Helots, the serfs who formed the lowest grade in the Spartan population, consisting originally of the Achaean landowners who had been enslaved by the Doric invaders. In many respects they resembled the mediaeval villeins - e.g. they worked for individual proprietors, to whom they paid a fixed rent in kind, and they could not be sold away from the land to which they were bound. They belonged to the state, which alone could grant them freedom. In war they usually served as light-armed troops, but occasionally they were enrolled as a part of the regular army. They were very cruelly treated, and the murder of Helots was one of the duties entrusted to the "secret commissions" of Spartan youths.