This list contains horror as well as horror-comedies and some thrillers; I'm also pretty generous with what I classify as 'not sucking.' If I've seen it and it's not in this list, it's probably pretty fucking awful.
The list is in alphabetical order (except the first six, obviously) with movies in the same series grouped together.
If you're going to watch the movies in any kind of order, you should try to watch them from oldest to newest; newer films often build upon what the older ones brought to the genre.
See the notes for more info.