Creatures are the "class" that makes up any unit in an army, and the only compulsary element of a unit.
They include humans, orcs, imps, vermins, elementals and other equippable creature types, as well as siege-type units that take up more cases and cannot be equipped.
Although the range indicated is 0 for most creatures, they can actually attack unarmed if they have damage, which has a single melee case range.Damage unarmed is 0.5 hp.