Julian was the Roman emperor commonly known by the epithet “the Apostate.”
Julian ruled from 361 to 363 CE and was the last non-Christian emperor of the Roman Empire. He had been raised as a Christian but later rejected Christianity and promoted traditional Roman and Greek religious practices, which led Christian writers to label him “the Apostate.”
Before becoming emperor, Julian gained military fame as Caesar in Gaul, where he defeated Germanic forces and strengthened Roman control. As emperor, he attempted to restore pagan institutions, reform administration, and limit the privileges of Christian clergy. His religious policies were reversed after his short reign.
Julian died during a campaign against the Sasanian Empire in 363 CE. Although later emperors remained Christian, his reign is important because it briefly interrupted the empire’s increasingly Christian political direction. The epithet refers to his religious change, not to a military or constitutional act.