Editing Tetrarchy (section)

== Emperors ==
{| class="wikitable"
! Portrait
! Name
! Reign
! Co-ruler(s)
! Ref
|-
|[[File:Istanbul_-_Museo_archeol._-_Diocleziano_(284-305_d.C.)_-_Foto_G._Dall'Orto_28-5-2006.jpg|123x123px]]
| align="center" |[[Diocletian|'''Diocletian''' "Jovius"]]<br/><small>Gaius Aurelius Valerius Diocletianus</small>

('''''Whole, then East''''')
|20 November 284 – 1 May 305<br/><small>(20 years, 5 months and 11 days)</small>
|[[Maximian]] <small>(''caesar'', 21 July 285; co-''augustus'', 1 May 305)</small>

[[Galerius]] <small>(''caesar'', 1 March 293)</small>

[[Constantius Chlorus|Constantius I]] <small>(''caesar'', 1 March 293)</small>
|<ref name=":0">{{Cite book|last=Cooley|first=Alison E.|author-link=Alison E. Cooley |date=2012|chapter=Imperial titles, Augustus–Justinian (Appendix 2)|url=https://www.cambridge.org/core/books/cambridge-manual-of-latin-epigraphy/imperial-titles-augustusjustinian/5EA1B4FCD0E56D0F6FC9DD3903C7A7FD|access-date=2020-06-26|title=The Cambridge Manual of Latin Epigraphy|pages=488–509|chapter-url=https://books.google.com/books?id=VlghAwAAQBAJ&pg=PA488|doi=10.1017/cbo9781139020442.007|isbn=9780521840262}}</ref>
|-
|[[File:Musée_Saint-Raymond_-_2017-09-02_-_Inv._Ra_34b_-_4654.jpg|136x136px]]
| align="center" |[[Maximian|'''Maximian''' "Herculius"]]<br/><small>Marcus Aurelius Valerius Diocletianus</small>
('''''West''''')
|1 April 286 – 1 May 305<br/><small>(19 years and 1 month; retired)</small>pac

28 October 306 – 11 November 308<br/><small>(2 years and 14 days)</small>
|[[Diocletian]] <small>(''augustus'', 21 July 285; co-''augustus'', 1 May 305)</small>

[[Galerius]] <small>(''caesar'', 21 March 293)</small>

[[Constantius Chlorus|Constantius I]]  <small>(''caesar'', 1 March 293)</small>

[[Maxentius]] <small>(co-''augustus'', 306–308)</small>

[[Constantine the Great|Constantine I]] <small>(rival ''augustus'', 25 July 306; co-''augustus'', 307)</small>
|<ref name=":0" />
|-
|[[File:Romuliana_Galerius_head.jpg|137x137px]]
| align="center" |'''[[Galerius]]'''<br/><small>Gaius Galerius Valerius Maximianus</small>

('''''East''''')
|1 May 305– 5 May 311<br/><small>(6 years and 4 days)</small>
|[[Diocletian]] <small>(''augustus'', 21 March 293–1 May 305)</small>
[[Maximian]] <small>(''augustus'', 21 March 293–1 May 305)</small>

[[Constantius Chlorus|Constantius I]]  <small>(''caesar'', 1 March 293; co-''augustus'', 1 May 305–25 July 306)</small>

[[Severus II]] <small>(''caesar'', 1 May 305; co-''augustus'', August 306–April 307)</small>

[[Maxentius]] <small>(''caesar'', 28 October 306; junior co-''augustus'', April 307–May 311)</small>

[[Licinius]] <small>(designated ''augustus'' for the West, 11 November 308–311)</small>

[[Maximinus Daza|Maximinus II]] <small>(''caesar'', 1 May 305; co-''augustus'', 1 May 310–early May 311)</small>
|<ref name=":0" />
|-
|[[File:Const.chlorus01_pushkin.jpg|138x138px]]
| align="center" |[[Constantius Chlorus|'''Constantius I''' "Chlorus"]]<br/><small>Marcus Flavius Valerius Constantius</small>

('''''West''''')
|1 May 305 – 25 July 306<br/><small>(1 year, 2 months and 24 days)</small>
|[[Diocletian]] <small>(''augustus'', 1 March 293–1 May 305)</small>
[[Maximian]] <small>(''augustus'', 1 April 286–1 May 305)</small>

[[Galerius]] <small>(''caesar'', 21 March 293; co-''augustus'', 1 May 305–25 July 306)</small>

[[Severus II]] <small>(''caesar'', 1 May 305 –July 306)</small>

[[Maximinus Daza|Maximinus II]] <small>(''caesar'', 1 May 305–25 July 306)</small>
|<ref name=":0" />
|-
| align="center" |[[File:Konstantin_I._(Bronze).jpg|150x150px]]
| align="center" |[[Constantine the Great|'''Constantine I''' "the Great"]]<br/><small>Flavius Valerius Constantinus</small>

('''''West''''')
|25 July 306 – 18 September 324<br /><small>(18 years, 1 month and 25 days;<br/>sole emperor 324–337)</small>
|[[Maximian]] <small>(rival ''augustus'', 306–307; co-''augustus'', 307–308)</small>

[[Maxentius]] <small>(rival ''augustus'', 306–307; co-''augustus''; 308)</small>

[[Licinius]] <small>(rival ''augustus'', 308–310; co-''augustus'', 310–316; rival, 316–324)</small>

[[Crispus]] <small>(''caesar'', 1 March 317–324)</small>

[[Constantine II (emperor)|Constantine II]] <small>(''caesar'', 1 March 317–324)</small>

[[Martinian (emperor)|Martinian]] <small>(rival ''augustus'', 324)</small>
|<ref name=":0" />
|-
|[[File:Severus II Aureus Joanneum.jpg|100x100px]]
| align="center" |'''[[Severus II]]'''<br/><small>Flavius Valerius Severus</small>

('''''West''''')
|25 July 306 – April 307<br/><small>(8 months)</small>
|[[Galerius]] <small>(''augustus'', 25 July 306–April 307)</small>
[[Maxentius]] <small>(rival ''augustus'', 28 October 306)</small>

[[Constantine the Great|Constantine I]] <small>(rival ''augustus'', 306–307)</small>

[[Maximinus Daza|Maximinus II]] <small>(''caesar'', 1 May 305–April 307)</small>
|<ref name=":0" />
|-
|[[File:Maxentius02_pushkin.jpg|133x133px]]
| align="center" |'''[[Maxentius]]'''<br/><small>Marcus Aurelius Valerius Maxentius</small>

('''''West''''')
|28 October 306 – 28 October 312<br/><small>(6 years)</small>
|[[Maximian]] <small>(co-''augustus'', 306–308)</small>
[[Severus II]] <small>(rival ''augustus'', August 306–April 307)</small>

[[Licinius]] <small>(rival-''augustus'', 11 November 308–28 October 312)</small>

[[Constantine the Great|Constantine I]] <small>(rival ''augustus'', 25 July 306–28 October 312)</small>
|<ref name=":0" />
|-
|[[File:Bust of Licinius, Kunsthistorisches Museum.jpg|151x151px]]
| align="center" |'''[[Licinius]]'''<br/><small>Valerius Licinianus Licinius</small>

('''''West, then East''''')
|11 November 308 – 19 September 324<br/><small>(15 years, 10 months and 8 days)</small>
|[[Constantine the Great|Constantine I]] <small>(rival ''augustus'', 308–310; co-''augustus'', 310–316; rival, 316–324)</small>
[[Valerius Valens|'''Valens I''']] <small>(designated Western ''augustus'', October 316–February 317)</small>

[[Licinius II]] <small>(''caesar'', 1 March 317–324)</small>

[[Crispus]] <small>(''caesar'', 1 March 317–324)</small>

[[Constantine II (emperor)|Constantine II]] <small>(''caesar'', 1 March 317–324)</small>

[[Martinian (emperor)|'''Martinian''']] <small>(designated Western ''augustus'', July–September 324)</small>
|<ref name=":0" />
|-
|[[File:Gold Aureus of Maximinus Daia, Alexandria, AD 311 - AD 313.jpg|100x100px]]
| align="center" |[[Maximinus Daza|'''Maximinus II''' "Daza"]]<br/><small>Galerius Valerius Maximinus</small>

('''''East''''')
|310 – c. July 313<br/><small>(3 years)</small>
|[[Constantius Chlorus|Constantius I]]  <small>(''augustus'', 1 May 305–25 July 306)</small>
[[Galerius]] <small>(''augustus'', 1 May 305–25 July 311)</small>

[[Severus II]] <small>(''caesar'', 1 May 305; ''augustus'' 25 July 306)</small>

[[Maximian]] <small>(''augustus'', late 306–November 308)</small>

[[Maxentius]] <small>(rival ''augustus'', 310–312)</small>

[[Constantine the Great|Constantine I]] <small>(rival ''augustus'', 310–313)</small>

[[Licinius]] <small>(''augustus'', 308–313; rival ''augustus'', 313–313)</small>
|<ref name=":0" />
|}