A Roman general, son of a Vandal captain under the emperor Valens; on the death of Theodosius I., under whom he served, became the ruler of the West, and by his military abilities saved the Western Empire; defeated Alaric the Goth in a decisive battle and compelled him to retire from Italy, as he did another horde of invading barbarians afterwards; aspired to be master of the Roman empires, but was assassinated at Ravenna in 403.