Count of Tusculum.
Son of Alberic, who secured John's election to the papacy at age 18.
Notoriously immoral, his pontificate was such a disgrace that the Lateran was known as a brothel.
He called on Otto I to help him against Berengar II of Italy, and in return he crowned Otto the first German emperor on 2 February962.
Later, deciding he did not care for the emperor meddling in papal affairs, John sided with Berengar party against Otto; Otto invaded Rome, and called a synod that deposed John on 4 December963, and elected Leo VIII as pope.
John was restored by Roman insurrectionists 26 February964, but died soon after.