O’ Domhnaill, O’ Donel, Ó Domhnaill
Ó Domhnaill comes from the personal name Domhnall meaning ‘world-mighty’. The name is most strongly connected with Co. Donegal in the north-west of Ireland, although there were other septs of the same name in a number of areas, including west Clare and east Galway. The O’ Donnells of Donegal were part of the Uí Néill tribal grouping. The name now ranks as forty forth most numerous in Ireland, and it remains strongest in Co. Donegal.