O'Sullivan Name History

O'Sullivan Name History


O'Sullivan (Irish: Ó Súilleabháin), also known as simply Sullivan, is an Irish Gaelic clan based most prominently in what is today County Cork and County Kerry. The surname is associated with the southwestern part of Ireland and was originally found in County Tipperary before the Anglo-Norman invasion. It is the third most numerous surname in Ireland. Due to emigration is also common in Australia, North America, Britain and the rest of the world.

The O'Sullivans are the medieval and modern continuation of the ancient Eóganacht Chaisil sept of Cenél Fíngin, being descendants of Fíngen mac Áedo Duib, king of Cashel or Munster from 601 to 618. They are thus understood to be of royal extraction. Fedelmid mac Crimthainn (died 847), the celebrated King of Munster and nearly High King of Ireland, was the last king of the Cenél Fíngin/O'Sullivan line. Later they became the chief princes underneath their close kinsmen the MacCarthy dynasty in the small but powerful Kingdom of Desmond, successor of Cashel/Munster. 


The O'Sullivan clan claimed a descent from the mythological followers of Milesius who were the first Celts to colonize Innis Fáil, their "island of destiny". They had migrated from an area of the northwest coast of Spain which is now known as the province of Galicia. There they had founded a city they called Brigantia. They had remained there for several generations before embarking on the last leg of their odyssey. They arrived in their promised land in approximately the year 800 B.C

Learn more about the O'Sullivan

The Framed Irish Family Name History, (#1760) has more information on the O'Sullivan surname. There is a wide selection of O'Sullivan coat of arms products at The Irish Rose. Please visit the Irish Coat of Arms page.

Visit O'Sullivan's Pub in Ireland

You can visit at least two O'Sullivan's Pubs in Ireland.

If you can't visit in person, our personalized pub gifts are the next best thing!

Notable people named O'Sullivan

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