Based the voice of Wakko Warner (from "Animaniacs" (1993)) on Beatle John Lennon.
He states in "Animaniacs Live" in the special features of Volume 1 of the DVDs that for Wakko Warner he did a John Lennon voice, then when he saw the picture of Wakko and how small he was, he changed the voice by making it more high pitched, like a small John Lennon.
Originally he fashioned the voice of Wakko Warner, in Animaniacs, after John Lennon, but upon seeing the cartoon, played Wakko with more of a Ringo like voice.
Was the only voice actor to portray two characters in Transformers (2007). He was also the only voice actor to portray both an Autobot and a Decepticon in the film. He provided the voices for both, Ironhide and Barricade.
Browse biographies section by name