Irish Last Name Generator

Irish surnames were among the first hereditary family names in Europe, fixed by the 900s and built almost entirely from two words. Ó means "grandson" or "descendant of" and Mac means "son of", so Ó Briain is the line of Brian Boru and Mac Cárthaigh the line of Cárthach. English records rendered them O' and Mc or Mac (and often dropped the prefix altogether, which is why Sullivan, Reilly and Connor exist alongside O'Sullivan, O'Reilly and O'Connor). A smaller group came with the Normans after 1169: Fitzgerald, Burke, Power, Roche, Barry, Butler and Prendergast are Irish by seven centuries of residence, and in Irish they take de (de Búrca, de Paor).

In the Irish language the surname changes with the bearer. A woman is Ní (daughter of Ó) or Nic (daughter of Mac), and the name that follows usually softens: Ó Briain becomes Ní Bhriain, Ó Murchú becomes Ní Mhurchú. Many names also point to a county: O'Sullivan, McCarthy and Twomey to Cork and Kerry, Gallagher and O'Doherty to Donegal, Joyce and Conneely to Connemara, Kavanagh and Byrne to Wicklow and Wexford.

The list mixes the top names with hundreds of real but less familiar ones, plus Gaelic spellings for historical, Gaeltacht and fantasy use, so a cast of characters does not end up being three Murphys and a Kelly.