The Thing (a 1982 movie) starring Kurt Russell, Wilford Brimley (now deceased) and Keith David (among other highly talented actors) is just the sort of movie every horror fan should see at least once. It received nominations from the Academy of Science Fiction, Fantasy and Horror Films for Best Horror Film and Best Special Effects.
For those blog-fans who don't care about any movie's public acclaim too much, let me just say this film really is creepy thanks to its premise. Certainly the film is rather old now but the animation used at the time it was made was most compelling and advanced for its day. Not only that? But this the story behind "The Thing" is much more creapy than any demon-possession story because instead of the individual surviving a paranormal attack, the human-victim is completely cannibalized (murdered) and the evil alien entity assumes its victim's behaviorisms, looks and professional identity. Survivors do not know who is a cannibalistic alien and who might genuinely still be their friend/coworker.
Here's video footage from the movie, after Kurt Russell's character figures out how they can test blood to determine WHO is still human, or not: