The Dark Ones - dark stalkers and dark creepers - are strange humanoid-looking dwellers in the underdark. Their language incomprehensible and their motives inscrutable, the creatures busy themselves gathering up small magical items, gems, and jewelry, often off of adventurers who pass near their lairs. They are known to explode in light and fire when slain, often ruining many of the items they carry.
The Underdark supplement for fourth edition detailed the dark ones as residents of the Shadowdark, where the world of shadow overlaps with the underworld below the surface. It is mentioned that they make able and willing servitors for a variety of Shadowdark dwellers, with the exception of drow.