Antipope Sylvester IV

https://en.wikipedia.org/wiki/Antipope_Sylvester_IV

Sylvester IV, born Maginulf, was a claimant to the Papacy from 1105 to 1111 in opposition to Paschal II. A priest before his election, he was probably a native of Rome. He had the backing of the Roman militia and initially of the Holy Roman Emperor, Henry IV, who later forced him to abdicate. Today he is regarded as an antipope.