Anglicized form of the Irish given name CEALLACH or the surname derived from it Ó Ceallaigh. As a surname, it has been borne by actor and dancer Gene Kelly (1912-1996) and actress and princess Grace Kelly (1929-1982).
Irish name of uncertain origin, traditionally said to mean "bright-headed". Alternatively it could be derived from Old Irish ceallach "war, strife" or ceall "church".