Nonnus (Ancient Greek: Νόννος, Nónnos) was a bishop of Edessa in the mid-5th century.
Nonnus was preceded as bishop of Edessa by Ibas (Donatus), who was irregularly deposed.
Ibas was deposed on 1 January 448 and Nonnus enthroned as his replacement on 21 July 448.
Ibas was held in prison but freed on 27 October 451, the earlier proceedings against him having been found irregular and unjustified.
Similarly, he is sometimes conflated with the Egyptian Christian epic poet Nonnus of Panopolis, who was a rough contemporary.