Libius Severus (died 465), sometimes enumerated as Severus III, was Roman emperor of the West from 461 to his death in 465.

A Roman senator from Lucania, Severus was one of the last Western emperors, with no effective power (the real power was in the hands of the magister militum Ricimer) and unable to solve the many problems affecting the empire; the sources describe him as a pious Christian.