John Doukas (, ca. 1064 – before 1137) was a member of the Doukas family, a relative of Byzantine emperor Alexios I Komnenos (r. 1081–1118) and a senior military figure of his reign. As governor of Dyrrhachium, he secured the imperial possessions in the western Balkans against the Serbs. Appointed megas doux, he scoured the Aegean of the fleets of the Turkish emir Tzachas, suppressed rebellions in Crete and Cyprus, and then recovered much of the western coast of Anatolia for Byzantium.