Faustinus was an usurper against Tetricus I, the last emperor of the Gallic Empire. Not much is known about him. Neither his complete name nor the year of his birth are known. Few literary sources mention that Faustinus instigated a mutiny among the troops of Tetricus I. He rebelled in Augusta Treverorum, the provincial capital of Gallia Belgica. Faustinus held the office of a provincial governor, so he was probably praeses of Gallia Belgica when he rebelled.
The exact date of his rebellion is uncertain. The rebellion most likely occurred some time between late 273 and the early summer of 274. Some ancient sources suggest, that Faustinus continued his revolt after Tetricus I surrendered to Aurelian.