John XIII of Constantinople

John XIII (Greek: Ἰωάννης; died after 1320) was the Ecumenical Patriarch of Constantinople from 1315 to 1319. Prior to becoming the patriarch, he had served in the laity and his name was Glykys Melodos; he was sometimes referred to as John Glykys. One of his students was the Byzantine astronomer and scholar Nicephorus Gregoras.