Sevērus, Flavius Valerius in Harper's Dictionary

A Roman emperor (A.D. 306-307). He was proclaimed Caesar by Galerius in 306, and was soon afterwards sent against Maxentius, who had assumed the imperial title at Rome. The expedition, however, was unsuccessful; and Severus, having surrendered at Ravenna, was taken as a prisoner to Rome, and compelled to put an end to his life. See Maxentius.

Link: http://www.perseus.tufts.edu/hopper/text?doc=Perseus:text:1999.04.0062:alphabetic+letter%3DS:entry+group%3D11:entry%3Dseverus5-harpers