Alien Invasion

"If you were going to take over the world, would you blow up the White House Independence Day-style, or sneak in through the back door?"

- Casey, The Faculty

One of the oldest stories in Speculative Fiction: Beings from space come to Earth to conquer. There are three main forms of this:
 * 1) The All-Out Attack. Technologically superior forces aim their weapons of war and three legged walkers at Earth, which bravely fights back, driving them off through cunning, bravery, or just dumb luck... most of the time.
 * 2) The Infiltration. Aliens are replacing, brainwashing, or controlling humans in order to take over from within. Generally, the populace at large doesn't even know it's happening. May involve The Virus.
 * 3) 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 Benevolent Alien Invasion, 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 H. G. Wells's novel War of the Worlds. It was actually a variation on another theme popular at the time, the "invasion story", where another country's army, usually France or Germany (depending on who relations were worse with at the time), would try to conquer Britain. Then World War I happened. Today, similar themes are found in techno-thrillers, and crop up in works like Red Dawn and The Tomorrow Series.

A common Tomato Surprise nowadays is for the invaders to be human.

See also Demonic Invaders, Easily-Thwarted Alien Invasion, We Come in Peace, Shoot to Kill and Aliens Are Bastards; and for fun, How to Invade An Alien Planet and Why You Should Destroy the Planet Earth.

Anime and Manga

 * Axis Powers Hetalia: Paint It White The plot involves an alien invasion of Earth
 * Eureka Seven: TV series the Scab Coral in literally drove humanity out of Earth for 10,000 years (unintentional) when it arrived. It grew and formed an outer layer around earth, fooling humanity into thinking it is another planet when they settled in. The Scab Coral later spawned human Coralians to live among humans to study and communicate with them. The Big Bad uses this planet takeover history to justify his actions against the Scab Coral which was just trying to communicate with humanity.
 * GantzThe various aliens that appear in the manga series. It is not known when, how and why the aliens appear on Earth. The aliens use a variety of technology and abilities to infiltrate the earth where the Gantz team hunts them.
 * Parasyte: Infiltration by aliens called parasites which are worm-like creatures that enter human bodies and transform their brain, killing them. They then go about disguised as their host secretly eating other humans.
 * Pokémon: Destiny Deoxys: Rayquaza thinking this is happening is what kicks off its conflict with Deoxys.
 * Project Blue Earth SOS: Is essentially a homage to 1950s/1960s-style science fiction shows, with two kids acting as the main protagonists and finding out about the incoming invasion and doing everything they can to stop it.
 * Super Dimension Fortress 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 more reasonable than the Earthlings despite being genetically programmed for war) decides that Earth is a threat.
 * UFO Robo Grendizer: An early Anime example and the third series of the Mazinger Z trilogy. The Vega homeworld had become unstable due to the radioactive materials within it and the King decided to expand his militaristic empire to find a suitable planet to settle on. The main character lived in Fleed, one of the first planets the Vegan army attacked and was forced to run away. He landed on Earth and settled peacefully in there. Then two years later the Vegan army struck his new homeworld.

Comic Books

 * Paperinik New Adventures:This Italian Disney series features the Evronians, a hostile species of H.R. Giger-inspired aliens, planning the invasion of the Earth. The main thing standing in their way? Donald Duck in a superhero suit.

Film

 * The Avengers: Loki brings the aliens known as the Chitauri to Earth to act as "his" army.
 * Battle: Los Angeles : The alien invaders land off of the coast near California and immediately launch a military offensive. The movie is notable for using reasonably accurate in presentation of the military and the aliens operating as a military force.
 * Ben 10 live action movies.
 * In the first Race Against Time, it was time traveling creatures of which the leader needed to activate a specific device to make the invasion happen.
 * In the second movie, Alien Swarm, it was alien nano-chips.
 * Independence Day: The aliens send several massive ships over major cities. They then use powerful Wave Motion Gun to destroy the cities. They later launch assault with fighter craft to attack the human military attempting to fight back.
 * Invasion of the Body Snatchers: Is one of the most famous versions of The Infiltration as Communist metaphor. Humans are kidnapped and replaced with alien lookalikes..
 * It Came from Outer Space (1953) : A subversion 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.
 * Knowing: Aliens have been secretly visiting Earth to prepare themselves in to extract the chosen life forms from Earth in light of the Earth's destruction by the Sun. They disguise themselves as humans to do so (though they never speak human language).
 * Little Shop of Horrors (1986):
 * Mars Attacks! : A parody which drew inspiration from the trading cards of the same name. Like the trading cards the movie portrays a military invasion by the Martians.
 * Monsters vs. Aliens: An animated film that portrays and alien invasion by Gallaxhar seeking out the last remaining sources of quantonium. The invasion starts off with a giant robot sent to reclaim the remaining quantonium.
 * Signs:The aliens attempt a military invasion but are stopped by their crippling vulnerability to water.
 * They Live!: Space aliens use infiltration via technology and manipulation of the human mind to take over or place themselves in places of power.
 * The Thing: A strange alien found in the artic with the ability to mimic any living creature, whether it intended to go to Earth in the first place is unclear. It still threatens to take over.
 * Skyline: A military invasion aided by a blue light that mesmerizes humans allowing the aliens to suck them up into their ships. They also use large walking life forms and squid like entities on the ground.
 * Slither: The alien invader uses infiltration by taking over human beings. The movie Includes a Homage to the movie ‘‘Thing’’, by naming the town's mayor after Kurt Russell's character, R. J. MacReady.
 * Starship Troopers : Inverted. After a series of attacks on human colonies and a direct attack Buenos Aires Earth humanity declares war and invades the bug worlds.
 * Transformers: Dark of the Moon :Everyone's favorite evil robots the Decepticons, decide to give the All Out Attack a shot. The Autobots are of course the good aliens helping out humanity here.
 * The 1953 and 2005 film adaptations of the very first modern story of aliens initiating a military invasion of the earth.

Literature

 * Animorphs: The aliens use infiltration, with only five kids armed with alien technology and one helpful alien available to fight the threat.
 * Invasion by Mikhail Akhmanov : The novel details the arrival of a giant Human Alien starship from another galactic arm in order to conquer and enslave humans, who only have a tiny fleet of ships with no shields, Antimatter, or FTL capability. After the humans barely survive (thanks to ), the following novels chronicle humanity using the leftover technology to build an interstellar empire (well, more of a federation but with Gunboat Diplomacy).
 * Battlefield Earth: Has two of them, one a thousand years before the book starts when the evil Psychlos took over the planet, and then a coalition of other races swoop in after humanity retakes Earth. Thought it is more of an Alien Incursion or Alien Fracas than an all-out invasion in the second case, as the alliance is more interested in leftover Psychlo plunder and selling the humans into slavery than the planet itself.
 * Bolo book series: Several of the all-out invasion variety occur in the stories, one ultimately resulting in a near mutual genocide of humanity and their alien opponents.
 * Doom: Novel series, Doom: Hell on Earth. As the name implies, is about the aliens and their genetically-engineered-to-scare-humans creations attacking planet earth.
 * Footfall :The 1985 Larry Niven/Jerry Pournelle novel has a hard science look at this trope; the elephant-like Fithp ruined their own planet and have come in a SleeperShip to claim ours. A military type invasion is launched against the earth.
 * The Greks Bring Gifts:Has a unique form of infiltration;.
 * Posleen War Series by John Ringo: Initially presented as an invasion of the benevolent kind, but not too far into the first book of the series, hints start showing up that the Darhel, the putative leaders of the Galactic Federation, have other plans, which aren't terribly beneficial to mankind. Earth is also invaded by the rapacious Posleen who conquer and devour their way across the galaxy. This invasion folds in the plans of the Darhel.
 * The Puppet Masters by Robert A. Heinlein: A novel made into several movies. Of course, one of the major problems with making it into a movie is that near the end everyone 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 True Meaning of Smekday, a combination of types 1 and 2 occurs. The Boov aliens are speaking to Gratuity's mother through a mole in her neck. They then abduct her to teach them English. Then they invade and force all the humans onto reservations in Florida.
 * Under Alien Stars a young-adult novel by Pamela Service: The planet is annexed as a military base by magenta-skinned Humanoid Aliens who are fighting a Bug War. Although generally arrogant, callous, quite willing to wipe out whole neighborhoods, and by no means a Benevolent Alien Invasion, they're by far the lesser of evils compared to their foes.
 * The War of the Worlds: The Trope Maker and one of the earliest sci-fi novels. The alien tripods attack earth in a military invasion.
 * When The Tripods Came: The tripods utilize infiltration by mind control. A tv show is used to assert temporary control with caps used to assert permanent control. The populace is manipulated with the mind control until “The Capped” are in control in a majority of places.
 * The Wild Boy: The Lindauzi, who killed off millions with a virus, then showed up with a cure to draw what was left of humanity to them. After getting rid of humanity's companion creatures, they began keeping humans like dogs and breeding them to be replacement bond creatures for themselves.
 * The Worldwar series by Harry Turtledove: This is a variation: the aliens invade during World War Two and this forces the warring sides to 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, conservative. Like, they've been ruled by the same dynasty for 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.

Live-Action TV

 * Dark Skies: A series on FOX was pretty much a textbook type 2, infiltrating with parasites and (at the end) electronic implants. The point of the series was that many of the events of the 20th century were secretly part of the infiltration, such as the Kennedy assassination.
 * Doctor Who: Uses all three variants of invasion. The series also inverts this tropes 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.
 * Falling Skies: A TNT Show takes place about six months after an alien invasion devastates most major cities and wipes out a large percentage of the population. The show describes a ragtag group of survivors trying to find food and shelter to get by, while avoiding murderous aliens and roving bands of outlaws and trying to survive and fight back. While the series avoids showing the actual invasion (the background is told by a child and a series of drawings in the pilot), it involves huge circular Ominous Floating Spaceships appearing over major cities. They hang there for a while, but the world leaders decide not to strike first, hoping the aliens are friendly. They aren't. The ships emit powerful EMP waves, shutting down power grids and defense systems before proceeding to obliterate most major cities. They land ground troops with infantry and mechs (the survivors note that the mechs are bipedal, despite the aliens having 6 legs) that proceed to wipe out much of the adult population, while capturing children and putting Mind Control harnesses on them (presumably, to make them slaves). The large ships depart, while the invading forces begin constructing large structures in places of destroyed cities. The human survivors are forced to retreat and use only basic weaponry (rifles, machineguns, and C4), as any heavy munitions tend to piss off the aliens, and their bombers simply level the entire area.
 * First Wave: Presents an infiltration approach. The Gua aren't quite sure what to expect from humans and are trying to find ways to weaken Earth's defenses. Their goal is turn humans into slaves in preparation for an all-out attack.
 * One episode revealed that the government was secretly preparing for an alien attack, building a series of satellites armed with nukes which were set to face away from Earth.
 * Invasion : A 2005 ABC show 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 exact appearances (sans scars or other non-genetic marks) and memories of the dead humans they replace. This makes (most of) them unaware that they are are infiltrating aliens. It was cancelled after one season, so the actual goals of the invaders are never made clear.
 * The Outer Limits both versions did several infiltration invasion plots.
 * One episode dealt with a group of people locked in bunkers completely unaware of what was happening in the world. The last thing they heard was that a fleet of alien ships was heading for Earth with suspicions that they were here to colonize. The episode ends with only one of these people alive, as he is preparing to be rescued, unaware that the invasion has already succeeded.
 * Star Trek: The Next Generation and Star Trek: First Contact : The Borg invasions of Earth Shout Outs to The War of the Worlds (e.g. one of the ships fighting the Borg is named Thunder Child).
 * 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.
 * Several episodes show us alternate universes where the aliens do succeed in taking Earth.
 * The BBC series based on The Tripods book trilogy. The aliens utilize mind control for their infiltration and subsequent invasion.
 * V: is about a Villain with Good Publicity form of The Infiltration, with familiar overtones.
 * War of the Worlds: A television sequel to the 1953 film adaptation of the War of the Worlds novel, showing heavy influence from Invasion of the Body Snatchers.
 * "The Invaders" (1967) with Roy Thinnes as a man who accidentally sees a flying saucer land and can't convince people that we've been invaded. They use the infiltration method, altering their bodies to look like humans. Because of the year there was a lot of heavy handed storylines involving race and the youth culture.

Music

 * Running Wild's "Iron Heads" from the Death Metal split-album and Masquerade is about version 1.
 * "Weird Al" Yankovic wrote Slime Creatures from Outer Space, which is a version 1.
 * Invader by Judas Priest. At this point, if that's what it was at all, it didn't get far yet, but the narrator anticipates one.

Tabletop Games

 * Monsterpocalypse has two extra-terrestrial factions, both launching All-Out Attacks at the same time. The Martian Menace uses Tripods and Flying Saucers whereas the Planet Eaters use Kaiju and a Horde of Alien Locusts.
 * The point of the Alien monsters in the Yu-Gi-Oh! card game.

Video Games

 * Achron: The game starts immediately after the greatest space fleet humanity has ever assembled has been all but completely destroyed by the alien invaders. They did this despite actually being outnumbered and outgunned by the human forces. It turns out that Time Travel actually gives you a hell of an advantage.
 * City of Heroes: Takes place in the aftermath of an extra dimensional alien invasion, which was hard-won and remnants of the Rikti forces still infest the world.  The Rikti's weakness? Magic. The Shiva in Bloody Bay are the remains of a planet-devouring entity that was destroyed in deep space but is now trying to rebuild itself by conquering Earth for its resources.
 * Command & Conquer 3: Tiberium Wars marks the debut of the Scrin, whose arrival throws the ongoing GDI-Brotherhood of Nod conflict into chaos and force the two sides to work together. But it's more complicated than an "All-Out Attack" example: the Scrin are trying to harvest the Tiberium they seeded the Earth with, and expected for the xenoforming crystals to have wiped out the planet's indigenous population, but Kane tricked them into arriving early. The Scrin expedition is actually a mining operation, not a formal army, and once they're driven back by the humans they vow to return with a proper invasion force... a Sequel Hook utterly ignored by Command & Conquer 4.
 * The Conduit : The game subverts this trope. It starts off with an invasion by the Drudge, a race of Big Creepy-Crawlies. Later,
 * Destroy All Humans! subverts this trope: YOU are the invading alien. Crypto utilizes both infiltration and outright military force.
 * Doctor Who’’: In the first chapter ‘’The Adventure Games, City of the Daleks: The Doctor and Amy arrive in London to discover it has been conquered by Daleks and have to travel back in time to stop the invasion.
 * Duke Nukem 3D with an all out assault and in Duke Nukem Forever the aliens come back. And they come back angry.
 * Ecco the Dolphin: Both game 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. Word of God has it that The third game involves some completely different aliens called the Foe; their time travelling shenanigans actually work to change Earth's future, until Ecco stops them.
 * Gungrave: The "infiltration" method is used in the games..
 * 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 where different aliens came through and defeated Earth.
 * Halo: Follows the "All-Out Attack" example, with The Covenant attacking Earth colonies before finally taking the fight to Earth. 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 Covenant find Earth anyway, but this particular strategy allowed humanity to fight for years, when otherwise they would have been defeated in weeks or months.
 * Iji Starts six months after the almost all-out attack has succeeded. Then looms the danger of a really all-out attack.
 * Mario and Luigi: Partners In Time The main plot has the Mario Bros. team up with their infant selves to thwart the invasion of the alien Shroobs.
 * Mass Effect: The Reapers, the Man Behind the Man in Mass Effect 1 and Mass Effect 2 in the threats to the galaxy at large, directly assault earth in a massed invasion in the opening of Mass Effect 3.
 * Mega Man Star Force : In the game, with interesting takes on the infiltration variation. In the story, alien life forms, called 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.
 * Kid Hero Geo Stelar and a renegade FM-ian, Omega-Xis, merge into Mega Man 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 Doomsday Device on Earth.
 * Metal Slug 2: The Mars People arrive War of the Worlds 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 Beneath the Earth that considers them snack food.
 * StarCraft: the Terrans are facing two invasions: the Zerg and Protoss. The Zerg favor infiltration (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 more missiles at it" past "throw in lasers for good measure" and on to "screw it, let's just sterilize the planet". Notable in all of this is the Battle of Tarsonis, where the Zerg, Protoss, and Terran rebels all try the All-Out Attack on the poor planet at the same time. The Protoss were not as much invading the Terrans as they were containing the Zerg who would then perform an all out invasion on the Protoss.
 * Universe At War: Earth Assault: An all out attack, 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 Tykebombs arrive on Earth and the ancient Atlanteans awake, both species intent on bloody revenge against the Hierarchy for crimes committed against them in the past.
 * X-COM: The various aliens in the game series are generally set on utterly destroying humanity. The infiltration method they attempt in the first game was merely a tactic toward the goal of total destruction.

Web Comics

 * The Inexplicable Adventures of Bob: Subverted, 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. Space Pirates 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!"
 * Titanzer: They not only invaded but punched the head off the statue of liberty.

Western Animation
"Fry: So what, Earth gets invaded twice a week. It's how I remember to brush my teeth."
 * Ben 10 Alien Force first season finale climaxed with the Highbreeds beginning their planned invasion of Earth. Oddly enough, they so much as fought off as
 * Futurama: Happens from time to time. To paraphrase a Futurama comic:


 * The professor actually looks forward to them. According to him, the last invaders made all the smartest humans "pair off and mate continuously... oh yes."
 * Invader Zim: the show is about an alien using the infiltration method. He's really bad at it. However the Irkens are really good at what they're doing, no matter how bad Zim is. We've seen them successfully take over several planets and they seem to run a galactic monopoly that can't be challenged by any other being in the Universe (to our knowledge).
 * Jimmy Neutron: Three separate times. The first time the Yokians arrived to Earth they stole every adult in Retroville (except Miss Fowl) only to take them to their planet. The second time they arrived on Earth they successfully earned everyone's trust and tried to kill off all the adults once more. Then there is Grandma Tater's, who's apparently one of many similar aliens that take over planets using hypnosis.
 * DC Animated Universe:
 * Darkseid invades the Earth in the Superman: The Animated Series episode "Apokolips... Now!" The good Alien role is filled by his heroic son Orion, who threatens a counter-invasion from New Genesis, forcing Darkseid to retreat.
 * He does so again in "Legacy", using a brainwashed Superman as a weapon.
 * Justice League: The very first story arc, "Secret Origins", sees the Justice League come together for the first time to combat the White Martians, 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 J'onn J'onnz, the sole survivor of a Martian civilization that these invaders had destroyed centuries ago.
 * The Season Two Grand Finale "Starcrossed" sees the League nearly destroyed by another invasion. The infiltration was far more effective, because they had a 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,  who learns of their true intentions for Earth and is unable to go through with it.
 * The Justice League Unlimited episode "Dark Heart", in which the League faces Grey Goo from outer space.
 * The JLU Grand Finale "Destroyer" has Darkseid leading the forces of Apokolips on an All-Out Attack on Earth. The League is forced to temporarily team up with the remaining members of the Legion of Doom in order to fight them off. Utimately, Lex Luthor saves the day, offering Darkseid the Anti-Life equation he had been searching for his entire life - but when Darkseid touches it, both villains are apparently vaporized.
 * Kim Possible: The Grand Finale had the previously once introduced Scary Dogmatic Aliens invade Earth for rather no real reason at all. All they did was send in Humongous Mechas while the two 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.
 * Little Audrey cartoon "Dizzy Dishes": In Audrey's dream there are alien invaders attacking with a disintegrator.
 * The 2003 Teenage Mutant Ninja Turtles series had a 3-part episode, "Space Invaders", centered on the Triceratons invading Earth in their frantic search for the Fugitoid.
 * Teen Titans: In the episode "Troq". Gets inverted The Titans launch a preemptive attack against the robotic, alien menace on their own, alien planet. Our heroes succeed in killing the entire planets’ population off! Then they tell off the guy who brought them there for being a racist douche.
 * The Simpsons did this many times with Kang and Kodos. The best was prior to the 1996 presidential election where they kidnap Clinton and Dole and take their places (infiltration method). In the end they are discovered but still win because they have both major candidates and "It's a two party system. You have to vote for one of us." Someone suggests voting for a third party candidate: Alien: Sure, THROW your vote away!" In the end they are our rulers.
 * The 2011 ThunderCats episode "Journey to the Tower of Omens" has a massive invading army comprised of multiple Slave Races housed in a giant Battlestar. They are depicted invading an unidentified planet to serve as Planet Looters, combing over land and sea in seach of a single, extremely valuable Amulet of Concentrated Awesome called the War Stone, by order of their commander.

Real Life

 * An Introduction to Planetary Defense, by Travis S. Taylor, Bob Boan, R.C. Anding and T. Conley Powell, is a nonfiction look at the possibilities of an alien invasion of Earth. They make various suggestions, discuss issues regarding first contact, and possible ways to help deal with an invasion.
 * When Aliens Attack is a production on the National Geographic Channel that takes a look at the trope, using input from scientists, military personnel, and various other professionals.