Very late to the game here, but one character that grates on my nerves is Marvin Suggs (the Whatnot who regularly whaled on the Muppaphones in TMS). I find his voice (Which Oz described as designed to be very annoying) extremely irritating. His entire demeanor is unpleasant (understandably so, as the point of his character is to be the perpetrator of unnecessary brutal violence towards others).
He reminds me a bit of Pirelli from Sweeney Todd.