Arsenius, Antorianus, head of a monastery in Nicea, afterward a hermit on Mt. Athos. He was appointed Greek patriarch about 1255, and ordained deacon, priest, and patriarch in the same week. On the death of Th. Lascaris II he was charged with the tutelage of his son John. Michael Palaeologus, aiming at the sole authority, put out the eyes of the young prince, and Arsenius excommunicated him, and refused to remit the sentence unless he would abdicate in favor of the legitimate heir. Paloeologus refused. Arsenius remaining firm, a synod held in Constantinople, 1264, deposed him. He died on an island in the Propontis in 1267. Here he wrote his Ecclesics Grcecce Monumenta (Paris, 1681, 4to); and also Synopsis Divinorum Canonum, published in Justellus's Bibliotheca Jur. Canon. vol. ii (Paris, 1661).-Cave, Hist. Lit. anno 1255.