The Wendigo (Windigo, Wituku) is a legend of the Algonquin speaking tribes of North America, who inhabit the North and North Eastern US and Canada. According to the legend, the Wendigo is a spirit that rides the winter wind and can possess humans causing the possessed person to develop an insatiable craving for human flesh.
Another version of the tale describes people becoming wendigos after a period of starvation, as during a harsh winter when supplies may have run low, when the only means of survival was to turn cannibal and eat other members of the tribe or hunting party. Anyone who broke the taboo against cannibalism could become a horrible creature who would hunt down and eat any human they could find.
Many cultures used to belive that eating human flesh could confer strength or speed to the eater. The wendigo legend takes it a step further. Wendigos are supposedly perfect hunters, fast, strong, and deadly. Wendigos are said to resemble starving men, or frostbite victims. They are always described as tall. Some have described them as being covered with matted hair, and others as green skinned and corpse-like. They are said to have no lips covering their sharp teeth.
One thing that almost all the tales agree on is that a wendigo has a heart of ice. To kill a wendigo you must destroy or melt its ice heart. Fire and silver are supposedly effective against these beasts.
Supernatural - Season 1, Episode 2, Windigo: Sam and Dean Winchester faced a Windigo when they followed a set of coordinates left for them by thier father that led them to a place called Black Water Ridge, Colorado. The windigo would hibernate for twenty or thirty years at a stretch, then wake to feed. Its attacks had been written off as bear attacks. It was tall and green skinned, very fast, a perfect hunter. They killed it with an emergency flare to the heart.
Charmed - Season 1, Episode 12, The Wendigo: Piper is attacked by a white-furred, werewolf-like wendigo and begins to transform into a windigo herself. In the Charmed mythology a wendigo is a person who's heart has been broken and turns to ice. The curse can also be transfered by a scratch or bite, as with a werewolf.
Blood Ties - Season 1, Episode 7, Heart of Ice: Homeless people have been vanishing. When Vicki and Henry investigate they meet a Native American man named Peter who claims that the killer is a Wendigo, a hunger spirit. They go into the sewers to find the monster and it atacks them, dragging Peter away and killing him. The wendigo is shown as a corpselike creature with shaggy white hair and very big teeth. They use silver bullets to kill it.