Prospero Colonna (c. 1410 — 1463) was a cardinal-nephew of Pope Martin V (Odo Colonna), whose election ended the Western Schism. Colonna was excommunicated for a period due to his rebellion against Martin V's successor, Pope Eugene IV, becoming one of the few excommunicated cardinals. Despite this, Colonna was the leading candidate to succeed Eugene IV in the papal conclave, 1447, where he was two votes away from election for the first three days. Colonna is also known as a patron of Roman humanism.