A 4th–5th-cent. heresy of uncertain origin. Priscillian was the leader of an ascetic movement in Spain, whose adherents included two bishops, Instantius and Salvianus, and many women. Despite the condemnation at Saragossa in 380 of doctrines attributed to him (though Priscillian was not named), he became Bp. of Ávila soon afterwards. In 381 he and his followers were exiled. In Italy they got the decree of exile annulled by the secular authorities and, returning to Spain, won a large following. The new Emperor, Maximus, however, wanted the support of the Catholic bishops, and in 386 Priscillian was tried in the imperial court on a charge of sorcery, convicted, and executed. The fall of Maximus in 388 produced another change in imperial policy and Priscillianism flourished; it is possible that the shrine at Compostela is on the site of Priscillian's burial-place. The movement did not disappear until the end of the 6th century.
Our knowledge of Priscillianist doctrine is derived mainly from a collection of anonymous writings generally attributed to Priscillian or possibly a disciple of his. From these it appears that Priscillianism was a movement of spiritual renewal. Priscillian set great store by asceticism. He rejected the accusation of Manichaeism, though several features of his teaching made him vulnerable to it, notably his interest in the cosmic dimensions of the ascetic struggle, his demand for celibacy coupled with his tolerance of the lower virtue of married Christians, and his taste for the occult.