John the Eunuch (Greek: Ιωάννης Ευνούχος) was a dignitary of the Empire of Trebizond who lived during the first half of the 14th century. There is no evidence in the sources regarding his descent, but apparently he did not belong to any notable aristocratic family. It is more likely that he rose thanks to his competence. He bore the high title of megas doux which meant that he was commander of the naval forces of Trebizond.[1] He lived in Limnia, a town on the coast of the Black Sea, which was a naval base. John played an important role in the internal affairs of the Empire of Trebizond until his assassination in March 1344.[2]