Ó Neighill
Ó NEIGHILL—I—O Nehill, O Nihill, O Nyhill, O'Nial, Nehill, Nihill, Nyhill; 'descendant of Nigel' (a Norse form of Niall); the name of an old Thomond family, still well known about Limerick. The family is said, but perhaps erroneously, to be a branch of the O'Neills of Thomond; it is more probably of Norse descent. The name, however, is really the same as Ó Néill.
Alphabetical Index to Irish Surnames