We can split all horror movies into few different types. First, and, as I think, most prevalent type is movies where only one bad guy, but he keeps all neighbourhood in deep fear. Movies like this makes you scare of thought you have a man behind your front door like this one, and he will come in your house very soon, and tear you apart (none of these people understands, why would bad guy need to kill them in particular - because it doesn’t really matter, they just want to be scared that way). It’s movies like Friday the 13th, A Nightmare on Elm Street, and some more.
Second type is the movies about crowds of monsters killing everything that comes in their way - zombies, mutants, aliens, or different creatures. They are really scary, because often they show us a picture when you’re all alone and the whole world is standing against you and there’s nothing you can do - just run and hide in silence and dark places. Of course, I never really understood why zombies, for example, want to eat brains and bodies of living people, and why they don’t want to do it with each other - maybe it’s because we’re very tasty? But no, movies showing us that they’re just hungry. I don’t think that brain of zombie really differs from brain of people who’re not yet dead, and if you download Scary Movie 5 and watch it, you will have no more doubts about it.. There are many movies in this type - Dawn of the Dead, World War Z, and I can even refer to this type I am Legend full movie (with all endings, of course, or it won’t be full picture).
Third type became popular no so long ago, and maybe Paranormal Activity series was a start for movies like this. It’s about something we don’t understand, can’t see and can’t fight against - so, these movies bring fear in your heart because of obscurity. For example, this Paranormal Activity 5 full movie online, which you can watch right here and right now, showing us a little family living in peaceful place, when something strange start to happen in their house every day. Well, all of series of these movies is like this, so you can’t complain about it.
And fourth type is most dull horror movies, because only way they can really frighten you is suddenly showing scary pictures and using loud noises in the middle of dark and stressful scene. Main hero walks downstairs in the cellar (as usual), when suddenly his light is broke down (or batteries out), and he doesn’t turns on lights or getting away from the house with loud screams of panic, no, he just keeps moving down to the darkness and strangeness, and suddenly (when no one expect this, of course), from the corner shows up creepy creature who screamed loud and jumps on the camera.
Yes, after all we have another pictures which we can refer to the horror type, but they’re not really a horror. Final Destination, Machete Kills, The Critters (my beloved movie since I was a child!), and many more. These movies just contains scenes with disgusting pictures or they’re parodies to the horrors, so we can say it’s a fifth type. Generally - they’re not scary. What do you think of this separation of horror movies, maybe you can add something?