The peltasts (in ancient Greek peltastaí, from péltê, light shield) are, from the 4th century BC, the mercenary infantry characteristic of Greek and then Hellenistic armies.
The peltasts are initially recruited in the Greek cities of the coast of Thrace and then they come later from more varied horizons. This light infantry, as opposed to the heavy infantry made up of hoplites, is made up of soldiers carrying a light wicker shield (peltè), either round or crescent-shaped, and armed with a javelin and a sword. The peltè is sometimes covered with goatskin or sheepskin, sometimes even with polished bronze.
Initially, they form only a support troop, used against cavalry charges, with the massive throw of their javelins, then they then use their swords. They probably also served in pursuit of the vanquished. However, given the low cost of equipment, large corps could be formed, and sometimes they had success against more powerfully armed hoplites, as at Lechaion or Sphacteria where they forced the Spartan army (locked in in the islet facing the harbor of Pylos) to go.
In the Macedonian army, the corps of hypaspists plays an identical role with, however, a slightly different armament.