There are lots. The first two that come to mind are:
Vampire bats of the subfamily Desmodontinae. Creepy because they hit you while you’re sleeping.
The nematode Myrmeconema neotropicum, which incidentally has NO observations on iNaturalist. Creepy because it does mind control, like many internal parasites.
I don’t find lampreys to be as creepy, because it’s pretty obvious when you have a garden hose hanging off of you. They don’t have that “sneaky” factor of you being asleep, or doing mind control on you.