Basil of Seleucia, Bishop and ecclesiastical writer, date of birth uncertain; d., probably, between 458 and 460; was distinguished during the period when the Eastern Church was convulsed by the Monophysite struggles, and was necessarily obliged to take sides in all those controversies. Those of his writings which have come down to us, though somewhat too rhetorical and involved, prove clearly that he was a man of great literary ability.
He was appointed Bishop of Seleucia in Isauria, between the years 432 and 447, and was one of those who took part in the Synod of Constantinople, which was summoned (448) by the Patriarch Flavian for the condemnation of the Eutychian errors and the deposition of their great champion, Dioscurus of Alexandria. Curiously enough, though Basil seems to have agreed to these measures, he attended the Latrocinium, or Robber Synod, of Ephesus, held in the next year (449), and, induced probably more by the threats and violence of the Monophysite party than by their arguments, he voted for the rehabilitation of Eutyches and for the deposition of the Patriarch of Constantinople, and was thus regarded for a time as a supporter of Monophysite opinions. Like the other prominent supporters of Dioscurus, he should have been removed from his see had he not in the meantime accepted the doctrine contained in the Dogmatic Epistle of Pope Leo to Flavian, and joined in the condemnation of Eutyches and Dioscurus. After this period he seems to have continued a zealous opponent of the Monophysite party, for we find that in the year 458 he joined with his fellow-bishops of Isauria, in an appeal to the Emperor Leo I, requesting him to use his influence in forwarding the Decrees of Chalcedon, and in securing the deposition of Timotheus Aelurus, who had intruded himself (457) into the Patriarchate of Alexandria. This is the last reference we find to Basil, and it is commonly supposed that he died shortly afterwards.
Forty-one sermons (logoi) on different portions of the Old Testament have come down to us under his name, and are found in Migne (P.G., LXXXV, 27-474), where is also his history of the protomartyr Thecla and of the miracles wrought at her grave (ibid., 477-618). Most of these sermons may be regarded as genuine, though some of them are now generally assigned to Nestorius: According to Photius, Basil also dealt in verse with the life and miracles of Thecla.