Martyr of Rome, with Concordia and other companions, he is a controversial figure who censured Pope St. Callistus I. Hippolytus was slain in Sardinia where he had been exiled for being elected as an antipope, the first in the history of the Church. He was reconciled to the Church before his martyrdom. His writings were important, including A Refutation of All Heresies, Song of Songs, and The Apostolic Tradition.