was a Roman emperor who ruled the Western Roman Empire from 425 to 455 CE. He became emperor at just six years old under the regency of his mother, Galla Placidia, and later the general Flavius Aetius. Valentinian’s reign was marked by the empire’s continued decline, including territorial losses to the Vandals, Huns, and Goths. Aetius played a key role in maintaining stability, defeating Attila the Hun at the Battle of the Catalaunian Plains in 451 CE. However, Valentinian killed Aetius in 454, destabilizing his reign. In 455, Valentinian was assassinated, leading to further chaos in the crumbling Western Empire.