First published in 1938 in Astounding Science Fiction, the novella Who Goes There? takes place in a remote Antarctic base staffed by a bunch of researchers. This group of hardy fellows stumbles upon the wreck of an alien spaceship in the ice, along with an alien corpse that turns pretty frisky once it thaws out.

From that point forward, alien and researchers are locked into respective races against time. The alien (deemed ‘The Thing’) is parasitic in nature, and capable of imitating any living organism; it tries to use its powers of imitation to hide out until it can escape to the outside world. Meanwhile, the researchers work to isolate the base and destroy the alien.

Eighty-three years after it came out, the story is still a masterwork of suspense, which is perhaps no surprise considering its author, John W. Campbell Jr., was an intensely prolific sci-fi author and editor (Isaac Asimov called him “the most powerful force in science fiction ever.”). During the climax, Campbell even anthropomorphizes a flamethrower, and how often do you see a deadly weapon given a personality?

Who Goes There? directly inspired two firms: The Thing from Another World (1951) and The Thing (1982); a prequel to the latter, also called The Thing, came and went in 2011.

For your maximum rampaging-parasite pleasure, pair a reading of Who Goes There? with The Things, a short story by Peter Watts that won the Shirley Jackson Award after its 2010 publication in Clarkesworld. It’s the same tale of Antarctic suspense, only from the alien’s perspective as it attempts to infect all the scientists before they can burn it out.

“The names don't matter,” the alien recounts at the beginning, as it rattles through all the humans it has assimilated. “They are placeholders, nothing more; all biomass is interchangeable. What matters is that these are all that is left of me. The world has burned everything else.”

Watts is brilliant in depicting an utterly strange point of view, and the implications of the ending are terrifying. There’s no sympathy for the devil here; just the promise of a lot more horror and pain.

A young couple ends up hijacked by an escaped convict and his girlfriend; the group arrives at a rural gas station already under attack by a parasitic creature that turns everyone it infects into a spiny, gooey monster straight from hell. Besieged, the humans barricade themselves in the gas station’s walk-in freezer, where they figure out the creature’s weakness—but is that knowledge enough to help them escape?

Splinter wasn’t a huge hit when it came out, although it racked up a bunch of award nominations. If you’re interested in a parasite-themed film that’s soaked with just the right kind of ick, it might just have what you need.

Long before Guardians of the Galaxy and The Suicide Squad, James Gunn made his directorial debut with Slither (2006) a tasty slab of horror-comedy featuring alien parasites invading a small town. It’s funny as hell, and increasingly gross once the parasites begin turning the people of quaint Wheesley, South Carolina into zombies. It’s also reminiscent of Robert Heinlein’s iconic The Puppet Masters, about interstellar slugs who telepathically control their hosts…that is, if Heinlein had inhaled a big dose of nitrous oxide before sitting down to write.

David Cronenberg is arguably the king of cinematic body horror, and Shivers (1975) might be his masterpiece on that front. An engineered parasite turns everyone it infects into a mindless sexual deviant, and it’s loose in an apartment complex in Montreal. The climax in the complex’s pool is pulpy and debauched, and the whole film teeters on the edge of crass exploitation—held back largely by Cronenberg’s technical skill.