What's a theme or idea that the horror genre hasn't touched in movies yet?

Horror is like Rule 34. Rule 34 is, if it exists, there’s porn about it on the internet. I find the horror genre to be similar. Horror of course will continue to treat its main elements such as monsters, murderers, evil forces, ghosts, zombies, whatever. But it often uses some subject or theme that has nothing to do with the primary elements that define horror.
Body modification, vehicles, fossils, food, war, the internet, addictions, you name it. Of course some themes that had nothing to do with horror before became prominent based on a movie’s success, like animals, toys or the medical field. I’m sure if Stephen King wanted to write a novel about all those single shoes you always find on the highway, he could. But still, it seems to me that horror borrows from so many different sources, that I’m wondering if there’s something it hasn’t touched yet. So what subject or theme hasn’t been made into a horror movie yet? (humour welcome)