Parmenio (born c. 400 bc—died 330, Ecbatana, Media) was a Macedonian general usually considered the best officer in the service of Philip II and his son Alexander the Great.
During the reign of Philip, Parmenio won a great victory over the Illyrians (356). In 336 he was sent with Amyntas and Attalus, his son-in-law, to Asia Minor to make preparations for the conquest of Asia. In the confusion that followed Philip’s murder, he declared for Alexander and assisted in the murder of members of the faction opposed to Alexander. Parmenio became Alexander’s second in command throughout the conquest of Persia and commanded the left wing of the army at the battles of Granicus, Issus, and Gaugamela. When Alexander continued eastward after the conquest of the Persian Empire, he left Parmenio in Media to guard his communications. During the campaign, Philotas, Parmenio’s son, was charged with conspiring to murder Alexander, tried, and put to death. Though it is likely that Philotas was innocent, Alexander had Parmenio murdered.