Chief conspirator against Cæsar; won over Brutus to join in the foul plot; soon after the deed was done fled to Syria, made himself master of it; joined his forces with those of Brutus at Philippi; repulsed on the right, thought all was lost; withdrew into his tent, and called his freedmen to kill him; Brutus, in his lamentation over him, called him the "last of the Romans"; d . 42 B.C.