The top 100 Irish last names explained

Find out more about your Irish roots and where your family name hails from

(O) Shea - Shee  Ó Séaghdha; mod. Ó Sé (séaghdha, hawklike, secondary meaning stately). Primarily a Kerry sept, but (as in Shee) it is notable as the only Gaelic-Irish name among “the Tribes of Kilkenny’ to which county and Co. Tipperary a branch of the sept migrated in the thirteenth century.

(O) Sheehan - Sheahan Ó Síodhacháin. (The obvious derivation from síodhach, peaceful, is not accepted by some Celtic scholars). The Dalcassian sept which spread southwards accounts for the majority of Sheehans who are now very numerous in Co.s Cork, Kerry, and Limerick. Formerly also there was an Uí Maine sept of this name which, however, is rarely found in Connacht today.

(O) Slattery - Ó Slatara, Ó Slatraigh (slatra, strong). Of Ballyslatterly in east Clare. The name has now spread to adjacent counties of Munster.

Smith - Smyth  When not the name of an English settler family, Smith is usually a synonym of MacGowan, nearly always so in Co. Cavan.

(Mac) Spillan(e) -  Mac Spealáin (derivation as O’Spillane). The family is, however, quite distinct from Ó   Spealáin (O’Spillane) Spollan and Spollin, rarely retaining the prefix Mac, are numerous in County Offaly. Older anglicized forms were Spalane and Spalon.

(O) Sullivan - Ó Súileabhain. (While there is no doubt that the basic word is súil (eye) there is a disagreement as to the meaning of the last part of the name). This is the most numerous surname in Munster and is third in all of Ireland. Originally of south Tipperary, the O’Sullivans were forced westwards by the Anglo-Norman invasion where they became one of the leading septs of the Munster Eoghanacht. There were several sub-septs, of which O’Sullican Mor and O’Sullivan Baere were the most important.

(Mac) Sweeney - Swiney  Mac Suibhne (the word suibhne denotes peasant, the opposite of diubhneI). Of all galloglass origin it was not until the fourteenth century that the three great Tirconnell septs of MaSweeney were established; more than a century later a branch went to Munster.

(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.

​
Nster.com