Gratian (Latin: Gratianus; 18 April 359 – 25 August 383) was emperor of the Western Roman Empire from 367 to 383. The eldest son of Valentinian I, Gratian was raised to the rank of Augustus as a child and inherited the West after his father's death in 375. He nominally shared the government with his infant half-brother Valentinian II, who was also acclaimed emperor in Pannonia on Valentinian's death. The East was ruled by his uncle Valens, who was later succeeded by Theodosius I.
Gratian subsequently led a campaign across the Rhine, attacked the Lentienses, and forced the tribe to surrender. That same year, the eastern emperor Valens was killed fighting the Goths at the Battle of Adrianople, which led to Gratian elevating Theodosius to replace him in 379. Gratian favoured Nicene Christianity over traditional Roman religion, issuing the Edict of Thessalonica, refusing the office of pontifex maximus, and removing the Altar of Victory from the Roman Senate's Curia Julia. The city of Cularo on the Isère river in Roman Gaul was renamed Gratianopolis after him, which later evolved to Grenoble. In 383, faced with rebellion by the usurper Magnus Maximus, Gratian marched his army towards Lutetia (Paris). His army deserted him. He fled to Lugdunum and was later murdered.