Nepotianus (died 30 June 350), sometimes known in English as Nepotian,[1] 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.

[5] After the revolt of Magnentius, Nepotianus proclaimed himself emperor and entered Rome with a band of gladiators[4] 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.

According to Eutropius, Nepotianus was killed in the resulting struggle (on 30 June), his head put on a lance and borne around the city.