A politician of the Roman Empire. He held appointments under the emperors Constantius II, Julian, and Valens. Previously a pagan, he converted to Arianism under Valens, and was sent by Valens to mediate between the Arian and Nicene factions with Basil of Caesarea. While he was in Antioch, Julian appointed Modestus as praefectus urbi of Constantinople, an office he held from 362 to 363. Under Emperor Valens he was Praetorian prefect of the East (369-377) and consul in 372.