Domitian II (Latin: Domitianus) was a Roman soldier of the mid 3rd century who was acclaimed emperor, probably in northern Gaul in late 270 or early 271, and struck coins to advertise his elevation.

It is now generally assumed that this man is to be equated with the Domitianus who is twice mentioned in the literary sources as a significant figure in the politics of the age, but on neither occasion as an outright contender for the Imperial throne.

Given that his reign lasted for, at best, only a few weeks after his acclamation and he does not seem to have secured significant military or political support, Domitianus is more properly categorized as a Roman usurper rather than an emperor.

If Historia Augusta’s assertions as to his military reputation are correct it is not unlikely that he would have been welcomed into the entourage of the Gallic Emperor and his successors.

The evidence of his coins suggests that the Domitianus was almost certainly a military figure associated with the rebel Gallic Empire who commanded troops close enough to one of the mint cities of Trier or Cologne to ensure that his Imperial pretensions were proclaimed in the traditional manner.

In this circumstance it would not have been surprising that a faction may have been tempted to put forward a figure such as Domitianus who had an established military reputation – particularly if he was, indeed, the same man as the conqueror of the Macriani mentioned in Historia Augusta.

On the other hand, the literary evidence does suggest that the forces favouring Tetricus I as the new Emperor were able to assert themselves so swiftly and decisively that Domitianus's elevation was hardly remarked outside the provinces controlled by the Gallic Empire.

The most likely interpretation of the evidence of the coins is that Domitianus was involved in the officers' coup that overthrew Victorinus and managed to secure temporary control of one of the Gallic mints.

The circumstances in which the Chalgrove specimen was discovered leaves no doubt that it was, indeed, struck by somebody in the early 270s, but we have to consider that it might have been produced by a faction of the Rhine army officer cadre which hoped to use Domitianus as a figurehead, possibly without his knowledge or approval.

A second possibility is that he was defeated by Placidianus, a general loyal to Aurelian who had been stationed to guard the lower Rhône valley during Victorinus' assault on Autun in 270.