Creeptolli 

A person who seems normal, then one day bursts into an unexpected fit of violence and anger.

Did you see Creeptolli in math class today? He shoved me against the chalkboard! I thought he was just an average guy all this time.

Creeptolli by JimJim13 January 12, 2009

Creeptologist

One who studies creeping, creepiness, and, of course, creepers.

Jim: How you know about me looking into that one girl's room?

Bob: I told you, I'm that creeptologist!

Creeptologist by creeptologist 101 May 20, 2010