When it comes to time travel, the genre that uses it most tends to be straight science fiction films for very obvious reasons. However, it's worth noting that the idea of time travel is well-suited for the horror genre for a couple of different reasons. There is the fact that when a character travels into the past or the future, they might think they know what they are going to encounter, but the fact of the matter is that all kinds of nightmares can unfold.
It turns out that horror movies tend to combine with science fiction more often than people realize. Certainly, there are monsters or killers that aren't rooted in science at all. But there are plenty of times when the villains are either using an aspect of science or birthed by science itself. Time travel is one of those aspects of science that is easy to lean on when trying to show the dangers of science fiction precisely because so much can go wrong. That's why some of the best horror movies out there tend to use time travel as a major plot device.
Project Almanac
Some might find Project Almanac to be an odd movie to start off this list because it's not strictly a horror movie. However, it does have dark enough elements that it can be featured as a horror movie that relies heavily on science fiction. The movie features a group of teens that first discover and then complete a time machine that has limited range but still gives them plenty of ability to travel back in time and change things so that they can benefit.
Fixing ever-growing mistakes horror aspect as things start to go wrong at a rather alarming rate. But it's the fact that when these teens actually run into themselves in the time stream, they essentially wipe themselves out that the movie really starts to grip its audience as a horror movie. Especially since the way that they are obliterated is very, very creepy.
Triangle
When it comes to some of the best horror movies that deal with time travel, it's really about being caught in a time loop that makes them scary. Melissa George stars in this particular time loop/time travel movie where she and a group of friends board a seemingly abandoned ocean liner that just happens to be in the Bermuda Triangle. At first, they think it's quite an interesting little setting but things soon turn violent and deadly as they realize that a hooded figure is hunting down the friends and killing them one by one.
It turns out that the killer is actually none other than George's character who is attempting to break the time loop she's realized they're all trapped in. This movie is one of the better but lesser-known horror movies that deal with time travel because it has a little of everything. There are the more traditional slasher aspects of the film, mixed in with the time loop to give it a pretty original premise.
Haunter
While Abigail Breslin's best-known horror movie is likely Zombieland, she starred in another spooky ghost story that involved time travel and time loops. In Haunter, Breslin plays a ghost girl by the name of Lisa who is doomed to relive the day in 1985 when her entire family was killed. She has to do this while the rest of the world moves on around her. However, while Haunter starts out as a movie that's about a kind of time loop, it eventually turns into something a little more time travel-focused like Quantum Leap.
Lisa realizes that she can essentially "jump" into the present by inhabiting the body of another young girl who now lives in the house. Unfortunately, she soon finds out that the killer can do the same kind of body leaping that she can. The film does a nice job of combining a more straightforward slasher film with an interesting spin on a ghost story that is told from the perspective of the ghost and a time loop aspect.
The Endless
Yet another movie that is more about the inability to travel in time, than time travel, this time loop-based horror movie still counts thanks to the fact that parts of this world move in different times depending on where the characters are located. The movie by Justin Benson and Aaron Moorhead sees them star as a pair of brothers who escaped a kind of cult years ago. They end up going back to where the cult was located and discover that many of the people they left behind decades ago don't seem to have aged at all. The cult, Camp Arcadia, is located on a strange plot of land filled with various time loop pockets that allow for a very original take on the kind of cosmic horror that comes from time travel. There's also a really good mystery wrapped up into this film that amps up the tension and that makes the horror of the situation that much better.
Army Of Darkness
While some people might feel that Army of Darkness is more of a comedy than a straight horror movie, it's important to note Sam Raimi simply liked to add a dash of humor into his horror films. The third film in the original Evil Dead trilogy saw Ash get transported back in time by the Necronomicon. He ends up being transported to the middle ages where he has to try and help the folks there overcome an invasion of the evil dead.
While there are plenty of good and funny moments in this movie, such as Ash explaining to everyone what his "boomstick" is, there's also plenty of monsters and skeletons and creepy crawlies that were no doubt plenty creepy, especially when the film first came out. This is one of those films that isn't going to have chills running up and down a viewer's spine but it certainly fits into the horror genre thanks to quite a bit of death and destruction that takes place thanks to truly evil beings.