Gratian was a Roman Emperor who ruled from 367 to 383 AD. He became emperor at a young age and was known for his efforts to maintain stability in the Roman Empire during a time of increasing external threats. Gratian was the first emperor to reject the title of "Pontifex Maximus," signaling a shift towards a more Christian-oriented leadership. During his reign, Gratian faced challenges from various groups, including the Goths and Persians. He appointed his half-brother, Valentinian II, as co-emperor to help manage the empire's vast territories. Gratian's reign ended when he was assassinated in 383 AD, leading to further instability in the empire.