Leo I was an Eastern Roman emperor who ruled from 457 to 474. Born in Thrace to a Thraco-Roman family, he previously served as a military officer. His reign was characterized by efforts to support the declining Western Roman Empire and by his move to use Koine Greek for official imperial legislation. He is also remembered for introducing Christian elements into the traditional Roman coronation ceremony, a practice that influenced future European monarchs. He died in Constantinople in 474.