Baldassarre Cossa (c. 1370 – 22 December 1419) was Pisan 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.