(d. 964), Pope from 955.
The son of a ruler of Rome, he became Pope when he was 18. He appealed to Otto I of Germany to help him against the rulers of N. Italy, King Berengar II and his son. In 962 he crowned Otto Roman Emperor. Otto issued the ‘Privilegium Ottonis’ recognizing the Papal territories in central Italy, but then demanded allegiance to himself. John engineered a revolt among the imperial troops and sought aid from Berengar and the Byzantines. In 963 Otto presided over a synod in Rome which deposed John and elected in his place a layman (Leo VIII); he also issued a revised form of the ‘Privilegium Ottonis’ requiring that a newly elected Pope should take an oath of fealty to the Emperor before consecration. In 964 John returned to Rome and deprived Leo but was killed soon afterwards.