Constans I (kŏn´stănz), b. 320 or 323, d. 350, Roman emperor, youngest son of Constantine I. At his father's death in 337 he received Italy and Africa as well as Pannonia and Dacia, while his brothers, Constantine II and Constantius II, received other portions of the empire. Trouble arose among them, and in 340 Constantine invaded Italy to win some of Constans' territory. Constantine was, however, killed in an ambush, and Constans was left to rule until his extortions and infamous conduct led to his assassination 10 years later.