I'm Cold and Hungry

Wikipedia:

The Wendigo was usually presumed to have once been human. Different origins of the Wendigo are described in variations of the myth. A hunter may become the Wendigo when encountering it in the forest at night, or when becoming possessed by its spirit in a dream. When the cannibalistic element of the myth is stressed, it is assumed that anyone who eats corpses in a famine becomes a Wendigo as a result. The only way to destroy a Wendigo is to melt its heart of ice.

Perhaps this myth was used as a deterrent and cautionary tale among northern tribes whose winters were long and bitter and whose hunting parties often were trapped in storms with no recourse but to consume members of their own party. It could be indicative of starvation that the Wendigo is said to consume moss and other unpalatable food when human flesh is unavailable. Its physical deformities are suggestive of starvation and frostbite. So the Wendigo may be a myth based on a personification of the hardships of winter and the taboo of cannibalism.

Actual Wendigo murder trials took place in Canada around the beginning of the 20th century. The anthropologist Morton Teicher has described the alleged clinical condition of believing oneself to be a Wendigo, which he calls Windigo Psychosis (note the spelling in this context: Windigo, rather than Wendigo).