Isaija the Monk (Serbian: Инок Исаија or in English: Inok Isaija; ca. 1300–after 1375), also known as Elder Isaija (Elder Isaiah) (Старац Исаија) and Isaija of Serres (Elder Isaiah of Serres) (Исаија Серски), was a 14th-century Serbian monk, one of many Serbian monk-scribes in the Middle Ages who translated ancient Greek manuscripts into the Serbian recension of Old Church Slavonic. His major work is the translation of the works of Pseudo-Dionysius the Areopagite from Byzantine Greek. Isaija's commentaries on political events occur in the context of the fall of the Serbian principality of Serres in 1371, which led the descendants of these local governors to accept Ottoman suzerainty.