Wendigo () is a mythological creature or evil spirit originating from the folklore of Plains and Great Lakes Natives as well as some First Nations. It is based in and around the East Coast forests of Canada, the Great Plains region of the United States, and the Great Lakes region of the United States and Canada, grouped in modern ethnology as speakers of Algonquian-family languages. The wendigo is often said to be a malevolent spirit, sometimes depicted as a creature with human-like characteristics, which possesses human beings. The wendigo is said to invoke feelings of insatiable greed/hunger, the desire to cannibalize other humans, and the propensity to commit murder in those that fall under its influence.

In some representations the wendigo is described as a giant humanoid with a heart of ice; a foul stench or sudden, unseasonable chill might precede its approach. Possibly because of longtime identification by European-Americans with their own myths about werewolves, for example as mentioned in The Jesuit Relations below, Hollywood film representations often label human/beast hybrids featuring antlers or horns with the "wendigo" name, but such animal features do not appear in the original indigenous stories.

In modern psychiatry the wendigo lends its name to a form of psychosis known as "Wendigo psychosis", which is characterized by symptoms such as an intense craving for human flesh and an intense fear of becoming a cannibal. Wendigo psychosis is described as a culture-bound syndrome. In some First Nations communities other symptoms such as insatiable greed and destruction of the environment are also thought to be symptoms of Wendigo psychosis.