The Fly (1986)

David Cronenberg's remake of the 1958 movie with Vincent Price is one of those rare instances where the original has been improved upon.  Mind you that's if you are able to tolerate the extreme body horror, a theme that has always fascinated the director from his earliest films and which reaches new levels of revulsion for the less stout-hearted here.  As for your scribe, as mentioned previously, I have a high tolerance for the horrors on display as scientist Jeff Goldblum's form begins to change after he accidentally teleports himself in the same pod as a housefly -- one can't be too careful when teleporting! I well remember my first viewing of this movie and was suitably impressed, especially when pregnant girlfriend Geena Davis dreams of giving birth to a huge slug-like creature.  If that sort of thing turns you off, as well it may do, then stick to the original film.  At any rate don't bother at all with the sequels to either movie.