Horror movies....

How about House, House II: The Second Story, and House IV: Home Dead Home. I have never found an explanation as to why there was never a House III.

EDIT: Apparently, House III was released under a different name, The Horror Show. Haven't seen that one, so I don't know anything about it. From reading the synopsis, it sounds a lot like Shocker. The Horror Show has Lance Henriksen in it, but if you want a good horror movie with Lance Henriksen, watch Pumpkinhead.