The Kings of Umaill were rulers of Umaill, a kingdom or territory located in the west of what is now County Mayo, Ireland.
Its earliest rulers were the semi-historical Tuath mhac nUmhoir. The Umaill, its early historical rulers, were renamed the Uí Briúin Umaill to claim a fictitious relationship with the Uí Briúin. By the 12th century the ruling family adopted the surnameÓ Máille, and were reckoned with the Ó Dubhda, Ó Flaithbheartaigh and Mac Conraoi as supreme seafaring clans of Connacht.
Cormac mac Eoghan Ó Máille, died 1523 (1523. O'Maille, i.e. Cormac, son of Eoghan O'Maille, general supporter of the hospitality and nobility of the west of Connacht, mortuus est. Domhnall, son of Thomas O'Maille, assumed his place.)