With Halloween fast approaching, it might be appropriate to spend some time considering horror films in detail. A more structured set of articles will appear soon (and no, I haven't forgotten SpaceSquid vs. The X-Men, I just need more time to research Mimic, I can't read more than three pages without passing out with boredom), but since I'm short of time this evening we'll dip our toes into the water with the following question: why do I like horror in the first place?
Much of this post was born out of arguing with Gooder (I expect he'll appear pretty quickly in the comments section to tell me everything I've said is wrong and that I've totally misrepresented his position), who is simultaneously the go-to guy on any given film question, and almost totally disinterested in horror as a genre. He has on several occasions described horror as a roller-coaster ride, and there's certainly some truth to that analogy. If films are designed to do anything, they're intended to instill emotion in the viewer, and horror movies are based around the build-up of apprehension, stepping up to fear (hopefully, if the film-makers are any good) which then explodes in a sudden (or perhaps not quite so sudden) shock, followed by release. Not too dissimilar from a fairground ride.
Of course, while the analogy may not be inaccurate (and I do like roller coaster rides, or would do if my general cynicism didn't make me sure that every one I get on will inevitably collapse and then burst into flames), it also doesn't go far enough, any more than likening Some Like It Hot to a joke book would. There is much, much more to the genre than that.
Uniquely amongst cinema genres, horror films are sold on the quality of their antagonists . There are two levels to this. Most obviously, there are any number of films where the villains themselves are the immediate draw. The various horror franchises are clear examples of this. Freddy Krueger, Jason Voorhees, Michael Myers, the Tall Man, on and on and on and on and on. In almost every other movie franchise I can think of, villains can come and go but the heroes stay the same (until they jump ship, anyway). With horror films, though, the heroes are almost entirely incidental. I literally cannot remember the name of a single character from the Nightmare..., Friday... or Halloween series (Phantasm is an important exception, though Reggie the sex-pest is hardly what one would call heroic) other than the indestructible killer. Whilst it is true that once a franchise reaches a certain point each new installment becomes less of a story and more of an exercise in box-ticking, it is still of interest that in this case the boxes are entirely based around the actions of the villains (well, there probably has to be tits in it as well, in fairness). Interesting antagonists often vastly improve a movie, and can even save one entirely (see Die Hard and Robin Hood: Prince of Thieves, respectively, both of which owe a massive debt to Alan Rickman), but in horror the villain is the starting point. Adversary, then plot, then hero, if there's time. Many trailers spend some time setting up the situation the protagonists have found themselves in, but it isn't often outside of horror movies that much time is spent plugging specific villains (unless they're being played by someone famous).
Obviously, sometimes this is sheer name recognition; Dracula, Frankenstein , Nosferatu (again, though, how many non-horror films are named after the bad guy?). On other occasions, though, individual monstrosities are less important than the overall genus. Marauding zombies (Romero class, natch), vicious werewolves, radioactive mutants; even starting with such basic templates, often the individual traits of the "heroes" are quickly overwhelmed. That's not to say that the protagonists are necessarily particularly poorly written (although they often are), simply that the enemy always seems to hog all the attention. Who remembers anything the Carter family did in The Hills Have Eyes remake other than end up on the crappy end of a bunch of radioactively-scarred hillbillies? I can remember exactly two moments from Wrong Turn, and both of them involve a particularly grim death at the hands of an outraged genetic deviant. Even in the cleverest horror films (The Last Broadcast, Ring, the original Day Of The Dead), the most iconic scenes involve the opposition, with the protagonist(s) essentially reduced to cannon-fodder.
There is a second way that these films often take shape around their villains. Many of the best horror films combine a monstrous protagonist with an interesting mystery. Science fiction and fantasy often manage this as well, as (obviously) do thrillers, though the necessarily prosaic puzzles of the last category mean they are of less interest to me. What makes these enigmas particularly fascinating in the case of horror is, in part, that one is invited to solve them without being sure which of the established laws of the universe actually apply in this case. It's an exercise in lateral thinking. As I say, this often applies to science fiction and fantasy as well (though less frequently), but what makes horror unique in this regard is that the process of gathering together the threads goes on at the exact same time as your brain is being distracted by swells of sinister music and mutilated corpses are falling out of wardrobes. You're trying to engage your cortex whilst your reptile brain keeps screaming for attention. It's like trying to sit an A-level French paper inside a burning building.
That's why so many of these films revolve around "Who is the killer?", or "What is inside the puzzle box?" or "Why is it that before you die, you see the ring?". At least, that's what the best of them do . Even the comparatively straightforward examples of the genre contain something along these lines, mainly because horror by its very nature demands it. It can be as simple an idea as "What's on the other side of that door?" or "What is it with all these undead cannibals, Barbara?", but horror thrives on that sense of unknown. It's the unknown that's scary, after all. In a crime drama, when the FBI agent pulls a gun on a Mafia Capo, we know the criminal might escape, or disarm the Fed, or have reinforcements waiting in the wings, but him turning into a giant cockroach or making his enemy's head explode with mind-bullets are possibilities we generally discount.
So that's my case. Horror films rely on fear where most other genres at most reference it from time to time. They focus on the machinations and/or the nature of their antagonists in a way that sets them apart from other films. They can promote deductive reasoning at the very same time as they desperately attempt to rob us of it. Last, but not least, they rely on plumbing the depths of the unknown, which appeals to my sense of monkey curiosity, and I'd wager I'm not alone in that.
That's how I see it all, anyway. Puzzles and monsters and the darkness over the next hill that you know you shouldn't go to look at, but you just can't help yourself.
 Obviously there are individual films that are sold on the villain (though as my esteemed flatmate points out, in this case they are often referred to as anti-heroes), but these are rarities in any genre beyond horror.
 OK, so Frankenstein himself is technically the protagonist (though it would be a stretch to call him the hero). Note though how many people think it's the name of the monster. Still, if you want to be pedantic about it, you could always replace Frankenstein with King Kong if you want. And don't tell me King Kong isn't horror, it's original incarnation is a fairly par-for-the-course creature feature, albeit one with more class than most.
 I'd be careful about pigeon-holing it as horror, though there would be some logic in doing so, but Dark City (absent the cheat-code initial voice-over, obviously) is one of the best examples I've ever seen of attempting to piece together a complex puzzle whilst avoiding being distracted by all the crazy shenanigans (in this case brightly-coloured energy-spiders and a bunch of murdered hookers. And Richard O'Brien). Shallow Ground and (especially) The Last Broadcast (which if you haven't seen, you must see now, alone and in the dark, because I did and it almost killed me and I dare you to prove your worth!) boast a similarly intricate jigsaw, but with a somewhat greater degree of OH HOLY SHIT WHAT WAS THAT!?!