I like a good horror movie as much as the next blogger, but horror comes in all different forms. That's the funny thing about genre, that it always branches off into various subgenres which themselves have subgenres all characterized by specific iconography and patterns. Horror is one of the best examples of such branching.
One of the most well-known branches would be the slasher film, which is characterized by its formula. The typical plot of a slasher film is a group of teens get stalked by an unnecessarily invincible killer and get picked off one by one. Usually most of the teens are a bit stupid and get killed while having sex, but the virgin manages to survive. The slasher is just the best-known. There are plenty of other subgenres of horror, such as psychological horror, paranormal horror, body horror, macabre or gothic horror (such as the stories of Edgar Allen Poe) and monster movies.
Those in turn often have many divides of their own. For instance the monster movie encompasses a whole other genre in zombie films, along with the likes of vampires, werewolves, Frankenstein's monster and so forth. That's not even getting into the numerous ways those subgenres can overlap and be combined with other genres (Event Horizon, for instance, is essentially a haunted house movie with the "house" replaced by a futuristic spaceship).
What I'm interested in is a particular kind of horror, one which I feel is a bit underrated. It's not normally listed alongside the other types of horror, even though it is one of the most fascinating and has been explored by some of the most iconic names in horror (including H.P. Lovecraft, Stephen King, and John Carpenter). It's even become something of a popular area for video games (Dead Space and Mass Effect). This is a type of horror known as Cosmic Horror.
Cosmic horror works a bit differently from other forms of horror in that it is based on a very bleak philosophy. There are many different places to draw fear from, but this particular one might be one of the greatest sources you can find. While cosmic horror stories can (and often do) have big scary monsters, body horror, psychological horror, paranormal activity, and just good old fashioned fear of the unknown, those are not the primary sources of terror in themselves.
Instead, what happens is that those are used as an agent of sorts by which to convey the greater fear. A cosmic horror story doesn't just try to scare you with blood and gore and scary monsters. Instead it is aims to depress you by forcing you to realize just how meaningless existence really is. The fear in a cosmic horror story comes from the knowledge that mankind is little more than a spec of dust in the grand scheme of things.
As the name implies this means that the horrors are often on a cosmic scale, not actively hostile towards us so much as indifferent. There are things out there that could wipe us out in a second with no effort, and they don't really care what happens. A common analogy is that these... things would see us the same way we would see bugs on the sidewalk.
You know how sometimes when you're walking down the street you might see an anthill and while you don't actively try to destroy it, you don't really bother yourself with the possibility of something happening to it, even though there are plenty of things that could easily end its existence? Imagine that on a cosmic scale, except now with Earth in place of the anthill, and you will get a sense of what cosmic horror truly entails. It is an intriguing philosophy, one that is not always easy to explore.
So obviously if you want to give a sense of mankind's insignificance in the universe you're going to want some means by which to convey that fear. This is where the the other horrors come into play. Often times you will see scary monsters of some sort, or at the very least you will feel their presence. That alone is another aspect of the cosmic horror story: fear of the unknown. Mankind is such a tiny, barely noticeable part of the universe that these horrors are usually things we cannot begin to understand.
Take one of the most famous cosmic horror monsters, for instance: Cthulhu. Part of what makes him such an effective character is how truly alien he is.We never really get into his head, we just know (based on unreliable information) that one day "when the stars are right" he will rise from the ocean, and apparently we will become something like him (the Lovecraft story alludes to massive violence and chaos that would happen when that time comes). His reign of terror is averted when he is struck by a boat, but the story makes it clear that this is little more than an inconvenience that will delay him. The worst part of it all? Cthulhu is actually one of the weaker beings in the overall mythos. If you think he's bad, let's not even get started on Azathoth or Yog-Sothoth.
Even the city of R'lyeh in which Cthulhu lives is beyond our range of understanding, said to be filled to the brim with "non-euclidean geometry". I can't even begin to describe what that word means or how it applies to the city. That's another thing that is common in cosmic horror. A lot of these stories have the monsters as things that are better left unseen. Sometimes they are so mind-bogglingly alien that simply looking at them is guaranteed to drive you to madness... and that's a best case scenario. Images like the one above depicting these beings are little more than approximations because their true appearance is literally indescribable.
That said, sanity-shattering monsters are not essential to a compelling cosmic horror story. The Whisperer in Darkness, The Shadow Over Innsmouth, and At the Mountains of Madness are all stories by Lovecraft himself that feature creatures described in a bit more depth. At the Mountains of Madness despite being very much a cosmic horror story, features some of the few beings that are actually cast in a sympathetic light (not that you'd want to meet them, but their story does leave you to wonder what could eventually happen to humanity).
Prometheus is a movie that has been occasionally labeled as a cosmic horror story, and it lacks any of the sanity-shattering abominations. However, it does still touch on the theme of humanity's insignificance in that we were just some experiment of an ancient race of aliens. Essentially, the universe is just one big construction site to them, and we were one small project. Much like how we might take a wrecking ball to an old building to make way for something new, these "Engineers" believed they needed to "demolish" our species so they could create something else.
Even 2001 borders on cosmic horror at times. While it has a fairly optimistic outlook on humanity's place in the universe, it still emphasizes that we have a long way to go. Those monoliths are also built by aliens so mind-bogglingly complex they couldn't be shown, not to mention we never even get a solid answer to the question of just what the heck those things are. They seem to be in some way designed to inspire humanity to keep going, but how they work or what their purpose was is beyond anyone's capability to understand.
So in the long run, the key to a good cosmic horror story is to look at the fact that the universe is so complex that we still are unable to understand everything. Earth is one of eight planets orbiting one of a hundred billion stars in one of billions upon billions of galaxies. Ultimately we are a very tiny part and while we have not (yet) faced any of the Great Old Ones, there are things that could in theory wipe out our planet under the right circumstances (although none are inevitable). The true terror comes not from the monsters, but from the understanding of that simple idea.
I have divulged the secrets of cosmic terror, but I fear that I may know too much. The cult still lives, and so does Cthulhu. One day they will return. The Great Old Ones shall rule the Earth once more. All will bow down before their might. Yog-Sothoth knows the gate. Yog-Sothoth is the gate. Yog-Sothoth is the key and guardian of the gate. Beware the wrath of the Crawling Chaos that is Nyarlathotep.
They're coming. We're doomed. We're all doomed. Ia Shub-Niggurath. Cthulhu Ftagn. The end is near. Something is coming, I can hear it. OH GOD! THAT HAND! IT'S HERE! IT'S HERE! IT'S COMING FOR ME! THE WINDOW! THE WINDOW! I CANNOT DESCRIBE IT! THOSE EYES! THAT THREE-LOBED EYE! THE MONSTROUS TENTACLES! I SHALL NOT LET IT GET TO ME! I WILL NOT LET IT FIND ME! THE WINDOW! THE WINDOW!