Alien Invasion - Television Tropes & Idioms

alt title(s): Alien Invaders

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 two main forms of this:

The All-Out Attack. Technologically superior forces aim their weapons of war at Earth, which bravely fights back, driving them off through cunning, bravery, or just dumb luck.
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.

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 HG 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 would try to conquer Britain. Then World War One happened.

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

Examples

Anime

Probably tied with "Revolution IN SPACE" for the most popular plot in Real Robot Humongous Mecha anime (Super Robot shows veer toward Monster Of The Week, 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? Super Dimension Fortress Macross is probably the most iconic member of this subgenre.
The aliens in Blue Drop are quite special in that they are all female and use their own people as explosives during their attacks.

Film

Invasion Of The Body Snatchers is probably the most famous version of The Infiltration as Communist metaphor.
Independence Day is a modern example of the All-Out Attack.
Mars Attacks!

Literature

Animorphs is another Infiltration, with only five kids armed with alien technology and one helpful alien available to fight the threat.
Second Apocalypse is a fantasy series with an invasion by ray-gun wielding aliens in its backstory.
The 1985 Larry Niven/Jerry Pournelle novel Footfall has a hard science look at this trope; the elephant-like Fithp ruined their own planet and have come in a Sleeper Ship to claim ours.
The Puppet Masters, a good novel made into several awful 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 Posleen War Series by John Ringo.
The World War series by Harry Turtledove 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.
Battlefield Earth has two: one a thousand years before the book takes place when the evil 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...

Live Action TV

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 Villain With Good Publicity form of The Infiltration.
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.
Doctor Who, 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.
Star Trek Voyager 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 Star Trek The Next Generation and Star Trek First Contact are arguably better examples, with lots of Shout Outs to The War Of The Worlds (e.g. one of the ships fighting the Borg is named Thunder Child).

Video Games

Halo follows the "All-Out Attack" example, with The Covenant attacking Earth colonies before finally taking the fight to Earth.
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 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.
The Scrin from Command And Conquer are something of an odd example: although they do land an "All-Out Attack" in Command&Conquer 3: Tiberium Wars, they did so only because they mistakenly believed that their terraforming agent, Tiberium, had completed it task of eliminating the indigenous population.
The main plot Mario RPG game Mario and Luigi: Partners In Time has the Mario Bros. team up with their infant selves to thwart the invasion of the alien Shroobs.
The first Half-Life is about aliens coming through a portal to Earth, albeit unintentionally. The second is set in a 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 basically 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. Must be karmic justice from a previous racial existence...
Starcraft: the Terrans are facing two invasions: the Zerg and Protoss (who incidentally are not the [[Warhammer40000 Tyrannids and Tau]]. Just don't go there.) The Zerg favor infiltration (actually, 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 main plot of the Gears Of War series takes place right in the middle of one of these, and follow's humanity's attempts to win the war against the aliens.

Webcomics

Dresden Codak. However, rather than actual aliens, as such, Earth is attacked by time colonists. It still fits the All-Out Attack version of the trope.
The other dimension seen in the Sluggy Freelance chapter "Aylee" is in the middle of one of these, though few people know that this is the origin of the "ghouls".
Subverted in The Inexplicable Adventures Of Bob, 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!"

Western Animation

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.
The Grand Finale of Kim Possible had the previously once introduced Scary Dogmatic Aliens invade Earth, for rather no real reason at all. And all they did was send in HumongousMechas while the 2 aliens just sat and relaxed.
Used several times in Justice League and Justice League Unlimited.
- 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 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 Thanagarian 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, Hawkgirl, who learns of their true intentions for Earth and is unable to go through with it.
- 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.
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.