Flavius Aetius
Valentinian III was designated Honorius' heir in 421, although he was not proclaimed "caesar", only given the title of "nobilissimus puer". In 423, after the death of Honorius, a usurper named Joannes rose up, forcing Valentinian III to flee with his family to the court of the Eastern Emperor Theodosius II. He was installed as Western Emperor in 425, after Joannes was defeated by Theodosius in Ravenna. Valentinian was killed on 16 March 455, by Optila, a friend of Flavius Aetius, whom Valentinian had killed.