Umm… Probally any of them (except Mike, of course, I would have loved having him in my room), because I was scared of lots of things when I was little.
heheh nice topic!
Waternoose for me too…that chase scene at the end was quite scary…
Out of all the monsters I’d say Sulley and Randall would freak me out the most. That’s if I hadn’t seen the film, know Sulley’s character so well and if the monsters turned out to be real, I’d scream at the sight of them really. Some times I think I’m such a chicken 
Waternoose, no contest. Everyone else is a little too cuddly to be scary.
Randall would have scared me the most probably. I’ve always been one to be nervous when I think I hear noises and then try to find the source. I’d probably end up extremely curious and wanting to befriend the misfit pretty fast though.
Mr. Waternoose, because he looks a lot like a spider.
Some kind of wasp/bee/hornet monster would scare me. I have a phobia of those. I don’t hate them or want them killed but they do scare me.
So none of the mosnsters in the actual movie are really my phobia.
To me he always looked more like a crustacean of some kind.
I think he is supposed to be a crab, but I still think he looks a lot like a spider.
Having a giant crab-man in my room would’ve certainly freaked me out, so Waternoose would’ve certainly scared me. And Randall’s ability to camouflage himself could create some creepy effects. Sully could be scary too, although his blue and purple colouring might be a little too friendly-looking to be properly scary.
None of them scared me in the movie when I was a kid, but if they came into the real-world and looked a bit more realistic, they’d be able to scare me today lol
Yeah he’s a lot like a crab…which kind of bothers me since my star sign is a crab(cancer) and in general I like crabs but I don’t like Mr. Waternoose.
I can see where the spider-ness comes from though…it’s the legs.
I’m going to agree with a lot of people and say Waternoose. I find his crab like appearence freaky.
To me, Waternoose kind of looks like a mix between the two.
Who knows maybe one of his parents was more like a spider monster and the other was more like a crab monster?
I’m surprised that there wasn’t a monster in the movie that had wings…at least I don’t recall there being one.
Yeah, maybe he had both of those traits from his mother and father.
Really none of them, maybe Waternoose, but most of them look to cartoonish. Sid and the omnidroid look scaryer in my opinion.
Yeah I have to admit none of the monsters in Monsters Inc. were truly really scary. Perhaps if they were too scary the kids watching the movie would have been too freaked out.
This is a much more scary looking animated monster:
3.bp.blogspot.com/_STqajwcqIds/S … e_Form.jpg
Believe it or not, that’s actually the true form of the character I’m dressed as in my sig and avatar. 
Probably all of them, since I always get nervous even when I hear inexplicable noises in the night.
Randall is one of them, a thought of snake-like monster who can sneak close to you because he’s invisible is scary. And I think the creepiest appearance would belong to that red slug-like monster with spikes. I wouldn’t like to see him in my bedroom at night 
So I guess a slug-like monster with all the spikes that could go invisible like Randall would be the most creepy to you? XD
Probably, though I can’t imagine that slug-like monster move noiseless, therefore no point in invisibility:)
I think I’d have been a useful source for old Monsters,inc. anyway.
Haha, yeah Envy’s true form is downright creepy. Especially in the animated version where you can actually SEE the heads moving and hear them all talking over each other. 
(I’m getting the last volume of the manga for Christmas and I can’t wait to see how FMA ends!!! (I don’t want to read it online lol, so I’ve been avoiding spoilers for months))
A slug-monster could be pretty creepy if it were big enough, although it probably wouldn’t move very quickly so it might be easy to escape. Although I think that waking up to the sight of a giant slug twice your size would be pretty horrifying