Hetairoi (ἑταῖροι/hetaîroi, ‘companions’) constituted the king's retinue in Greek monarchies, even on the battlefield (e.g. Hom. Il. 1,179).
In the Classical period hetairoi were especially important in Macedonia: selected by the king himself, they made up his immediate entourage as his closest advisers and as the next generation of leaders. The king went to war at the head of their unit, which probably resulted in the original, military meaning of the term. Hetairoi (often supplemented by βασιλικοί, basilikoí) are attested for the Macedonian cavalry with …