[edit] Tetrarchy
| Western Empire |
Eastern Empire |
| Augustus |
Caesar |
Augustus |
Caesar |
| Name |
Tenure |
Name |
Tenure |
Name |
Tenure |
Name |
Tenure |
Maximian
 |
See above |
Constantius Chlorus
 |
March 1, 293 |
Diocletian
 |
See above |
Galerius
 |
May 21, 293 |
May 1, 305
(resigned) |
May 1, 305
(elevated to rank of Augustus) |
May 1, 305
(resigned) |
May 1, 305
(elevated to rank of Augustus) |
Constantius Chlorus
|
May 1, 305 |
Flavius Valerius Severus
 |
May 1, 305 |
Galerius
|
May 1, 305 |
Maximinus
 |
May 1, 305 |
July 25, 306
(natural death) |
August 306
(elevated to rank of Augustus) |
May 311
(natural death) |
May 1, 310
(elevated to rank of Augustus) |
Flavius Valerius Severus
|
August 306 |
Constantine I
 |
July 25, 306 |
Galerius
|
May 1, 305 |
Maximinus
|
May 1, 305 |
April 307
(resigned) |
Summer 307
(elevated to rank of Augustus) |
May 5, 311
(natural death) |
May 1, 310
(elevated to rank of Augustus) |
|
