Nolan Bushnell was at MakerFaire this spring. Bushnell, among other things, founded the Pizza Time Theater restaurants, which later became Chuck E. Cheese. The character was originally just the MC of the animatronic band that played in the restaurants.
He revealed, in his speech, that Chuck E. Cheese, the rat, was originally supposed to be . . . well, he didn't provide a name, but it was going to be a coyote. The shop that provided the costume for the pitch meeting sent a rat suit instead of a coyote suit, so the character was hastily re-named and re-specied.