Mongán mac Fiachnai
（重定向自Mongan）
Mongán mac Fiachnai (died ca. 625) was an Irish prince of the Cruthin, a son of Fiachnae mac Báetáin. Little is certainly known of Mongán's life as only his death is recorded in the Irish annals. He appears as a character in the Cycles of the Kings where he is said to have been the son of Manannán mac Lir and perhaps a reincarnation of the legendary hero Finn mac Cumaill of the Fenian Cycle.