Theodore the Black was a 13th-century Russian prince and military commander who served the Golden Horde. Born in Smolensk around 1233, he held various titles, including Duke of Mozhaysk and ruler of both Smolensk and Yaroslavl. After leaving his first family to serve Khan Mengu-Timur, he rose to high status within the Mongol Empire, eventually marrying a daughter of the Khan. He is remembered for his military service to the Horde and his eventual return to Russia to reclaim his ancestral lands.