For me, it has to be the naked mole rat. Seeing them at the zoo just made me uncomfortable. The Pipa toads (aka Surinam toads) that I saw at Toronto Zoo, on the other hand, I found to be interesting. I know that the sea creatures mentioned are pretty ugly, but at least they are the way they are due to their environment. Naked mole rats, however, just don’t seem to be right somehow.
I kinda feel bad about this because I consider myself an animal lover- but apes are just hideous to me. All of them. They look like ugly dirty hairy people :\
Leave Christina Aguilera alone!
You realise, of course, that this means war.
And have you ever seen the under side of an armadillo?
Red uakaris also win no beauty prizes in the monkey domain…
Heh, that thing is both adorable and hideous at the same time. 
OK, a) that’s horrific, and b) “feed on fish mucus” is a phrase I’d never thought I’d see. Thanks Wikipedia!
Something about it makes me feel as though it should be teaching children the alphabet or something. Like a Muppet.
Dammit! Now I’m going to have to find a way to give a blobfish some cake, see if it cheers him up. 
I don’t think there’s any animals I actually find hideous, the thing that comes closest is the weird fish thing that comes in at 4:26 in this, the Blue Planet, deep sea episode- it looks like some sort of skinned zombie seal pup, out for revenge…
Aww, it looks like BatBoy.
The Blobfish always reminded me of Mr. Saturn for some reason.
The lamprey is a good choice. Does anyone else get the same sort of disgusted, freaky feeling as when you look at holey things, a la lotus boob?Might there be a phobia of giant, toothed phallic looking things?
I never heard of this, so I wiki’d it. I think they are cute, and I love the idea of a venonmous mammal. And the females have teats on their ass!
Blobfish needs a bow, BOING!
Kinda reminds me of Huang Chuncai, the Chinese “Elephant Man.” I’ll let you look up photos at your own risk.