John II Megas Komnenos (, "Iōannēs II Megas Komnēnos") (c. 1262 – 16 August 1297) was Emperor of Trebizond from 1280 to 1297. He was the youngest son of Emperor Manuel I and his third wife, Irene Syrikaina, a Trapezuntine noblewoman. John succeeded to the throne after his full-brother George was betrayed by his archons on the mountain of Taurezion. It was during his reign that the style of the rulers of Trebizond changed; until then, they claimed the traditional title of the Byzantine emperors, "Emperor and Autocrat of the Romans", but from John II on they changed it to "Emperor and Autocrat of all the East, the Iberians, and the Transmarine Provinces", although Iberia had been lost in the reign of Andronikos I Gidos.