Altered States (1980) is a horror movie directed by Ken Russell. The list below collects the movies that people who loved it enjoyed most, best known first.

★ 6.5 · 9,707 votes · Sci-Fi, Horror
A biologist signs up for a dangerous, secret expedition into a mysterious zone where the laws of nature don't apply.
Movies like Annihilation →
★ 7.5 · 10,736 votes · Sci-Fi
Thirty years ago, aliens arrive on Earth. Not to conquer or give aid, but to find refuge from their dying planet. Separated from humans in a South African area called District 9, the aliens are managed by Multi-National United, which is unconcerned with the aliens' welfare but will do anything to master their advanced technology. When a company field agent contracts a mysterious virus that begins to alter his DNA, there is only one place he can hide: District 9.
Movies like District 9 →
★ 7.1 · 8,517 votes · Horror, Drama, Mystery
Several friends travel to Sweden to study as anthropologists a summer festival that is held every ninety years in the remote hometown of one of them. What begins as a dream vacation in a place where the sun never sets, gradually turns into a dark nightmare as the mysterious inhabitants invite them to participate in their disturbing festive activities.

★ 6.9 · 3,033 votes · Horror, Thriller
A hedonistic man finds a mysterious puzzle box that summons a group of gruesome beings known as the Cenobites. These otherworldly entities open the doors to a dominion where pain and pleasure are indivisible.
Movies like Hellraiser →
★ 6.9 · 1,823 votes · Crime, Mystery, Thriller
Two French policemen, one investigating a grisly murder at a remote mountain college, the other working on the desecration of a young girl's grave by skinheads, are brought together by the clues from their respective cases. Soon after they start working together, more murders are committed, and the pair begin to discover just what dark secrets are behind the killings.
Movies like The Crimson Rivers →
★ 7.3 · 3,396 votes · Mystery, Sci-Fi
A man struggles with memories of his past, including a wife he cannot remember, in a nightmarish world with no sun and run by beings with telekinetic powers who seek the souls of humans.
Movies like Dark City →
★ 8.1 · 8,348 votes · Horror, Mystery, Sci-Fi
A research team in Antarctica is hunted by a shape-shifting alien that assumes the appearance of its victims.
Movies like The Thing →
★ 7.2 · 11,831 votes · Thriller, Mystery, Sci-Fi
The life of an unsuccessful writer is transformed by a top-secret 'smart drug' that allows him to use 100% of his brain and become a perfect version of himself. His enhanced abilities soon attract shadowy forces that threaten his new life.
Movies like Limitless →
★ 6.6 · 3,521 votes · Horror, Sci-Fi, Mystery
In 2047, a group of astronauts are sent to investigate and salvage the starship Event Horizon which disappeared mysteriously seven years before on its maiden voyage. However, it soon becomes evident that something sinister resides in its corridors.
Movies like Event Horizon →
★ 6.5 · 708 votes · Horror, Sci-Fi
The Resonator, a powerful machine that can control the sixth sense, has killed its creator and sent his associate into an insane asylum. When a psychiatrist becomes determined to continue the experiment, she unwittingly opens the door to a hostile parallel universe.
Movies like From Beyond →
★ 6.3 · 1,378 votes · Sci-Fi, Horror, Thriller
Two brothers return to the cult they fled from years ago to discover that the group's beliefs may be more sane than they once thought.
Movies like The Endless →
★ 6.7 · 324 votes · Horror, Sci-Fi
After the death of his father, a brilliant college student returns to his family home where he learns that the horrors from his childhood aren't as dead and gone as he once thought.
Movies like The Return →
★ 6.9 · 522 votes · Action, Sci-Fi, Horror
When average, law-abiding citizens suddenly turn to a life of hedonistic behavior and violent crime, Detective Tom Beck is tasked with helping young FBI agent Lloyd Gallagher determine the cause.
Movies like The Hidden →
★ 6.4 · 576 votes · Horror, Thriller
A Harvard anthropologist is sent to Haiti to retrieve a strange powder that is said to have the power to bring human beings back from the dead. In his quest to find the miracle drug, the cynical scientist enters the rarely seen netherworld of walking zombies, blood rites and ancient curses. Based on the true life experiences of Wade Davis and filmed on location in Haiti, it's a frightening excursion into black magic and the supernatural.
Movies like The Serpent and the Rainbow →
★ 7.6 · 19,480 votes · Mystery, Thriller, Horror
Chris and his girlfriend Rose go upstate to visit her parents for the weekend. At first, Chris reads the family's overly accommodating behavior as nervous attempts to deal with their daughter's interracial relationship, but as the weekend progresses, a series of increasingly disturbing discoveries lead him to a truth that he never could have imagined.
Movies like Get Out →