Wild animals
In horror movies, one common scare tactic is jump scares, using the surprise factor as a weapon.. Nature itself can give us some of the biggest jump scares. The best (or worst) thing about them is you can never prepare for what will happen. Surprises can be disastrous.
You never know when a real bear will pop up outside your window. Bears are wild, dangerous animals that can smell any food you have out. Not all bears are violent, but would definitely jump if we ever saw one up close.