Theodoros Ziakas (Greek: Θεόδωρος Ζιάκας) is a former municipality in Grevena regional unit, West Macedonia, Greece. Since the 2011 local government reform it is part of the municipality Grevena, of which it is a municipal unit. It was named after Theodoros Ziakas, a 19th century leader of the Greek struggle for independence. Population 2,855 (2001). The seat of the municipality was in Mavranaioi. The village stands at 900 meters elevation.