Flavius Claudius Constantius Gallus (326 – 354) was a statesman and ruler in the eastern provinces of the Roman Empire from 351 to 354, as Caesar under emperor Constantius II (r. 337–61), his cousin. A grandson of emperor Constantius Chlorus (r. 293–306) and empress Flavia Maximiana Theodora, and a son of Julius Constantius and Galla, he belonged to the Constantinian dynasty. Born during the reign of his uncle Constantine the Great (r. 306–37), he was among the few male members of the imperial family to survive the purge that followed Constantine's death. Under Constantius II, Gallus served as deputy emperor, based in Antioch and married to Constantius' sister Constantina. He dealt with a Jewish revolt in the years 351-352. Gallus ultimately fell out of favor with Constantius and was executed, being replaced as Caesar by his younger half-brother Julian.