Another little-known movie for your consideration:
Ravenous -- Starring Guy Pearce, better known for Memento.
It’s hard to come up with an “original” horror movie, but this one comes pretty damn close. The setting is the American West, sometime before the Civil War. A disgraced Army officer is assigned to a remote, sparsely manned fort where he assumes he can serve in obscurity. Things go awry, of course, and what follows is a unique story blending elements of the freakish (and true) Donner Party tragedy with the Native American legend of the wendigo.
Great subtitle: “You are who you eat.”