My favorites are Dog from "CatDog", Heffer from "Rocko's Modern Life," Ice King from "Adventure Time" and Eduardo from "Foster's Home for Imaginary Friends.
Anime Superhero Forum
Rabbitearsblog
AnimaniacNutso
I loved him as Heffer from "Rocko's Modern Life, SpongeBob SquarePants, and Eduardo from "Foster's Home for Imaginary Friends"
superkeegan9100
I don't have a favorite.
JoeMabbon
Plastic Man, The Narrator (Powerpuff Girls), Ice King, and Starscream (and his male Allspark Clones).
Rabbitearsblog
@JoeMabbon Oh! I didn't know that Tom Kenny voiced Starscream at one point!