Cathal mac Donnubáin is the second known son of Donnubán mac Cathail, king of Uí Fidgenti and an ancestor of the medieval and modern O'Donovan family. He may have succeeded his brother Uainide mac Donnubáin as King of Uí Chairpre Áebda (Cairbre Eva) at his death in 982, no ruler(s) being known after that until 1014. However, this is confused by two notices of the death of Cairpre mac Cléirchín in 1013 or 1014, where in one he is styled king of Uí Chairpre and in the other of Uí Fidgenti, leaving it uncertain which Cathal might actually have been if either. Rivalry between the two families is unknown but cannot be ruled out.