Some years, it's tough to decide what the best horror movie was and some years, it is so obvious that it's not even worth mentioning other movies from the same year.
In 1989, Pet Sematary hit the big screen.
Yet the film's (and the novel it is based on) greatest strength is the reality of the family at its heart. The Creeds move to a rural Maine town where they don't know anyone. The marriage between Louis and Rachel is mostly happy: in other words, they get a long but there is some latent tension that builds as the stress of the move and the eventual death of their youngest son comes between them. Even without the supernatural element, this is a family in trouble. Long-held secrets and new lies join forces to divide Louis and Rachel at the time when they need each other most.
The other strength of the film is that the real villain of the story is never seen nor heard from. We only see the results of giving in to the influence of the Micmac burial ground. We don't need a ghost or a werewolf. We only need man's good intentions to go wrong for this film to have its monsters.
As with everything good, there are rumors of a remake. Please, if you have anything to do with that, just stop. Your movie will not be as good as the original. If you are so keen to make a Stephen King movie, remake one of the movies they blew or adapt one of the novels or short stories that hasn't been done yet. There are plenty to be had.