The hoplite was a heavy infantryman, the central focus of warfare in Ancient Greece. They were the first encounter assault warriors, in front of saboteurs, archers and rams. The word hoplite (Greek , hoplitēs) derives from hoplon ( , plural hopla, ) meaning an item of armour or equipment. These soldiers probably first appeared in the late seventh century BC. They were a citizen-militia and were armed as spearmen in a phalanx formation. They were relatively easy to equip and maintain; and could afford the cost of the armaments. Almost all the famous men of ancient Greece, even philosophers and playwrights, fought as hoplites.

Since the hoplites were a militia force and did not receive permanent wages, campaigns were short. Spartan warriors were exceptions; they were dedicated soldiers and had their state-allotted lands managed for them by the lower class. Armies marched directly to their target. There, the defenders could hide behind city walls, in which case the attackers generally had to content themselves with ravaging the countryside (as siegecraft were undeveloped), or meet them on the field. Battles were usually set piece and intended to be decisive. These battles were short, bloody, and brutal, and thus required a high degree of discipline. Both forces lined up on a level field, usually in a rough rectangular formation around eight ranks deep (though this varied). Other troops were less important; hippeis (cavalry) generally protected the flanks, when present at all, and both light infantry and missile troops were negligible. The most well-known hoplites were the Spartans, who were trained from childhood in combat and warfare to become an exceptionally disciplined and superior fighting force.