The following is a list of usurpers in the Roman Empire —individuals who unsuccessfully claimed and/or attempted to usurp the throne of a ruling emperor (augustus). The ancient term was "tyrant" (Latin: tyrannus), which had negative connotation in and of itself. Usurpation was common during the whole imperial era; virtually all imperial dynasties rose to power through usurpation and conspiracies. The "imperial office" established by Augustus never defined an stable system of succession, and emperors often had to rely solely on military power to survive.
In the Eastern Roman Empire (395–1453), rebellion and usurpation were so notoriously frequent (in the vision of the medieval West, where usurpation was rare) that the modern term "byzantine" became a byword for political intrigue and conspiracy. For usurpation in the Eastern Roman Empire, see List of Byzantine usurpers.
Usurpers who became legitimate emperors
The following individuals began as usurpers, but became the legitimate emperor either by establishing uncontested control of the empire or by confirmation of their position by the Senate or by the legitimate emperor. Emperors marked in bold are those who managed to secure the throne for themselves; all other emperors, unless noted, were murdered in office.
First civil war
- Galba (68–69)
- Otho (69)
- Vitellius (69)
- Vespasian (69–79)
Second civil war
- Pertinax (193)
- Didius Julianus (193)
- Septimius Severus (193–211)
Crisis of the Third Century
- Macrinus and Diadumenian (217–218)
- Elagabalus (218–222), restored the Severan dynasty
- Maximinus I (235–238)
- Gordian I and Gordian II (238)
- Philip (244–249)
- Decius (249–251)
- Trebonianus Gallus (251–253)
- Aemilian (253)
- Valerian (253–260) ― captured by the Persians
- Claudius Gothicus (268–270) ― died of plague
- Quintillus (270)
- Aurelian (270–275)
- Florian (276)
- Probus (276–282)
- Carus (282–283) ― died in Persia
- Diocletian (284–305)
4th–5th centuries
- Constantine I (306–337)
- Maxentius (306–312)
- Alexander (308–310)
- Nepotianus (350)
- Magnentius (350–353)
- Vetranio (350) ― deposed and spared
- Julian II (360–363)
- Procopius (365–366)
- Magnus Maximus and Victor(383–388)
These last emperors of the West Empire were all accepted by the Senate but never recognized as colleagues by the Emperor of the East.
- Constantine III and Constans II (407–411), recognized by Honorius
- Priscus Attalus (409–410)
- Joannes (423–425)
- Petronius Maximus (455)
- Avitus (455–456)
- Majorian (457-461)
- Libius Severus (461–465) ― natural death
- Olybrius (472) ― natural death
- Glycerius (473–474) ― deposed and spared
- Romulus Augustulus (475–476) ― deposed and spared
Unsuccessful usurpers or rebels
1st century rebels
All "usurpers" began as rebels, but not all rebels claimed the imperial titles. These early figures rebelled against the emperor, but most likely did not claim the imperial title.
{| class="wikitable" style="width:100%; text-align:center;"
! width="8%" |Coin
! width="21%" |Name
! width="15%" |Emperor
! width="18%" |Tenure
! width="42%" |Life details & notes
! width="3%" |Ref
|-
| colspan="2" |"Pseudo-Agrippa" Clemens
|Tiberius<br /><small>(14–37)</small>
|AD 16
|Former slave of Agrippa Postumus, the grandson of Augustus. Pretended to be him and marched to Rome to claim the throne.
|
|-
| colspan="2" |L. Arruntius Camillus Scribonianus
|Claudius<br /><small>(41–54)</small>
|AD 42
|Consul in AD 32, appointed legate of Dalmatia in AD 41. He rebelled with the support of Vinicianus, but was killed within five days.
|
|-
|frameless|100px
|L. Clodius Macer
| rowspan="2" |Nero<br /><small>(54–68)</small><br />Galba<br /><small>(68–69)</small>
| May–October AD 68
|Rebelled against Nero and proclaimed himself propraetor; continued his revolt after his death, but was put to death by Galba
|
|-
| colspan="2" |C. Nymphidius Sabinus
| June AD 68
|Nero's Praetorian prefect, plotted to usurp the throne after Nero's suicide, claiming to be the illegitimate son of Caligula. Killed by the Praetorian Guard as Galba approached Rome.
|
|-
| colspan="2" rowspan="3" |"Pseudo-Nero"
|Otho<br /><small>(69)</small>
|AD 69
|In Achaia, modern Greece; the first Nero imposter.
| rowspan="3" |
|-
|Titus<br /><small>(79–81)</small>
|AD 79
|A rebel named Terentius Maximus who claimed to be Nero reborn; supported by the Parthians in Syria.
|-
|Domitian<br /><small>(81–96)</small>
|AD 88
|An obscure figure; supported by the Parthians.
|-
| colspan="2" |L. Antonius Saturninus
|Domitian<br /><small>(81–96)</small>
|January AD 89
|Governor of Germania Superior, started a rebellion in Mainz. He was killed by Lappius Maximus.
|
|}
2nd century
{| class="wikitable" style="width:100%; text-align:center;"
! width="8%" |Coin
! width="21%" |Name
! width="15%" |Emperor
! width="18%" |Tenure
! width="42%" |Life details & notes
! width="3%" |Ref
|-
| colspan="2" |C. Avidius Cassius
|Marcus Aurelius<br /><small>(161–180)</small>
|April – July 175<br /><small>(3 months and 6 days, in Syria)</small>
|Suffect consul in 166, governor of Syria. Declared himself emperor upon the rumor that Marcus had died, continued his revolt even upon learning that he was alive.
|
|-
|frameless|100px
|C. Pescennius Niger
| rowspan="2" |Septimius Severus<br /><small>(193–211)</small>
|April 193 – April 194<br /><small>(1 year, in Antioch)</small>
|Governor of Syria and former suffect consul. Proclaimed himself emperor after the murder of Pertinax and the elevation of Julianus. Killed by Septimius Severus while attempting to flee to Parthia.
|
|-
|frameless|100x100px
|D. Clodius Albinus
| December 195 –<br />19 February 197<br /><small>(1 year and 2 months, West)</small>
|Governor of Britain and former suffect consul. Proclaimed emperor in April 193, but allied himself with Septimius Severus, who gave him the title of caesar (heir). Rebelled after learning of the appointment of Caracalla as Severus' new caesar. Killed at the Battle of Lugdunum.
|
|}
3rd century
{| class="wikitable" style="width:100%; text-align:center;"
! width="8%" |Coin
! width="21%" |Name
! width="15%" |Emperor
! width="18%" |Tenure
! width="42%" |Life details & notes
|-
| colspan="2" |Verus
| rowspan="2" |Elagabalus<br /><small>(218–222)</small>
| rowspan="2" |c. 218<br /><small>(Syria)</small>
|Senator and commander of the Legio III Gallica; proclaimed emperor in Tyre.
|-
| colspan="2" |Gellius Maximus
|Son of a doctor; commander of the Legio IV Scythica.
|-
| colspan="2" |Taurinius
| rowspan="3" |Severus Alexander<br /><small>(222–235)</small>
| rowspan="2" |c. 232<br /><small>(Syria)</small>
|Governor in Moesia; mentioned by Polemius Silvius. Probably a descendant of king Antiochus IV of Commagene and Marcus Antonius.
|-
| colspan="2" |Seleucus<br /><small></small>
|Former suffect consul; proclaimed emperor against his will. Drowned himself in the Euphrates to avoid punishment.
|-
| colspan="2" style="background:#EBEBEB;" |Ovinius Camillus
|style="background:#EBEBEB;" |
|style="background:#EBEBEB;" |Fictitious usurper of the Historia Augusta
|-
| colspan="2" |Magnus<br /><small></small>
| rowspan="2" |Maximinus Thrax<br /><small>(235–238)</small>
|<small>late 235<br />(in Germania)</small>
|A patritian ex-consul; said to have been hailed emperor after Alexander's murder. Herodian suggests that he was actually incriminated.
|-
| colspan="2" |Quartinus<br /><small></small>
|<small>late 235 / early 236