We're about 1/3 of the way through 100 ideas for horror movies, so let's shake things up a bit. The next few ideas follow a theme: They've already been done.
Sometimes I'm halfway through writing an original idea for a horror movie, when I get to the extensive research phase of the process and realize that it's already been done by somebody else. Here are the smelly aborted corpses of ideas that never even had a chance:
30. Killer Pigs: Pigs are evil and kill people and - DAMN! Someone's already making "Pig Hunt".
31. Killer Sheep: There are a lot of sheep in the world, and - BAH! Already done, and with a much better title: Black Sheep. "There are 40 million sheep in New Zealand; AND THEY'RE PISSED OFF!". Couldn't have said it better myself.
32. Killer Nuns: Nuns are just so repressed, they're bound to - OH SNAP! There's not just one movie, but an entire genre of movies on this. Click for more info on Nunsploitation (seriously).
33. Killer Cops: OK OK, killer cops is nothing new. But how about REALLY evil killer cops, who, like, taser 15 year old autistic kids. No, no, even better, they taser old ladies in wheelchairs until they die. And then - OH NO, BRO! It's not only been done, but it's been done in real life. The kid and his awesome beard survived, but the old wheelchair lady is still dead. It's not so funny when it's real life horror.
34. Killer Vagina: It's about ... well ... oh, why do I even try any more? Just click to find out more about "Teeth."
Conclusion: Everything's been done. There's no such thing as an original idea for a horror movie. I quit.
See also: #25 - 29.