Ó Conalláin
Ó CONALLÁIN—I—O Connellane, O Conlan, Connellan, Conlan, &c.; 'descendant of Conallán' (diminutive of Conall); the name of a Roscommon family; but in the 16th century, it was found in all the provinces. Its anglicised forms cannot always be distinguished from those of Ó Caoindealbháin, which see.
Alphabetical Index to Irish Surnames