antipope from 355 to 365. Originally an archdeacon, Felix was irregularly installed as pope in 355 after the emperor Constantius (Constantius II) banished the reigning pope, Liberius. In May 357 the Roman laity, which had remained faithful to Liberius, demanded that Constantius recall the true pope. The Emperor planned to have Felix and Liberius rule jointly, but Felix was forced to retire to Porto when Liberius returned.

Resented by the Romans while alive, he was remembered more kindly after his death. He has been erroneously called saint after an error in the Roman martyrology that was based on spurious documents. The martyrology gave July 29 as his feast day, but he is now officially listed as an antipope in the Annuario Pontificio.