The O’Neill surname
Ó Néill in Irish. ‘Descendant of Niall’. The name is usually traced to Niall Glúndub, a High King killed in 919.
The O’Neills were the leading family of the Cenél nEógain in Ulster, centred on what is now County Tyrone. For centuries they were among the most powerful families in Ireland, and Hugh O’Neill, Earl of Tyrone, led the Nine Years’ War (1593–1603).
Medieval genealogies trace the wider Uí Néill dynasty back to Niall Noígíallach – ‘Niall of the Nine Hostages’ – a figure who sits between history and legend.
Your surname is linked to ‘Niall of the Nine Hostages’
O’Neill is one of the surnames of the Uí Néill, the dynasty that claimed descent from Niall of the Nine Hostages.
The honest caveat: Niall of the Nine Hostages is semi-legendary – historians aren’t sure how much of his story is true. A 2006 study by Trinity College Dublin researchers found a Y-DNA pattern common in north-west Ireland and among some Uí Néill surnames, but it does not prove that everyone called O’Neill descends from one man, or from Niall himself. Use it as a story to explore, not a fact about you.
Other spellings to search
Neill, O’Neil, Neil, Nihill (in Clare, a separate family)
Where the name is strongest
County Tyrone, County Antrim, County Armagh, County Derry
Tips for finding O’Neill ancestors
- Many O’Neills from Ulster will be on GRONI (Northern Ireland records) for births after 1921.
- The ‘O’ was often dropped in records from the 1700s and 1800s, so search ‘Neill’ too.
Start with the free official sources, or our guide to finding a grandparent’s birth record.
Sources
- Edward MacLysaght, The Surnames of Ireland
- Moore, McEvoy et al., ‘A Y-chromosome signature of hegemony in Gaelic Ireland’, American Journal of Human Genetics, 2006
- Dictionary of Irish Biography (dib.ie), entries ‘Niall Glúndub’, ‘O’Neill, Hugh’
Surname stories are for interest. Sharing a surname is not proof of descent from anyone, and it says nothing about citizenship.