Pope Liberius was the bishop of Rome from 17 May 352 until his death. According to the Catalogus Liberianus, he was consecrated on 22 May as the successor to Julius I. He is not mentioned as a saint in the Roman Martyrology. That makes him the earliest pontiff not to be venerated as a saint in the Catholic Church and, along with Anastasius II, one of only two popes to be omitted from Catholic sainthood in the first 500 years of church history.

The pope, also known as the supreme pontiff, Roman pontiff or sovereign pontiff, is the bishop of Rome, visible head of the worldwide Catholic Church, and has also served as the head of state or sovereign of the Papal States and later the Vatican City State since the eighth century. From a Catholic viewpoint, the primacy of the bishop of Rome is largely derived from his role as the apostolic successor to Saint Peter, to whom primacy was conferred by Jesus, who gave Peter the Keys of Heaven and the powers of "binding and loosing", naming him as the "rock" upon which the Church would be built. The current pope is Francis, who was elected on 13 March 2013.