Wolverine

Here is a bit of interesting comic history.  Wolverine was originally planned to be a real wolverine.  No really. The character's original origin tied into the High Evolutionary, who was a common foe of many Marvel heroes, especially the Avengers, during the 1970s. the High Evolutionary was especially known for his evolutionary experiments on animals, making them bipedal and giving them human or near human intelligence. 

 

Under this version of his origin, the High Evolutionary would have experimented on a wolverine, giving him human intelligence and stature but keeping his aggressive nature. Wolverine would have escaped from Wundargore Mountain, unaware of his true nature and becoming an agent of the Canadian government and later an X-man. This version of his origin was, of course dumped, although some trace of it remained in early issues, especially when he was captured and scanned and the results indicated unusual readings indicating something odd about his mutant status.  After those first issues, the matter was never mentioned agin.