There are 32 million Americans with Irish ancestry. Most of them carry a surname that points — like a compass — back to a specific county, a specific landscape, a specific way of life in Ireland. These names survived the Famine, the coffin ships, the tenements of Boston and New York. They are still here.
1. Murphy — The Most Irish Name in the World
Murphy comes from the Irish Ó Murchadha, meaning descendant of Murchadh — a name meaning sea warrior. It originated in County Cork and County Wexford, and today there are more Murphys in Ireland per capita than any other surname. In America, the Murphys came largely from Cork and Munster during and after the Great Famine of the 1840s.
2. Kelly — From the Ancient Kings of Connacht
Kelly comes from Ó Ceallaigh, meaning descendant of Ceallach — a name associated with war or strife. The Kellys were kings of Uí Maine in what is now County Galway and County Roscommon. Today Kelly is the second most common surname in Ireland and one of the most recognisable Irish names in America.
3. Sullivan — The Dark-Eyed Ones of Munster
Sullivan comes from Ó Súilleabháin, possibly meaning dark-eyed or hawk-eyed. The Sullivans were a great Munster family, dominant in Cork and Kerry for centuries. County Cork has more Sullivans than anywhere else in the world. If your name is Sullivan, your roots are almost certainly in the south-west of Ireland.
4. Walsh — The Welsh Settlers Who Became More Irish Than the Irish
Walsh is unusual — it means Welshman in Irish, from the word Breathnach. The Walshes descended from Welsh soldiers who came to Ireland with the Norman invasion in the twelfth century and settled so thoroughly that they became one of the great Irish families. They are most common in Connacht and Leinster.
5. O'Brien — The Royal Blood of Thomond
O'Brien comes from Ó Briain, meaning descendant of Brian — specifically Brian Boru, the High King of Ireland who defeated the Vikings at the Battle of Clontarf in 1014. The O'Briens ruled the kingdom of Thomond, covering what is now Clare, Limerick and North Tipperary. There is an O'Brien's Bridge on the River Lee in Cork city that has stood since the fifteenth century.
6. Ryan — From the Little King
Ryan comes from Ó Riain, meaning descendant of Rían — a name possibly meaning little king. The Ryans were a powerful family in County Tipperary and County Limerick. Today Ryan is one of the most common surnames in Munster and one of the most recognisable Irish names in America.
7. Connor — The Lover of Hounds
Connor — or O'Connor — comes from Ó Conchobhair, meaning descendant of Conchobar, a name meaning lover of hounds or high will. The O'Connors were kings of Connacht and produced the last High King of Ireland, Ruaidrí Ua Conchobair, who died in 1198. The name is most common in Connacht and Clare.
8. Reilly — The Prosperous and Valiant
Reilly — or O'Reilly — comes from Ó Raghallaigh, a name of uncertain meaning though possibly relating to prosperity or valour. The O'Reillys were the ruling family of Breifne, the ancient kingdom covering what is now Cavan and Leitrim. They were one of the most powerful Gaelic families in Ulster.
9. Dolan — From the Black Defiance
Dolan comes from Ó Dubhláin, meaning descendant of Dubhlann — a name combining dubh (black) and lann (blade or defiance). The Dolans were a Connacht family, most common in Roscommon and Galway. It is a less common name than the others on this list, which makes it all the more distinctive.
10. McCarthy — The Sons of the Loving One
McCarthy comes from Mac Cárthaigh, meaning son of Carthach — a name meaning loving. The McCarthys were the dominant family of Munster after the Norman invasion displaced the earlier Gaelic kings. Their heartland was County Cork, and their castles still stand across the south of Ireland today.
These names survived the Famine, the coffin ships, the tenements of Boston and New York. They are still here — carried across an ocean by people who had nothing else to bring.
If your surname is on this list, it is not just a name. It is a coordinates — pointing back to a specific place in Ireland, a specific landscape, a specific history. And that place is still there, waiting.
Receive a monthly letter from Ireland, personalized to your family name and county →
Published 2026-05-01 · Written from County Cork, Ireland