MENONNUS, bishop of Ephesus. — He lived between the end of the 4th century and the first half of the 5th century; he was already bishop of that Church in 431, when the great Council was convened.
During its proceedings he vigorously supported St. Cyril of Alexandria (v.) against the partisans of Nestorius; but at first he had forbidden them the use of the churches and denied them permission to celebrate the feast of Pentecost there.
By the synod of the Orientals he was deposed together with Cyril, and imprisoned, but was immediately released by order of the Emperor Theodosius and left in his see. A letter of his to the Constantinopolitan clergy is preserved.