(died 325) Roman emperor (308–324). Born of Illyrian peasant stock, he advanced in the army and in 308 was appointed augustus by his friend the emperor Galerius. Because the empire was split up among several emperors at that time (seetetrarch), his domain was confined to Pannonia. After the death of Galerius in 311, he allied with Constantine I, defeated his competitor Maximinus in Asia Minor, and partitioned the empire (313). Although reputedly converted to Christianity, he grew alienated and launched a campaign of mild persecution against the Christians c. 320. Constantine soon drove him from power and had him executed.