The first time he saw it, King reportedly declared Stand By Me the best film ever adapted from one of his works. A coming-of-age classic that marked Rob Reiner's first foray as a director from comedy to drama, Stand By Me is one not only one of the best films based on King's work, it's also one of the best films of its type ever made.
If this were a list of the best performances in Stephen King adaptations, Kathy Bates' performance as Annie Wilkes would be a solid threat for the number one spot. The personification of every artist's worst fear of what it means when someone embraces their work, Bates' performance, and the film itself, are more than powerful enough to withstand the many parodies and take offs that the character and premise have inspired.
The real monster is adolescence. A movie so good that it transcends genre (not many horror movies can boast earning Oscar nominations for its actors) and so mesmerizing that multiple attempts have been made to repeat its success in the form of a sequel, a TV movie designed to be a pilot for a series, a remake, and even a short-lived Broadway musical (no, seriously). But it's the original that retains the power.
Get busy living or get busy dying. The film that routinely jockeys with The Godfather for the number one spot on IMDB's Top 250, The Shawshank Redemption is one of those films that some people are compelled to revisit over and over again, the experience never getting old. It's easy to understand why: it's a great film built around two great performances, one of which I would go so far as to call iconic.
This is Stephen King's nightmare, of course, since he famously detests the film version of The Shining, but the power of the film is undeniable. Not just a film about madness, it's a film that also seems to inspire madness (just see the documentary Room 237, which is all about fan theories about The Shining and what it all "means," if you don't believe it) and it stands as one of the greatest works of a filmmaker who had no shortage of great works.