in person :
Freakest thing is probably a "Sea Moray" near a hotel room we lived at which was right up against the ocean, you could step out to the porch and jump in the sea.

Right next to where you could jump in, there where rocks and a Moray was there.
It scared the crap outta me as a kid, because their dangerous looking (and their bite kills (bacteria)).
I mean just look at it (picture of what a moray looks like below):

Bedbugs. They're super creatures, really.

They are hard to sport, hard to get rid of, have developed resistance to most insecticides. Even when you get rid of them, if you don't live in a detached house, they will infest your neighbour's house and come back to yours when the insecticides you sprayed levels go down and stop being effective.

They can live for 18 months without feeding on you, so even if you move out temporarily, they will not leave your house due to the lack of food.

You also worry about inviting friends over, because you don't want a pregnant female bedbug finding its way to their homes causing them sleepless nightmares.

Monkeys/ Apes

They've gone to space for Christ's sake. Able to manifest near-human intelligence and empathy (perhaps more).

See this pic of a monkey doing oone f the most remarkable things that humans do.