High Quality Content by WIKIPEDIA articles! Pope John XII (c. 937 – May 14, 964), born Octavianus, was Pope from December 16, 955, to May 14, 964. The son of Alberic II, Patrician of Rome (932–954), and his stepsister Alda of Vienne, he was a seventh generation descendant of Charlemagne on his mother`s side.