Hus

Hus was the chief antagonist of the Buffy episode "Pangs" - he was a vengeful spirit who sought bloody retribution for the mistreatment of his people by early settlers in Sunnydale.

History
Hus was a Native American spirit warrior of the Chumash tribe which returned to exact vengeance against the residents of Sunndyale for the way they had horribly abused and tortured his people throughout their history. His spirit was somehow bound within an old Sunnydale Mission which was burried by a huge earthquake in 1812. Everyone assumed the mission had been leveled by the earthquake, and the town unknowingly built over it: only adding further to his anger and belief that Sunnydale was still filled with people that hated his kind. Due to his status as a ghost he was able to corporealize at will; turning from a green mist into his human. He was also able to assume animal forms, particularly a flock of crows, a coyote and a black bear (all of which are stereotypical imagery of Native American mythology). His victims were Professor Gerhardt and Father Gabriel. Afterwards he went after Buffy Summers, whose strength, due to Hus' warrior mentality, marked her as a figure of authority. Hus battled Buffy and her friends in the form of a black bear and was killed again when Buffy stabbed him in the neck with his own knife, which seemed to destroy him and his followers.

Hus was one of Buffy's more difficult villains in the fact Willow in particular had strong feelings about not killing him - indeed Hus' anger was somewhat justified but like many spirits he had allowed his anger and fear to turn him into a monster and ultimately made him no better than the people who had tormented his people all those years previously..