Baldassarre Cossa (c. 1370 – 22 December 1419) was
antipope John XXIII (1410–1415) during the
Western Schism. The Catholic Church regards him as an
antipope, as he opposed the Pope whom the Catholic Church now recognizes as the rightful successor of Saint Peter. He was eventually deposed and tried for various crimes, though later accounts question the veracity of those accusations.