Origin of the O'Sullivan Clan Name

The name O'Sullivan is derived from the irish term meaning “one eye”, O Suilleabháin meaning one-eyed man. There origins are illustrious as they are descended from Eoghan Mor, father of Oilioll Olum and together with the McCarthys, O'Keeffes and O'Callaghans became the leading familiesof the Munster Eoganachta.

They originally inhabited the areas of Cahir in County Tipperary but today they are mainly found in Cork, Kerry and Limerick. When the Normans arrived in Ireland many clans were forced to retreat west as their homelands became parts of the new Norman or Anglo-Irish territories. In 1192 this happened to the O'Sullivans and they were forced into the territory of the O'Driscolls, whom they drove inot the sea and the Beara peninsula.

O'Sullivan Clan

Once established in the west the two septs of O'Sullivan Mor and O'Sullivan Beare rose to prominence. The O'Sullivan Mor had their principal seat at Dunkerrin on the shores of Kenmare Bay. The O'Sullivan Beare seat was in Beara and Bantry and their stronghold at Ardloe. Between 900 and 1600 an O'Sullivan led the Eoganachta nine times and their seat was at the Rock of Cashel in Tipperary.

In the 1300s when royalty was being established and recognised in Europe, the O'Sullivan-Mors managed to succeed where most other families and lines had failed and their royalty was acknowledged and is marked by the crown on their crest.

Many septs of this clan were actively involved in the seminal events of Irish history, up to the battles at Kinsale in the 1600s and their independence fiercely defended.

Today it remains one of the most popular surnames in Ireland and is third after Kelly and Murphy. The O'Sullivans are still living in their ancient homeland in counties Cork, Kerry and some in Limerick. 

There are more than 200,000 carriers of the name Sullivan in the United States.