The best sci-fi horror movies aren't always the most expensive ones or the most well-known, some were even once considered flops. But things change...

On paper, it might seem as though the science fiction and horror genres are too different to work well together. But sci-fi's love of spectacle and horror's focus on building suspense often results in compelling movies that are full of intriguing concepts and engrossing atmospheres.

It’s a tough line to walk, but there are plenty of great sci-fi horror movies. From the crew of the Nostromo battling against a xenomorph to a found-footage flick about a kaiju attack, the best sci-fi horror movies incorporate a number of subgenres into their stories, making for some of the most inventive and original films ever made.

Updated on October 19th, 2021 by Mark Birrell: The best sci-fi horror movies aren't necessarily the most expensive ones or the most well-known. As times and attitudes change, so too does the impact of the social commentary seen in either genre. Naturally, new modern classics emerge while other older films can be cemented as having timeless qualities even if they were poorly received upon release.

Upgrade (2018)

• Available on Fubo TV

Before putting his own spin on The Invisible Man, writer and director Leigh Whannell stepped from the world of horror into science-fiction for a gleefully gory revenge story about a man who gives control of his body over to an advanced AI program that can turn him into an unstoppable killing machine.

Upgrade doesn't skimp on the graphic kills throughout but the horror of the movie is mostly found in the story, perfectly intermingled with some classically frightening sci-fi concepts about technology's role in the loss of free will, the illusion of control, and the human desire to run from culpability.

Cube (1997)

• Available on Pluto TV, IMDb TV, and Fubo TV

Though it ostensibly appears to be a body horror movie based around characters being horribly killed by the sadistic traps in a highly advanced maze, Cube is a movie predominantly driven forward by its conversations and its dissection of various attitudes and personality types within society.

The characters of the movie each wake up inside a giant structure of interconnected hollow metal cubes with no understanding of how or why they're there. Their arguments, as they attempt to figure out what's happening and how they can escape, delve into ideas as broad and complex as purpose, morality, and the psychology of authoritarianism.

Coherence (2013)

• Available on Tubi, Pluto TV, and Crackle

Dinner parties make great settings for horror movies as it's a potentially uncomfortable situation that just about everybody has some experience with, bringing together an ideally interesting group of people with interpersonal dynamics that can shoot off in all kinds of directions. Coherence takes this idea to its apex through the application of a simple science-fiction concept that has labyrinthian implications.

The group of friends that comes together for a simple dinner party in the movie does so on the eve of a comet's passing and they quickly discover that it has caused a bizarre event in space and time. The movie's theme of indecision, and how it affects possibilities, is played out in a disturbing diorama of a group of encroaching-middle-age intellectuals dealing with their past mistakes and regrets when alternate versions of themselves are all thrust together into the same reality.

Predator (1987)

• Available on Peacock

Though veritably dripping in machismo action, Predator is a much smarter science-fiction movie than it's given credit for and has some similarly underrated stalking horror amongst the bloodier moments.

The impotence of the muscle-bound supersoldier squad against the alien hunting them in the movie reflected the tone of many post-Vietnam War films featuring military-like characters and the final design of the alien itself evoked classic science-fiction concepts like H.G. Welles' use of technology in War of the Worlds, flipping the tables on characters who were used to being the most advanced predators in their ecosystem.

Prometheus (2012)

• Available on Peacock and Prime Video

What is effectively a prequel story to Ridley Scott's iconic sci-fi horror movie Alien delves far more into the themes presented in the director's other infamous sci-fi film, Blade Runner. Prometheus incorporates more directly philosophical or religious ideas, like the relationship between creator and creation as well as humanity's insatiable hunger for answers and meaning.

There's plenty of disturbing alien designs and body horror in the film but its real horror comes from its true monster, the murderously Machiavellian robot butler, David. The simmering evil lurking beneath the refined mannerisms of Michael Fassbender's performance makes the character a true horror movie villain in the same vein as Universal's classic monsters, like Frankenstein and Frankenstein's monster, rolled into one.

Pitch Black (2000)

• Available on Showtime

Vin Diesel’s most popular franchise will likely always be Fast & Furious, but the Riddick franchise also holds a special place in sci-fi fans' hearts thanks in large part to the enduring qualities of the first installment in the series of movies.

Director David Twohy’s Pitch Black focuses on a space crew getting stranded on a planet where bloodthirsty creatures come out at night, and a month-long eclipse is about to take place. With limited weapons and light sources, the crew is forced to rely on Diesel's dangerous outlaw character, Richard B. Riddick, and his augmented eyes that allow him to see in the dark, making for a smart survival horror situation that spawned a lastingly popular cult sci-fi antihero.

Slither (2006)

• Available on Peacock

Before Guardians of the Galaxy made him one of the most famous directors working today, James Gunn wrote and directed Slither, an underrated monster movie about an alien parasite invading a small town.

Slither acts brilliantly as a spiritual successor to Fred Dekker’s classic B-movie spoof Night of the Creeps, with copious humor and body horror throughout as the space slugs take over people's bodies and mutate them into hideous monstrosities. It may not be the most thought-provoking horror movie or science-fiction story but it fearlessly taps into the funniest and grossest parts of both genres.

The Fly (1986)

• Available on Fubo TV

Body horror pioneer David Cronenberg created one of the subgenre’s finest works with The Fly, the story of a scientist whose teleportation experiment transforms him into a human-fly hybrid. Jeff Goldblum is compelling in the lead role, while Chris Walas and Stephan Dupuis’ makeup effects are delightfully disgusting.

Ultimately, The Fly is a tragedy. The film was loosely adapted from a 1957 short story by George Langelaan, but its cautions about the dangers of playing God can be traced back to the themes explored in Mary Shelley’s Frankenstein.

Frankenstein (1931)

• Available for purchase on Prime Video

Mary Shelley’s Frankenstein is widely regarded to be the first science fiction story ever written, while James Whale’s film adaptation was one of the first horror movies ever made. It’s tough for the first of something to hold up after the decades of derivative knockoffs that follow. But 1931’s Frankenstein still stands as a sci-fi horror classic.

From Boris Karloff playing The Monster as a Miltonian tragic figure to terrifying moments that censors tried to cut, Frankenstein is a cinematic masterpiece.

Scanners (1981)

• Available on HBO Max

Scanners is most renowned for the iconic scene in which a man’s head is blown up by a telepath but that’s just the tip of the iceberg; the movie has so much more to offer in not just its outstanding practical effects, including an all-time great movie villain performance by Michael Ironside as Daryll Revok.

The story of an evil corporation targeting mind-readers and one roguish mind-reader fighting back is one of the most riveting in the history of blending sci-fi and horror.

Mimic (1997)

• Available for purchase on Prime Video

Guillermo del Toro’s Mimic is a masterclass of blending science fiction and horror. Three years after scientists created a bloodthirsty insect to wipe out the cockroaches that were spreading a deadly virus around New York, the insect returns to take on its worst enemy: humankind.

With great a cast anchored by Mira Sorvino and Josh Brolin, del Toro crafted a horror movie with plenty of scares and a poignant hidden message about genetic engineering.

The Mist (2007)

• Available on Fubo TV

In Frank Darabont’s movie adaptation of Stephen King’s story The Mist, a thick ocean of mist descends upon a small town and is revealed to be filled with bloodthirsty Lovecraftian beasts.

Thomas Jane plays an everyman holed up in a supermarket with his son, plotting to get out in the open and return home to see if his wife is okay. It’s an incredibly dark movie, with some harrowing twists and turns along the way, but its dissection of how society and civility break down under pressure is far more potent a sci-fi concept than any of the terrifying monsters.

Event Horizon (1997)

• Available on HBO Max

Although it was slammed by critics and failed at the box office, Event Horizon has gone on to become a cult classic adored by sci-fi and horror fans alike.

When a missing spacecraft called the Event Horizon reappears, the rescue crew discovers that it went through a tear in the spacetime continuum, allowing a terrifying entity hiding in its own dimension to take control. Supernatural horror and theoretical physics blend together for an unforgettably gory ride.

Under The Skin (2013)

• Available on Showtime

Scarlett Johansson is compelling in this arthouse sci-fi chiller about an alien who masquerades as a beautiful woman to lure men into a deadly trap. The movie has an engrossing atmosphere and was shot with an almost documentary-like coverage style.

With a high degree of realism in most of the scenes, there's little of the fanfare that usually accompanies such high-concept ideas and the story focuses much more on subdued themes of identity and sexuality, but the minimalistic sci-fi designs still pack a big punch too.

Attack The Block (2011)

• Available on Hulu and Prime Video

Joe Cornish’s Attack the Block brings the alien invasion genre to a London housing block as a nurse teams up with the gang who mugged her earlier in the night to survive a horde of furry, neon-toothed E.T.s.

The modern cult classic blends comedy, horror, and sci-fi action together to dizzying effect, with then-newcomer John Boyega stealing the show in his breakout lead role.

Cloverfield (2008)

• Available on HBO Max

Matt Reeves and J.J. Abrams put their heads together to cook up this found-footage gem about a giant monster attacking New York and spawned one of the most well-known sci-fi horror franchises today.

The characters are initially filming the night’s events because they’re throwing a going-away party for their friend, and they keep filming as they run through the streets of the city, desperately trying to survive the onslaught of a massive unknown terror. The mixture of monster movie and found-footage horror proved to be a crowd-pleasingly unconventional combo.

Annihilation (2018)

• Available on Paramount+

Both thoughtful and action-packed, Annihilation sees a small team of scientists enter into a mysterious and ever-growing alien zone that surrounds the crash site of a meteorite impact. As time and physiology progressively blur and distort the further that they move into the zone, deadly creatures and bizarre body horror fates begin to befall the team.

The sci-fi elements of the film aren't merely surface-level, however, and the story explores the tendencies of self-destruction and metamorphosis in both human relationships and organic life itself.

The Terminator (1984)

• Available for purchase on Prime Video

James Cameron’s The Terminator incorporated themes of technophobia and self-determination into its time travel story about an advanced robot sent back in time to kill the mother of the man who will one day lead a resistance against the autonomous machines and their war on humanity.

Both a cautionary tale about the dangers of developing sentient artificial intelligence and a bloody horror-fuelled thrill ride that moves through its dense plot at a breakneck pace, The Terminator is an outstanding horror, science-fiction, and action film.

The Thing (1982)

• Available on Starz

This remake of The Thing from Another World is a claustrophobic tale about a group of researchers at an Antarctic outpost that is infiltrated by a deadly alien that can imitate any living creature. Before too long, they have no idea who they can trust.

Thanks to eye-popping practical effects and an unremitting feeling of tension in almost every scene, The Thing is a defining masterpiece of the sci-fi horror hybrid genre despite the fact that it was critically reviled upon release.

Alien (1979)

• Available on Fubo TV

Alien doesn’t rush into the terror; it’s a slow-burn chiller and this works because director Ridley Scott used the gore-free first 45 minutes of the movie to develop the characters and their relationships, so, when an alien lifeform begins ripping through them, the audience feels the crew's confusion and terror with them.

H.R. Giger’s designs remain some of the most iconic seen in genre filmmaking. The xenomorph, in particular, stands out as a distorted, disturbing rendition of the human form, but the design of everything else in the movie—the ship, the alien planet, the “space jockey” etc.—is just as hauntingly beautiful.

NEXT: 5 Ways Alien Is A Great Horror Movie (& 5 Ways It's A Great Sci-Fi Movie)