Absolute Xenophobe

"Ask not "Why kill the alien?" Rather, ask, "Why not?" "

- Battle-Brother Artemis, Warhammer 40K

A significant subtrope of Scary Dogmatic Aliens, the Absolute Xenophobe does not work and play well with others. Whether from instinct or acculturation, these aliens are horrified at the mere idea that other sentient life exists, and will not rest until they have annihilated every other intelligent species they know of. Differs from The Virus, Horde of Alien Locusts, Planet Looters, et cetera in that the Xenophobes don't necessarily gain anything other than a (false?) sense of security from their wars—they don't want to eat us, transform us, or scavenge resources from our planet (although that's a bonus); they just want us dead and gone.

See also the equally though less expansively genocidal Feeling Oppressed by Their Existence and Kill All Humans, and the even more extreme Omnicidal Maniac.

If this xenophobia is a result of cultural influences, it may be possible to knock some sense into them and make peace. If they're instinct-driven, it's probably them or us. Such aliens may bear a resemblance to (or, as in the case of the Daleks, be explicitly based on) Those Wacky Nazis. Contrast Intrigued by Humanity, or The Xenophile. Compare and contrast the Master Race, who may want to kill other races/species but would rather conquer them.

Since there are no actual aliens that we know of, only hypothetical ones, No Real Life Examples, Please. Unless it's someone who wants to wipe out all aliens (if they exist).

Anime & Manga

 * The  in Tengen Toppa Gurren Lagann, follow an eternal mission to wipe out all sentient life

Comic Books

 * Unicron, the evil overlord of the Transformers, has made it his final goal to wipe out all creation and leave nothingness in his wake so he may be at peace in an endless void. Out of eternal hate, he finds other living things appalling- save for those that worship and follow him. Even then, he's just saving them for last.
 * Gah Lak Tus, the Ultimate Marvel Galactus, is a fleet of killer robots motivated by a thorough loathing of all organic life; they don't just try to kill everything fleshy, they do so in the most hideous and painful ways they can come up with.
 * Oddly enough, this loathing is almost completely irrational. The moment  tries to make contact with it, it spasms with revulsion and opens fire on Earth. In the end,  . Oh, and they also shoot it with   for good measure.
 * The Termight in Nemesis the Warlock is on a perpetual crusade to wipe all non-human sapient life from the galaxy.
 * The Daxamites of The DCU are a ridiculously xenophobic society. They ban space travel, indoctrinate their children with fears of aliens, and teach them that Daxam is their entire universe. Green Lantern Sodom Yat was a rare exception. His own parents had to brainwash him to rein him in, which backfired immensely when he broke free of it. He even chastised his own people for not getting outside help when the Sinestro Corps invaded Daxam.
 * In Superman's, Kryptonians were another example from The DCU. While they weren't xenophobic to the same genocidal extent as their distant cousins, the Daxamites, they did look down on other species, and they, too, banned space travel research. That ban on space travel is why there are so few Kryptonians left—when Krypton blew up, most of the people had no means of escaping the planet. The only survivors were either stuck in a prison dimension, trapped in an off-world miniaturized city, or sent away in experimental, illegal spacecrafts.
 * It's actually worse. The Kyptonians were all affected by the Eradicator (which is a genetic enginering project, an AI and a bunch of other things, it's complicated), the upshot of which was even if they found a way off the planet they'd just die.
 * Sergeant Preus of the Superman storyline Godfall takes this to new heights, desiring to exterminate all of Metropolis for the unforgiveable sin of not being ruled by Kryptonians.

Literature
"They flew out of the cloud. They saw the staggering jewels of the night in their infinite dust and their minds sang with fear. For a while they flew on, motionless against the starry sweep of the Galaxy, itself motionless against the infinite sweep of the Universe. And then they turned round. "It'll have to go," the men of Krikkit said as they headed back for home. On the way back they sang a number of tuneful and reflective songs on the subjects of peace, justice, morality, culture, sport, family life and the obliteration of all other life forms."
 * The Dyson Primes from Peter F. Hamilton's Commonwealth Saga are the definition of this. Primes exist as sentient, immobile "immotiles" and sub-sentient motile servants that can merge to create new immotiles. Immotiles control vast armies of motiles and battle each other for resources and out of instinctive paranoia, since their biological imperative for perpetual expansion means they'll always clash sooner or later (and prefer it being sooner). You can guess what happened when they started building nukes. Also, the moment one of them (Morning-Light-Mountain) discovers wormhole technology, it exterminates all others and starts building a vast fleet in order to kill off every single living thing in the universe other than itself, not capable of comprehending the notions of sharing and coexistence. In its own words: "There is only one Universe and it can only contain one life. Me."
 * Just to clarify how utterly whack these guys were, they had gone so far as to exterminate every plant and animal life form from their own homeworld other than themselves and their food crops.
 * MorningLightMountain hates fish.
 * The Ryall from the Antares trilogy are a classic example of the instinct-motivated Xenophobe: throughout their early development, they were preyed on by another sentient species, until they went to war and wiped the egg-eaters out. They see other intelligences only as competitors, and feel a deep need to kill them all.
 * David Weber likes this trope a lot:
 * The Achuultani of the Empire From the Ashes novels have been quartering the galaxy for seventy million years, exterminating every sentient species they can find because they believe every other sentient species would do the same to them.
 * The Shirmaksu (or Kangas) in The Apocalypse Troll come from the same situation as the Ryall above, reinforced by a religion which holds that God made them in His image and all other intelligences are demons in disguise.
 * The Gbaba from the Safehold series appear to be instinctive Xenophobes, though we have yet to fully understand why. One character speculates that they've lost their sapience and are governed entirely by instinctive behavior.
 * The Krikkiters in Life The Universe And Everything, the third novel of The Hitchhiker's Guide to the Galaxy, were initially unaware that there was a universe beyond their solar system, and are now determined to destroy it all.

- Douglas Adams, Life The Universe And Everything


 * The reason for this is that the story is recycled from an old Doctor Who script Douglas Adams wrote. The Krikkiters were Captain Ersatzes of the Daleks.
 * The Pitar in Alan Dean Foster's Humanx Commonwealth novels appeared nearly human, and even held out a cautious hand of friendship at first...but this concealed a species-wide psychosis that drove them to attempt to wipe out humans, thranx, and anyone else they could find.
 * From the works of Michael Moorcock: John Daker, called to an alternate earth to be the champion of humanity against their dreaded foes, the Eldren, discovered that these humans were Absolute Xenophobes, doing their best to exterminate a peaceful culture who had never done one damn thing to deserve it. He defected to the Eldren and tried to defeat humanity and strike a peace...but the humans fought to the death, every last man, woman, and child. For his "crime" against his own species, the Cosmic Balance sentenced Daker to be reincarnated again and again across a million worlds as the Eternal Champion.
 * The Ekhat in The Course of Empire are utterly mad creatures, devoted not only to killing all sentients (albeit saving some, temporarily, if they're useful as slaves), but to transforming the entire universe so that all that exists "is" Ekhat in some way.
 * Inverted in Anne McCaffrey's Decision at Doona, where mankind's "no contact with intelligent aliens ever" policy came about when, upon the first-ever such contact in history, the alien species in question promptly .
 * They're not exactly aliens, but the Auditors of Reality from the Discworld series probably count. They regard life, especially sentient life, as a blight on the universe (and a major bookkeeping headache), and want to see it eradicated.
 * Their hatred of life is such that it even applies to themselves. They aren't technically alive to begin with, but if they show any signs of individuality (such as refering to themselves as "I"), they burst into flames. The "logic" is that if something is an individual, it has an identity. If it has an identity, it is a person. If it is a person, it is alive. If it is alive, it will die someday. And from the point of view of the immortal Auditors, a mortal lifespan is so short that it might as well end it instantaenously.
 * A race of aliens like this appears in the Star Trek: The Original Series novel Windows on a Lost World.
 * The Molothos in Ryk Spoor's Grand Central Arena hate all other sapients, but are forced by the Arena system to interact with them on a non-destructive basis. This does not make them any happier.
 * Certain eras of the Xeelee Sequence by Stephen Baxter present the rather disquieting specter of humanity acting this way to everything else, essentially out of a deeply psychotic sense of Sibling Rivalry stemming from our second-place status to the Xeelee.
 * Humanity also becomes this in Ender's Game.
 * Interestingly enough, the Buggers are theorized to be this at one point.
 * The Yevetha from The Black Fleet Crisis trilogy (Star Wars Expanded Universe). They consider all other life to be vermin and their ambassadors scrub themselves clean with painful showers after any contact with other races.
 * Despite having not yet even formally ventured into space, the Fenachrone from the Skylark Series have spent several generations planning to conquer the universe and exterminate any sapients they may find. (They're also almost inconceivably overconfident.)
 * In the Cthulhu Mythos, one has the Yekubians, who literally slaughtered every other intelligent race in their entire galaxy before heading towards ours.
 * Three words: Delores Jane Umbridge. The woman cannot stand anything that is not unarguably 100% wizard from a pure wizarding family.

Live Action TV
"All inferior creatures are to be considered the enemy of the Daleks and destroyed!"
 * In Doctor Who, the Daleks would like nothing more than to exterminate all non-Dalek life, and even remake the universe itself to serve Dalek purposes alone. They were created by Davros as a means of ending a centuries-long, hopelessly stalemated war between the Kaleds (his people) and the Thals. Davros programmed them to "survive" by any means necessary, having decided, based on the endless war, that the only way for any one species to survive is by completely subjugating all others.

""They plan to exterminate the Sebaceans, but they won't stop there! Nor with Luxans, Delvians, Baniks, or a thousand other lower life-forms. They'll stop - when they're the only sentient species left. And if they discover wormhole technology before we do - the galaxy is theirs. And eventually, John, they will find Earth. Your race is defenseless. They'll be raped and slaughtered unless you help us!""
 * The Daleks hate each other and themselves almost as much as everyone else. They have been known to start civil wars over trivial differences, one commits suicide in the new series when it discovers that it has been tainted with foreign DNA, and a new faction can't stand its own existence because they were created by the emperor using human cells, making them even nuttier than usual. Even the Cult of Skaro, specifically intended by the Daleks to be individuals and consider new ideas, turned on their leader when he favored becoming less "Dalek" in order to ensure the survival of their race.
 * Probably the most extreme example from the humans is the Last Human, Lady Cassandra. She removed bits of herself that she saw as being similiar to aliens or altered (inbred) humans. In the end, she became just a single sheet of skin with a face. To current era humans, she would be much, much more alien than many of the aliens.
 * And just to add icing on the cake, it's stated off hand she's transgendered. While absolutely no one holds this against her, it smacks of Irony that someone who wasn't born the sex they are now is so utterly obsessed with body purity.
 * Sutekh the Destroyer was a Physical God and Sufficiently Advanced Alien with these tendencies. To preclude the possibility that something that could challenge him might evolve, He wanted to erase all life in the universe, down to viruses and bacteria. He started out by trying to exterminate his own race, the survivors of whom ganged up on him and imprisoned him on Earth. The conflict itself was observed by the Egyptians and became part of their mythology.
 * The Peacekeepers in Farscape are initially presumed to be this: however, though they are extremely xenophobic - particularly around new species - and opposed to hybrids on general priciple, they aren't really true examples of this trope in that they are more interested in conquest than genocide. However, even their usual reputation for xenophobia is largely due to regulations that not all Peacekeepers pay attention to: quite a few frontier officers and captains have been seen flirting with alien females, and some aliens and hybrids (like Scorpius) have managed to attain high office in Peacekeeper command.
 * The Scarrans however, at least according to Scorpius (who, though biased, has shown a strong understanding of Scarran nature), play this trope straight. This is best summed up in this quote:


 * This is the attitude of some of the demons in the Buffy the Vampire Slayer world. The Scourge is the best example; they would like nothing more than to purge the world of humans,vampires and impure demons. Of course, they fail to see that they likely have human blood in them as well...

Tabletop Games

 * The K'kree in Traveller are limited Xenophobes: they're on a genocidal crusade to wipe the galaxy clean of all carnivorous organisms. No matter whether or not said organisms pose any threat to the K'kree at all, or are even capable of metabolizing K'kree flesh, or even if they're vital to the ecosystems of worlds the K'kree have colonized: meat-eating is EVIL and must be ended at all costs. Omnivores get a pass if they're willing to go vegan; obligate carnivores are out of luck.
 * During the K'kree-Hiver war the Hivers introduced meat sauce to a few K'kree colonies, they were so horrified that they sterilized the planets in question.
 * Several factions of Warhammer 40,000. Most notably, the Imperium of Man generally maintains an official policy of Absolute Xenophobia, but it's far from 100% honored, and there are valid reasons for it not being honored, such as that some aliens are harmless and destroying them would be a waste of resources, or that they're actually useful if kept at a "safe distance". Rogue Traders are also explicitly exempt from the usual restrictions on contact with Xenos, and are allowed to trade and interact with them as long as it is done in the interest of the Imperium. (But the average human being is taught to just fight/fear them). The Necrons, for their part, kill all lifeforms, not even limiting themselves to sentient ones.
 * The Necrons aren't so bad. Sometimes, they just use weird tortures and spread terror, or set themselves up as gods. The C'tan do have a sense of fun.
 * Well, the Void Dragon and the Deceiver anyway, the other two are crazy.
 * The Ciaphas Cain novels, specifically For the Emperor!, examine this in more detail. The Imperium and the Tau do not like each other, but are not continuously at war. Cain actually allies with a Tau squad when their interests align, but they split up as soon as it's convenient.
 * This is also due to him being practical. After all, wouldn't you prefer those plasma guns and rail rifles to be pointed at the genestealers, rather than you?
 * The Rigelian Protectorate in the Starfire universe. Their worlds were sterilization bombed to end the threat, after it was concluded that co-existence was impossible.
 * The Army of the Expeditionary Force in 3:16 Carnage Amongst the Stars seeks to destroy all non-terran life in the universe. This includes non-sentient life.
 * In case that's not blunt enough, let's be clear that their policy makes the Imperium of Man look like it cherishes and respects all life by comparison. Let's give an example of space gerbils just sort of harmlessly gerbiling around on their homeworld. Faced with this, the top ranks of the Imperium of Man would decide that these could never conceivably be enough of a threat to justify the resources it would take to destroy them. The top ranks of the Army of the Expeditionary Force would decide that they could never conceivably be enough of a threat to justify blowing up their entire star system, and they should be genocided the old fashioned way.
 * The Sathar in Star Frontiers.
 * Daemons in Pathfinder, though it's more about wanting to end all life than racial purity. The only reason they don't slaughter each other (much) is because they're all working toward the same end; once all other life in creation is gone, they'll most likely commit racial suicide.
 * The 2nd and 3rd editions Dungeons and Dragons had the beholders, who were so paranoid and xenophobic that each individual thought that it was the perfect manifestation of ideal beholderhood, and all other beholders were inferior fakes. When a beholder gives birth, it picks out the young that look most like itself, and kill all the others.

Video Games

 * In The Ur-Quan Masters, the titular Ur-Quan are divided into two factions: Kohr-Ah and Kzer-Za. The Kohr-Ah want to wipe out all other sentient life in the universe. The Kzer-Za will settle for enslaving or confining all other sentient life in the universe. Similar to the Ryall, it basically comes down to a species-wide Freudian Excuse - eons ago, they were all enslaved by a race of evil creatures with mind-control powers, and after finally casting off their shackles (in a thoroughly horrible way, at that - turns out, the evil aliens couldn't maintain control of a being in absolute agony), they basically decided that they couldn't risk it happening again. So they went to war with all other sentient life. The intervening generations have not mitigated their trauma - Genetic Memory means that it effectively happened to all of them.
 * In the first Galactic Civilizations 2 expansion, the Drengin undergo a similar (and reference-riffic) split: Their largest and most powerful clan, called the Korath clan, decided to exterminate all non-Drengin life, while the rest of the Drengin simply wanted to enslave the galaxy.
 * The Ascalonians of Guild Wars. Whose attitudes were that charr were strange and must be culled, and then that the other human nations were weird and must be culled. Pretty much anything or anyone that wasn't from Ascalon needed to die. They did love their cleansing.
 * The Glomdoring Commune of Lusternia subscribe to this notion. It's their ultimate goal to seed the Glomdoring throughout the rest of the known world, while forcibly converting the other civilizations to their own viewpoint as they do. Resistance results in death.
 * The Shivans of Free Space...may or may not fall under this. They do kill anything that isn't Shivan on sight, but they tend to ignore planets unless they are populated by a space-faring species they're exterminating at the time, and certain unexplained actions they take near the end of the second game have cast considerable doubt on their motives.
 * The Zuul from Sword of the Stars believe in a divine purpose for their race, which is to enslave and kill off every other species but their own and their "master's". Word of God says this is partially due to culture and partially built-in instinct; the Zuul were bred by a race of Abusive Precursors as a living bio-weapon to exterminate other civilizations. In-game, making NAPs and alliances with Zuul is all but impossible: Their default state towards everyone is war.
 * The Reapers from the Mass Effect series certainly seem none too fond of any other species. It's kind of hard to tell if xenophobia is their main motive for doing what they do, but (at least in the first game) it seems to heavily factor into it.
 * Actually
 * Actually

Webcomics

 * The cultural dogma of the Ob'enn from Schlock Mercenary calls for "the eventual extermination of all non-Ob'enn". They do, however, recognize the usefulness of trading with other species and "borrowing" their expertise, where appropriate, until such time that they can get to exterminating.
 * The dark-matter Pa'anuri. They have one name for baryonic-matter entities (which would include us, Earth, our Sun, and all observable (to us) matter in the universe), which is "ANNOYING". Using teraports (since they create gravitic tunnels in space; sort of like having a blind man drilling holes through your house) angers them, and if a species develops to the point of being able to teraport, they blow up that specie's sun. After drawing an extremely costly war against the Gatekeepers, the Pa'anuri moved shop to the Andromeda galaxy, where they began routinely destroying any civilization that invented the radio. The first baryonic space-farers from the Milky Way who went there found several radio shells... All of which are thirty years wide, and then scrambled by a supernova shell. By Earth standards, we would barely have invented the tank by the time our sun would have been blown up.
 * The Kvrk-Chk of Quentyn Quinn, Space Ranger have two categories of lifeform: "Other Kvrk-Chk" and "food". With these two categories forming a VERY disturbing Venn diagram....
 * Part of this comes from their world being an EXTREMELY hostile environment, where most non-Kvrk-Chk species would die instantly just from atmospheric pressure or the toxic atmosphere, or the wide variety of scavengers and predators. Due to how hostile and aggressive their environment is, they literally have to eat their food alive just so the scavengers and decomposers of their world don't rot their food before it reaches their mouth. As part of their culture, a visiting Kvrk-Chk offers the master of the house one of it's own severed limbs as food. Oh, and they consider "Awake and Screaming" a flavor, and sentient lifeforms "chatty food".
 * In a subversion, their treatment of "chatty food" and declaring war on every species out there didn't work very well for them when one of their new enemies incinerates one of their solar systems in retaliation. They listen to them now.

Web Original

 * The Global Guardians PBEM Universe features the Kalish'chahine, a horrifically warlike alien race who view all other forms of life as food resources. They breed so quickly that they exceeded their home planets' capacity to keep the population fed, and are capable of digesting pretty much any carbon-based life. To them, Earth is a smorgasbord waiting to happen.
 * SCP-682 finds all Earthly forms of life disgusting and abhorrent. Thus, it tries to kill anything it comes across. The Foundation has been working on figuring out how to kill it first...without much success, since it has a powerful Healing Factor and promptly adapts to anything it's exposed to. Curiously, there's one thing 682 did not attack on sight: SCP-053, an apparently normal human child who any person who is around her for more than about a minute will attempt to murder. Much to the confusion of the Foundation, they got along famously.

Western Animation

 * The Brain Spawn in Futurama wish to wipe out all conscious thought from the universe because "the thoughts of others screech at them like the forced laughs of a thousand art house patrons." Later, their plan is to collect all knowledge in the universe and then destroy it to keep any new knowledge from appearing.
 * The Traash species in Adventures of the Galaxy Rangers, Big Creepy-Crawlies with the usual tropes that apply, were so xenophobic that "in Traash space, there exists no other lifeform but the Traash." When the Rangers' telepath was able to communicate with them, it was discovered that they hadn't even considered the idea that another species would try to make peace instead of attacking.
 * Fanon of Invader Zim often depict the Irkens as this, based on the canonical facts that they wish to take over the galaxy and enslave and/or destroy all other species. In-series, however, only Zim himself seems to have this direct hatred of other species - the other Irkens seem to be merely acting out of a desire for power and a sense of superiority.
 * In most incarnations of Transformers, Decepticons hate anyone who isn't a Decepticon, or anything that is organic in nature.