LATE FOURTH CENTURY. Spanish bishop. A follower of Priscillian,* he may have been deposed by a synod at Saragossa in 380. When Idacius, bishop of Emerita, obtained a rescript from Gratian that he could use against them, Instantius and Salvianus (another bishop and follower of Priscillian) accompanied Priscillian, whom they had made bishop of Avila, to Italy to seek the aid of Damasus and Ambrose. Unsuccessful in this, they nevertheless gained the aid of Macedonius, the magister officiorum, who used his influence to obtain their protection. Gratian's assassination, however, brought another change of fortune. Priscillian and Instantius were summoned before a synod at Bordeaux in 385. Instantius was deposed. When they appeared before Maximus at Treves, Priscillian was put to death on a charge of witchcraft, and Instantius banished. He may be the author of eleven treatises attributed by G. Schepps to Priscillian and published from a Würzburg MS in 1886.