Top 100 Irish last names explained

IrishCentral has put together a list of the top 100 common Irish surnames.

(O) Tierney - Ó Tighearnaigh (tighearna, lord): There were three septs of this name, in Donegal, Mayo, and Westmeath, but it is now scattered. It is much confused with Tiernan in Mayo. In southern Ulster this is usually of different origin, viz., Mac Giolla Tighearnaigh, which was formerly also anglicized MacIltierney.

Walsh -  Breat(h)nach (Welshman): which is re-anglicized also as Brannagh, Brannick etc. A name given independently to many unconnected families in different parts of the country and now the fourth most numerous of all Irish surnames. It is sometimes spelt Welsh, which is the pronunciation of Walsh in Munster and Connacht.

(O) Whelan  Ó Faoláin (faol, wolf). A variant form of Phelan numerous in the country between Co. Tipperary and Co. Wexford. Whelan is also sometimes an abbreviation of Whelehan and occasionally a synonym of Hyland. Whelan is rare in Ulster.