The original was made in the early 1950s and was released as The Thing From Another Planet. John Carpenter's love for it led to it being featured in Halloween, and being remade in 1982, starring Kurt Russell, Wilford Brimley, Keith David, and Richard Masur. Everything comes together so well in this version, starting with the visuals that led to an oppressive state of paranoia, continuing on with the music, through special effects (of the time, of course) leading to the overall tone. Read another fan's complete love of all things Morricone here.
Another feature of this movie that stands out among others is its all-male cast. It seems to point out that the fear of being violated and implanted with the alien, in the midst of a group of males who have been isolated for far too long, becomes the predominant dread of its audience. Compare this with the all-female cast of The Descent, where being trapped within a dark, unexplored space with mysterious semi-human killers is the main thrust. The fun of this type of monster/thriller/suspense film is in its ambiguity. You can see it as simply entertaining on a superficial level, with people fighting for their lives. You can see it as a political/medical allegory, in tune with the times in which it was made. Maybe the next time you watch it, you can focus on its gender strengths and weaknesses, see how the power structure could have shifted if there had been women cast in each role.
There have been several other suspicion-based stories set in the Arctic/Antarctic that follow in this movie's footsteps, but so far none have come close to achieving the epic status of this strong example. Recently I've seen The Thaw, which looked like it was trying to live up to the heights of Carpenter's work but couldn't. The characters didn't have the same withdrawn duplicity of Brimley and Masur, the music didn't attack your soul in the same way, and overall feel was disappointing.
There seems to be another version in the works, 2011's The Thing. Going to hold out to see it before judging, but it has very big shoes to fill before it can achieve the greatness of the 1982 version.