Devils

The devils mainly held power throughout the second age, but lost their power in the third age, when the undead took over. Now, they are largely known for holding power of High Crest, at least to those that live in High Crest.

Asmodeus
Asmodeus is the king of all devils, and also a god, possibly, depending on one's interpretation of the cosmology.

The Cult of Asmodeus
They worship the devil god Asmodeus, and currently run High Crest. They've attained the unique accomplishment of being hated by every faction in the world.