Parmenion (also Parmenio; Greek: Παρμενίων; c. 400 – Ecbatana, 330 BC) was a Macedonian general in the service of Philip II of Macedon and Alexander the Great, who was assassinated on a false charge of treason. Parmenion was a nobleman and father of Philotas. Parmenion rose to become Philip's chief military lieutenant and Alexander's Strategos (military general).
During the reign of Philip II, Parmenion achieved a great victory over the Illyrians in 356 BC. Ten years later, Parmenion destroyed the southern Thessalian town of Halos. He was one of the Macedonian delegates appointed to conclude peace with Athens in 346 BC, and was sent with an army to oversee Macedonian influence in Euboea in 342 BC.
In 336 BC Phillip II sent Parmenion, with Amyntas, Andromenes and Attalus and an army of 10,000 men into Anatolia to make preparations to free the Greeks living on the western coast and islands from Persian rule. At first, all went well. The Greek cities on the western coast of Anatolia revolted until the news arrived that Philip had been murdered and had been succeeded by his young son Alexander. The Macedonians were demoralized by Philip's death and were subsequently defeated near Magnesia by the Persians under the command of the mercenary Memnon of Rhodes.
Although Alexander was recognized as king in Macedonia in October 336 BC his accession was opposed by Attalus, a general in Parmenion's army. In response, Parmenion put the general to death even though Parmenion was related to Attalus. However, Parmenion recognised that this was a necessary act if Alexander's succession was to be smooth. As a consequence, Alexander was in Parmenion's debt particularly given that Parmenion was his most experienced general and commanded a large army.
As a result, a number of Parmenion's relatives were placed by Alexander in key positions in the Macedonian army. His youngest son Nicanor became commander of the infantry regiment known as the Shield bearers, his son-in-law Coenus commanded a phalanx battalion while another relative named Nicanor became admiral of the navy made up of Macedonia's Greek allies. Parmenion's friend Amyntas and his brother Asander were placed in key positions. Parmenion's oldest son Philotas was made commander of the Companion cavalry, a unit of 1800 horsemen that was Macedonia's most effective weapon in its battles. Parmenion became Alexander's second in command, the same position he had held under Philip.