Donnubán mac Cathail

Donnubán ('donuva:n), Donndubán ('donðuva:n), or Donnabán mac Cathail, anglicised Donovan, son of Cahall (died 980), was a tenth-century ruler of the Irish regional kingdom of Uí Fidgenti, and possibly also of the smaller overkingdom of Uí Chairbre Áebda within that. In contemporary sources he is only named king of the former, but his sons and later descendants appear as dynasts of the latter. In addition, at his death in 980 Donovan is styled King of Ressad, a unique title in the surviving Irish annals, and the identity of which place is uncertain. He is the progenitor of the medieval and modern O'Donovan family.

Playing a notable role in the early twelfth century fictional political saga Cogad Gáedel re Gallaib (CGG), Donovan is notorious for his alliance with his apparent father-in-law or at least relation Ivar of Limerick, the last Norse king of Limerick, and with Máel Muad mac Brain, king of Desmond, against the rising Dál gCais in the persons of Mathgamain mac Cennétig, king of Cashel, and his famous brother Brian Bóruma, later High King of Ireland. The latter would prove the victors, altering the political landscape of Munster and Ireland forever. It was Donovan's assistance that made Máel Muad King of Munster from 976 to 978.