Zemarchus (, fl. c. 568) was a Byzantine official, diplomat and traveller in the reign of Justin II. In the middle of the 6th century, the Göktürks conquered the Sogdiana and thus gained control of the silk trade, which then passed through Central Asia into Sassanid Persia. The Persian king, Chosroes I, dreading the intrusion of Turkish influence, refused to allow the old commerce to continue. The Turks, after many rebuffs, consented to a suggestion made by their mercantile subjects of the Soghd, and in 568 sent an embassy to Constantinople to form an alliance with the Byzantines and commence the silk trade directly with them, bypassing the Persian middlemen. The offer was accepted by Justin II, and in August 568, Zemarchus the Cilician left Byzantium for Sogdiana.