(Εὐτύχιος), was originally a monk of the town of Amaseia, whence he was sent by his fellow-citizens to Constantinople, as proxy for their bishop. The great talent he displayed in some theological controversy gained him general admiration, and the emperor in A. D. 553 raised him to the highest dignity in the church at Constantinople. In the same year he accordingly presided at an ecumenical synod, which was held in that city. In A. D. 564, he incurred the anger of the emperor Justinian, by refusing to give his assent to a decree respecting the incorruptibility of the body of Christ previous to his resurrection, and was expelled from his see in consequence. He was at first confined in a monastery, then transported to an island, Princepo, and at last to his original convent at Amaseia. In 578, the emperor Tiberius restored him to his see, which he henceforth retained until his death in 585, at the age of 73.