The easiest way to write an Alien Invasion is to make the invaders nigh unstoppable by giving them technology and weapons we can't even comprehend, defend against or overpower. If they were just like a human army, it might as well be a war story; there must be something about the aliens that makes them distinct from any other army. But the heroes and humanity can't just be dispassionately crushed under a cosmic steamroller, because a Cosmic Horror Story would be a box office dud due to the bleak narrative and Downer Ending. Besides, who would want to read that kind of story?
So what authors do is craft an Easily Thwarted Alien Invasion. To compensate for the aliens' seemingly invincible power they build in a glaring and common weakness that the heroes and humanity can use to beat back this alien menace once it's identified.
This doesn't just apply to armies, but can be done for individual aliens and non-sentient alien monsters. Maybe their skin is tough enough to stop bullets, or they're telepathic, or they have mind-control powers, or they have some sort of martial society and cannot comprehend "mercy", "surrender" or "peaceful coexistence". Whatever their advantage or power, it's always balanced by a vulnerability to an over the counter product.
And sometimes, that Achilles' Heel is so serious that the humans don't even have to figure it out; the planet takes care of them without any help from us at all. The flora and fauna will make them all die naturally without human intervention, be it from the common cold or water or daffodils. Sometimes, the aliens don't even know it's a weakness (or can't conceive of it as one) until they begin dropping like flies from it.
This can extend to making the cleanup after the invasion a snap. By handing humanity victory on a silver platter and having an epilogue where the characters happily explain how easy it was to destroy the aliens and return to life as if nothing had happened. Grimmer portrayals will give humanity one chance to exploit the weakness after they devastate the planet, making the victory a Bittersweet Ending.
This trope can sometimes be justified if the "alien invasion" is actually only carried out by a few individuals, especially if they're completely ignorant about Earth, as is the case in many old Science Fiction movies.
- Subverted in Super Dimension Fortress Macross, when just as the main cast finally deduce the aliens' weakness, the Zentradi wipe out Earth anyway.
- Sgt. Frog:
- While mostly the characters are too lazy to pull off an invasion attempt, when they do you can bet it'll fall apart pretty easily.
- One season finale involved a massive, monolithic alien the size of a city that was defeated when it slipped on a banana peel, which sent it hurtling into the sun.
- Urusei Yatsura has a few of these. The series started with the Oni deciding to invade Earth, but then deciding to call it off if a randomly chosen earthling could beat Princess Lum in a game of Tag. Naturally, Ataru manages to win (even if he does end up unintentionally proposing to their princess in the process). Other invaders include a bunch in a spaceship that got mistaken for a rugby ball (the battering it took, plus the way Ataru chased the princess in charge after being miniaturised into it scared them off). Also there was the time a shapechanging alien came to Earth and tried brainwashing the locals... unfortunately he disguised himself as Ataru... and his brainwashing technique involved pressing his lips against his victim's.
- Heroman. The Skrugg are only around for about a whole of 8 or so episodes, and while they totally destroy the US Government, Joey and Heroman still manage to kick their butts to hell and back in a timespan of two or so days. Also subverted near the end of the series, where they're not just back, but even stronger.
- Dragon Ball Z:
- When Freeza and his father stop by with a ship filled with soldiers, they are killed quickly by Trunks with no casualties.
- When Frieza returns in Resurrection 'F' he fares a little better, managing to destroy a city and in Dragon Ball Super he kills Piccolo. The invasion is still easily handle with only a few of the Earth's strongest fighters, and Goku and Vegeta were more than enough to take care of Frieza even with his power-up.
- Played with in One-Punch Man. The alien invaders are said to be among the strongest in the galaxy, led by Galactic Conqueror Lord Boros because of The Prophecy stating that he'll find an opponent strong enough to satiate his boredom. He finds that in Saitama, who in the midst of their fight destroys the spaceship they and the alien invaders were in. The other top heroes manage to take out one of the alien generals as well. However, a city does get completely levelled in fighting off the invasion, which one of heroes (who's a Slave to PR, and wasn't even there to help because he was busy doing a promotional interview for his upcoming film) chews all the others out on.
- In Gate, men with medieval armor, accompanied by a variety of monsters, all serving an empire from another world, invade Tokyo and try to claim the area as their own. Their main weapons consist of swords and bows and arrows, which are not a match for the modern weapons of the Japanese military. Inverted, since the majority of the invaders were also human, albeit not from Earth.
- One old Bloom County arc features an invasion by creatures called Zygorthians, who blast cities with death rays, enslave women, serve the entire Mormon Tabernacle Choir as hors d'oeuvres, and lock Pat Robertson in a room full of AIDS activists. How are they thwarted? By serving them with a Congressional subpoena.
- Toyed with in Blue Beetle, with the Reach, a race of invaders who know they're easily thwarted in a stand up fight (at least when Green Lanterns and Kryptonians are involved)... so they come on like friendlies and engage some very long-term planning that will give them the planet in a couple of hundred years. When their plans are exposed, Earth's governments (DC Earth being no stranger to alien invasions) immediately demand the Reach's surrender. They get it.
- In JLA: Year One the ruler of a planet of elemental giants sends seven of his greatest warriors to a certain backwater planet for a grand battle to decide the new leader. The battle never happens; all seven are defeated by local superheroes within minutes of their arrival. The warlord decides that Earthlings are too dangerous to live and orders a full-scale invasion. And is, of course, beaten.
- In Green Lantern, when Kyle Rayner gains the cosmic powers of Ion, when a fleet of crystaline aliens shows up to invade, the JLA scrambles to respond. Kyle keeps his feet on the table and informs them he 'handled it'. They didn't even last long enough to give us an ultimatum...
- The Invasion! event from DC Comics is a Crisis Crossover event wherein all the antagonistic alien races of the universe decide to pool their resources to invade Earth because Earthlings are getting too big for their britches. How does this invasion end? Just like the Skrull-based Secret Invasion event, the aliens make landfall for five minutes, start talking like they've won, then summarily get kicked back into space to get curbstomped by the various Earthling superheroes. Oh, and one of the races of this coalition, the Dominators, drops a gene-bomb on Earth, causing a Mass Super-Empowering Event for humanity. Nice job uplifting thousands of those humans you came to destroy, alien dipsticks!
- Played with with the Vespa in Irredeemable. At first, it seems that one lone Badass Normal hero snuck into their ship and forced them all to leave Earth just when things looked grimmest. Turns out he struck a Deal with the Devil with them instead.
- Another easily-thwarted alien invasion out of the pages of DC Comics comes from the Magog solo series written by Keith Giffen. Late in the series, an alien with The Assimilator-based abilities dubbed Killer App makes landfall. It assimilates all the technology and life from a small town before uploading itself into tech-based hero the SHIELD where it ends up trapped. Then another alien invader, the Mass, starts heading to Earth. Magog travels into space and scares it off, ending that particular alien invasion before it even begins.
- Of all the aliens in the Marvel Universe, the easily thwarted award has to go to the shapeshifting Skrulls. Their first appearance in Fantastic Four #2 sees Reed Richards tricking them into thinking Earth is too dangerous to invade by showing them drawings of monsters.
- In Kieron Gillen's series X-Men: SWORD, the Drenx demand heavy tribute or face invasion. Beast and Abigail Brand bring a mop to the negotiations, gesture in the direction of Thor's good buddy Beta Ray Bill, one of at least a dozen supers in that power class on world at the time, and indicate SWORD's job isn't just to protect the Earth from alien invasions, but to protect alien invasions from the Earth, so they don't have to use the mop to clean things up. The Drenx take the point and beat a hasty retreat from Earth space.
- Played for Laughs in another storyline in which an alien invasion is thwarted by three X-men. The ground assault is derailed since the soldiers are introduced to the wonders of beer and gambling, and the entire fleet is wiped out by a drunken Havok.
- Subverted in Paperinik New Adventures: at first it seems that the might of the galaxy-spanning Evronian Empire is being held back by Paperinik, AKA Donald Duck's Super Hero alter ego (they were risking their first defeat ever, according to the commander of the invasion force), but as the story progresses it's made clear that, due a combination of rebellions among their subject species and one of their previous successes unleashing the sci-fi equivalent of a Physical Goddess against them, they're overstretched to the point the Humans can beat back a direct assault, and Paperinik is doing nothing more than thwarting their attempts at soften up our defences.
- The Ultimates: The Chitauri organized a deep and complex infiltration that would allow them to destroy humanity's free will and turn everyone into mindless drones, as their race had been doing on many other planets. But then, the main Chitauri fleet shows up and orders those on Earth to pack and leave, because of intergalactic reasons. Without time to purify the planet, they leave a bomb for a Earth-Shattering Kaboom, but Thor managed to teleport it to another dimension.
- At the end of the second incarnation the Communication, the Puella Magi, an intergalactic class spaceship, is built with the power to travel the multiverse.
- This trope gets downplayed by the Chitauri invasion in the MCU fanfic series, There Was Once an Avenger from Krypton. While the Avengers did win, it's acknowledged that they got lucky and were close to failing, not to mention the invasion caused a lot of collateral damage and death. The severity of the invasion, coupled with how it caused other hidden heroes to reveal themselves, is a major reason for why the Avengers are working to expand their ranks earlier than canon.
- In the classic horror movie The Day of the Triffids, the eponymous carnivorous plants are killed off by sea water. Contrast with the original novel in which the invasion isn't thwarted, the survivors instead having to adapt to the Cosy Catastrophe.
- Independence Day. A fleet of scientifically advanced homicidal aliens has its force field defense taken out by a computer virus uploaded from a Mac, allowing the humans to blow up their base ships by attacking the ship's primary weapons as they fire. While they do a ton of damage to Earth's cities before this happens, there is a huge disparity between what their technology indicates they should be capable of, and what they actually manage to accomplish.
- The Mind Controlling viral aliens in The Invasion had, in a matter of three or four days, infiltrated most of the Washington population and (going by the Shuttle debris pattern) must have had agents all over the US and the world, painting a scenario where humanity will inevitably fall no matter what it does. But, the heroes discover that some people who had a rare kind of bacterial infection in the brain were resistant to their virus, and in a matter of hours after delivering one such person had created a Magic Antidote which they delivered to everyone infected via dispersing it in the air. The film concludes with a near Reset Button, one character points out that we might never find and cure all infected individuals, but notes that we are in control of the planet because there are still wars.
- A very humorous example: Mars Attacks!! involves a full-blown alien invasion. The enemies are going to exterminate all of humanity for shits and giggles, they have ray guns, Humongous Mecha, technology that allows them to shrug off nuclear weapon attacks... and they are fatally vulnerable to yodeling.
- In Signs it turns out plain old water is pretty much a deadly acid to the aliens. Yes, they clearly felt like a challenge invading Earth. Although their weakness is not really that necessary given that this is a race that can be stopped by a pantry door that probably wouldn't have kept a determined human in. Amazingly, they conduct their invasion unarmed save for a natural poison gas gland on their wrist that exhales a small amount of localized gas. And worse still the aliens also forgo armor or clothing of any kind. They're also weaker, slower and clumsier than the average human with apparently no concept of hand-to-hand combat, to the point where one of the main characters beats an alien to death with a baseball bat and it doesn't even try to put up a defence. It's like if humanity invaded an acid-covered world, with frequent acid rain and despite the hostile environment decided to engage the natives naked. Some argue the movie drops hints that they aren't really aliens, but demons who cannot enter a room with a preacher, and can be harmed by holy water... which would simply make it an easily thwarted demon invasion as they're still naked and unarmed. In either case, the entire global invasion incident was resolved off screen in a few days with no noted lasting damage on humanitys part.
- Evolution had the aliens thwarted by Head and Shoulders Shampoo's Selenium Sulfide, which they hadn't even tested on an alien organism beforehand.
- Prince of Space. The chickenmen of Krankor are able to travel half a million miles to invade Earth (even though their fuel capabilities lag far behind ours) where they have their asses handed to them repeatedly by a man who has no superpowers, but can skip reasonably well. Turns out that their weapons have no effect on him.note
- The French comedy Le Gendarme et les extra-terrestres (The Gendarme and the Extra-Terrestrials) has police sergeant Ludovic Cruchot discover that aliens have landed in Saint-Tropez. They appear to be Mechanical Lifeforms with the ability to take on anyone's appearance and have Mind over Matter abilities. They also easily rust from water, which is how the gendarmes defeat them. The thing is, it's never made explicit that the aliens had hostile intentions. In fact, one of them appears to Cruchot in the form of his Da Chief and offers flowers as a peace gesture. Cruchot's response? Try to kill the alien for... not sure what.
- In The Thing (1982), it's extremely fortunate that the ship carrying The Thing crashed on an ice desert continent with very little life to assimilate. It's even more fortunate that the few humans available for consumption have access to flamethrowers. The Thing quickly realizes it's at a disadvantage and attempts a Divide and Conquer strategy so it can pick off the camp one by one. Every time it is forced to reveal itself, it only manages to kill one or two people before being quickly immolated or blown up. It's made quite clear that if not for these circumstances (or if it were to get out), this trope would be very much averted.
- In Slither, the alien parasite that has been stated to be responsible for multiple planetary genocides is stopped after destroying a small remote town. Sure, people died, but it's nothing compared to every living thing on Earth being destroyed. It's possible none of the previously-conquered planets had explosives- the alien planet that Kylie sees when the worm tries to take her over doesn't appear to have had any sort of civilization on it when the parasite arrived.
- The Chitauri invasion in The Avengers (2012) consisted of what amounts to light infantry and a handful of much hardier Leviathans. Yet Loki and The Other were positively certain they'd be enough to take over the entire planet. While they do have the titular Super Team on the ropes at one point, their lack of tactics past a Zerg Rush and the fact they're susceptible to human sidearms makes a longterm victory unlikely. However, that doesn't even come to pass when a single (mostly accidental) attack on their home dimension reveals they're a Keystone Army and they're instantly killed.
- The other invading aliens in Avengers: Infinity War are the Outriders, who are worse than the Chitauri: they're completely unarmed, die even easier,note have no aircraft or vehicles at all besides a handful of unarmed thresher-wheel things (that explode when War Machine sprays minigun fire at them), and don't even appear to be sapient, having no tactics except running in a straight line across an open field. There are also only a few thousand of them. The few Avengers who actually do pack regular weapons (War Machine, Falcon, Bucky) waste them en masse, and they're only ever a danger to the protagonists due to a serious case of Hollywood Tactics and Schizo Tech on the part of the defenders.
- In Thor: Ragnarok, Hela plans to conquer several worlds with an army of undead Asgardians, specifically her former army when she was still Princess. Unimpressive numbers aside, they never even get off the planet because the bulk of them are mowed by Skurge with a pair of regular M16s he got on a trip to Texas.
- Plan 9 from Outer Space has an invasion that involves a zombie apocalypse consisting of three non-contagious zombies.
- Exaggerated in Coneheads; Beldar and Prymaat aren't exactly the most competent invaders, crashing within minutes of arriving, with the Earth never even knowing about the attempted invasion.
- Exaggerated and parodied in Spaced Invaders, where the aliens are Harmless Villains who wind up helping the community they invade far more than hurting it. It didn't help that they were on completely the wrong planet; the fleet sent to the real target did even worse.
- Battle: Los Angeles. The alien drone ships are controlled by a single vessel that for some reason is operating from the ground instead of from orbit where it would be difficult to destroy and have better signal coverage.
- Once Superman is brought back to life in Justice League (2017), the plans of the New God Steppenwolf are casually thwarted.
- Animorphs: The Helmacrons are a microscopic species with egos the size of planets. Their one invasion force is a single ship the size of a plastic toy, and they still think they can win. To quote Marco, who snaps after constant exposure to their bravado:
"You couldn't hope to go mano-a-mano with a maggot and win. And that's sad, because maggots don't even have manos."
- Ultimately, the entire Yeerk invasion that the series is based around ends as this, with the Yeerks mostly contained to a single California city for the whole of the story and ultimately being beaten without even managing to conquer that. In a what-if alternate story where the titular Animorphs don't acquire their morphing powers but get pulled into the war anyway, the Yeerk invasion is literally thwarted in days. Some great alien conquerors they turned out to be. Much of this is because the Yeerks could do an actual open-war invasion, but this would defy their whole objective, which is to obtain a large number of usable hosts and avoid being noticed by the Andalites. Because of this, they're stuck with a slow-and-steady approach.
- Arrivals from the Dark: In Mikhail Akhmanov's Invasion, the super-powerful alien starship wipes out a large chunk of Earth's fleet and shrugs off a nuclear Macross Missile Massacre without a scratch. In a Deus ex Machina fashion, a different alien teleports onboard and gives the hero a device that destroys the ship's brain, shutting down all systems. In a brutal subersion of No Endor Holocaust, many major cities get hit with smaller falling alien ships full of antimatter, with the casualty count in the tens of millions, not to mention all the material damage. Earth recovers remarkably quickly in the sequel, though.
- In Arthur C. Clarke's Space Odyssey series, the godlike aliens who blow up planets and mess with humanity's evolution from apes are found to be vulnerable to computer viruses... the code for which are buried in a mountain on the moon. However, the supercomputer that the virus is uploaded to helped humanity upload it. Also, it is explicitly explained that the viruses in question are not just your regular run of the mill viruses - they exploit the laws of mathematics such that ANY computing system that uses numbers is vulnerable, no matter how advanced, and NO countermeasures of ANY kind are possible.
- The Body Snatchers, the short story upon which the film versions were written, had the aliens simply give up when the figure out they can't tolerate human resistance. The films tend to end on a darker note...
- In the backstory of Charlie and the Great Glass Elevator, the Vermicious Knids have tried to invade and conquer Earth the way they did the Venus, the Moon, and Mars, but Earth's atmosphere is too much for them — what look to humans like shooting stars are actually Vermicious Knids burning up when they try to pass through. In the novel's present, they invade Space Hotel USA and manage to eat some of its crew, but the rest are rescued by Willy Wonka and company using the titular elevator to tow their ship to safety. When the aliens attempt to drag the humans to their home planet, Mr. Wonka instead steers the elevator and ship back into Earth's atmosphere, finishing the monsters off.
- Harry Turtledove's short story The Road Not Taken (prequel to Herbig-Haro written to expand on the invasion in the backstory) posits that the secret of interstellar travel is an absurdly simple technological concept (so much so that it seems obvious in retrospect, like the wheel), and yet Earth, by sheer happenstance, never stumbles upon it. Later, Earth is invaded by aliens in wooden spaceships armed with cannons and black powder muskets... who are confronted by humans who, having never discovered FTL drives, have instead devoted their research to other scientific pursuits, such as weapons that outclass the invaders' by centuries of development. The story ends with the captive aliens horrified that the humans will be able to discover the secret of hyperdrive from their ship, unleashing the violent, tremendously advanced (compared to other species) humans upon the rest of the galaxy.
- The High Crusade: Invaders landing in England in AD 1345 can only defend themselves against energy weapons, leaving themselves helpless against swords and arrows.
- The Hitchhiker's Guide to the Galaxy: In the first book:
"For thousands of years the mighty starships tore across the empty wastes of space and finally dived screaming on to the planet Earth - where, due to a terrible miscalculation of scale, the entire battle fleet was accidentally swallowed by a small dog."
- Children's book I'm Coming To Get You by Tony Ross featured a horrifying alien creature who proceeded to land on an alien planet, wreck everything there, and consume the population before finally eating out the whole planet itself like an apple. The book even shows the monster has repeated this on several planets that have crossed it's path before learning of Earth. The alien then travels to Earth ready to devour a human boy when it sees him, only for the kid to walk right past the monster because it turns out to be comparitively no bigger than a cherry. Upon realizing this the suddenly much less fearsome invader beats feet and retreats.
- While not a full-blown invasion, the Hunters' raid on a Canadian hockey game in The Jenkinsverse is easily thwarted due to humans being a death world species by the standards of the Hunters (and the entire Milky Way galaxy, really), to the point that not only were their weapons a No-Sell against humans, but also the aliens themselves might as well have been Made of Plasticine. By the time the game's audience had finished turning the aiens into ludicrous gibs, they had were honestly more distraught with the fact their game had been cancelled for the night rather than the fact they had just fought off an alien attack.
- Subverted in When The Tripods Came, the Tripods prequel. The first three Tripods are easily destroyed, and everyone believes this trope. But then The Trippy Show comes along, and...
- Out of the Dark by David Weber goes along a similar premise to World War except that it takes place in the modern day and the aliens get most of the world's governments to surrender within days by dropping large amounts of rocks. But their ground forces still get Curbstomped by the various Resistance groups that crop up ranging from an alliance between Al-Qaeda and an American Armor Battalion to a couple survivalist families in the Midwest. Up until the aliens rediscover nerve gas, but then Vlad Drakul wakes up and kicks alien ass.
- Anne McCaffrey loves this trope.
- In the Catteni series, the preferred host species of the Eosi (body-snatching Evil Overlords) is deathly allergic to a plant that grows in abundance on Botany, the planet the main characters were stranded on. La Résistance manages to sneak boatloads of the plant's pollen into the ventilation system at a suspiciously fortunate gathering of 90% of the Eosi. The surviving Eosi were too few and scattered to retain their grip on their servant races.
- In the Acorna Series, the Khleevi (Always Chaotic Evil planet despoiling insectoids) are easily cowed by one squadron of battleships fighting back (though they were portrayed as bullies who preferred easy targets). And, after that, the heroes find a plant whose sap acted like purest acid on Khleevi exoskeletons.
- In the Talents series, the Hivers (a more rapacious version of the Buggers from Ender's Game) prove to be completely unprepared for human telekinesis. Later, humanity found a pheromone combination that turned the Hivers from Borg-like aggressive conquerors to more docile, agrarian types.
- In the Dragonriders of Pern books, Thread is a ravenous mycorrhizoid spore that can eat virtually anything carbon-based and burrow into the earth. But water (even a good soaking thunderstorm) kills it, as does fire and cold. In one book, the Pernese don't realize that Threadfall has started because the first few falls are over the northern area of the continent during winter. Also grubs, but those were genetically engineered.
If it seems improbable that Thread could ever live on any planet with anything worth eating, that's because it is. It's a deep-space organism which only falls on Pern due to a very unfortunate accident. Once Thread falls, it's doomed — but it can still do a hell of a lot of damage before it dies.
- Older Than Television: The War of the Worlds did this with bacteria. In fact, it's pretty much the Trope Maker and Trope Codifier for the "The planet takes care of the invaders itself" version of this trope. The novel implies that the Martians were severe germaphobes who rid their native habitat of all microbial life, thus blessing themselves with major suck right before the invasion of Earth. It's also - as the first chapter makes pretty clear - a metaphor for British imperialism, since British colonial soldiers stationed in Africa were dying of malaria in droves around the time the book was written. Wells wanted to stress that the aliens did not belong on Earth, to express his real point: Britain did not belong in Africa.
- Robin Cook's Invasion had the Replicant Snatching aliens thwarted by the release of a rhinovirus, AKA the common cold.
- Keith Laumer wrote a hilarious short story in which aliens invade a dying civilization — only to discover that the locals were in fact immortals whose metabolisms shut down if they didn't get enough of a certain gas in their air. Guess what the invaders exhaled. And the locals who were still up and about were the weakest of their species; the invasion revived all of their brawny badasses.
- The invasion of the Gorg in The True Meaning of Smekday. For some reason, the Gorg try to kill every single cat on planet Earth. As it turns out, the Gorg are allergic to cats due to cloning themselves so much.
- Christopher Anvil short stories did this several times.
- In The Gentle Earth covers a long campaign in which the invaders are slowly worn down, but they're defeated in such a thorough and humiliating fashion that it goes under this trope anyway. Their errors and catastrophes include but are not limited to failing to prepare appropriately for Earth's much colder winters, dismissing tornadoes as a legend (having landed in Tornado Alley), and drastically underestimating Russia's missile supply.
- In The Underhandler the aliens suffer a major setback (giving the rest of the world time to reorganize) when they start off by trying to capture all of the oil in the Middle East, not expecting such an underdeveloped region to have as many guns as they end up having. Then, after a hard fought war, they decide to fake a treaty offer, invite the human they see as the linchpin of the military efforts against them to be an ambassador, then fly off and return in a couple generations when hopefully the humans will have gotten softer and more complacent. This attempted second invasion never even gets off the ground, because instead they find the humans more heavily armed than before and suspicious Because they [[Is This Thing Still On? didn't think to turn off their transmitter while they were coming up with that plan to trick the Earthlings between screen-sharing negotiation efforts.
- In We from Arcturus the aliens plotting to kidnap and eat the humans turn out to have keen enough senses they their overwhelmed by the smell of the all the human pollutants.
- In Compensation the alien scouts decide to beat a hasty retreat and recommend against invading in the first place after they find out about missiles.
- In Stephen Baxter's novel Space has the solar system invaded for use as an stellar fuel depot by the Crackers, which will result in the explosion of the sun. Having battled through the friendly Gaijin fleet, they are utterly destroyed by Nemoto's secretly modified and transplanted Moon Flowers, which use the top layer of Mercury's soil as cosmic buckshot.
- Lampshaded by the character of Zellaby in John Wyndham's The Midwich Cuckoos (1957), where he brings up a few examples of this trope common in British and American science fiction at the time in a strategy discussion. He then concludes the alien invasion they face is a war like any other, and takes the appropriate measures.
- The Sirens of Titan by Kurt Vonnegut features a Martian attack on Earth. The Martians originate from human colonists and appear to be extremely well-prepared and equipped, but several (deliberate) mistakes in their plans make it extremely easy for Earth to repel the (drastically outnumbered) invasion. Which was their leader's plan all along: scaring earth-bound humanity into banding together to slaughter the out-classed Martian invaders, then exposing what a non-threat they had been all along, thus triggering a global My God, What Have I Done? in order to usher in an age of peace and unity
- A novel titled Invaderby Albert Fay Hill had humanity's astronomers spot the massive energy release as the invasion fleet slowed from near-lightspeed, so the world's governments funded the construction of a massive gamma-ray emitter. One carefully-aimed shot killed every living thing in the fleet, and the now-dead ships just drifted past Earth back into the void.
- The aversion is discussed in Vladimir Vasilyev's Wolfish Nature by Rasmus. According to him, Earth is woefully unprepared for an invasion by any alien power capable of interstellar travel, in large part because the Bio-Correction turned all dog-humans into pussies incapable of killing without going insane. Really, Earth's only saving grace is the lack of anything even remotely useful to any aliens (e.g. resources, strategic position, technology). The last time they found something useful was a few hundred Medieval warriors to use as shock troops in their interstellar wars. Rasmus is their leader.
- Ultramarine series of Warhammer 40,000 features a Tyranid invasion on Tarsis Ultra. It was a tendril that made up half of supposedly unstoppable Hive Fleet Leviathan that was annihilated by 2 companies of Space Marines, 2 Imperial Guard regiments and rather small and underwhelming Imperial Navy battlegroup. note The battle was won when Ventris poisoned the Hive queen, but still. Unfortunately, there are so many similar victories in novels and codices that it makes fans question: if just so few IG regiments and Astartes companies can thwart galaxy-ending threat, why hasn't Imperium that has millions regiments and thousands companies of Astartes won already?
- The Easy Way Out by Lee Correy, pseudonym of G. Harry Stine. Scouts of an alien invasion force are stumped by encountering a grizzly, which attacks them and kills one despite their blasters. Then they see a wolverine attack another grizzly. Then they see that the wolverine is subordinate to a human juvenile. The aliens' attempt to calculate the earth creatures' "Ferocity Index" breaks down at this point, and they decide that discretion is the better part of valor and go invade somewhere else.
- In Randall Garrett's story "The Best Policy", alien invaders kidnap a human from a colony world for questioning under a lie detector. By giving cleverly worded but technically true answers, he convinces the aliens that humans are immensely powerful beings and that he is only putting up with them out of politeness.
- In Stanisław Lem's short story "Invasion from Aldebaran" (Inwazja z Aldebarana, 1959), two Starfish Aliens from Aldebaran scouting for planets to conquer for their galactic empire land on Earth, at a random spot which turns out to be in rural Poland. Although the Aldebarans are technologically highly advanced and command an arsenal of sophisticated bioengineered devices, their attempt to reconnoitre the nearby village is impeded by the poor state of the local roads. Before they have reached the town, they meet their doom by getting into a brawl with a late-night drunkard who clobbers them to death in a drunken stupor, mistaking them for someone else. Unfortunate to them, their bioengineered weapon system is disabled by the man's alcoholic breath, as alcohol is apparently poison to all organisms from Aldebaran.
- America's Funniest People host Dave Coulier requested viewers to send in videos depicting an alien invasion. Most of them were this. The first showed an alien who details his entire plan, only to be flattened by a car tire bigger than he is.
- Doctor Who loves this trope, with dozens of aliens invasions ranging from single vessels to vast fleets (The World Is Always Doomed, after all) being Easily Thwarted by a single person with unusual dress sense, albeit one with thousands of years of experience and access to some of the most advanced (if somewhat unreliable) technology ever created. The spin-off series The Sarah Jane Adventures plays it even straighter than its source material. This generally reaches its extreme whenever the Doctor fends off Dalek fleets. For reference, Daleks are the scourge of the universe, with precious few civilizations being able to stand against even small numbers of them.
- This trope is referenced in Farscape when the crew of Moya ends up on Earth.
D'Argo: (gently) I've seen lots of your movies. And in every film - the aliens are always evil and Earth always is victorious.
Bobby: You mean we have to learn there are good aliens?
D'Argo: (long pause) No - I mean you have to learn you won't always win.
- Both John and Aeryn also note in the episode that Earth's defenses would be woefully ineffective if any alien race decided to attack.
- An attempt to invade Earth happens in the series finale (prior to the wrap-up mini-series), when the Scarrans send a single warship to conquer Earth. John ends up destroying it in flight, but is forced to collapse the wormhole to do it.
- Lost in Space episode "Invaders From The Fifth Dimension" features Will Robinson abducted by a group of aliens who are repulsed by the sight of tears due to being unable to understand emotions, and eventually let him go as a result.
- The Science Fiction Sketch of Monty Python's Flying Circus, in which blancmanges from Andromeda seek to win Wimbledon by turning everyone in the world into a Scotsman. They were thwarted when two people ran out onto the tennis court and ate the blancmanges. It would have been more easily thwarted, but the camera rudely cut away early in their first appearance.
- Referenced in the Mystery Science Theater 3000 episode Prince of Space. After the villain, Krankor, announces his plans to conquer the Earth, we cut to newspapers flying off the presses and the 'bots imagine the headline:
Crow: "Krankor: Nothing to Worry About!"
- The Outer Limits (1963) episode "Specimen: Unknown" had alien plants that release a deadly gas and spread like wildfire. A spaceship carrying them crashes on Earth and it looks like the human race is doomed. Worse yet, a thunderstorm is brewing overhead, and the plants will spread even faster when they get some rain, right? Wrong. The rain causes them to shrivel up and die, and the world is saved. Think of it as the opposite of a Cruel Twist Ending.
- Most alien invasions in Power Rangers. Almost universally taken out by "teenagers with attitude". Also, supersuits and giant robots. And not much in the way of attitude, when you get down to brass tacks. Nonetheless, five teens restricted to a single city with no military skill or training whatsoever fend off entire armies that know where they live, who they are, and what they like to do in their free time.
- A Saturday Night Live sketch from the '80s ("Target: Earth") featured an invasion by a race that has a spaceship... but in every other way appears to be far less advanced than Earth.
1st Alien: So, what is your answer? Do you agree to come quietly and be our slaves or do you face the awesome power of our muskets?
- Stargate SG-1: "Politics" is about a Senator who believes that the Goa'uld are this, thus wants to cut SG-1's funding. He's not entirely wrong but underestimates the Goa'uld considerably since SG-1 keeps coming back alive. Destroying the Goa'uld by uploading a computer virus to their ship is sarcastically mentioned.
- Star Trek: The Original Series episode "Day of the Dove". An alien powerful enough to destroy a Klingon battlecruiser, transmute matter and control the minds of hundreds of beings simultaneously takes control of the Enterprise. How do the humans and Klingons get rid of it? By laughing at it. Seriously.
- The Anterians from the Suite Life on Deck episode "Starship Tipton". The ant part of their name probably should have been a tip off.
- StarCraft: due to being something of a Keystone Army, the feral zerg aren't much of a threat in the absence of a ruling intelligence directing them. Their basic units are as dangerous per capita as usual, but they have no unit cohesion beyond the pack level, lack access to the highest-level breeds, can't travel at FTL speeds unless the pack is lucky enough to have broken off with a Leviathan,note and seemingly don't breed as fast. Feral colonies have had their assaults repulsed by little more than outnumbered civilians with improvised weapons and small arms (e.g. Broken Wide, Liberty's Crusade), and StarCraft II: Wings of Liberty reveals that some of their "invasions" are so weak that local rednecks hunt them for sport.
- Doom: in most of the games, the armies of Hell invade Mars and are defeated almost solely by a single Badass Normal mostly using a 12-gauge shotgun and a minigun.
- Subverted in City of Heroes- the extra-dimensional Rikti invaders turned out to be vulnerable to magic, so they targeted magic users as soon as they found out. Their invasion still caused massive devastation, though not quite to After the End levels, and decimated the Superhero population.
- And then they started learning how to use magic themselves.
- Averted entirely in Universe at War - The tutorial mission is the only time you play the humans and its Unwinnable; Earth has to be rescued by other aliens.
- In the original X-COM: UFO Defense, the aliens' weakness is logistics. They simply don't have enough forces available at the beginning of the game to launch more than a couple of small missions a month (though their forces build up more and more later), requiring them to operate in secret through infiltration and subversion of national governments, showing the world that X-Com is too weak to defeat them and attacking and destroying X-Com bases instead of open warfare. Meanwhile, even one crashed alien craft allows for humans to import their phlebotinum, and enough research allows them to take the fight to the alien base on Mars.
- Xenonauts has its first research consisting of explaining "Why we haven't already lost." The Aliens are invading a planet that is nothing like the ones belonging to any of the constituent alien species, Higher oxygen levels, thicker atmosphere, ETC, ETC. The Alien ships need to be refitted for atmospheric combat, which is logistically intensive, and time consuming, forcing them to rely on small scout craft for the early phases of the invasion. Ultimately, this gives humans time to research, and reverse engineer their technologies, to hopefully stop the alien invasion before it gets intense enough to actually become a full scale invasion, which is less then a year.
- The aliens are not trying to outright exterminate humanity, but subjugate them to see what genetic traits can be gleaned from them, which explains why they don't just nuke us all from orbit and get it over with. The Game Over screen implies that the fate of the last humans is nightmarish.
- Later on it is revealed that the alien empire covers an entire galactic arm, so like the Asterix comics, the aliens are the Romans and Earth is the plucky Gaulish village just barely hanging on in the face of massive military and industrial muscle. However humanity has a chance because the alien empire is organised among feudal lines: the High Praetor overseeing the invasion is at the end of the day just a two-bit warlord invading the planet as a personal project; if his invasion fails, the rest of the empire won't care much.
- The aliens in UFO: Aftermath are a death cult limited in resources and technology to what they could make off with; the empire they hail from liked humanity and is pissed.
- The Rhombulans in Elite Beat Agents are so vulnerable to music that rhythmically beat garbage can lids is enough to knock out their soldiers. The easily-thwarted part happens when you remember what genre this game belongs in, at least from a story point-of-view.
- Guild Wars 2's main threats, the Elder Dragons, are mountain-sized entities that essentially restarted the world in the past... and yet the Vigil alone is shown to have enough resources to wage war against them on as much as three fronts. And the only thing keeping them from actually defeating the dragons is, apparently, their childish unwillingness to work with the spy and the scientist orders. While a lot of work is done to find the dragons' weaknesses, starve them of their respective sustenance, and build technology that directly counters their magic, it's still a relatively small number of people doing this work. In the ancient past, precursor races working together could only manage to barely protect a handful of races from the devastation. In the present, most of the world hasn't even been involved in the dragon plots yet.
- The Shroobs in Mario & Luigi: Partners in Time. Right at the very end of the game, baby Luigi's crying on a Shroob Mushroom reveals that the Shroob materials dissolve when exposed to baby tears. The present-time E. Gadd creates an immeasurable amount of water with the same composition as baby tears in response to this. He then pumps it through the time-holes, saturating the past Mushroom Kingdom in baby tears, completely removing any traces of the Shroobs from the Mushroom Kingdom. However, it seems Bowser had Shroob-napped a few survivors and put them in the deep freeze, to be battled in the next game of the series
- In Earthbound Beginnings a troupe of three small children (albeit with Psychic Powers) defeats an all-powerful alien by singing. Justified as the song being sang belonged to a human who helped heal the alien, you are essentially guilt-tripping him into leaving.
- The premise for the Dawn of Victory mod for Sins of a Solar Empire is loosely based on the Worldwar series by Harry Turtledove (see Literature). The Scinfaxi (not their real name) are a vast interstellar empire, who set their sights on Earth. Same deal, their invasion force arrives centuries after the initial probe, and they land in the middle of WW2. However, their tech is more akin to the aliens from The War of the Worlds. Despite being shocked at humanity's rapid technological progress (Scinfaxi are conservatives when in comes to progress), they manage to conquer most of the world before the Russians manage to steal one of their nukes and blow it up. The Germans and the US follow suit, scaring the aliens into retreating to the southern hemisphere. A century later, humans abandon Earth and nuke the hell out of it, to kill any Earthbound Scinfaxi. Thus begins a war between the aliens, Soviets, Germans, and Americans... IN SPACE!!
- In Sword of the Stars when the Hivers first struck humanity, they soon respond by launching hundreds of nuclear missiles, forcing the Hivers to turn tail.
- The Qularr invasion in Champions Online features as the tutorial. They aren't wiped out, but it seems most of their fleet attacks a single city and are driven off when their mothership is brought down. They are generally kicked around by all the other heroic and villainous groups; one open mission is called Nadir Of The Invaders.
- A possibility in the Expansion Pack to Sid Meiers Alpha Centauri. The two Progenitor factions have powerful battle fleets waiting for a signal from their respective scoutships. However, if you defeat the aliens, then their fleets never show up, since they simply assume that the scoutship perished without discovering the location of Manifold Six (their name for Planet). Additionally, while the aliens are much more advanced, their scoutships destroy one another, and the survivors land in Escape Pods and must rediscover lost technology, putting them on par with the humans.
- Seemingly played straight in Command & Conquer 3: Tiberium Wars: GDI manages to shut down the Scrin invasion of Earth after a lot of effort and massive destruction across the globe, and while being hampered by the Brotherhood of Nod which (except for a few token efforts) isn't even bothering to fight against the aliens and is actually prioritizing GDI as a target over the Scrin. Then it's a Subverted Trope when you play as the Scrin campaign and you find out the fleet wasn't an Alien Invasion, it was a mining operation with a small security detail. For most of their time on Earth, the Scrin forces were running an Indy Ploy barely hanging on with lots of Improvised Weapons and uncaring leadership that were willing to let the entire force get wiped out.
- The Zuvorg Alliance in Super Robot Wars Original Generation, particularly the Guests, though this is mainly due to getting the short end of the Sorting Algorithm Of Villainy. While the Inspectors at least had some time as the main threat of OG 2 (before getting hijacked by the Shadow Mirror and the Einst), in 2nd OG the Guests aren't even able to make landfall on Earth ( thanks to Mekibos providing intell to the Federation) and the threat they pose is quickly eclipsed by the Ruina, Youkijin and ultimately Euzeth Gozzo.
- In From the Depths, the Scarlet Dawn faction is the leftovers of a failed alien invasion that suffered setback after setback. After having been on ice for centuries while in-flight to the planet Neter, the aliens were extremely frail upon awakening. When they set down a pair of Von Neumann factories to the surface, the machines malfunctioned and lost their shackles, allying themselves to the planet's governing body for protection. And finally, upon landing the planet's extremely violent shifts in temperature, weather, and light allowed their laser-spamming high-altitude fighters to be beaten back by the government using little more than armor-piercing cannons and missiles.
- Endless Sky has the Pug, whose primary weakness is their habit of deliberately limiting themselves enough to be beatable by whoever they are fighting, and hence won't bring out their big guns for the invasion of human space. It is also implied that the goal of the invasion is to be defeated — in the right way, so as to produce the right result in humanity.
- In The Inexplicable Adventures of Bob!, Every Man Bob has thwarted two alien attacks, one by Fructose Riboflavin and one by the Pirates of Ipecac, though in both instances he had help.
- Saturday Morning Breakfast Cereal: "Blast! Their iron is much stronger than our bronze!"
- Sparky of Lady Spectra & Sparky convinced an alien invader to call off his attack by offering him a bouquet of flowers.
- The aliens in It's Walky! are mostly dimwitted pop-culture junkies who are perfectly vulnerable to earth weapons, and can't even operate their own technology properly, because the suits they must wear to survive on earth dampen their telepathic abilities. Attempting to create an army of super-powered human slaves who can use their tech results in an army of super-powered human not-slaves who devote themselves to fighting the invaders with their tech. Oops.
- Parodied in a Tiffany and Corey cartoon where an advance alien scout learns the true size of Earth people compared to his own.
- Parodied in Futurama's version of The Twilight Zone, The Scary Door.
"In the end, it was not guns and bombs that defeated the aliens, but that humblest of all God's creatures, the Tyrannosaurus rex."
"The human was impervious to our most powerful magnetic fields, yet in the end he succumbed to a harmless sharpened stick!"
- Another humorous example, this time from a B-Movie on a planet of killer robots:
- Fry repels the Brain invasion by trapping them in a story full of plot holes and spelling errors. It Makes Sense in Context... sort of.
- The Omicronians invade just to see a thousand-year-old TV show that they had missed. The Planet Express crew reenact the episode for them, and they all go home.
- The Simpsons
- In a Halloween special, after humans have destroyed all known weapons, an alien invasion consisting only of Kang and Kodos alone, are able to Take Over the World, wielding only a slingshot and a bat. Eventually the two of them are overthrown and chased away from Earth by a rebellion, consisting only of Moe wielding a more advanced weapon than than Kang and Kodos can conceive of... a board with a nail in it.
- Another attempt was done when Kodos creates a portal which sends an army of aliens to Earth; it was thwarted by the U.S. Army which easily slaughters all the aliens, since they only have weapons like swords or spears.
- In one episode of Care Bears: Adventures in Care-a-Lot, Care-a-Lot is invaded by Gobblebugs, tiny bugs that eat any and all plants, except ones that are yellow. Once the Care Bears realize this, they turn all the remaining plants yellow, and the bugs lose interest and leave.
- Invader Zim:
- Not all the Irkens are idiots. Most of them (Especially Invaders) are actually pretty competent. The one assigned to Earth on the other hand, Zim, is so stupid that they sent him into an uncharted area of space to find a planet they made up just so that he would die slowly and horribly due to starvation. They didn't anticipate Zim actually finding the planet. Despite all the advanced technology at his disposal, he is kept at bay by a lone Conspiracy Theorist (with occasional help from his sister).
- This trope is also parodied in the episode "Germs", where an Easily Thwarted Alien Invasion (by germs) in a bad sci-fi movie makes Zim paranoid about falling into the same pit-trap, and Hilarity Ensues.
- Agent Bishop faked up one of these to get extra funding for his organisation in the 2003 Teenage Mutant Ninja Turtles series.
- Aqua Teen Hunger Force gives us the Moonenites, the Plutonians, the Jupiterians, Travis of the Cosmos, and the Frat Aliens.
- In the Grand Finale of Kim Possible, two aliens and their robot army invade the world "in the time it takes to order a pizza", but only hold on to it for a few hours before being defeated.
- Not a direct example, but in one episode of the original Transformers cartoon, the Decepticons ceased their attack on the Autobot base because the chaos caused activated its fire-repellent systems... which was made up of fire-retardant foam being sprayed from the ceiling. According to Megatron, if they stayed and continued the attack, the foam would permanently damage their internal circuitry and they would shut-down for good. These are highly advanced Mechanical Life Forms who have been shown surviving being frozen in ice for centuries and being submerged in the deepest areas of the sea and yet apparently the one thing most damaging to them could potentially be found in fire extinguishers. Imagine how easy it would be to get the Decepticons off planet if they just used those? Remember, aim at the base and sweep.
- In The Powerpuff Girls episode "Beat Your Greens", Earth is invaded by a race of broccoli aliens after all of the adults are brainwashed by eating modified broccoli. Naturally, the children escape this fate and fight back, by literally eating the invading aliens. Naturally, the aliens (and probably some viewers), were absolutely horrified by this.
- Although the invasion is never shown to have actually happened, in Lilo & Stitch Earth avoids invasion by being the natural habitat of a highly endangered species... mosquitoes. What's more, the decision was apparently based on the testimony of the Earth-native who tricked them, with not even a basic survey done to see if it was true.
- There was a little bit of implied help from the seemingly Obstructive Bureaucrat, who in a twist of that trope was helping the good guys for once. At the very least, when they get (back) to Earth, she recognizes the secret agent that masterminded the whole shenanigans to save the world in the first place when they showed up the first times, and seems to be on relatively friendly terms.
- In Big Guy and Rusty the Boy Robot, the alien Squillacci are the ones who draw Crop Circles and experiment on cattle. Their repeated invasion attempts are stopped only by a guy in a Humongous Mecha and an android the size and mentality of a child.
- In Journey to Saturn, the alien invasion is thwarted by having the heroes throw and shoot beer at them. It probably wasn't a good idea to invade Denmark.
- In the Birdman episode "Skon of Space", Skon, the advance scout for an alien invasion, attacks Birdman. Birdman defeats him and sends him home with the warning that everyone on Earth has powers like him, so any invasion would be futile. Birdman calls Falcon 7 and warns him to prepare for an invasion just in case Skon's superiors are not as gullible as him.
- Usually justified to an extent in the original Ben 10 series, where most invasions are stopped by Ben before they could actually reach a large scale (such as the Great One in "The Big Tick," or the Mycelium in "Camp Fear"). Same for Vilgax, whose army is mostly composed of Mecha-Mooks, meaning they will stop working once their leader is gone.
- Bump in the Night featured a pair of aliens named Sleemoth and Gloog as a pair of recurring villains. Mr. Bumpy, Squishington, and Molly Coddle always beat their plans to invade easily because they are rather overconfident and incompetent.
- Oh Yeah! Cartoons featured a rather unusual example in the short "The Boy Who Cried Alien", where Floyd, who spent the short delivering paranoid ramblings about an alien invasion being imminent, ends up obliviously eating the unexpectedly tiny aliens with his cereal.
- Exploited in an episode of Fangface when the title character starts Playing Sick to convince the alien vanguard that the Earth is full of contagious diseases, and that a full-scale invasion would be a very bad idea.
- Parodied in Robot Chicken, when a bunch of drunken celebrities are revealed to be lizard aliens a la Series/V1983; they start their invasion because they've been drinking tons of alcohol to kill our deadly atmospheric bacteria, and were unaware of the side-effects. (The only exception is Mel Gibson, he was there for the uniforms and "team hatred".) As you'd expect from a bunch of drunk-as-a-skunk celebrity aliens, it goes poorly and they all wind up dead by the end of the skit.