Mercurius becomes Pope John II, the first pope to adopt a new name upon elevation to the papacy.

Pope John II, born Mercurius, was the Bishop of Rome from 2 January 533 to his death on 8 May 535. As a priest at St. Clement's Basilica, he endowed that church with gifts and commissioned stone carvings for it. Mercurius became the first pope to adopt a new papal name upon his elevation to the office. During his pontificate, John II notably removed Bishop Contumeliosus of Riez from his office, convened a council on the readmission of Arian clergy, and approved an edict of emperor Justinian, promulgating doctrine opposed by his predecessor, Pope Hormisdas.

The pope is the bishop of Rome and the visible head of the worldwide Catholic Church. He is also known as the supreme pontiff, Roman pontiff, or sovereign pontiff. From the 8th century until 1870, the pope was the sovereign or head of state of the Papal States, and since 1929 of the much smaller Vatican City state. 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 Leo XIV, who was elected on 8 May 2025 on the second day of the 2025 papal conclave.

January 2 is the second day of the year in the Gregorian calendar; 363 days remain until the end of the year.