Priscillian, the founder of a religious sect in Spain and Gaul, born in the neighborhood of Cordova, died in Treves in 385. He was of high birth, and possessed wide learning and great rhetorical talents. It is said that he was instructed by a certain Egyptian called Mark, and by Elpidius and Agape. He appeared as a religious reformer with the pretension of having been called to preach the true doctrine and a spiritual asceticism, and to found within the Catholic church a special secret society of initiated and saints. He was excommunicated by a synod held at Saragossa about 380, but to no effect, as he was soon after ordained bishop of Avila. The emperor Gratian was thereupon persuaded to publish an edict exiling Priscillian and his friends, but a revocation of the edict was obtained by bribing some of the court officials. Another synod, held at the instance of Bishop Ithacius at Bordeaux in 384, when Maximus had usurped the throne, again gave an adverse decision. Priscillian appealed before the emperor, who sentenced him to death and decreed the confiscation of his property. Priscillian's execution is the first instance of a Christian condemned to death for heresy.

The doctrines held by the Priscillianists were a mixture of Manichaeism and Gnosticism.