"He was a candidate for a Midwestern congressional seat, and he hired me to manage his campaign advertising. Unfortunately, his opponent turned up something in his past with which we could not cope."
"Let me guess: he was secretly a liberal."
"Worse. An alien."
"You're kidding?! An undocumented alien running for—"
"No. A space alien, Ms. Walters."
"Let me guess: he was secretly a liberal."
"Worse. An alien."
"You're kidding?! An undocumented alien running for—"
"No. A space alien, Ms. Walters."
— The Sensational She-Hulk #11, Jan. 1990
A character of extraterrestrial origins. For tropes about what makes them alien, at least from a biological standpoint, see Bizarre Alien Biology.
If you thought it meant "illegal aliens" and signed up, click Race Tropes. For interspecies romantic or sexual interactions, see the Interracial and Interspecies Love Index.
If there are no aliens at all, see Absent Aliens.
Compare Fantastic Sapient Species Tropes. Not to be confused with Otherness Tropes, though there may be some overlap.
Tropes:
Related indexes:
- Alien Works: An index of fiction works starring/revolving around aliens.
- Sliding Scale of Anthropomorphism
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Levels of the ladder of alien strangeness
- The Ageless: Aliens who can't succumb to old age but can still die with other methods.
- Alien Animals: Aliens that look exactly like Earth animals or aliens who are actual Earth animals not from Earth.
- Alien Blood: An alien bleeds a strangely-colored substance that isn't the red blood of humans.
- Alien Catnip: A substance that's fine for humans but affects aliens sort of like a drug.
- Alien Fair Folk: Aliens that look like fantasy creatures from Earth's folklore (fairies, gnomes, trolls, goblins) or fantasy creatures who pretend to be aliens.
- Alien Hair: List of hairstyles fictional aliens often have.
- Alien Kudzu: A plantlike alien arrives on Earth and starts "seeding".
- Aliens Never Invented Democracy: When humans are the only culture with a democratic political system.
- Aliens Never Invented the Wheel: Aliens never invented a specific technology (such as the wheel) but are otherwise normal.
- Amazing Technicolor Population: Humanlike alien species with skin colors vividly outside the human range.
- Angelic Aliens: Graceful aliens that look sort of like humans and are seen as extremely beautiful.
- Bee People: A race of aliens that have workers, drones and queens like bees.
- Bizarre Alien Biology: Aliens have biology and physiology vastly different from that of humans.
- Bizarre Alien Psychology: Aliens think a lot differently than humans.
- Blob Monster: Aliens that resemble shapeless blobs.
- Blue-and-Orange Morality: A set of morals that are completely bonkers to most humans.
- Brain in a Jar: A disembodied brain kept alive in a jar.
- Cat Folk: Humanoid aliens based on cats.
- Cute Little Fangs: Aliens with small fangs to make them look cute.
- Ditto Aliens: A species of aliens where all the individuals look the same.
- Eldritch Abomination: An alien that just makes no sense.
- Enclosed Extraterrestrials: Aliens that wander around all covered.
- Energy Beings: Non-corporeal aliens.
- Exposed Extraterrestrials: Aliens that wander around naked.
- Extremophile Lifeforms: Aliens and other beings evolved to live in conditions seemingly hostile to life.
- Fangs Are Evil: Fanged aliens portrayed as bad or malicious.
- Fish People: Aquatic, humanoid aliens who look sort of like fish.
- The Flatwoods Monster: Red-faced, spade-hooded humanoid aliens that are also lumped with cryptid lore.
- Frog Men: Humanoid aliens who look and act rather like frogs.
- Genius Loci: A sapient place.
- Green-Skinned Space Babe: An alien woman who looks like a human except for one or two obvious differences, and who at least one person in the main cast is attracted to if she's not just Ms. Fanservice.
- The Greys: Grey, usually naked, short, humanoid aliens with large heads.
- Human Alien Discovery: A human discovers that they're actually an alien Raised by Humans.
- Human Aliens: An alien which looks, sounds, and to some extent, acts human.
- Humanity Came From Space: Aliens who are actual humans not from planet Earth.
- Humanoid Aliens: Aliens who are humanoid, but don't look human.
- Human Outside, Alien Inside: An alien that looks like a human on the surface but has some wacky parts and whatnot inside their body.
- Human Subspecies: 'Aliens' who are related to humans.
- Indo-European Alien Language: Non-human languages are based on the languages of their creators.
- Inhumanly Beautiful Race: Similar to the above, aliens being beautiful far beyond normal human standards.
- Insectoid Aliens: Aliens based on Earth bugs.
- Intelligent Gerbil: An alien that's basically like a sapient, bipedal version of an Earth animal.
- Killer Space Monkey: Aliens that look like monkeys or non-human apes and are evil.
- Law of Alien Names: Common formulas writers use for making names for aliens.
- Little Green Man in a Can: Aliens that you can't tell what they look like as they all wear strange outfits.
- Little Green Men: Short, green aliens who drive flying saucers, and usually have antennae.
- Living Gasbag: Floating aliens that are literally full of gas.
- Living Program: Aliens made of code and data.
- Living Ship: A ship that's alive.
- Lizard Folk: Aliens that look like humanoid reptiles.
- Long-Lived: It's quite common for alien races to have much longer lifespans than humans.
- Lunarians: Aliens from the Earth's Moon.
- Martians: Aliens from the planet Mars.
- Mechanical Lifeforms: A race of robots or cyborgs that are treated as a real species.
- Mechanistic Alien Culture: Aliens that are organic, but act like robots and have very tight schedules.
- Mirror Chemistry: References to chirality in aliens.
- Monstrous Mandibles: Aliens with mandibles in addition to or instead of a more human-like mouth.
- More Teeth than the Osmond Family: Aliens with a lot of teeth.
- Mushroom Man: Aliens that look like a cross between a human and a mushroom.
- My Brain Is Big: An alien with a huge brain.
- No Such Thing as Alien Pop Culture: Aliens that have no popular culture.
- Not Quite Human: An alien that is practically the same as a human except for one difference.
- Octopoid Aliens: Aliens that look like squids, octopi or jellyfish.
- Palette-Swapped Alien Food: Alien food looks like human food but colored differently.
- Plant Aliens: Aliens that look like or are partly made of plants.
- Pointy Ears: Aliens with pointed ears or ear-like appendages.
- Predator Pastiche: Humanoid aliens based on the stealthy alien hunter of Predator.
- Pupating Peril: Very nasty aliens emerging from cocoons.
- Puppeteer Parasite: Alien parasites that take over their hosts' personalities.
- Really 700 Years Old: Older, or downright ancient, aliens appearing much younger than they actually are.
- Rubber-Forehead Aliens: An alien whose face is significantly different from a human's, but only in their face.
- Sand Worm: Giant alien worms that live in the desert.
- Silicon-Based Life: Aliens that are made of mostly silicon.
- Solar System Neighbors: Aliens who come from other bodies in the Solar System near Earth.
- Space Elves: Aliens who think they're superior (or might even be superior in some cases) to us, and act like a certain fantasy race.
- Space Orcs: Aliens who are brutish, violent and primitive, often very apelike.
- Space Whale: Aliens which look like whales and can "swim" though space.
- Starfish Aliens: Aliens that are radically different from humans.
- Starfish Language: Aliens speaking a bizarre language.
- Stronger with Age: A species that gets stronger as they age.
- Sufficiently Advanced Alien: Aliens that are so advanced that their technology seems like magic to humans.
- Telepathic Spacemen: Aliens with telepathy.
- Tentacled Terror: Tentacles are a common feature of aliens, octopoid or otherwise.
- Transhuman Aliens: A group of 'aliens' are revealed to have evolved from humans.
- Transplanted Humans: Human populations originally from Earth who were brought to other worlds.
- Ultraterrestrials: A species originating from Earth that left and now wants to return.
- Unusual Ears: A humanoid with non-human ears.
- Ursine Aliens: Humanoid aliens similar to bears.
- Xenomorph Xerox: Extraterrestrials with the appearance and/or reproductive cycle of the eponymous creatures of the Alien franchise.
SFX
- Muppet: A type of puppet like in The Muppet Show.
- People in Rubber Suits: Aliens (usually evil) that wear skin-tight suits.
- Serkis Folk: Characters created by dubbing an actor with CGI.
Interspecies relations
- Alien Abductees Fight Back: Humans abducted by aliens rebel against their captors.
- Alien Abduction: One or more aliens kidnap/s one or more humans.
- Alien Among Us: An alien living with a bunch of humans and trying to keep their alienness secret.
- Alien Arts Are Appreciated: Art made by one species is appreciated by aliens.
- Alien Autopsy: Humans study dead aliens.
- Alien Invasion: Aliens try to conquer Earth.
- Alien Non-Interference Clause: Humans don't interfere with the development of alien culture because they have a law against it.
- Aliens Are Bastards: All aliens in a work are evil.
- Aliens Love Human Food: Despite being more technologically advanced than Earth, Aliens appreciate the humans' "primitive" food.
- Aliens of London: Aliens who speak human languages in a particular accent.
- Aliens Speaking English: Aliens can speak human languages for no reason.
- Aliens Steal Cable: Aliens learn about Earth from radio and TV.
- Aliens Steal Cattle: Aliens abduct cows and bulls, not people.
- Anal Probing: Aliens studying humans by sticking things up their butts.
- Anatomically Ignorant Healing: An alien tries to heal a human but have no idea how.
- Ancient Astronauts: Aliens visited Earth sometime in the distant past and apparently did things like build pyramids or were mistaken for gods in old times.
- Area 51: Aliens being hidden in Area 51, a US Air Force base (which is a real place, but no aliens are being hidden there in real life that we know of).
- Automobiles Are Alien: Aliens don't understand cars and other automobiles.
- Benevolent Alien Invasion: Aliens invade but they do the humans well.
- Brown Note Being: Just sensing the alien makes humans sick.
- Crop Circles: Large geometric patterns in fields of crops, thought to be (and in some cases, actually) done by aliens.
- Descriptively-Named Species: A species that has a name based on their appearance/behavior.
- The Dog Is an Alien: An alien disguises itself as a pet.
- Easily Thwarted Alien Invasion: Humans can easily defeat invading aliens.
- E.T. Gave Us Wi-Fi: The idea that aliens invented or helped invent some modern technology.
- Far-Out Foreigner's Favorite Food: An alien's favorite human food.
- First Contact: Humans meet an alien species for the first time.
- First Contact Farmer: When aliens first arrive on Earth, chances are that the first human to observe or interact with them will be a farmer.
- First Contact Faux Pas: A misunderstanding happens during first contact that usually leads to war.
- First-Contact Math: Trying to make first contact by doing math.
- First Contact Team: People suspect aliens are around and make a plan with dealing with first contact.
- Higher-Tech Species: One alien race is more technologically advanced than the others.
- Hostile Terraforming: Altering a place, often a whole planet, to be less suitable for native life and more suitable for alien life.
- How to Invade an Alien Planet: A joke guide for aliens on how to invade Earth or some other planet.
- Hugh Mann: An alien impostor who does a terrible job at appearing human.
- Humanity on Trial: Aliens put humanity on trial for their supposed misdeeds.
- Humans Are Smelly: Aliens that hate the smell of humans, even if said humans are clean.
- Humans Need Aliens: Aliens which protect humans from different aliens.
- Humans Through Alien Eyes: Aliens who think humans are bizarre.
- Humorless Aliens: Aliens that don't understand humor.
- I Come in Peace: During first contact, one species lets the other know they don't intend to harm them.
- If I Am Ever Head of an Alien-Monitoring Agency: A joke page for how to be the Men in Black's leader.
- Imported Alien Phlebotinum: Humans using alien technology.
- Innocent Aliens: Aliens that are well-meaning and clueless.
- Inscrutable Aliens: Aliens that we have no idea how to communicate with and don't know much about.
- Insufficiently Advanced Alien: Aliens that don't make sense because they managed to travel to Earth but otherwise seem to have no idea what technology is or how it works.
- Klingons Love Shakespeare: An alien likes a piece of human culture.
- Mars Needs Water: Aliens trying to steal water from Earth.
- Mars Wants Chocolate: Aliens trying to steal Earth snacks.
- The Men in Black: Generic agents often involved with investigating or denying aliens' existence.
- Mistook the Dominant Lifeform: Aliens want to talk to our pets instead of us.
- Panspermia: Creatures on Earth evolved from alien microbes/simple alien animals, or vice versa.
- Planet Looters: Aliens robbing us.
- Precursors: A mysterious alien culture that precedes all others.
- Protocol Peril: A race of aliens with strict rules that have severe punishments for breaking them, which is bad news if humans are visiting.
- Puny Earthlings: All the aliens have cool powers that we don't.
- The Right of a Superior Species: Aliens that think they are superior to humans and therefore allowed to do bad things to them.
- Roswell That Ends Well: Aliens associated with the alleged UFO crash-landing in Roswell, New Mexico in 1947.
- Scary Dogmatic Aliens: An evil group of aliens with a strict ideology.
- Servant Race: A race made to serve another.
- Sidekick Creature Nuisance: A small alien sidekick who annoys everyone.
- Slave Race: A race of aliens that were enslaved by another.
- Smorgasbord Test: Someone discovers a new creature and tries to find out what it eats by offering it many different foods.
- Solid Gold Poop: One species' waste (poop, urine, tears, etc.) is valuable to another species.
- SoYouWantTo.Write An Alien Invasion Story: A guide for writing stories about alien invasions.
- Stay with the Aliens: Aliens want to take a human with them.
- Superior Species: A race of aliens that are somehow superior to humanity.
- Take Me to Your Leader: Aliens want to be taken to humans' leader.
- Technology Uplift: Aliens who feel they're responsible for sharing technology with other species.
- They Look Like Us Now: Evil shapeshifting aliens learn to look like humans.
- To Serve Man: Aliens eat humans.
- Touched by Vorlons: A character gains powers or their powers get enhanced due to interaction with aliens.
- Two of Your Earth Minutes: Aliens mention that they are using human time, not their time.
- Vichy Earth: Aliens invade and become humanity's new rulers.
- We Come in Peace — Shoot to Kill: First contact with aliens ends badly with one side attacking the other.
- What Measure Is a Humanoid?: A romance between a human and a non-human humanoid is not seen as Squicky as a romance between a human and a non-humanoid.
- What Measure Is a Non-Human?: Humans are seen as the only relevant species.
- The Xenophile: A human who likes aliens.
Reproduction
- Bizarre Alien Reproduction: Aliens have sex in a weird way.
- Bizarre Alien Sexes: An alien species with a weird set of sexes.
- Boldly Coming: Sex with aliens.
- Chest Burster: An alien parasite leaves its host's (usually a human) body by bursting through their chest.
- Designer Babies: A human is genetically modified in utero to make them "better" somehow.
- Dominant Species Genes: Two creatures of different species have a kid that has the traits of the most "dominant" parent.
- Dying Race: A race of sentient beings who are dying out.
- Exotic Equipment: Aliens with unusual privates.
- Face Full of Alien Wing-Wong: A creature reproduces by impregnating another species (often a human).
- Hot Skitty-on-Wailord Action: Two aliens/monsters of different species have sex, but it begs the question just how they did it.
- Immortal Procreation Clause: Immortals who can't have babies.
- Interspecies Romance: A human and a non-human who end up in a romantic relationship.
- Mating Season Mayhem: An alien character goes through animal-like mating seasons.
- Mars Needs Women: A male alien/robot/monster/whatever attracted to human women.
- Only You Can Repopulate My Race: An alien woman whose species is in danger of extinction has to mate with a human male.
- Planetary Parasite: Parasites that use a whole planet as their host.
- Uterine Replicator: Babies are made in a machine instead of a woman's womb.
- Xeno Nucleic Acid: Alien DNA has a different structure than terrestrial DNA.
Genders
- Alien Gender Confusion: The difficulty of members of one species to judge the genders of another.
- Bizarre Sexual Dimorphism: An alien race where the males and the females look way different from one another.
- Gender Equals Breed: Somebody's species depends on their gender.
- Non-Human Non-Binary: A character is not a human and does not exclusively identify as male or female.
- One-Gender Race: A species that's all male or all female.
General tropes and other features
- Abusive Alien Parents: Aliens are bad parents.
- Alien Episode: Aliens visit Earth for one episode.
- Alien Princess
- Alternative Number System: Aliens with a different way of counting than humans.
- Amusing Alien: A funny otherworldly character.
- Bar Full of Aliens: A bar full of many different aliens.
- Came from the Sky: An alien falls from the sky and is initially thought to be a meteorite.
- Dramatic Alien VTOL: Dramatic music plays when an alien spaceship takes off or lands.
- Eldritch Starship: An incomprehensible starship.
- Fantasy Aliens: Aliens in a traditionally fantasy setting.
- Flying Saucer: A disc-shaped starship.
- Great Gazoo: An eccentric, possibly immature alien with incredible powers.
- In Working Order: Alien technology can instantly and easily be used by humans.
- Klaatu Barada Nikto: Shout Outs to the famous phrase from The Day the Earth Stood Still (1951).
- Mistaken for Aliens: One or more people mistake someone or something or a group of people for aliens.
- Multicultural Alien Planet: An alien planet with several cultures.
- Named After Their Planet: The name of an alien race is derived from the name of their home planet.
- No Biochemical Barriers: Aliens can live on Earth (and humans can live on alien planets) perfectly fine.
- Not of This Earth: An unknown object or substance is found, analyzed, and revealed to be not from Earth.
- Ominous Floating Spaceship: An enormous alien starship floating above a city without doing much looks foreboding.
- Operator Incompatibility: Devices designed for aliens unable to be operated by humans, or vice versa.
- People Jars: People in jars.
- A Planet Named Zok: Planets with rare letters from the Latin alphabet.
- Proud Warrior Race Guy: It's common for aliens to fall into this.
- Robot or Spaceman Alter Ego: A musician has a fake alien persona.
- SoYouWantTo.Create Believable Aliens: A guide for creating/writing realistic aliens.
- SoYouWantTo.Design An Alien Mind: A guide for crafting the inner workings of an alien's mind.
- Space Pirates: Pirates in space! Many examples of space pirates are extraterrestrial criminals, though they can also be humans or robots instead.
- Standard Alien Spaceship: Alien ships that are smooth and colorful.
- Transplanted Aliens: An alien population is relocated to another world.
- Tripod Terror: Three-legged alien land vehicles.
