@TulipWoodpecker - nope, leopard seals are as nasty as they look, their only natural predator is the orca, and they hunt other seals.
Having met a sloth, they're are as dopey as you'd expect - agree they're a bit weird, but generally quite sweet. Manatees are awesome - I've met them too - and are actually quite cute, except for the babies, which are exceedingly cute! Dolphins were a lot bigger than I think I had anticipated, and I'm not entirely sure they're trustworthy, but they're kind of sweet to look at.
I agree about angler fish, they're just the stuff of nightmares.
Naked/hairless anything - mole rat, cats, rats, dogs; I'm sure some of them are lovely, but they look like they'd be eager to prove that being hairless doesn't make them weak, and I just can't get on board with that energy.