Photinus (died 376) was a Christian theologian and bishop of Sirmium in Pannonia. He was deposed on charges of heresy. Photinus grew up in Ancyra in Galatia, where he was a student and later a deacon of bishop Marcellus. Marcellus, a staunch opponent of Arianism, was deposed in 336 but reinstated by the Synod of Serdica in 343, which also made Photinus bishop of Sirmium. In 344, the Synod of Antioch deposed Marcellus and drew up the Macrostich, a creed which listed their beliefs and objections to Marcellus' doctrines (among others).