In real life, dark matter is a kind of hypothetical matter that constitutes most of the matter of our universe. Its existence is only ever detected via its gravitational and radiation effects, and so far, no one is certain what a "dark matter" actually looks like.
Perhaps owing to its hypothetical nature, in fiction, dark matter is interpreted in various ways. As a phlebotinum mainly, dark matter may be a Power Source, Toxic Phlebotinum, something behind Minovsky Physics, etc. A common assumption in visual media is that it's literally dark; in reality, of course, if dark matter comprised clouds of blackness floating through the universe, we'd be able to see it. Scientists only call it "Dark" because they're in the dark about it.
Note that simply naming a character or a device "dark matter", especially as a proper or brand name, isn't sufficient: dark matter must be portrayed as a substance of some kind.
May be related to Casting a Shadow when used as a superpower. Compare Technobabble, when writers throw together scientific terminology without regard for the words' actual definitions, and Photoprotoneutron Torpedo, which similarly makes something science fictiony by appending the name of a real or fictional subatomic particle. No relation to the Dark Matter TV series or Offscreen Villain Dark Matter. For hypothetical characters whose existence can only be inferred, see Unknown Character.
- A Twelfth Doctor story in Doctor Who (Titan) has sentient dark matter that can possess people and is plotting to blot out the sun. Yeah, it's pretty silly.
- Dark Nights: Metal introduces the Dark Multiverse to the DCU, a realm of dark matter and dark energy inhabited by nightmarish versions of various heroes.
- In the Marvel Universe, people with Casting a Shadow powers sometimes refer to the weird shady stuff they summon as "dark matter". It seems to drain all light and heat from the immediate vicinity, and can vary in consistency between "syrupy" and "hits like a bullet from a compressed air gun".
- Thor: The Dark World has the Aether◊, one of the six Infinity Gems. Which, despite the name, is more of a wibbly-wobbly ebby-flowy fluid capable of converting regular matter into dark matter. Also despite the name, it's visible to the naked eye with a sinister red glow, and is if not sapient, intelligent enough to want to protect itself.
- In Transformers: Age of Extinction, dark matter is used to power Lockdown's ship.
- A Certain Magical Index: The Number 2 Level 5, Kakine Teitoku, has the esper power called Dark Matter, and it's the ability to generate material that has its own laws of physics. However, Kakine's "Dark Matter" is explicitly not like the real dark matter.
Kakine: The Dark Matter that I produce is a substance that does not exist in this world. I don't mean it hasn't been discovered, but that it should theoretically exist; I mean, it actually does not exist. Matter that doesn't exist operates under laws which don't exist. Like say, turning the light from the sun into rays that can kill a man.
- Aeon 14: Faster-Than-Light Travel is accomplished by transitioning to an alternate layer of spacetime called the dark layer where dark matter has physical form. Dark matter is depicted as pure unadulterated mass that drifts like icebergs according to gravity patterns and tends to be denser inside star systems. It's also fed on by Eldritch Abominations that live in the dark layer and have been known to eat ships as well. As such, it's very dangerous to transit into the dark layer inside a star system.
- The climax of Destiny Lost uses this to justify an Unrealistic Black Hole. The Bollam's World Federation is using graviton generators, which work by pulling gravitons from the dark layer, to artificially expand a brown dwarf so that it doesn't ignite normally and therefore acts as a helium-3 factory. Ships from the Hegemony of Worlds blow up the generators, which causes the planet to collapse all at once, setting off a titanic fusion explosion that compresses the lower layers below the black hole threshold. The explosion also provides energy to keep the generators' portals to the dark layer open, and the black hole begins to consume dark matter, resulting in a "dark matter black hole" that is much larger and more powerful than the object it originally formed from.
- Alexis Carew: Darkspace is an alternate layer of spacetime where dark matter and dark energy have physical form. This is used mainly to make darkspace an ocean: dark matter forms "shoals" and "reefs" around star systems that can enmesh and destroy ships. Privateer in particular takes place in a region of space called the Barbary where dark matter formations are much denser. Space Pirates have set up a base inside a system that is all but blockaded by dark matter except for small difficult-to-navigate passages, and Alexis makes two attempts at penetrating it.
- In And Another Thing..., Wowbagger's (stolen) starship is made of dark matter, making it into a Shadow Walker that phases into a "dark dimension" for FTL travel unlike any other method used in the setting. Looking out the window while traveling this way is as disquieting as ten near-death experiences, and causes you to confront all your deep-seated emotional baggage (rather handily for character development purposes).
- In His Dark Materials, dark matter (introduced as Dust in Lyra's world) is a central part of the trilogy, and is the substance that angels are made up of. In addition, some creatures (like the mulefa) can see it and use it to identify intelligent beings, as it gathers around them in large quantities.
- In Lucifer's Star, the universe has a second dimension called Jumpspace. It is a mysterious dimension which underlines everything else. It is full of bizarre alien entities, sanity blasting visuals, and weird gravitonic anomalies.
- Parodied in one of the Discworld books, where, after discussing the notion of a mysterious form of matter that makes up most of the universe, the narrator concludes that it must be the paperwork.
- The Flash uses dark matter as its go-to Applied Phlebotinum for Super Empowering. If there's a metahuman then chances are they were hit by dark matter at some point. Most notably the STAR Labs Particle Accelerator explosion was a Mass Super-Empowering Event that released dark matter all over Central City.
- Star Trek: Typically used as part of technobabble, often in the form of dark matter nebulae.
- Star Trek: Enterprise: In "First Flight" Vulcan scientists are said to have excited dark matter in experiments, causing it to give off light, by bombarding it with metreon particles. The Enterprise crew do the same to a dark matter nebula encountered in the episode.
- Star Trek: Discovery: In "Magic to Make the Sanest Man Go Mad", Harry Mudd uses capsules of dark matter as weapons against the Discovery crew. They're shown as little purple-glowing balls that disintegrate people they hit.
- Star Trek: The Next Generation episode "In Theory" features the Enterprise exploring a dark matter nebula which caused bits of the ship to randomly vanish. This caused activity from Spot (Data's cat) exiting Data's room without using the doors to a crew member falling through the floor after it vanishes and then getting killed when it comes back.
- Star Trek: Deep Space Nine: In "Rocks and Shoals", Sisko et al. attempt to evade Jem'Hadar pursuit by flying into a dark matter nebula, but suffer damage and crash on a planet inside it.
- Star Trek: Voyager:
- "Cathexis": Chakotay and Tuvok pass a dark matter nebula in a shuttle and are attacked by energy beings living inside it, which becomes a Body Surfing/Demonic Possession plot.
- "Threshold": Neelix says he once lost a warp nacelle traveling through a dark matter nebula, which gives Paris and Kim inspiration on how to finish building their transwarp drive.
- "One Small Step..." featured a dark matter asteroid, which looked like the shape of an asteroid but was see-through.
- "Good Shepherd": Voyager encounters a species of dark matter lifeforms that again take over a Red Shirt's body and try to communicate. The guest star panics and kills one of them, and the aliens attack the ship.
- In The Outer Limits (1995) episode "Dark Matters", the commercial transport ship Nestor is thrown out of hyperspace into a starless void. In this void, they find a huge quantity of dark matter and two ships, the UNS Slayton and an alien ship. Everyone on both of those ships is dead. An apparition of Captain John Owens of the Slayton appears to the crew of the Nestor and tells them that their "souls" are trapped in the pocket of space created by the dark matter. As such, they cannot move on to whatever comes next, whether that be Heaven, Hell or oblivion. The same fate has befallen the aliens.
- An episode of The X-Files had a scientist exposed to dark matter in the lab; afterwards, his shadow causes anyone who touches it to melt into a puddle.
- In the Dark Matter campaign setting, the Earth passes through a high concentration of dark matter. The total amount of magical and psionic energy increases and gates to other dimensions open up, allowing weird monsters to come through.
- The Destiny games hint at the mysterious, civilization-killing Darkness being linked to dark matter, as it and entities associated with it tend to emit phaetons, axions, and sterile neutrinos (all theoretical particles potentially linked to dark matter) when their Reality Warping properties come into play. Intriguingly, Destiny 2 revealed that dark matter is the "flesh" of the equally enigmatic Nine: nine galaxy-spanning loops of (physically accurate: undetectable and only interacting with gravity) dark matter centered on nine bodies of the Solar System, with their consciousness "seeded" by the minuscule gravitational fluctuations of living things moving around on them propagating across each loop. The connection between them, if any, is currently unclear.
- In the Final Fantasy games, dark matter usually takes the form of a rare item that's used in high-end item combinations.
- Golden Sun: Dark Matter is a forgeable item, dropped by firebirds. The gear crafted from it is among the best there is, but it's all cursed (can't be unequipped without a priest, and occasionally stuns the wielder without a specific one-of-a-kind item).
- In Half-Life 2, dark matter is a power source used by the Combine.
- Recurring villain Dark Matter in the Kirby series is a living blob of darkness that flies through space, finding planets to be corrupted/consumed. There are multiple Dark Matters in the universe, all of them coming from their master/"core", Zero (another Cosmic Entity).
- In League of Legends, "Dark Matter" is the name of one of Veigar's spells, which causes a meteor to fall.
- In the LittleBigPlanet games, dark matter is an anti-gravity material used to make objects in levels float.
- In Metroid Prime 2: Echoes, Samus's Dark Beam fires blasts of dark matter.
- The Dark Matter Gun from Quake IV. It fires Unrealistic Black Holes.
- In Spiral Knights, dark matter is one of five forms of minerals used to level Battle Sprites.
- In Super Mario Galaxy and Super Mario Galaxy 2, dark matter exists as a form of Grimy Water that causes Mario and Luigi to instantly disintegrate upon falling into it. It's also capable of warping reality, creating holes in space that will cause you to fall off platforms moving through the stuff if you don't jump over them.
- Schlock Mercenary has a whole story arc about a race of beings from another galaxy made of "dark matter", with which the Milky Way galaxy is currently at war.
- In Exosquad, dark matter is used as spaceship coating for Stealth in Space. It also makes humans who come in contact with it extra irritable and aggressive.
- In Futurama, dark matter exists as an oil-like substance and also in an extremely dense solid form (1 pound of it weighs over 10,000 pounds, according to Professor Farnsworth) defecated by Nibblonians, typically employed as starship fuel. The episode "The Birdbot of Ice-Catraz" revealed that the liquid form could induce hyperfertility in animals, in this case, penguins, and even induce egg-laying in males, which led to a potential Overpopulation Crisis.
- An evil clone of Jimmy Neutron once duplicated the entire planet and everyone on it, but used a "dark matter chip" to turn the whole dupe-Earth into a world of Card Carrying Villains. After he snapped the chip in frustration, it unleashed a huge black billowy cloud that began to swallow everything around it.
- In League of Super Evil, the most powerful dark matter in the universe is found in the shape of black licorice, of all things. Red Menace is the only character shown who enjoys the stuff.
- In Ninjago, dark matter is a Psycho Serum found on the Island of Darkness that the Overlord describes as being able to "turn a man's heart as black as night". After using one of the heroes as a guinea pig, he uses bombs filled with the stuff to attack Ninjago.
- In Rick and Morty, Rick was kidnapped by Zygerions who made a convoluted scheme to obtain the recipe for concentrated dark matter from him. The episode ends with Rick giving them a fake recipe that blew up their ship when they added bottled water to the concoction.