-->''If you were going to take over the world, would you blow up the White House ''IndependenceDay''-style, or sneak in through the back door?''
-->-- '''Casey''', ''TheFaculty''

One of the [[OlderThanRadio oldest stories]] in SpeculativeFiction: Beings from space come to Earth to conquer.

There are two main forms of this:
# The All-Out Attack. Technologically superior forces aim their weapons of war and [[TripodTerror three legged walkers]] at Earth, which bravely fights back, driving them off through cunning, bravery, or just dumb luck.
# The Infiltration. Aliens are replacing, [[{{Brainwashed}} brainwashing]], or [[ThePuppetmasters controlling]] humans in order to take over from within. Generally, the populace at large [[{{Masquerade}} doesn't even know it's happening]]. May involve TheVirus.
# A combination of the above, with an infiltration paving the way for an all-out attack.

Sometimes, there are good aliens that help us against the invaders; unfortunately, they tend to be much weaker and/or less numerous, since if they were equally or more powerful, the focus would be taken off humanity. Then there's the BenevolentAlienInvasion, where the invaders ''are'' the good aliens.

Often an allegory for some Earth-based conflict, either one that's happened in the past or one that people fear may happen. The Infiltration is especially popular as a metaphor for Communism.

This trope, in its modern form, was created by HGWells's novel ''WarOfTheWorlds''. It was actually a variation on another theme popular at the time, the "[[DayOfTheJackboot invasion story]]", where another country's army, usually France or Germany, would try to conquer Britain. Then [[UnfunnyAneurysmMoment World War One happened.]] Today, similar themes are found in techno-thrillers.

A common TomatoSurprise nowadays is for the invaders to be human.

See also DemonicInvaders, EasilyThwartedAlienInvasion, WeComeInPeaceShootToKill, and for fun, HowToInvadeAnAlienPlanet.

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!!Examples:

[[foldercontrol]]

[[folder:Anime]]
* Probably tied with "Revolution [[RecycledInSPACE IN SPACE]]" for the most popular plot in RealRobot HumongousMecha {{anime}} (SuperRobot shows veer toward MonsterOfTheWeek, which may or may not be a succession of aliens). Usually an All-Out Attack, otherwise why would they be using enormous war machines to fight it? ''SuperDimensionFortressMacross'' is probably the most iconic member of this subgenre.
** ''Macross'' is also a deconstruction of this trope; it shows what would actually happen if a vastly superior alien race (which spends the majority of the series showing restraint, gathering intelligence, and generally being [[HumansAreBastards more reasonable than the Earthlings]] despite being genetically programmed for war) decides that Earth is a threat. [[spoiler: Earth gets slagged, wiping out all of humanity in a single barrage. Only the titular Macross and her crew and refugees survive]]
* The aliens in ''BlueDrop'' are quite special in that [[OneGenderRace they are all female]] and [[WhyAmITicking use their own people as explosives]] during their attacks.
[[/folder]]

[[folder:Film]]
* ''InvasionOfTheBodySnatchers'' is probably the most famous version of The Infiltration as [[RedScare Communist metaphor]].
* ''IndependenceDay'' is a modern example of the All-Out Attack.
* ''MarsAttacks!'' which drew its ship designs from the older HarryhausenMovie ''Earth vs. The Flying Saucers''.
* Subverted in ''ItCameFromOuterSpace'' (1953) where the aliens appear to be carrying out a classic Infiltration-style attack, but are only trying to quietly repair their spacecraft which crashed due to a malfunction.
* ''MonstersVsAliens''
* In ''{{Signs}}'' the aliens use type one except without the technological superiority. And with a crippling [[WeaksauceWeakness vulnerability to water]].
* Several {{Godzilla}} and other {{Kaiju}} movies, sometimes infiltration, sometimes all-out... and then there is ''DestroyAllMonsters'', which is kind of both (the Aliens themselves don't really go all-out, but they capture and mind-control the Kaiju and make ''them'' do all the work).
* ''{{District 9}}'': [[spoiler: Leaves a SequelHook for one that most viewers [[HumansAreBastards will agree that we]] ''[[HumansAreBastards deserve]]''.]]
** Or...''not'', because [[spoiler: humanity does not equal the MNU, thank you very much.]]
* ''Film/TheThing'', although whether it intended to go to Earth in the first place is unclear. It still threatens to take over.
* The film version of ''StarshipTroopers'' inverts this, where humans are invading the alien planet after coming up with a vague, dishonest justification.
* ''{{Slither}}''. Includes a {{homage}} to the above ''Thing'', by naming the town's mayor after Kurt Russell's character, R. J. [=MacReady=].
[[/folder]]

[[folder:Literature]]
* ''{{Animorphs}}'' is an Infiltration, with only five kids armed with alien technology and one helpful alien available to fight the threat.
* [=~Prophet's House~=] is dark {{fantasy}}/{{steampunk}}, and the BigBad is a flesh-eating [[OurAngelsAreDifferent angel]] from space. Yes. That's right.
* ''SecondApocalypse'' is a fantasy series with an invasion by ray-gun wielding aliens in its backstory.
* RobertAHeinlein's ''Literature/ThePuppetMasters'', a good novel made into [[AdaptationDecay several awful movies]]. Of course, one of the major problems with making it into a movie is that near the end ''everyone'' [[AuthorAppeal walks around naked]] all the time, as it is a defense against the aliens. The aliens use, if you haven't guessed, the infiltration method.
* The 1985 LarryNiven/Jerry Pournelle novel ''Footfall'' has a [[MohsScaleOfSciFiHardness hard science]] look at this trope; the elephant-like Fithp ruined their own planet and have come in a [[GenerationShips SleeperShip]] to claim ours.
**Somewhat now has also become a case of AlternateHistory, as it portrays a 1990s with the Soviet Union around.
* The ''PosleenWarSeries'' by JohnRingo. Initially presented as [[BenevolentAlienInvasion an invasion of the benevolent kind]], but not too far into the first book of the series, hints start showing up that the [[CorruptCorporateExecutive Darhel]], the putative leaders of the [[TheFederation Galactic Federation]], have other plans, which aren't terribly beneficial to mankind.
* The ''[=WorldWar=]'' series by HarryTurtledove is a variation: the aliens invade during WorldWarTwo and this forces the warring sides to [[EnemyMine unite against them]]. Also, the aliens are deliberately given contemporary (at time of writing, i.e. 1994) levels of technology plus a little extra to allow them to travel between stars, rather than the usual insanely advanced aliens vs. present day humans. They are also really, really, ''reeeeeealy'' [[TheyChangedItNowItSucks conservative]]. Like, they've been ruled by the same dynasty for [[SciFiWritersHaveNoSenseOfScale tens of thousands of years]] and are surprised that humans have advanced from the medieval era to the present in only a few hundred years, conservative.
**To the point where an American character points out that even the most radical alien is still more conservative then the most devoted southern republican.
** As in, they react to discrimination blow "That's a human", mammalian reproduction, and any government that isn't a full blown monarchy with the same levels of horror.
* ''BattlefieldEarth'' has two: one a thousand years before the book takes place when the evil [[MeaningfulName Psychlo]] took over the planet, and a combination of other races swooping in after humanity retakes Earth. Thought its more of an Alien Incursion or Alien Fracas than an all-out invasion in the second case... (The alien alliance doesn't want Earth per se, just the Psychlo technology left behind there.)
* In Pamela Service's young-adult novel ''Under Alien Stars'', the planet is annexed as a military base by [[AmazingTechnicolorPopulation magenta-skinned]] HumanoidAliens who are fighting a BugWar. Although generally arrogant, callous, quite willing to wipe out whole neighborhoods, and by ''no'' means a BenevolentAlienInvasion, they're by far the [[BlackAndGrayMorality lesser of evils]] compared to their foes. [[spoiler:Not that humanity doesn't have to find that out the hard way before the two races finally team up against the common enemy...]]
* The [[StarWars New Jedi Order]] novels show the extreme end of this - how can there be an alien invasion when the entire galaxy is populated and civilized? With aliens from ''another galaxy'' of course...
* As noted above, ''TheWarOfTheWorlds''.
[[/folder]]

[[folder:Live Action TV]]
* ''[[Series.WarOfTheWorlds War of the Worlds]]'', a television sequel to the 1953 film adaptation of the trope-making novel, showing heavy influence from ''Invasion of the Body Snatchers''
* ''{{V}}'' is about a VillainWithGoodPublicity form of The Infiltration, with [[ANaziByAnyOtherName familiar overtones]].
* Ironically, in ''{{Stargate SG-1}}'', the protagonists spend all their time trying to stop aliens from ''destroying'' Earth (and the Galaxy in general), only to end up with a Goa'uld infiltration of the NID on their hands. Several characters comment on this, citing the low priority this infiltration has compared to more pressing matters, such as the building of the [=McKay=]-Carter Intergalactic Gatebridge.
* ''DoctorWho'', of course, has both. In some cases, it's not necessarily Earth that the aliens want to invade, nor is the species invaded human at all. In many future-based stories, humans are themselves the invaders. We're usually not outright malicious, but we're often quite destructive to native species, paralleling historical imperialism and colonization.
* ''StarTrekVoyager'' shows the Borg launching the invasion of a planet with an armada of cubes ("Dark Frontier"). As one cube was enough for the Federation this change in tactics looked particularly chilling - already hinted at in "Hope and Fear".
-->"The outer colonies were the first to fall - 23 in a matter of hours. Our sentry vessels tossed aside, no defense against the storm. And by the time they had surrounded our star system - hundreds of cubes - we had already surrendered to our own...terror."
** The Borg invasions of Earth in StarTrekTheNextGeneration and StarTrekFirstContact are arguably better examples, with lots of {{Shout Out}}s to TheWarOfTheWorlds (e.g. one of the ships fighting the Borg is named ''Thunder Child'').
* ''FirstWave'' presents a textbook infiltration. The Gua aren't quite sure what to expect from humans, and are trying to find ways to weaken Earth's defences and turn humans into slaves, in preparation for an all-out attack.
* In the backstory to BabylonFive, the Minbari annihilated humanity's entire defense fleet--causing 250,000 casualties--but ultimately ''surrendered'' after reaching Earth orbit and did not invade or bomb the planet. The Minbari were expected to exterminate humanity but this was not foreshadowed by their tactics up to the point of their surrender.
* The 2005 ABC show ''Invasion'' is a bizarre case of the infiltration type in which the main aliens are seen only as glowing orange lights in the water, but the infiltrating "hybrids" have the [[EvilTwin exact appearances]] (sans scars or other non-genetic marks) ''[[GeneticMemory and memories]]'' of the dead humans they [[CloningBlues replace]]. This makes (most of) them ''[[TomatoInTheMirror unaware]]'' that they are are inflitrating aliens. It was cancelled after one season, so the actual goals of the invaders are never made clear.
* The upcoming NBC series ''Day One'' appears to be the latest example.
* The standard source of villains for ''PowerRangers'', used in eight out of seventeen seasons. The others feature DemonicInvaders or something that has TurnedAgainstTheirMasters.

[[/folder]]

[[folder:Video Games]]
* ''{{Halo}}'' follows the "All-Out Attack" example, with The Covenant attacking Earth colonies before finally taking the fight to Earth.
** In fact, in order to ''prevent'' an alien invasion, all ships that are losing a battle are commanded to wipe their memory banks and ''self-destruct'', denying the aliens knowledge of human colony locations, as well as Earth. In the end the Covenent find Earth anyway [[spoiler: though they were looking for something else]], but this particular strategy allowed humanity to fight for years, when otherwise they would have been defeated in weeks or months.
* ''{{Universe At War}}: Earth Assault'' features the first kind of this. In a subversion, humanity fails utterly at repelling the invading Hierarchy and are reduced to bit players, forced to watch as a race of mechanical {{Laser Guided Tykebomb}}s arrive on Earth and the [[AncientAstronauts ancient Atlanteans]] awake, both species intent on bloody revenge against the Hierarchy for crimes committed against them in the past.
* The Scrin from ''CommandAndConquer'' are something of an odd example: although they do [[spoiler:land an "All-Out Attack" in ''[=Command&Conquer=] 3: Tiberium Wars]]'', they did so only because they mistakenly believed that their {{terraform}}ing agent, Tiberium, had completed it task of eliminating the indigenous population.
* The main plot [[SuperMarioBros Mario]] RPG game ''[[MarioAndLuigiSuperstarSaga Mario and Luigi: Partners In Time]]'' has the Mario Bros. team up with their infant selves to thwart the invasion of the alien Shroobs.
** [[ItMakesSenseInContext It, uh...makes sense. In context.]]
* The first ''[[HalfLife Half-Life]]'' is about aliens coming through a portal to Earth, albeit unintentionally (though given the chance, the Nihilanth was more than happy to conquer, or try it anyway). The second is set in a [[{{Dystopia}} dystopia]] where different aliens came through and defeated Earth.
* The second novel based on the ''{{Doom}}'' series, ''Doom: Hell on Earth'', as the name implies, is about the aliens and their genetically-engineered-to-scare-humans creations attacking this planet.
* The aliens in the first ''{{X-COM}}'' game go both ways. One of the alien missions is an Infiltration mission, in which they try to sign a peace treaty with one of your funding countries. If they succeed, that country no longer funds you. On the other end, if you're being successful in dealing with the threat, the aliens will try to scout for your base, and if they find it you can expect a battleship to come shortly, and they aren't coming to negotiate. Hope you've set your base up properly!
** In general, however, from the plot, the X-COM games are all of the first type. The aliens have little interest in peace with humanity: even if every single funding country signs a peace treaty, the aliens inevitably destroy human civilization. The second game is all aliens destroying humanity out of revenge, as is Interceptor. And Apocalypse is an entirely different alien species, also launching an invasion in an effort to wipe out humanity. No one's sure what humanity did to deserve this treatment.
* ''{{Starcraft}}'': the Terrans are facing two invasions: the [[BugWar Zerg]] and [[WellIntentionedExtremist Protoss]] (who incidentally are ''not'' the [[{{Warhammer40000}} Tyranids and Eldar]]. Just [[FlameWar don't go there]].) The Zerg favor infiltration (actually, [[BodyHorror infestation]]) as a way to soften up targets for the Swarm. The Protoss, on the other hand, employ a range of tactics, from "shoot missiles at it" through "shoot [[MacrossMissileMassacre more missiles at it]]" past "[[BeamSpam throw in lasers]] for good measure" and on to "screw it, let's just [[ApocalypseHow sterilize the planet]]". Notable in all of this is the Battle of Tarsonis, where the Zerg, Protoss, and [[LaResistance Terran rebels]] all try the All-Out Attack on the poor planet [[BattleRoyaleWithCheese at the same time]].
* ''CityOfHeroes'' takes place in the aftermath of an extradimensional alien invasion, which was hard-won and remnants of the Rikti forces still infest the world. [[spoiler: And of course, it turns out that the Rikti are mutated humans. BUT, that leads into another possible future invasion by different aliens...]] The Rikti's weakness? ''Magic''. [[SoYeah Yeah.]]
** Of course once they figure this out they quickly hunt down magic-using heroes- as a result, the once-strong Midnight Squad was devastated.
** Also, the Shiva in Bloody Bay. Sort of: while the Shiva are aliens and they are invading, according to the fluff they're the remains of a [[CosmicHorror planet-devouring entity]] that was destroyed in deep space but is now trying to rebuild itself.
* This is more or less the main plot device of the first ''MegamanStarForce'' game, with interesting concepts to the invasion. In the story, alien life forms, called [[EnergyBeing FM-ians]], must fuse with humans who are very lonely thru manipulation in order to attack other people. This is because being energy waves, they have no physical form and thus can't harm physical beings under normal circumstances (They can't even be ''seen'' normally), fusing with humans allows the FM-ian to materialize and thus cause physical harm. They can also disrupt electronic devices or, if there is enough electromagnetic energy being emitted, turn people ''into'' energy waves to attack them.
** KidHero Geo Stelar and a renegade [[EnergyBeing FM-ian]], Omega-Xis, merge into MegaMan to defend the Earth from the FM-ians who, in turn, attempt to draw the pair out in order to defeat them and reclaim an item Omega-Xis has to unleash their DoomsDayDevice on Earth.
* Both ''EccoTheDolphin'' storylines involve aliens. In the first game, the Vortex aliens have been content to just suck up critters from Earth's seas every 500 years, but after Ecco beats them, their Queen follows him back to Earth in the second game, where she and her children proceed to mess everything up. Eventually, she flees back in time to infiltrate Earth from there. WordOfGod has it that [[spoiler:it worked, but not the way she wanted it to; the Vortex lose their identity as a species and give rise to arthropods.]] The third game [[ContinuityReboot involves some completely different]] aliens called the Foe; their time travelling shenanigans actually work to change Earth's future, until Ecco stops them.
* In ''MetalSlug 2'', the Mars People arrive - ''WarOfTheWorlds''-style aliens who attack using flying saucers. When they're driven off, one of them impersonates Morden and tries to use the Rebellion Army as a weapon in ''Metal Slug 3''. Once that's uncovered, the heroes attack their mothership and destroy their leader, Rootmars. Properly chastised, the Mars People become a bit more peaceful, and serve as allies in the sixth game to fight an invasion from BeneathTheEarth that considers them snack food.
* ''{{Iji}}'' starts six months after the ''almost'' all-out attack has succeeded. Then looms the danger of a ''really'' [[EarthShatteringKaboom all-out attack...]]
* ''{{Gungrave}}'' has the "infiltration" method, in the games at least. [[spoiler: A race of parasitic aliens called "Methuselah" came to the planet eons ago and just wanted to infect all living things with the substance that the main characters know as the designer drug called "Seed", which then turns humans/animals into mindless mutants subservient to the alien consciousness. It was these beings that manipulated and corrupted Harry in the original game, provided the technology that created the Necrolization Project, and gave Garino, the BigBad of ''Overdose'', power beyond imagination. Garino was even planning to leave the planet to continue spreading seed]].
* ''TheConduit'' starts off with an invasion by the Drudge, a race of BigCreepyCrawlies. Later, [[spoiler:it is revealed that the invaders are actually human-created clones as part of a GovernmentConspiracy.]]
[[/folder]]

[[folder:Webcomics]]
* ''DresdenCodak''. However, rather than actual aliens, as such, Earth is attacked by [[spoiler: time colonists]]. It still fits the All-Out Attack version of the trope.
* The [[AnotherDimension other dimension]] seen in the ''SluggyFreelance'' chapter [[spoiler:"Aylee"]] is in the middle of one of these, [[spoiler:though few people know that this is the origin of the "ghouls"]].
* Subverted in ''TheInexplicableAdventuresOfBob,'' where the Nemesites have legally owned Earth since before mankind even evolved. Until we develop good enough technology to leave Earth, they don't particularly ''care'' whether or not we know they own the planet. SpacePirates do attack Earth once, not to conquer it but to randomly steal stuff. Nemesite Princess Voluptua comes to stop them, informing them, "Earth is a ''nature preserve,'' you feebs! This isn't even piracy--It's ''poaching!"''
* ''{{ps238}}'' examines and {{lampshades}} this trope (along with PlanetLooters). As pointed out, [[http://nodwick.humor.gamespy.com/ps238/comics/index.php?date=2007-02-26 'Alien invasion' isn't a very applicable term when a portion of the planet's superheroes have alien origins.]]
[[/folder]]

[[folder:WebOriginal]]
* Red Panda had to worry about a magical one in "The Gathering Storm"
[[/folder]]

[[folder:WesternAnimation]]
* The original ''{{Transformers}}'' cartoon and comic focused more on the giant robots, but newer stuff, like the IDW comics and the 2007 movie, take it from the invasion aspect. It's a rare case where the good aliens are equally powerful as the bad aliens.
** Most versions just give a nod to the Infiltration before discarding it, but the IDW series focuses on it. (In fact, ''Transformers: Infiltration'' was the name of their first miniseries.) "Robots in Disguise" takes on a much more sinister tone.
** From a presentation at [=BotCon '95,=] a rejected premise for the ''BeastWars'' cartoon would have the Transformers use their animal and insect forms to infiltrate and influence the course of human history. What if the [[WhoShotJFK shooter at the grassy knoll]] was a Decepticon...?
* The GrandFinale of ''KimPossible'' had the previously once introduced ScaryDogmaticAliens invade Earth, for rather no real reason at all. And all they did was send in {{Humongous Mecha}}s while the 2 aliens just sat and relaxed.
** Rather than an "official" government-backed invasion, it appears that the whole attack was simply a private vendetta against Drakken/Earth on the part of Warmonga.
* Used several times in ''JusticeLeague'' and ''JusticeLeagueUnlimited''.
** The very first story arc, "Secret Origins", sees the Justice League come together for the first time to combat shapeshifting aliens. Initially, the aliens infiltrate society to undermine Earth's defense systems, then they begin their All-Out Attack. The Good Alien role is filled by [[MartianManhunter J'onn J'onnz]], the [[LastOfHisKind sole survivor]] of a Martian civilization that these invaders had destroyed centuries ago.
** The Season Two GrandFinale "Starcrossed" sees the League nearly destroyed by another invasion. The [[spoiler:Thanagarian]] infiltration was far more effective, because they had a [[TheMole Mole]] in the Justice League itself, providing them with the information to neutralize its members. These invaders initially present themselves as the Good Aliens, claiming that they're fortifying Earth to defend it from their enemies; the ''real'' Good Alien turns out to be their Mole, [[spoiler:Hawkgirl,]] who learns of their true intentions for Earth and is [[BecomingTheMask unable to go through with it]].
** The ''JLU'' episode "Dark Heart", in which the League faces Grey Goo from outer space.
** The ''JLU'' GrandFinale "Destroyer" has Darkseid leading the forces of Apokolips on an All-Out Attack on Earth. The League is forced to [[StrangeBedfellows temporarily team up]] with the remaining members of the Legion of Doom in order to fight them off.
* Happens from time to time on ''{{Futurama}}''. To paraphrase a Futurama comic this troper has read:
--> '''Fry:''' So what, Earth gets invaded twice a week. It's how I remember to brush my teeth.
[[/folder]]

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