Pope Callixtus III or Callistus III (31 December 1378 – 6 August 1458), born Alfons de Borja, was Pope from 8 April 1455 to his death in 1458.

He was the last pope to take the pontifical name of "Callixtus" upon his election. He was also responsible for the retrial of Joan of Arc that saw her vindicated. A member of the Borgia family, Callixtus III was the uncle of Pope Alexander VI.