Ishoʿ bar Nun (c. 745–828) was Catholicos of the Church of the East from 823 to 828 and a major biblical exegete. Educated as a monk and teacher in leading monasteries of Mesopotamia, he later lived in Baghdad and Mosul. He authored influential biblical commentaries, especially his Selected Questions on the Old and New Testaments, which combined traditional Church of the East exegesis with more spiritual and allegorical interpretation. His work significantly shaped later East Syriac biblical scholarship.