9 Animals With Creepy As F*** Horror Movie Powers
9. Mind Controlling Parasites

Any supernatural horror film worth its salt will feature a good old fashioned bit of mind control. As humans, we put a lot of stock in our ability to think for ourselves, and so the idea of that being taken away from us is prime horror fodder.
There is a genus of fungi known as the Cordyceps, which contains many species that specialise in taking over the brains of its victim. Ophiocordyceps unilateralis, for example, loves nothing more than tunnelling into the flesh of ants, driving them around for a bit like an ant-shaped sports car, forcing it to clamp itself to the underside of a leaf then erupting from its broken body with a couple of delightful "fruiting bodies" (which is exactly as gross as it sounds).
In the mollusc world, it's the Green-Banded Broodsac, that you've got to worry about. This guy gets into the bodies of snails via poop (because snails sure love to eat some poop), then forces its way up to the eyestalk of the snail (rude) and does its best impression of a delicious, wriggly caterpillar.
It does this in the hope of attracting the attention of a passing bird, so in order to maximise the chances of success, it also causally takes control of the snail's brain, forcing it to go and sit in a nice, bright, bird-filled spot. The bird eats it, the broodsac lays its eggs in the bird, which poops them out and another snail eats them. There is literally nothing likeable about this creature.
As yet, humans haven't quite found a way of taking over the minds of others (although we are getting there, but that's a different kettle of broodsac.)