Jovian (/ˈdʒoʊviən/; Latin: Jovianus; Ancient Greek: Ἰοβιανός, romanized: Iobianós; 331 – 17 February 364) was Roman emperor from June 363 to February 364. As part of the imperial bodyguard, he accompanied Julian on his campaign against the Sasanian Empire. Julian was killed in battle, and the exhausted and ill-provisioned army declared Jovian his successor. Unable to cross the Tigris, Jovian made peace with the Sasanids on humiliating terms. He spent the rest of his seven-month reign traveling back to Constantinople. After his arrival at Edessa, Jovian was petitioned by bishops over doctrinal issues concerning Christianity. He died at Dadastana, never having reached the capital.
From Jovian's successors Valentinian I and Valens to the fall of the Western Roman Empire, all subsequent administrations involved co-emperors governing a territory split into Eastern and Western jurisdictions. Jovian was consequently the last emperor to rule the entire empire for the whole of his reign.
