Oneill

Oneill is a masculine surname that has transitioned into occasional use as a first name. It derives from the ancient Irish Gaelic surname Ó Néill, meaning 'descendant of Niall.' The original clan was one of the most powerful in Irish history, claiming descent from Niall of the Nine Hostages, a legendary High King of Ireland from the 5th century. As a first name, Oneill gained modest popularity in the late 20th century, particularly in Irish-American communities seeking to honor their heritage. The name carries connotations of strength, leadership, and Celtic pride, though it remains relatively uncommon as a given name compared to its prevalence as a surname.

Pronounced oh-NEEL.

As of October 2026, Oneill ranked #13722 for boys in US births in 2017 SSA, peaked at #3913 for boys in 1943.