John Komnenos (Greek: Ἰωάννης Κομνηνός) was a Byzantine aristocrat, the nephew of Emperor Alexios I Komnenos (r. 1081–1118) and long-time governor (doux) of the strategically important city and theme of Dyrrhachium.
John was born probably circa 1074, the eldest son of Alexios's elder brother, the sebastokrator Isaac Komnenos, and his Georgian wife, Irene "of Alania". In 1081, his uncle, Emperor Alexios I Komnenos, proposed a marriage match between John and a German princess to the Holy Roman Emperor Henry IV (r. 1056–1105), but nothing came of this.
In early 1091, John was chosen by Alexios to replace John Doukas as the governor (doux) of Dyrrhachium, in modern-day Albania. The city was of great importance to the Byzantine Empire, as the "key of Albania" and the main point of entry from Italy into the Balkans, a fact illustrated by the role it played in the Norman invasion in the early years of Alexios's reign. Soon after the assumption of his duties, however, he was accused by Theophylact of Bulgaria of plotting against the Byzantine emperor. To defend himself against the accusation, John travelled to Philippopolis, where Alexios resided. It is not clear whether the allegations had any substance; nevertheless, the affair evolved into a family quarrel between Alexios and his brother Isaac, who was also present. Eventually, Alexios dismissed the allegations and reconfirmed John in his post.