Avitus, in full Flavius Maccilius Eparchius Avitus, (died 456), Western Roman emperor (455–456).
Born of a distinguished Gallic family, Avitus was a son-in-law of the Christian writer Sidonius Apollinaris, whose poetry is an important source for our knowledge of him. By taking advantage of his great influence with the Visigoths who were settled at Toulouse, Avitus was able in 451 to persuade their king, Theodoric I, to join the Roman general Aetius in repelling the invasion of Gaul by the Huns under Attila. Avitus was appointed magister utriusque militiae (“master of both services”) by the Western emperor Petronius Maximus (reigned 455). When Maximus was killed, the Goths proclaimed Avitus emperor at Toulouse, and this claim was upheld by the Gallo-Romans at Arles (July 9, 455). The new emperor proceeded to Rome but the general Ricimer defeated Avitus at Placentia (modern Piacenza) and forced him to abdicate (October 18, 456) and to become bishop of Placentia. He may have died while attempting to return to Gaul.