HYDATIUS (Hydatius). — Bishop of Mérida, died before 392. One of the most zealous opponents of Priscillian and his followers. He brought charges against the heretic before Pope Damasus I and at the Synod of Saragossa (4 October 380), at which he proposed a *commonitorium* for Christian life, against the singularities of the Priscillianists. In 382 he obtained from Emperor Gratian a decree against the “Manichaeans and pseudo-bishops.”
Hydatius himself was entrusted with the task of seeking out the guilty and denouncing them to the administrative authorities. Finally, he accused Priscillian of magic and Manichaeism, causing his condemnation, which was pronounced in 385 by the usurper Maximus. Priscillian’s adherents stirred up such agitation against Hydatius that in 388 he resigned his see voluntarily.