O'Neill (also spelled O'Neil) is a common surname of Irish origin.

Its original Gaelic form is Ó Néill or Ua Néill, meaning 'grandson of Niall'. The surname Ó Néill was taken from a much later man of the same name, Niall Glundubh of the Ui Néill.

In past usage, it refers to an Irish kinship group based in Ulster, descended from a family from which a number of High Kings of Ireland sprang in medieval times. The progenitor of the dynasty was Niall of the Nine Hostages (Niall Noigiallach), said to be High King and died c.450. The O'Neill was the traditional title of the head of this family, and during early English rule the holder of this title was considered by many to be the rightful High King of Ireland.

Spelling variants include O'Neil and O'Neal.

Places named O'Neill

• O'Neill, Nebraska, USA

Things named O'Neill

• The O'Neill wetsuit, a style of wetsuit

People named O'Neill

• O'Neill, Conn (1480-1559), 1st Earl of Tyrone
• O'Neill, Eugene, (1888-1953), American dramatist
• O'Neil, Henry, British painter
• O'Neill, Hugh (1540-1616), 2nd Earl of Tyrone and The O'Neill see also Flight of the Earls and Nine Years War (Ireland)
• Hugh Dubh O'Neill - 17th c soldier
• O'Neill, Jonjo , jockey
• O'Neill, Kevin (1953-), comics creator, artist of League of Extraordinary Gentlemen books
• Martin O'Neill- Glasgow Celtic football manager
• O'Neill, Paul Henry (1935-), executive
• O'Neill, Paul , musician
• O'Neill, Paul Andrew (1963-), American baseball player (ie. baseballer)
• Phelim O'Neill - leader of the Irish Rebellion of 1641
• Owen Roe O'Neill - leader of the Ulster Irish army during Irish Confederate Wars
• O'Neill, Thomas P. "Tip", (1912-1994), U.S. Senator

See also

• Uí Néill
• List of people by name: Ol-Oo