
Licinius
11 November 308 – 19 September 324 (15 years, 10 months and 8 days) West; then East
Licinius shared control of the Roman world with Constantine after the Tetrarchic civil wars. Their alliance deteriorated into conflict, ending with Licinius's defeat in AD 324.
Maximinus II 'Daza'
310 – c. July 313 (3 years; East)
Maximinus Daia ruled portions of the eastern empire during the collapse of the Tetrarchy. He continued anti-Christian policies before being defeated by Licinius in AD 313.
Valerius Valens
October 316 – c. January 317 (c. 2–3 months; West)
Valerius Valens was briefly elevated as a co-emperor by Licinius during his conflict with Constantine. His short-lived imperial status ended when Licinius had him executed.
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