ONeill

ONeill is a variant spelling of the Irish surname O'Neill. It derives from the Gaelic Ó Néill, meaning "descendant of Néill," with Néill a given name linked to Niall, a common figure in early Irish history and legend.

Historically, the Ó Néill were one of the leading Gaelic dynasties in Ireland, controlling Ulster for centuries. Distinct branches include the O'Neill of Tyrone and the O'Neill of Clandeboye, who played prominent roles in medieval and early modern Irish politics and resistance to English rule. The dynasty declined after the Flight of the Earls in 1607 and the subsequent Ulster Plantations, yet the name remains strong in Ulster and among the Irish diaspora.

Geographically, ONeill and its variants are widespread in Ireland and among Irish-descended communities in the United States, Canada, the United Kingdom, and Australia. Spelling variants include O'Neill, O'Neil, O'Neal, Neill, and, in some cases, ONeill without an apostrophe. Orthography often reflects regional or family history and migration patterns.

In modern times, the surname is common across professions and cultures, appearing in politics, sports, academia, and the arts. In literature and film, ONeill and its variants are used as family names for fictional characters as well. The name continues to be a marker of Irish heritage for many people around the world.

See also: O'Neill disambiguation.