The surname "Creagan" is of Irish origin. It is derived from the Gaelic name "Ó Croidheagáin," which means "descendant of Croidheagán." The Gaelic personal name Croidheagán is a diminutive form of "croidhe," meaning "heart." The name Cregan is primarily associated with Counties Galway and Limerick in western Ireland, where the Cregan clan was historically located.