As I was making a list of my 50 favorite horror crossover films, it suddenly struck me how many films, classified by most as science fiction, have a large horror/terror component to them. In fact, I had a difficult time not wanting to classify many of my favorite sci-fi movies as horror or at least horror crossovers. Alien is the perfect example. I have friends (really I do) who consider Alien strictly science fiction, but take a close look at the dark interiors, and the horrifying creature stalking the trapped crew – always just out of site. The reveals (or peeks) of the creature are more like something out of a classic horror/slasher film. And let’s not forget the first ever chest-burster debut! In fact all the sci-fi elements play second fiddle to the monster/alien. The movie starts out like a science fiction movie, but rapidly accelerates towards the horror side of the scale with every frame past the discovery of the crashed alien ship on the planet’s surface (a ship which I believe appears in the prequel, Prometheus). But I digress.
Sub-genres or Categories
It is my contention that most if not all sci-fi flicks fall into 5 basic sub-genres/categories:
1. Adventure/Opera: Star Trek , Space Cowboys , Cowboys and Aliens , Star Wars 
2. Discovery/Exploration: Stargate , First Men in the Moon , Time Machine [1960,2002]
3. Psychological/Bizarre: Pandorum , Event Horizon , Virus , Doctor Who [?]
4. Humor/Farce: The Hitchhiker’s Guide to the Galaxy , Dark Star , Galaxy Quest , Spaceballs 
5. Primarily Horror: Alien , Invasion of the Body Snatchers , I Am Legend 
(Obviously, this list is not all-inclusive, and films exist that cover multiple categories, but it should give you a pretty good idea of my categories.)
So what is the terror:sci-fi equation?
As I examine the above examples of science fiction, I see that all but the humor/farce films have elements of horror. (I would entertain the argument that even the humorous films have some element of horror or fear – though mocked or made melodrama.) Whether it’s villains, aliens, or just surviving the hazards of space and mad science experiments, the danger and the terror is there. So what is it about science fiction that makes us turn it into nightmares? We could be creating images of a Utopian world in which aliens and/or science has conquered all evils, and all sentients live in peace and harmony…but lets face it, that’s boring!
It’s much more interesting to create Dystopia, man-made monsters, science experiments gone terribly wrong, and aliens that want to eat our face off. Perhaps we secretly fear there is something intrinsically wrong with science. Honestly, despite our public schools (or because of our public schools), most people have very little understanding of science – especially the hard sciences; the kind required to make space travel and human-like robots a reality. We fear what we can’t understand.
We also fear the unknown (perhaps more than anything else), and if science teaches us anything, it is that there is a great deal we do not know – about “life, the universe and everything”*. This ability of humans to examine our fears, put them under a microscope, indulge them, poke them with a 1,000 megawatt cattle prod, and even seek them out on a regular basis, is truly amazing. Why do we do this to ourselves? Is it the thrill? Heck yes! Why else? Apparently, since saber-tooth tigers went extinct, life just isn’t exciting enough for us so we invent ways to make it so. One of those ways is by living vicariously through others – including characters in cave paintings, folk tales, books, movies and TV. We just can’t get enough fear. If we were in isolation and our brains were wired with a button to activate fear, we’d push that button rather than feel nothing. I suspect many of us might even become addicted. Perhaps we are already addicted. So, in order to reach the intensity that makes our earthly existence bearable, and in lieu of wiring our brains, sci-fi fans amp it up with healthy doses of horror.
What does all this amount to?
The possibilities presented by science fiction are interesting, but not so much so that we’re willing to pay to sit in a dark theatre without the thrill of adrenaline. The more real the fear the better we like it. I believe this fear transforms us, giving us the power to move beyond the barrier of the screen and live on the other side, if only for a little while. And life on the other side of the screen is full of deliciously terrifying possibilities (sans button).
On a personal note: I can’t wait to see what horror Ridley Scott has cooked up in Prometheus! I’m pushing my button right now, just to make sure my fear is in good shape.
* “Life, the universe, and everything,” is a quote from Douglas Adams’ The Hitchhiker’s Guide to the Galaxy series.