Imps are demon familiars with varying skin-colors, who are native to the Demonic Plane. Their entire culture revolve around training from their birth to one day be summoned as companions to warlocks. Some have wings, others do not.
A much different kind of imp creatures lived inside giant worms below the Ketten Wastelands - however, one of these worms would eventually gnaw its way to the North, through a tunnel below the ocean. Each group of these cannibal imps looked different from the other. They tamed Blargh beasts.