Ó Cathluain
Ó CATHLUAIN—I—O Collone, O Cullone, Calhoun, Colhoun, Colhoon, Culhoun, &c.; 'descendant of Cathluan' (battle-hound, battle-hero, or battle-joyful); originally a Breifney surname, now dispersed through Ulster. The Uí Cathluain are mentioned in the Annals at the year 1145.
Alphabetical Index to Irish Surnames