Constantine (Greek: Κωνσταντῖνος), surnamed Barbaros ("the barbarian", ὁ βάρβαρος), was a Byzantine eunuch servant who rose to become parakoimomenos (head chamberlain) of the Byzantine emperor Leo VI the Wise in 911–912, displacing his own former master, Samonas. He held again the post during the regency of Zoe Karbonopsina in 913–919, where he played an important role in the governance of the state. He lost his post after he supported his relative Leo Phokas the Elder in his unsuccessful rivalry with Romanos I Lekapenos over control of the throne, but he was later appointed to the post of primikerios by Lekapenos.