Pumpkinhead

Pumpkinhead is the central antagonist of the Pumpkinhead franchise - a powerful demon of vengeance who has varied origins depending on which film he appears in he is a demon that is much more alien in appearance than usual, being incredibly powerful and sharing a link with whoever summoned it.

Original Movie (1988)
In the original movie Pumpkinhead was summoned by Harley, the bereaved father of a young boy who was accidentally killed by a group of youths - unable to forgive them for what had happened Harley brought Pumpkinhead to life to exact vengeance on his behalf: however as the film progressed Harley couldn't live with the brutality he had unleashed (sharing a psychic link with Pumpkinhead - which was violently killing anything it came across).

Tracking down Pumpkinhead Harley attempted several unsuccessful attacks on the beast, only to realise that it was now a part of himself (a manifestation of his own rage and hate, perhaps) - in order to stop the demon once and for all, Harley decided to kill himself with a shotgun to the head - as he died Pumpkinhead perished with him.