The Gallienus usurpers were the usurpers who claimed imperial power during the reign of Gallienus (253–268, the first part of which he shared with his father Valerian). The existence of usurpers during the Crisis of the Third Century was very common, and the high number of usurpers fought by Gallienus is due to his long rule; 15 years was a long reign by the standards of the 3rd century Roman Empire.
Uprisings after the defeat of Valerian
After Valerian's defeat and capture by the Persians in 260, his son Gallienus become the only emperor. However, many uprisings happened, both in the East, with the formation of the Palmyrene Empire, and in the West, with the birth of the Gallic Empire. With the uncertainty of the period, the legions wanted to restore Roman power in the wake of Valerian's defeat, against the pressure of the barbarian people in the west and the Persians in the East.