The top 100 Irish last names explained

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

(O) Hogan - Ó hÓgain (og, young) Three septs are so called: one is Dalcassian and one of Lower Dormond (sometimes regarded as the same); there is also one of the Corca Laoidhe.

Kane - O Cahan  Ó Catháin. As lords of Keenaght the O’Kanes were a leading sept in Ulster up to the time of the plantation of Ulster. The name is still very numerous in its original homeland.

Keating - One of the earliest Hibernicized Anglo-Norman families whose name was gaelicized Ćeitinn. They settled in south Leinster. The historian Dr. Geoffrey Keating was of C. Tipperary. The name with the prefix Mac is associated exclusively with the Downpatrick area, where MacKetian is a synonym of it. The theory that Keating is derived from  Mac Eitienne  is improbable. Woulfe makes it toponymic. The most acceptable suggestion is that it is from Cethyn, a Welsh personal name.

(O) Kelly - Ó Ceallaigh (The derivation of Kelly is uncertain: the most probable suggestion is that is from ceallach, strife) The most important and numerous sept of this name is that of the Uí Maine. Kelly is the second most numerous name in Ireland. In 1890 less than one percent of them had the prefix O but this has been to some extent resumed.

Mac Kenna - Kennagh  Mac Cionaoith. A branch of the southern Uí Neill, mainly located in Co. Monaghan where they were lords of Truagh; the name is now fairly numerous also in Leinster and Munster. Locally in Clare and Kelly the last syllable is stressed, giving the variants Kennaw, Ginna, Gna, etc.

Kennedy - Ó Cinnéide (ceann, head-éidigh, ugly). An important Dalcassian sept of east Clare which settled in north Tipperary and spread thence far as Wexford whence came the family of President J.F. Kennedy. The Scottish Kennedys are by remote origin Irish Gaels.

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Lawless - Laighléis (from the Old-English laghles, outlaw). The name, introduced into Ireland after the Anglo-Norman invasion, is now numerous in Co.s Dublin and Galway. It was one of the ‘Tribes of Kilkenny’ but has now no close association with the city.

(O) Leahy - Ó Laochdha (laochda, heroic). This name is very numerous in Munster but not elsewhere It is basically distinct from Lahy though they have been used synonymously.

(O) Leary - Ó Laoghaire. (Laoghaire was one of the best-known personal names of Ancient Ireland). A sept of the Corca Laoidhe established in Muskerry, of importance in all fields of national activity, especially in literature, and in the military sphere both at home and as the Wild Geese.

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