Ó Cathláin
Ó CATHLÁIN—I—O Callaine, O Collhane, O Callan, Culhane, Callan, Callen, Callin, Cawlin, Clahane, Clehane, &c.; 'descendant of Cathalán' (diminutive of Cathal, battle-mighty); a shortened form of Ó Cathaláin, which see. Culhane is the usual anglicised form in Co. Limerick, but the name is sometimes metathesised to Ó Clatháin, anglicised Clahane and Clehane. Callan is more commonly the anglicised form in the North.
Alphabetical Index to Irish Surnames