Maximian (Latin: Marcus Aurelius Valerius Maximianus Herculius Augustus; c. 250 – c. July 310) is Roman Emperor from 286 to 305.

He is Caesar from 285 to 286, then Augustus from 286 to 305.

He shares the latter title with his co-emperor and superior, Diocletian, whose political brain complements Maximian's military brawn.

Maximian establishes his residence at Trier but spends most of his time on campaign.

In the late summer of 285, he suppresses rebels in Gaul known as the Bagaudae.

From 285 to 288, he fights against Germanic tribes along the Rhine frontier.

Together with Diocletian, he launches a scorched earth campaign deep into Alamannic territory in 288, temporarily relieving the Rhine provinces from the threat of Germanic invasion.

The man he appoints to police the Channel shores, Carausius, rebels in 286, causing the secession of Britain and northwestern Gaul.

Maximian fails to oust Carausius, and his invasion fleet is destroyed by storms in 289 or 290.

Maximian's subordinate, Constantius, campaigns against Carausius' successor, Allectus, while Maximian holds the Rhine frontier.

The rebel leader is ousted in 296, and Maximian moves south to combat piracy near Hispania and Berber incursions in Mauretania.

When these campaigns conclude in 298, he departs for Italy, where he lives in comfort until 305.

At Diocletian's behest, Maximian abdicates on May 1, 305, gives the Augustan office to Constantius, and retires to southern Italy.

In late 306, Maximian takes the title of Augustus again and aids his son Maxentius' rebellion in Italy.

In April 307, he attempts to depose his son, but fails and flees to the court of Constantius' successor, Constantine (who is both Maximian's step-grandson and also his son-in-law), in Trier.

At the Council of Carnuntum in November 308, Diocletian and his successor, Galerius, force Maximian to renounce his imperial claim again.

In early 310, Maximian attempts to seize Constantine's title while the emperor is on campaign on the Rhine.

Few support him, and he is captured by Constantine in Marseille.

Maximian commits suicide in the summer of 310 on Constantine's orders.

During Constantine's war with Maxentius, Maximian's image is purged from all public places.

However, after Constantine ousts and kills Maxentius, Maximian's image is rehabilitated, and he is deified.