Gratian (Latin: Flavius Gratianus Augustus; 18 April/23 May 359 – 25 August 383) is Roman Emperor from 375 to 383.

The eldest son of Valentinian I, during his youth Gratian accompanies his father on several campaigns along the Rhine and Danube frontiers.

Upon the death of Valentinian in 375, Gratian's brother Valentinian II is declared emperor by his father's soldiers.

In 378, Gratian's generals win a decisive victory over the Lentienses, a branch of the Alamanni, at the Battle of Argentovaria.

Gratian subsequently leads a campaign across the Rhine, the last emperor to do so, and attacks the Lentienses, forcing the tribe to surrender.

This same year, his uncle Valens is killed in the Battle of Adrianople against the Goths - making Gratian essentially ruler of the entire Roman Empire.

He favors Christianity over traditional Roman religion, refusing the divine attributes of the Emperors and removing the Altar of Victory from the Roman Senate.