"Nepotianus" on Revolvy.com

On June 3 350, Roman usurper Nepotianus, of the Constantinian dynasty, proclaimed himself Roman Emperor, entering Rome at the head of a group of gladiators. From the article"

"Julius Nepotianus (died June 30, 350),[1] sometimes known in English as Nepotian, was a member of the Constantinian dynasty who reigned as a short-lived usurper of the Roman Empire. He ruled the city of Rome for twenty-eight days, before being killed by his rival usurper Magnentius' general Marcellinus.[1]

Background
Nepotianus was the son of Eutropia, half-sister of Emperor Constantine I,[2] and of Virius Nepotianus. On his mother's side, he was the grandson of Emperor Constantius Chlorus and Flavia Maximiana Theodora.

Events
After the revolt of Magnentius, Nepotianus proclaimed himself "emperor" and entered Rome with a band of gladiators[2] on 3 June 350.[1] After attempting to resist Nepotianus with an undisciplined force of Roman citizens, the defeated Praefectus urbi Titianus (or Anicius, or Anicetus), a supporter of Magnentius, fled the city.

Magnentius quickly dealt with this revolt[2] by sending his trusted magister officiorum Marcellinus to Rome. According to Eutropius, Nepotianus was killed in the resulting struggle (on 30 June), his head put on a lance and borne around the city.[2] In the following days, his mother Eutropia was also killed, during the persecution of the supporters of Nepotianus, most of whom were senators."