John of Sabina; Sylvester III
He was Bishop of Sabina, and the Roman faction which had expelled Pope Benedict IX, elected him in opposition to the lawful pope after John had given them a large sum of money.
Pope Benedict descended on Rome with a body of troops and expelled the antipope who returned to his bishopric from which he continued to put forth claims at intervals during the pontificate of Gregory VI.
He attended the synod of Sutri, convened by Emperor Henry III, 1046, was deprived of all sacerdotal rank and condemned to be shut up in a monastery for life.
New Catholic Dictionary