Flavius Libius Severus Serpentius (Lucania, c. 420 – 15 August 465) was Western Roman Emperor from November 19, 461 to his death.
A Roman senator from Lucania Severus was one of the last Western Emperors, emptied of any effective power (the real power was in the hands of the powerful magister militum Ricimer), and unable to solve the many problems affecting the Empire; the sources describe him as a pious and religious man.