Great horror films always do a lot with a little. That's seen again and again in how B-movies become cult classics; many of them turn into franchises that spawn sequels—and prequels and reboots and really just about everything. With increased budgets and profiles, the franchise sometimes gets away from what made the original idea so good and overshadows the initial film.
Few, if any, horror franchises maintain a consistent track record, but some of the greatest have all-time great movies that have since been overshadowed by their sequels.
Saw
Saw debuted in 2003 with a simple but highly-effective premise. Several people awake, trapped inside a "test" designed by the Jigsaw Killer, and they are pushed to their very limits in an effort to escape with their lives. The first film proved very successful and spawned a franchise that now includes nine feature films.
Some of the subsequent entries were good, particularly Saw II, but it was overall a case of diminishing returns. The concept got recycled so much that the power of the first film wore off eventually.
Godzilla
It might surprise some to consider the original 1954 classic Godzilla a horror movie, but that's a testament to what happened after. The original Toho film captured the anxiety of the atomic age and delivered an iconic monster horror movie for the ages.
In later films, the action and effects became almost cartoonish, turning the character into something of a caricature. Modern films like Shin Godzilla have sought to recapture the terror of the monster, but all of it has gotten very far from the original movie.
Friday The 13th
The slasher film became so ubiquitous in the 80s and 90s that Scream eventually torpedoed the concept by exposing its tropes for what they were. In the beginning, it was very effective. One of the first movies of its kind, Friday The 13th provided a lot of chills and shocks.
While the movie hasn't aged well in many ways, the franchise that followed absolutely diminished the potency of the original film. Jason eventually ended up in outer space, and the whole thing became a joke.
Halloween
Halloween is another classic in the slasher genre of horror films. It also spawned an iconic character in Michael Meyers and a franchise with a very complicated legacy. Not every film in the series lived up to the potential of the John Carpenter original, and the most recent entries have tried to recapture the magic by bringing back Jamie Lee Curtis as Laurie Strode.
The further the franchise got from the original, the more it overshadowed the movie. That said, it did flirt with something unique in Halloween III: Season of the Witch.
A Nightmare On Elm Street
A Nightmare On Elm Street is a classic in the genre and one of Wes Craven's best movies. A slasher movie with a little bit more to the concept, the movie created an instant icon in horror cinema in Freddy Krueger.
The franchise that followed offered some interesting material, but, like others in the genre, fell prey to its worst instincts. Freddy even faced off against Jason in a monster mash-up that proved how tired the series had become, and, unfortunately, the original movie seems like a distant memory now.
Night Of The Living Dead
The zombie film is a genre onto itself and owes just about everything to the George Romero classic Night of the Living Dead. The original 1968 black-and-white movie was groundbreaking in many ways, particularly in how it snuck social commentary into what was essentially a very cheap B-movie.
Sequels and remakes and all the zombie movies that have followed in its wake have overshadowed the original impact of the movie somewhat. It's hard to deny its influence on the entire horror movie genre, though, which is amazing, considering it was Romero's first film.
Re-Animator
Re-Animator is a B-movie if there ever was one. Though the original 1985 film didn't do very well at the box office, it did very well on cable on home video. That led to a series of sequels and spinoffs that eventually overshadowed what made the first movie so good.
The movie features a fantastic performance by Jeffery Combs, who played numerous roles in various Star Trek series and leans heavily on the mythos of H.P. Lovecraft, making it easily one of the best adaptations of the complicated author's works of all time.
Final Destination
Final Destination quickly became a worthy entry in the teen horror franchise by introducing the concept of the characters knowing their fates ahead of time like seeing their death in a fiery plane crash. The idea of trying to avoid visions of the future become super repetitive super quickly, though, and the franchise that followed watered down the original film.
Sequels to the 2000 film upped the crazy in the number of kills—and how complicated they were—taking away from the core fear of just knowing a person's fate.
Cube
Cube is a 1998 low-budget movie with a high-concept. Somewhat similar to Saw, seven strangers wake up trapped inside a cube-like prison. They try to get out, but their escape attempt quickly proves to be fatal.
The surreal movie was a cult favorite and spawned a series of sequels of varying quality. As the franchise went on, the mystery and fear of the first movie got lost in the increasingly elaborate lore of the story and mathematics, which the concept leans on very heavily.
Alien
Few horror movies compete with the outright terror of the original Alien. The Xenomorph is one of the most frightening movie monsters of all time, and that was despite not being in the movie much, at all.
As the franchise developed, the Xenomorph became more front and center. Aliens is an all-time classic, but things went off the rails from there. Later films tried to explain a creature that didn't need explaining and created an uneven legacy that only overshadows what was in essence a perfect film.