Quintus Labienus Parthicus (died 39 BC), the son of Titus Labienus, was a Roman republican general, later in the service of Parthia. After the then main political power in Rome, Julius Caesar, was murdered by a conspiracy in 44 BC, Labienus took the side of the pro-republic conspirators, led by Brutus and Cassius, the latter of whom he served in the capacity of an ambassador to the Parthians.