Pope Callixtus I (died circa 223), also called Callistus I, was the bishop of Rome (according to Sextus Julius Africanus) from c. 218 to his death c. 223. He lived during the reigns of the Roman Emperors Elagabalus and Alexander Severus. Eusebius and the Liberian catalogue gave him five years of episcopate (217-222). He was martyred for his Christian faith and is venerated as a saint by the Catholic Church.