O'Neil
An Irish surname meaning “descendant of Neil,” ultimately tied to the Gaelic personal name Niall.
The #1,220 most common surname in the United States (2010 Census) — about 1 in every 10,665 Americans shares it.
Etymology
O'Neil is an anglicized form of the Irish Gaelic surname O'Neill, from Ó Néill. The prefix Ó means “grandson” or “descendant,” while Niall is an old Gaelic personal name whose exact original meaning is uncertain, though it is often associated with ideas like “champion” or “cloud.” In modern spelling, the apostrophe may be dropped, giving forms such as Oneil or ONeil.
History
The name is strongly associated with the great medieval O'Neill dynasties of Ulster, especially in counties Tyrone and Antrim. In later centuries it spread widely through Ireland and then abroad, particularly to the United States through emigration. The shortened or apostrophe-less spelling Oneil is a common modern variant in records and official documents.
Origin
Regions
Variant spellings
Fun fact
The O'Neill surname was carried by several powerful Gaelic ruling families, including the chiefs traditionally styled the O'Neills of Tyrone.