Severus: emperor of the Roman world (r. 306-307).
- date of birth and real name unknown
- 1 May 305: Flavius Valerius Severus Caesar
- August 306: Imperator Severus Augustus
- April 307: resigned
- 16 September 307: murdered
Successor of: Constantius I Chlorus
- children: Severianus
- 305 Appointed as caesar by Constantius I Chlorus in 305
- 306 Automatically made emperor when Constantius dies. He is forced to recognize the late ruler's son Constantine I the Great as caesar, and is faced with a rebellion in Rome, which is occupied by Maxentius, the son of Maximianus.
- 307 Consul (with Maximinus Daia); march on Rome, but forced to return to Ravenna; Maximianus, returned from retirement, forces Severus into surrender and orders him to abdicate.note[Zosimus, New History 2.10.1-2.] A couple of months later, he is murdered.
Succeeded by: Maxentius