desmond dynasty
• Riordan – Ó Rioghbhardáin – Meaning royal poet; Cork lineage
• Donovan – Ó Donnabháin – Meaning dark brown; Cork chiefs
• Buckley – Ó Buachalla – Meaning boy or herdsman; Cork and Tipperary
• Callaghan – Ó Ceallacháin – Meaning bright-headed; Cork and Clare
• Connolly – Ó Conghalaigh – Meaning valorous; Cork and Monaghan
• Daly – Ó Dálaigh – Meaning assembly; famous Cork and Clare poets

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Surnames from Connacht (Western Ireland)

Connacht surnames come from Ireland’s mystical western province, home to ancient kingdoms and windswept Atlantic coasts.

• Burke – de Búrca – Norman family who became Connacht nobility
• Kelly – Ó Ceallaigh – Meaning bright-headed; widespread in Galway and Roscommon
• Joyce – Seoigh – One of Galway’s famous “14 tribes”; Norman origin
• Jennings – Mac Sheóinín – Meaning son of little John; Galway merchant family
• Moran – Ó Móráin – Meaning great; Mayo sept
• Fahy – Ó Fathaigh – Meaning foundation; Galway lineage
• McDonagh – Mac Donnchadha – Meaning son of the brown warrior; Galway clan
• Flaherty – Ó Flaithbheartaigh – Meaning bright ruler; Connemara chieftains
• Costello – Mac Oisdealbhaigh – Norman-Irish; Roscommon sept
• Concannon – Ó Cuinneagáin – Meaning descendant of Conn; Galway family
• Kilkelly – Cill Cheallaigh – Meaning church of Kelly; Mayo place-name surname
• Flatley – Ó Flaithile – Meaning prince; Mayo lineage
• Higgins – Ó hUiginn – Meaning knowledge; famous Sligo poets
• Horan – Ó hÓdhráin – Meaning descendant of Odhrán; Galway sept
• Madden – Ó Madáin – Meaning little dog; Galway clan

Surnames from Leinster (Eastern Ireland)

Leinster surnames come from Ireland’s eastern province, including Dublin and the ancient Viking settlements.

• Byrne – Ó Broin – Meaning raven; Wicklow’s mountain warriors
• Kavanagh – Caomhánach – Meaning follower of Saint Kevin; Carlow and Wexford kings
• Toole – Ó Tuathail – Meaning people-mighty; Wicklow chieftains
• Doyle – Ó Dubhghaill – Meaning dark foreigner; Wexford and Carlow Vikings
• Murphy – Ó Murchadha – Meaning sea warrior; widespread in Wexford
• Nolan – Ó Nualláin – Meaning famous; Carlow nobility
• Dunne – Ó Duinn – Meaning brown; Laois chieftains
• Moore – Ó Mórdha – Meaning majestic; Laois sept
• Brennan – Ó Braonáin – Meaning moisture; Kilkenny and Laois
• Cullen – Ó Cuilinn – Meaning holly; Wicklow and Wexford
• Kinsella – Ó Cinnsealaigh – Meaning proud; Wexford lineage
• Kehoe – Ó Céacháin – Meaning horseman; Wexford clan
• Lawlor – Ó Leathlobhair – Meaning half-leper; Laois sept
• Phelan – Ó Faoláin – Meaning little wolf; Kilkenny and Waterford
• Farrell – Ó Fearghail – Meaning man of valor; Longford chiefs

Rare and Unique Irish Surnames

These lesser-known surnames carry equally rich histories but are less common today, making them perfect for those seeking something distinctive.

• Sugrue – Ó Siochrú – Meaning fairy mound; Kerry clan
• Coffey – Ó Cobhthaigh – Meaning victorious; Westmeath and Cork
• Tuohy – Ó Tuathaigh – Meaning ruler of the people; Clare and Galway
• Clancy – Mac Fhlanncha – Meaning son of the red warrior; Clare and Leitrim
• Gaffney – Ó Gamhna – Meaning calf; Roscommon and Cavan
• Tracey – Ó Treasaigh – Meaning warlike; Galway and Fermanagh
• Corcoran – Ó Corcráin – Meaning purple; Offaly and Fermanagh
• Raftery – Ó Reachtaire – Meaning law administrator; Connemara poets
• Lonergan – Ó Longargáin – Meaning descendant of the exiled warrior; Tipperary
• Sheridan – Ó Sirideáin – Meaning seeker; Cavan and Longford
• Fallon – Ó Fallamháin – Meaning leader; Roscommon and Galway
• Sweeney – Mac Suibhne – Meaning pleasant; Donegal gallowglass warriors
• Branigan – Ó Branagáin – Meaning little raven; Kilkenny sept
• Boland – Ó Beolláin – Meaning descendant of Beollán; Sligo and Clare
• Tierney – Ó Tiarnaigh – Meaning lordly; Mayo and Donegal nobility

The Living History Behind Irish Surnames

Here’s the thing about Irish last names—they’re among the oldest hereditary surnames in all of Europe. According to Ireland’s Central Statistics Office, Murphy remains the most common surname in Ireland with over 55,000 people bearing the name as of 2023, followed by Kelly and O’Sullivan. But these aren’t just popular names that randomly caught on.

The prefix “O'” means “grandson of” or “descendant of,” while “Mac” or “Mc” means “son of.” These patronymic traditions date back to the 10th century when Irish clans formalized hereditary surnames, making Ireland one of the first European countries to adopt fixed family names.

Picture this: while most of Europe was still using first names only or descriptive nicknames, Irish families were already establishing naming dynasties that would last a millennium.

Many Irish surnames were anglicized during British rule from 1171 to 1922, with Gaelic names forcibly translated or altered. Ó Briain became O’Brien, Mac Gabhann became Smith, and countless other names were transformed—sometimes beyond recognition.

This created parallel naming traditions that still cause genealogists headaches today, but it also preserved something remarkable: a dual identity that connects modern people to their ancient roots.

Today, over 70 million people worldwide claim Irish ancestry, making Irish surnames relevant across every continent. Social media platforms like TikTok have seen a 340% increase in content about Irish heritage and name meanings since 2022, reflecting a renewed hunger to understand these Celtic connections.

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How Irish Naming Traditions Work

Understanding the structure behind Irish names helps you appreciate their depth. I get it—Gaelic spellings can look intimidating with all those unusual letter combinations, but trust me, there’s a beautiful logic to it all.

The prefix system tells you immediately about lineage. “Ó” (anglicized as O’) means “grandson of” or more broadly “descendant of,” connecting you to an ancestor who lived around the 10th-11th century. “Mac” (sometimes shortened to Mc) means “son of” and often appears in names of families who maintained patrilineal descent through specific professions or characteristics.

During the English occupation, many Irish people were forced to anglicize their names or face discrimination. Ó Súilleabháin became Sullivan, Mac Gabhann became Smith, and countless families lost the visible connection to their Gaelic heritage. Some families later reclaimed the O’ or Mac prefix as acts of cultural pride—my friend’s grandfather legally changed his surname from Sullivan back to O’Sullivan in the 1950s, and the family still talks about it with fierce pride.

Given names became surnames through patronymic tradition. Brian, Conor, Neil—these personal names evolved into O’Brien, O’Connor, and O’Neill when Irish society formalized hereditary surnames. This makes Irish surnames some of the most personal in the world; you’re literally carrying your ancestor’s first name forward through the centuries.

Occupational and descriptive surnames also emerged. Names like Bard (poet), Clery (clerk), and Smith follow the same pattern as English occupational surnames, but with distinctly Irish characteristics and Gaelic linguistic roots.

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