The origin of the name O’Sullivan

The surname O’Sullivan or in Irish Ó Súilleabháin traces its origin from Míl Espáine or Milisius, King of the Milesians (or Celts), King of Spain through the line of his son, Heber, first absolute King of Ireland 504 BC. The surname O’Sullivan is derived from the words Súil (eye) and abháin, (one) and in its Irish form Ó Súillabháin means descendant of the one eyed or descendant of the hawk-eyed. The O’Sullivans were descendants of Eoghan (Owen) Mór, the father of the famous Olioll Olum, celebrated King of Munster in the third Century. Olioll Olum had three sons, Eoghan, Cormac Cais and Cian, and by his will he commanded that the kingdom should be ruled alternately by one of the descendants of Eoghan and Cormac Cais. From Eoghan, the eldest son of Olioll Olum, descended the Eoganachts or Eugenians, who were styled Kings of Cashel. The Eoghanachts possessed Desmond or south Munster, the present counties of Cork and Kerry; they also held most of the present county of Tipperary. The O’Sullivans were one of the principal families of the race of Eogan or Eoghanacht (i.e. descendants of Eoghan) of Munster. There were three principal branches of the O’Sullivan Clan:-

1. O’Sullivan Beara: This branch of the family had the ancient territory of Beara, now the baronies of Beare and Bantry in the county of Cork, and were called O’Sullivan Beara and styled princes of Beara.

2. O’Sullivan Mór: This branch of the family were lords of Dunkerron, they possessed the barony of Dunkerron near the river Kenmare and their chief seat was the castle of Dunkerron.

3. O’Sullivan of Croc Raffan: This branch of the O’Sullivans were chiefs of Knockgraffan in Tipperary and the territory they possessed in Tipperary was situated in the barony of Middlethird, between Cashel and Cahir.
The O’Sullivan family motto is Lamh foistenach abu meaning ‘The steady hand to victory’.
The name O’Sullivan and its variant forms are the third most numerous surname in Ireland. There are an estimated 41,500 bearers of the name resident in the island at the present time. However, we must not forget that there are possibly ten times that total of O’Sullivans living outside the shores of Ireland, in the two Americas, Canada, Australia, New Zealand, England, Europe, the African Continent and to a lesser extent Asia and the rest of the world. There is an O’Sullivan family in every county in Ireland, but the main branch of the
family is associated with the province of Munster.