Theodore Komnenos Doukas Palaiologos Synadenos (, ca. 1277 – ca. 1346), usually simply Theodore Synadenos, was a Byzantine magnate, senior official and military leader of the early 14th century, who played an important role in the civil wars of the period. The scion of a noble lineage, he became one of the first and most prominent supporters of Andronikos III Palaiologos in his struggle against his grandfather Andronikos II. Synadenos held various provincial governorships during Andronikos III's reign, including Epirus and Thessalonica. After the outbreak of the civil war of 1341–1347, he tried to surrender Thessalonica to his old friend John Kantakouzenos, but was driven from the city by the Zealots of Thessalonica. Forced to join Kantakouzenos's enemies, he was initially honoured with the high rank of "protovestiarios" but soon placed under house arrest in Constantinople, where he died impoverished in 1345 or 1346.