EDIT: i was thinking a Wendigo, a creature that was once a man but was remotely stranded from society and had to resort to cannibalism to survive, after eating many of his comrades, wendigos form from the inhuman thirst for more flesh, see eating flesh of your own gives you power and you eat enough of it, this is the result, but wendigos are to be feared, they are lightning fast and can only truly be hurt by fire, and look humanoid, but much different, they can mimic a human voice and often toy and confuse determined hunters that usually think there tracking a bear or something before brutally slaughtering and eating them. wendigos are mentioned on various rpgs like ff8 and my favorite tv show supernatural and many other things, the legend comes from the Cree Indians.