Marcian (märˈshən) [key], 396–457, Roman emperor of the East (450–57); successor of Theodosius II, whose sister Pulcheria he married in 450. Orthodox in religious affairs, he convoked (451) the Council of Chalcedon (see Chalcedon, Council of). He curtailed court expenses and endeavored to lighten taxation. His refusal to pay tribute to Attila precipitated the Hunnic invasion of the Roman Empire. With him the Theodosian dynasty came to an end in the East. Leo I succeeded him.