Antipope Felix V
Alexander of Masovia (pl: "Aleksander mazowiecki"; 1400 - 2 June 1444) was a Polish prince member of the House of Piast from the Masovian branch. He was Bishop of Trento since 1425, titular Patriarch of Aquileia since 1439, Cardinal nominated by Antipope Felix V as titular of the diocese of St. Lawrence at Damascus ("San Lorenzo in Damaso") since 1440, titular Bishop of Chur since 1442 and rector at St. Stephen's Cathedral, Vienna since 1442, a diplomat.