In Ancient Greek armies, the psiloi (Ancient Greek ψιλοί, singular ψιλός, psilos, literally "bare, stripped") were light infantry who typically served as skirmishers and missile troops. They were distinguished from the armored hoplitai (heavy infantry) by their light weaponry and lack of armor.
In Classical Antiquity and Late Antiquity and throughout the existence of the Byzantine Empire, the lightest-armed troops, typically equipped with ranged weapons, and which fought irregularly in a loose formation, were deemed 'the psiloi'. Numbered among the psiloi were archers, the toxotai armed with a bow (toxa), and slingers, the (sphendonetai) who hurled stones or metal bullets with slings (sfendonai). Others, the akontistai, used the throwing javelin (akontia). Some psiloi simply threw stones at the enemy and were referred to as lithoboloi.