Ó Ciaragáin
Ó CIARAGÁIN—I—O Kierregain, O Kerigane, Kerigan, Kerrigan, Kergan, and, by 'translation,' Comber, Comer; 'descendant of Ciaragán' (diminutive of ciar, black); the name of a branch of the Ui Fiachrach, formerly seated at Baile Ui Chiaragain, now anglicised Ballykerrigan, in the parish of Balla, Co. Mayo. Before the end of the 16th century, the name had ramified into Donegal and Tyrone. In the north of Co. Galway, it is often 'translated' Comber and Comer, from its supposed connection with 'cior,' a comb.
Alphabetical Index to Irish Surnames