Pinhead has his puzzle box and Jigsaw has his weird Rube Goldberg-style torture devices, but science fiction has built itself on whole galaxies full of bizarre and frightening technology. Whether it's about human-machine hybrids or homicidal AIs, good sci-fi bounces between forecasting the technology of the future (tricorders!) and dreaming up things that should never, ever exist (xenomorphs).
With that in mind, and because the modern day isn't scary enough, here are some of the choicest pieces of nightmare fuel from across the genre.
Rat Things from Neal Stephenson's novel Snow Crash
Neal Stephenson's sci-fi classic Snow Crash has a lot of weird stuff in it (Mafia-run pizza delivery services and weapons-grade motorcycle sidecars, for starters), but it's still credited with one of the first modern visions of the Internet. However, its vision of the future also included the Rat Things.
Rat Things are cybernetically enhanced dogs spliced with rat DNA who have been twisted and warped into nuclear-powered, ultra-fast attack animals that can decapitate a human with a single bite. Up close, they're eyeless, mechanical monsters with a long, whip-like tails, but most people never see a Rat Thing, just the aftermath: they move at hundreds of miles an hour to cool off their radioactive bodies, which have stegosaurus-like cooling fins grafted onto them. After killing an intruder, they zip back to their refrigerated hutches, waiting for the command to kill.
The Rat Things' nuclear isotope batteries and need for speed also have a terrifying side-effect: when some Rat Things jump a fence and begin running cross-country (away from their refrigerated hutches), their only choices are to keep running until they die, crash into things at Mach 1, or stop moving and have a meltdown because they can't stay cool. They're essentially hyper-fast, miniature Chernobyl disasters shaped like dogs.
What makes all this extra disturbing is that the Rat Things live in their own little sci-fi dystopias within their dog houses: when not murdering people, their minds inhabit a virtual reality where they eat porterhouse steaks that grow on trees and catch "blood-drenched Frisbees" thrown by no one. They're still dogs at heart, but they've been turned into radioactive abominations.
GLaDoS, from Portal 2
Portal introduced us to GLaDoS, the darkly humorous AI and overseer of Aperture Laboratories, but it was Portal 2 that took a closer look at who GLaDoS really was: a human mind forced into a machine, driven insane by the strain of keeping the labyrinthine Labs running smoothly.
A lot of attention is given to the fact that GLaDos is essentially immortal, but it's only in the Perpetual Testing Initiative DLC (which explores dozens of parallel versions of Aperture Science) that we get a glimpse of what it's like to be an "immortal being of pure intellect."
In one of the parallel universes, Cave Johnson puts his own mind into the GLaDos hardware and begins guiding the player through tests, mentioning offhandedly that he's busy adapting all human literature to be Ghostbusters spinoffs so he'll have something interesting to read. As the tests go on, however, Cave reflects that life is rapidly becoming tedious in the face of his massive intellect — all mystery or novelty has dried up.
Eventually, he muses that injecting his consciousness into a computer may have robbed him of "an eternal reward, spiritually speaking," causing him to ponder that Hercules made it into Olympus by killing all the world's monsters. Cave mutters, "Damn it…death was my monster! And I killed it! Where's my Olympus? Unless… Aperture was the monster. Aperture and everybody inside it…"
These lines hint that the original GLaDoS wasn't acting upon a desire for revenge when she killed everyone in Aperture — it seems that anyone who undergoes the process that created her will devolve into the same psychotic, existential crisis, which inevitably leads them to kill everyone in the facility out of twisted desire to escape what they have become.
The EVA Units, from Neon Genesis Evangelion
An entire article could be devoted to the nightmarish elements of Evangelion, but let's stick with the EVA Units. Major spoilers ahead.
Despite slightly alien heads and strangely long limbs, EVAs look like any other mecha — they have armor plates, cockpits, batteries, etc. But then the weird stuff starts to stack up: EVAs shoot out geysers of red blood when injured, they have biological (not mechanical) teeth and eyes, and the orange liquid that immerses their pilots in the cockpit smells like blood. Something's not right.
In Episode 19, the truth comes out in the most horrific way possible when EVA Unit 01 goes berserk on one of the series' monsters, rips it limb from limb, and begins cannibalizing its organs: the EVAs are giant biological beings with cyborg components, and their 'pilots' are just controlling their central nervous systems. Their 'armor' is actually meant to bind and restrain them, meaning they're basically giant, bleeding, screaming monstrosities wrapped in metal straitjackets. Oh, and each EVA is animated by the soul of its 14-year-old pilot's dead mother, which is trapped somewhere inside all that meat.
Of course, that's just the beginning
Later in the series, it's revealed that the true purpose of the EVAs is to bring about an apocalyptic scenario called the Third Impact. Naturally, this involves EVA Unit 01 being symbolically crucified by a group of nine eyeless EVAs, who then impale themselves in ritualistic fashion and vomit out new heads, all of which resemble mutilated versions of Shinji's friend Rei Ayanami, causing the most traumatized scream in anime history.
The Total Perspective Vortex, from Douglas Adams' The Hitchhiker's Guide to the Galaxy
Anyone who's been to a planetarium and tried to wrap their mind around the size of the Sun, then the solar system, then the Milky Way, then the local cluster, and then the billions of galaxies beyond that may have felt a twinge of vertigo (or despair at the sheer insignificance of their life choices). The Hitchhiker's Guide to the Galaxy took it a step further.
The characters in Hitchhiker's Guide treated one thing in particular with absolute dread: the Total Perspective Vortex. The machine was designed to condense all the knowledge of the universe into a single moment, wherein a person would finally understand their place in the vast cosmos. Remember, this is a series that makes a point of emphasizing that the universe is so mind-numbingly huge that anything imaginable can happen.
Instead of being enlightened by this moment of clarity, understanding the sheer magnitude of the universe "completely annihilates" one's brain — in fact, according to one of the characters, "you can kill a man, destroy his body, break his spirit, but only the Total Perspective Vortex can annihilate a man's soul."
Like that parallel Cave Johnson in Perpetual Testing Initiative, Hitchhikers seems to subscribe to the idea that the universe (or reality itself) can be the deadliest threat to human sanity. H.P. Lovecraft had the right idea.
The Space Marines, from Warhammer 40K
The mascots of Warhammer 40K trudge around the galaxy with standing orders to kill everything. They're usually portrayed as being roughly seven feet tall and six hundred pounds (and almost a thousand pounds in armor), but what a lot of people don't realize is that Space Marines aren't born this way — they're actually terrifying hybrid humans who are ritually implanted with 19 extra organs, subjected to chemotherapy, and brainwashed using hypnotic suggestion.
A Space Marine's life truly begins between the ages of 10 and 14, when they undergo their first surgery to gain a secondary heart. Over the course of the next four to six years, they will be implanted with organs that allow them to see in the dark, recover from traumatic wounds, and eat almost anything. Their implants cause their ribs to fuse into a single continuous chest plate, as well as give them glands to turn their saliva into corrosive poison — meaning that a Space Marine can literally chew through iron bars.
The most disturbing implants, however, are the Progenoid and Omophagea. The Omophagea is an organ that allows a Space Marine to eat an animal or a recently deceased foe and immediately gain their memories. Mutations in the Omophagea (as well as a lifestyle built on never-ending warfare) have become a major feature in some Space Marine Chapters, where the members engage in ritualistic slaughter and cannibalism to sate an unnatural hunger for flesh.
The Progenoid, on the other hand, is a set of glands that hold the genetic blueprint for all the aforementioned organs. It's harvested from fallen Marines to create their replacements. If the Progenoid gland mutates, every successive generation is affected — meaning that Chapter can turn into mutated hordes like the Black Dragons (who have giant bone growths jutting out of their bodies) or Wolf Brothers (who turned into werewolf-like monsters). Some chapters are defined by the psychoses inherent in their gene-seed, like paranoia or a trance-like state that is essentially a waking nightmare (called "Dorn’s Darkness").
And these are supposed to be the "good guys."