Pope Caius, also called Gaius, was the Bishop of Rome from 17 December 283 to his death in 296. Christian tradition makes him a native of the Dalmatian city of Salona, today Solin near Split, the son of a man also named Caius, and a member of a noble family related to the Emperor Diocletian. He was Illyrian.
Little information on Caius is available except that given by the Liber Pontificalis, which relies on a legendary account of the martyrdom of St. Susanna for its information. According to legend, Caius baptized the men and women who had been converted by Saint Tiburtius (who is venerated with St. Susanna) and Saint Castulus. His legend states that Caius took refuge in the catacombs of Rome and died a martyr.