The bizarre, unusual, and mystifying aspects of the science fiction genre have always captured the human imagination. From the Earth to the stars, endless possibilities are presented for humankind to explore, in the hopes of developing new technology, discovering new life, and making new opportunities to understand our presence in the universe. Filmmakers capture humanity’s greatest altruism with science fiction, as well as its darkest ambitions and fears.

From the deepest recesses of the human creative process have come countless creatures that find a flourishing home in sci-fi movies. These monsters take many forms, from the comical to the ferocious, but all present a level of menace that is exponentially greater than what can be achieved outside the realm of the most far-fetched. From the Stay Puft Marshmallow Man of Ghostbusters to the Sandworm from Dune, here are the 10 scariest ’80s sci-fi movie monsters, ranked.

THE STAY PUFT MARSHMALLOW MAN

While some may not think much of the Stay Puft Marshmallow Man, the adorable puffy white mascot of the Stay Puft Marshmallow brand, he’s pretty terrifying when he’s 50 stories tall. Just ask the Ghostbusters who fought him off to protect New York City - he was neither adorable nor puffy when he was crushing bystanders and kicking cars.

Ghostbusters had a lot of freaky creatures in it, from ghosts made out of green slime to red-eyed demon dogs to trans-dimensional demi-gods, but the Stay Puft Marshmallow Man reigns supreme as the most monstrous of all of them.

THE PIT MONSTER

Enemy Mine didn’t initially begin as any sort of creature feature, but its finale saw a myriad of monsters descend on its antagonists. Dennis Quaid and Louis Gossett-Jr. starred as two space explorers, the former human and the latter an alien Drac, whose conflict results in them crashing to a mysterious planet. The two enemies are forced to work together to survive the world’s hostile and horrific terrain.

One of the creatures they encounter is the Pit Monster, based off of the Japanese Kaiju, giant creatures like Godzilla and Mothra. It’s one of many alien species they encounter, but definitely the biggest and most formidable, with its tentacles and huge jaws evoking the hybrid of the Sarlacc and Rancor creatures from Episode VI: Return of the Jedi.

THE FLY

In what was one of the most disgusting sci-fi horror films of its time, The Fly featured Jeff Goldblum as you’ve never seen him before. He played a physicist attempting to build a teleporter, the trial run of which turned shocking when he climbed inside and didn’t notice a fly flew in as well. 

When he was supposed to re-materialize in another location the machine (which was supposed to break down human DNA and “reconstruct” it in another location much like a transporter on Star Trek) cobbled together a human and a fly hybrid. When he exited the machine, he began the slow metamorphosis from human into one of the most revolting monsters seen onscreen.

THE LEVIATHAN/DEEPSTAR SIX

We include the pairing of the creature from The Leviathan and Deepstar Six because they were basically the same damn thing. In Deepstar Six, a crew of US Navy engineers is constructing an underwater base when they inadvertently wake up a huge underwater beast. The crew tries to evacuate but it starts picking them off one by one.

In The Leviathan, a group of geologists and miners descend to the ocean floor to begin work on a mining project for a mega-corporation. When the discover a sunken ship and investigate it, they invite a malevolent entity on board, capable of mutating into members of the crew like The Thing under the sea.

THE ID MONSTER

There’s more than a few alien beasts populating Galaxy of Terror, a cult ‘80s sci-fi film that pits a crew of astronauts against an inhospitable world of untold danger. When the Guest ship sets off for the storm-ravaged planet of Morganthus, they have no idea that their journey may not have been entirely of their own making.

They encounter grotesque creatures that begin picking the crew off one by one, including the “id monster”, which basically amplifies your worst fears and then kills you with them. By the time the last crew member has to fight off zombie versions of his friends, you’d think the terror would end, but then he becomes the replacement for the leader of this galactic freakshow.

THE THING

Without a doubt, the creature created for John Carpenter’s The Thing is one of the most terrifying monsters in science fiction, if not cinema itself. Able to absorb the tissue of any living organism and replicate it, The Thing can assume the form of any person, even your closest friend.

The film didn’t do as well as Carpenter hoped when it was released, with critics panning its plot for being unable to unfold without excessive gore and graphic violence. It has since been appreciated for its application of psychological horror, as the research scientists of Outpost 31 slowly turn on each other in the solitary Arctic, with little hope of rescue and resources dwindling.

THE SANDWORM

The most recognized inhabitant of the Dune film and novel universe, the Sandworm was a giant creature found on the planet of Arrakis. It traveled beneath the vast stretches of desert that made up the world’s topography, bursting forth to devour anything that moved across the surface.

The sandworms hunting grounds are in the same area as the coveted spice, a highly sought after drug. Vehicles that go hunting melange end up getting hunted by sandworms, a necessary evil when you consider that the spice is actually a byproduct of their life cycle. Sandworms were based on Frank Herbert’s interpretation of dragons guarding treasure in medieval Europe.

THE TERMINATOR

Though the Terminator doesn’t have snapping jaws or sharp claws it’s one of the most terrifying monsters in sci-fi history. Appearing first in Terminator with the T-800 model (a role that would launch Arnold Schwarzenegger’s career), and later the advanced T-1000 (which could mold itself into any object or person), it’s many times stronger and faster than a human despite resembling one.

A Terminator doesn’t need sleep, food, or any of the comforts of society to do what it does best; track and kill. While later the Terminator was used by humans for protection purposes, its skills are primarily utilized best in the role of an assassin or super-soldier. It can instantly learn how to use any weapon, has processing capabilities that grant it superior reflexes, and can generally outrun, outsmart, and overpower anything in its path.

THE PREDATOR

Humans are no longer the apex predator when they come in contact with the most feared hunter in the known galaxy. A group of soldiers on a routine drop into South America suddenly find themselves fighting for their lives against an inhuman creature with superior strength, resourcefulness, and technology. However, the Predator has met his match in human’s last line of defense, Arnold Schwarzenegger.

Predator was one of the most successful sci-fi films of the ’80s, and the Predator alien became one of the most famous movie monsters of all time with its iconic mask, costume, and expanding jaws. Arnie went toe to claw against the Predator, using all of his guerrilla knowledge to beat it at its own hunt, but even after the epic fight several sequels would follow for fans who wanted more carnage.

THE ALIEN

No one thought a sequel could have out-shined the original quite like James Cameron’s Aliens, the action-packed follow up to Ridley Scott’s sci-fi horror masterpiece Alien. While it lacked the moody ambiance of the first film, about a lone spacecraft’s crew terrorized by an alien, it had a frenetic quality that heightened the terror once the alien is found to be colonizing other planets.

The “xenomorph”, with its powerful frame, snapping inner mandible, and its acid for blood became an even more vicious killing machine when it faced Earth’s Space Marines. Drones decimated their ranks, and the Queen nearly killed franchise heroine Lieutenant Ellen Ripley. Now with the Alien: Covenant franchise the xenomorph continues to be the most terrifying sci-fi movie monster.