Quick: who voiced the sultriest pig of all, Miss Piggy? Would you believe that it was an old bald guy with glasses (Frank Oz)?
Asylum has a short yet highly entertaining post about the five voice actors whose faces certainly didn't fit the characters they played: Link
http://www.marcsilk.com/
http://www.imdb.com/name/nm0000279/
Phil LaMarr has quite the list of voice acting work himself.