->''"It is not the strongest of the species that survives, nor the most intelligent that survives. It is the one that is the most adaptable to change."''
-->-- '''Leon C. Megginson'''

%%One quote is sufficient. Please place additional entries on the quotes tab.

This is an enemy whose power is to [[EvolutionPowerUp adapt]] to any power used against it.

Hit it with a fireball? Next time it's immune to fire. Same with any ElementalRockPaperScissors attack. Cut it, it now has armor. Psychic powers, it now has mindshields.

Logic would dictate the "easy" way to beat it is to use an overwhelming attack to begin with. However, this goes against most heroic codes, so by the time they've slowly cranked up the power of their attacks, the villain has "adapted" quite a bit.

Beings with an Adaptive Ability are very often [[TheSocialDarwinist Social Darwinists]], if they're not mindless monsters. When combined with a sufficient HealingFactor, it can effectively make them [[NighInvulnerability invincible]].

The result is ItOnlyWorksOnce. The good guys will easily be convinced that EvilEvolves. The functional opposite is PowerCopying. Compare and with EnergyAbsorption and FeedItWithFire, where the defender is actually ''powered'' by being attacked (with "energy" and fire, respectively). See also AdaptiveArmor.

They have a high chance of being an UltimateLifeForm.



[[folder:Anime and Manga]]
* In ''Manga/JojosBizarreAdventureBattleTendency'', Kars (the BigBad) uses the Red Stone of Aja to instantly become the ultimate creature, with all of Earth's evolution in hand and the ability to adapt to any attack. He is effectively immune to every possible attack because he could simply change into a form that resisted it before it even hit him. Even when thrown into a volcano, he surrounds his body with bags of air to insulate him from the immense heat. He's defeated by being shot into space by the volcano to float around forever until he eventually ceases thinking, effectively making him dead.
* Kuro Momotaro from ''Manga/YuYuHakusho''. His body possesses the ability to memorize the damage of any attack that hits him, while his weapons, the Steaming Spheres heal him from that damage, and give him the power to overcome it. [[LoopholeAbuse Probably a useless ability if he's]] [[OneHitKill killed in one shot]] though.
* Many of the enemies in ''Manga/SaintSeiya'' are fond of declaring that they could not be hit by a technique once they have already seen it. Given our heroes' reliance on StockFootage {{finishing move}}s, this seems like it would be a downright crippling handicap for them ...
* Shishioh from ''Manga/RurouniKenshin'' has a non-supernatural version of this. One of his skills is that he just innately knows how to counter any attack he sees once.
* ''Anime/DragonBallZ'':
** Anyone with Saiyan blood will receive large increases in strength upon recovering from near-fatal injuries. The Saiyans are the embodiment of the Nietzsche's famous quote. If they are near-death for whatever reason, when they are recovered, they will come back stronger. This ''also'' works with actual death, provided there's a way to come BackFromTheDead afterward. A few enemies were too powerful for this to matter much, though.
*** In the manga version of ''Super'', Future Trunks theorizes that this Saiyan ability yields diminishing returns over time, as in the manga version of his arc, he, Goku, and Vegeta get injured and healed several times and the strength increase is negligible.
** ''VideoGame/DragonBallZSuperSaiyaDensetsu'' had this implemented: If a Saiyan character won a battle with 5 or less HP remaining, they would gain a level immediately no matter what.
** Goku's adaptive ability allows him to become immune to almost any technique he has seen at least once. Like [[Manga/RurouniKenshin Shishioh]], it's because he innately knows how to counter them. This is best seen with his fight against Cell, where all Cell's copy techniques fail to harm Goku.
** Since Cell was partially cloned from Saiyan cells, he has this ability as well. In fact, the combined abilities to Self-Destruct + Survive so long as one cell remains + come back stronger from a near-death experience is quite dangerous.
** In Cooler's second movie, after his original body is all but destroyed, his mind merges with a sentient super-computer/space-ship. The ship rebuilds him as a mechanical lifeform, and now, thanks to the ship's enormous resources, whenever Cooler's body is damaged, the ship simply repairs his body or fabricates a new one with whatever vulnerabilities it learned about removed. This comes to a head when the computer decides Cooler's main flaw is that there's only one of him. Cue enormous army of Meta Coolers.
** Goku Black from ''Anime/DragonBallSuper'' possess an enhanced version of the Saiyan's power-up ability in that ''any'' damage caused to him will instantly cause him to become stronger. His powers have gone from being as strong as Super Saiyan 3 Goku to being able to NoSell Super Saiyan God Super Saiyan Vegeta in his base form before unlocking his [[spoiler: Super Saiyan Rose transformation]] that handily curb stomps him. And this is only the start of a series of power-ups that he obtains.
** Hit can improve his TimeStandsStill ability when facing opponents powerful enough to overcome its current limits.
* The [[EldritchAbomination D-Reaper]] of ''Anime/DigimonTamers'' showed an impressive capability for evolution (then again, it operated like a quantum computer); Originally, it ''just'' killed by touching. Then it developed "agents", foot soldiers who kept damaging attacks away from it. These agents then got more and more specialised; some were gunners, others anti-air units, others were scouts, melee fighters, defense specialists, etc. Upon a debilitating EMP attack, it then integrated all of these capabilities into one massive being and overwhelmed the signal. Ultimately, it was considered to be invincible so the only way they could deal with it was to [[spoiler: turn back ''time'' to regress it to a more primitive state, which means that it remained very much alive.]]
* The Evolutionary Invasion Objects in ''Manga/{{Nobunagun}}'' rapidly create new species based on their experiences from past battles. After Nobunagun shoots down a whole battalion of them, the next one they fight has tough armor that her bullets can't penetrate.
* In ''Manga/MagicKnightRayearth,'' the monster Atalante can do this. (What happens when you decide that overwhelming force is the way to go... ''after'' you've let it adapt way too much already? [[OhCrap Very bad things]].)
* One villain in one ''Anime/TenchiMuyo'' manga series had this power. Luckily for Tenchi, it turns out that Lighthawk Wings were much too powerful to copy.
* Taken to an annoying degree with Naraku from ''Manga/InuYasha''. He rarely shows up, preferring to attack through subordinates, but when he does, he's always too powerful to take down with whatever attack was effective against him last time. One has to wonder why Sango and Miroku even bothered to come along with Inuyasha, as their attacks eventually became utterly useless against Naraku and they were pointlessly risking their lives.
* [[BigCreepyCrawlies The Vajra]] in ''Anime/MacrossFrontier'', in episode 17, survive a direct hit from a ''nuclear weapon'' because it had been used against them a few episodes earlier.
** And yet Mecha sized K-bars Knives which have been used the entire series still work just fine on them... That said this isn't as insane as it sounds nor is the feat nearly as impressive as it sounds if one considers the actual physics involved. [[http://www.projectrho.com/rocket/rocket3x.html#nuke Read this and be enlightened]]. Executive Summary: Nukes aren't nearly as lethal in space and the range at which they'll do noticeable damage to anything even vaguely armored is surprisingly short. Nor were the hits in question really direct at least on those we see survive (and going by the stock footage used for the blast not all of them did...) as the missiles looked to be fired more for proximity detonation in the enemy formation then direct impacts.
*** Said range actually measures in tens or hundreds of kilometers even for the basic nukes (an elbow-pushing distance even at LEO), and reaction weaponry in Macross is, in fact, antimatter, that has much greater range. All this doesn't make much sense, but then, do the space battles as they are shown there really [[RuleOfCool have any sense whatsoever]]?
*** No it doesn't range is related to yield as both are just radiation bursts. Actually anti-matter will waste allot of energy if used as a proximity weapon as many byproducts quickly degrade to non-lethal particles within a very short distance. It makes no difference though as footage for the later attacks shows that even after they adapted the weapons were still vaporizing them if they were reasonably close to the blast. That's not what I call immunity.
*** Back on the knife thing, don't forget that the knives are supported by the Valkyrie's point barrier system, which basically lets it cut through armor like butter. It's basically a [[TabletopGame/{{Warhammer 40000}} Power Knife]].
* Byakuran in ''Manga/KatekyoHitmanReborn'' used this to an extend. He just didn't wait until someone used a certain tactic against him, he simply communicated with himself in alternate dimensions and linked their minds together to make himself crazy prepared for anything.
* Nurarihyon from ''Manga/{{Gantz}}'' had this as his power. In addition to adapting to become immune to attacks, he could also beat fighters at their own game by BiggerStick adaptation. [[spoiler:It turns out that he can't adapt to attacks that he can't see coming. The Gantz combatants snipe him to death.]]
* ''Manga/{{Bleach}}'':
** Every time he became injured or close to death, the Hogyoku gave Aizen a new form to counter it. At least until [[HoistByHisOwnPetard the Hogyoku got sick of it and withdrew its support]].
** Yhwach's Schrift allows him to assess everything that's thrown at him and predict accordingly. Haschwalth, then Yhwach himself, both assert that, once Yhwach has seen all that his opponent is capable of (or even what they will do ''in the near future''), defeating him is next to impossible.
** Mayuri Kurotsuchi reveals in the Vandenreich arc that he modified his Bankai to give it this ability. After gathering information on an enemy, it "gives birth" to a creature most suited to fighting it.
** Sternritter "D" of "The Deathdealing" Askin Nakk Le Vaar has this as part of his PoisonousPerson powers; by taking in a large amount of the substance he intends to make lethal, he can no longer be killed by said substance because he can adjust his resistance to it. It also works wonders for defense in that he tanks his opponent's attacks before adjusting his resistance to their Reiatsu, thus rendering all subsequent attacks useless.
** Urahara Kisuke's bankai has the ability to dissect and modify anything it wishes. When used defensively, it can take something damaged and make it stronger, and help it recover from or even resist whatever damaged it in the first place. Combined with his analytical mind, which enables him to [[ItOnlyWorksOnce counter any ability]] he's adjusted to, this makes him an extremely adaptable opponent and nigh-impossible to beat if you fail to do so in your first attempt.
* In ''Anime/ElHazardTheMagnificentWorld'', Ifurita seems to become immune anytime she's hit with a magic attack. And then she uses it on you...
* Gourmet Hunters in ''Manga/{{Toriko}}'' have this due to being infused with Gourmet Cells as well as their personal abilities. Most of them have AcquiredPoisonImmunity due to this.
* Kira Yamato with his [[spoiler: Ultimate Coordinator]] abilities in ''Anime/MobileSuitGundamSEED''. With his increased thought process speed and reflexes, he could reprogram his Gundam's Operation Systems to optimal efficiency matching his environment and situation, in mid-battle.
* Played with in a strange way in the 2003 ''Anime/AstroBoy'' series. Astro was built with the ability to evolve and adapt to any situation making him potentially one of the strongest Robots every created. However his reluctance to fight despite being pushed into it means he never fulfills his potential. He gains all his staple abilities (jetpack flight, a finger laser and an arm canon) within the first handful of episodes and never evolves any further than that because he never needs to.
* In ''WebComic/OnePunchMan'', Garou has the ability to heal and grow stronger every time he is defeated. By fighting [[OneHitKill Saitama]], he eventually becomes a nigh PhysicalGod. [[spoiler:Spoofed when Saitama continues to crush him, and his body decides he can't evolve any farther, so he starts ''devolving'' with each attack until he returns to ordinary human levels.]]
* ''Anime/NeonGenesisEvangelion'': The 11th Angel, Iruel, is a microscopic collective that evolves extremely rapidly in response to any stimulus as it spreads, making it nigh-impossible to combat. It's eventually defeated by having the MAGI simulate for it a situation in which the optimal evolution was to die, tricking the Angel into killing itself.
* In ''Manga/StealthSymphony'', this is protagonist Jig's main power, combined with CatchAndReturn: Any attack targeted at him done with intent to harm him will be automatically caught and nullified by a backpack-like device [[ClingyMacguffin stuck to his back]], which will then generate the same type of attack at double power back at the attacker. In spite of how overpowered this sounds, however, it has a number of loopholes, which Jig's enemies [[LoopholeAbuse quickly learn to exploit]].

[[folder:Card Games]]
* ''TabletopGame/MagicTheGathering'':
** The Slivers' more prominent traits were their fast evolution rate, adapting to overcome anything thrown at them. However, what made them so dangerous (both in the story and in game) was their species trait of ''sharing'' their adaptations with all other slivers in proximity. However, in-game, the slivers' abilities were conferred onto Slivers ''on all sides'', so a Sliver MirrorMatch could turn out deadly. Not to mention that there are some slivers with negative effects thrown in just to counter all-Sliver decks.
** The Phyrexians are half-mechanical monstrosities who constantly seek to improve themselves. In the novel ''Literature/TimeStreams'', Phyrexian leader Kerrick uses this ability, coupled with the fact that he lives in a fast-time bubble, to stay several steps ahead of Urza.
* ''TabeltopGame/SentinelsOfTheMultiverse'' villain Omnitron has a card called Adaptive Plating Subroutine. After getting hit by an attack, he becomes immune to damage of that type. Thankfully when he gets hit with a different type he switches immunities to the new type, so he is only ever immune to one type of damage at a time.

[[folder:Comic Book]]
* [[Comicbook/TheDeathOfSuperman Doomsday]] and (in UsefulNotes/{{the Silver Age|OfComicBooks}}) the Calculator and the Shaggy Man from Franchise/TheDCU. Doomsday is a notable example because his Adaptive Ability allows him to literally [[ResurrectiveImmortality come back from the dead]] immune to whatever killed him in the first place on top of his HealingFactor. It says something when Franchise/TheDCU heroes, after exhausting just about every option available to hurt/kill him, eventually had to send him to [[AfterTheEnd the end of time]] just to stop his rampage. In some stories, Doomsday becomes able to adapt offensive abilities to counter his opponents. For example, when fighting ComicBook/MartianManhunter, he becomes able to hit intangible beings and breathe fire as fire is a Martian's weakness. When Superman tries fighting him at a distance, he becomes able to fire his spikes like harpoons.
* Lots of anti-super robots in the Franchise/MarvelUniverse: later models of the mutant-hunting Sentinels (especially in the BadFuture of ''Comicbook/DaysOfFuturePast'', the Fury (from ComicBook/CaptainBritain's adventures), and the Shiva series.
* The [[MeaningfulName appropriately-named]] Darwin of the Comicbook/XMen has this as his mutant power -- he will immediately mutate whatever he needs to survive. Immerse him in water and he'll grow gills, burn him and he becomes fireproof, poison him and his body chemistry shifts to neutralize it, etc. It's really too bad that it only happens as an unconscious survival mechanism; with control over that power he'd be damn near omnipotent. It should be noted that his powers don't always give him the ability needed to ''win'' a fight, only to survive. When faced with [[ComicBook/IncredibleHulk the Hulk]], he gained the ability to [[ScrewThisImOuttaHere teleport several states away]].
* Random, another Marvel mutant, whose other power was [[ArmCannon turning his hands into guns]].
* There was a robot called appropriately the Super Adaptoid that did this. In one comic, it was defeated by [[ComicBook/FantasticFour Ben Grimm]] who was his normal human self at the time, but wearing a [[PoweredArmor suit]] that still gave him SuperStrength. Ben Grimm tricked the Adaptoid into copying his normal human self, then used the suit's power to punch the Adaptoid out in one blow.
** An early X-Men comic during the Mimic's brief tenure as a hero pitted him against the Super Adaptoid, that had already perfected the abilities of ComicBook/TheAvengers. After beating everyone else, including Professor Xavier, the Adaptoid fought the Mimic to a standstill until the Mimic threw the match and psychically convinced the Super Adaptoid to copy his powers. The Mimic's own power was to copy other people's powers, just like the Super-Adaptoid. The attempt to copy that power exceeded the Super-Adaptoid's capacity to duplicate. The feedback also temporarily shut down the Mimic's powers.
* ComicBook/{{Apocalypse}} caused battles for evolutionary purposes. When the X-Men beat his men, he thanked them for weeding out the weak.
* Lobo has this, as a side-effect of his HealingFactor. As with most of his powers, how effective or what it works ''on'' varies wildly between stories and writers. One notable problem arose when a magic spell de-aged him, and also resulted in him become immune to that kind of magic. Unfortunately, the traditional ''cure'' for his condition was from the same type of magic... And Marvel's even-further-over-the-top Lobo parody [[http://www.marvunapp.com/Appendix2/lunatikmerc.htm Lunatik]] has been adapting for six hundred million years, having started as a microbe and eventually eating all life on his homeworld.
* The ComicBook/UltimateMarvel version of Comicbook/IncredibleHulk has this to a degree-- he has adapted to environments as extreme as the (simulated) surface of [[DeathWorld Venus]]. This is also the reason why his condition can't be cured -- his body adapts to whatever agent is used to prevent the change. Mainstream Hulk has this too, but to a lesser degree and with less consistency since it's one of his lesser known/used/liked powers. He's been shown adapting the ability to breathe under water and survive the vacuum of space for extended periods.
** The ComicBook/UltimateMarvel version of ComicBook/{{Wolverine}} is implied to be the same; in addition to regenerating damaged tissue, his HealingFactor can modify his physiology to compensate for life-threatening injuries. [[spoiler: For example, decapitating him resulted in him developing the ability to directly oxygenate the blood for his brain through his skin. When his severed head was put in a total vacuum, he went into stasis until brought out.]] Ultimate Nick Fury theorizes that Wolverine's mutant power is less "HealingFactor" and more "survive anything".
* Another X-Men mutant, Lifeguard, gets whatever power is needed to save ''someone else''.
* Marvel's alien Kree were stuck in an evolutionary dead end, unable to adapt or mutate; so after trying a number of less-than-ideal solutions ([[NoBiochemicalBarriers breeding hybrids with other species]] led to [[AllOfTheOtherReindeer social stratification and prejudice]], setting off a mutagenic bomb led to-- well, a huge frikkin' ''bomb'' that killed half their population and left most of the rest sick and dying) they eventually turned themselves into the Ruul, who can self-adapt to any condition. Later writers seem to have undone most of this for no apparent reason.
* One of Comicbook/SpiderWoman Jessica Drew's original powers was that she became immune to any poison after being affected by it once.
* ComicBook/{{Legion of Super-Heroes}} member [[spoiler:and eventual traitor]] Nemesis Kid had the power to gain whatever abilities were needed to defeat any single opponent. [[spoiler:This backfired when he faced Projectra, after murdering her husband Karate Kid. His powers gave him the ability to see through her illusions, but when he tried to gloat over her helplessness, she [[Awesome/{{LegionOfSuper-Heroes}} snapped his neck with her bare hands]].]]
* Whenever DC's ComicBook/ResurrectionMan is killed by something, he is reborn immune to the way he died. In fact, when he was killed by extreme pain, [[GenderBender he came back as a woman]], because women are [[ScienceMarchesOn supposedly]] more resistant to pain.

[[folder:Fan Works]]
* In ''Fanfic/CoOpMode'', as usual for Gamer fanfics, James has this, and so do those in his Party. So far, he has gained AcquiredPoisonImmunity, DamageReduction to both ElementalPowers and physical attacks, and even a partial resistance to [[TimeMaster Clockblocker's]] power!
-->''Quote for <Time Resistance>'': "'''[[CrowningMomentOfFunny BULLSHIT!]]'''"
* ''FanFic/HereBeDragons'': Taylor's power starts out as a minor version of this, logical, due to possessing Lung's transformative powers. Later, [[spoiler: Contessa]] forces a second trigger event, giving her a far more potent version of this ability.
* Freddie gets this power in ''[[http://www.fanfiction.net/s/8532906/1/iFightCrimeWithVictorious iFight Crime With Victorious]]''. Useful, considering his number 1 aggressor aka Sam Puckett now has superhuman strength to torture him with.
* Taken to its logical extreme and closing off all loopholes along the way: The ''Manga/RanmaOneHalf '' fanfic ''[[http://www.talesfromthevault.com/relentless/ Relentless]]'', where the [[EldritchAbomination Reikoku]] has this ability. It's an unusual take as in the story, the Reikoku adapts to the characters' [[SupernaturalMartialArts techniques]].
* In ''Fanfic/TheBridge'', Enjin boasts that whatever kills him makes him stronger. After Kaiser Ghidorah breaks several of his bones including his neck and then throws him into a river, he crawls out and instantly heals with his body reinforced so it won't happen again. After Monster X hits him several times, his skin toughens up so that X hurts his own hands when he tries to punch him. The only way to beat him is to [[spoiler:knock him into the air so that he cannot draw strength from the ground and regenerate, then destroy his [[SoulJar core]]]].
* ''[[Fanfic/RyuugisTheGamesWePlay The Games We Play]]'':
** Hydras are an entire Grimm species with this as their main ability. They develop resistances and countermeasures to whatever hurts them. As a result, with few exceptions, Hydras are either killed young when a large number of Huntsmen fall on them like a tonne of bricks before they can develop any useful resistances, or not at all. As different Hydra adapt to deal with different threats, MixAndMatchCritters is the result on stronger Hydras.
** [[spoiler:Gilgamesh]] has an active version of this. Named "Intelligent Design", he is not limited to reacting to harm but can actively transform himself to gain the abilities needed to fight his enemies.
* In the AlternateUniverse ''Literature/{{Worm}}'' fanfic ''FanFic/{{Intrepid}}'', Anne's power set basically allows her to fully understand someone's power with a touch and then use a power to counter it. Such as using a cold wave to get rid of Lung's pyrokinesis and a teleportation power to get rid of Lung far enough to where he'll cool down.
* In the VideoGame/FinalFantasyVII fanfic, [[FanFic/CissneisPath Cissnei's Path]], Jenova possesses this as its key trait, making it hard to put down.
* ''[[http://fanfics.me/read2.php?id=127043 A RWBY Zanpakuto]]'':
** Ulquiorra's body adapts to threats whenever he heals. For example, when his head gets damaged, his brain redistributes itself through his body so that he cannot suffer brain damage anymore. When his eyes get damaged, his body sprouts eyes all over. He still loses because healing and adapting drains his energy until he can't do it anymore; it just takes a lot of work to get that far.
** The Hogyoku grants Aizen "Intelligent Design", the ability to actively alter himself to counter his enemies.

[[folder:Films -- Animated]]
* Syndrome's Omnidroid in ''WesternAnimation/TheIncredibles'' is a much more mundane version of this, insomuch as anything involving a giant robot can be mundane. The Omnidroid's A.I. is programmed to analyze and understand anything used against it, and then adapt its tactics accordingly. The Omnidroid was tested against supers, and whenever a version was destroyed, [[XanatosGambit Syndrome just built a new version based on that data and tested it against the same super]] (invariably defeating them). Throw rocks at it? It'll throw boulders back. Toss it in lava? It's {{Nigh Invulnerab|ility}}le and then will bathe its claws in lava to turn them red-hot. Outspeed, outmaneuver, or outthink it? The next version is faster, more agile, and smarter. [[spoiler:Control it using a remote? It will realize what's going on and attack the remote, removing it from your access. [[GoneHorriblyRight Syndrome finds this out to his own detriment when he attempts to stage a fight with the final version]].]]
* In ''WesternAnimation/DoctorStrangeTheSorcererSupreme'', Strange has the innate ability to absorb and adapt a defense for any magic thrown at him. Thus he goes from on-the-skids Muggle to Sorcerer Supreme in the course of one film and a grand total of one BossBattle.

[[folder:Films -- Live-Action]]
* The Xenomorphs from ''Franchise/{{Alien}}'', as they have the ability to breed with any organism and take [[LEGOGenetics genetic material]] from them, thus adapting to whatever environment the organism in question comes from.
* The enemy in the 2001 film ''Film/{{Evolution}}'' and its AnimatedAdaptation, ''WesternAnimation/{{Alienators|EvolutionContinues}}''.
* ''Film/XMenFilmSeries'':
** ''Film/XMenFirstClass'': Darwin's ability involves his body making whatever changes necessary to keep him from dying in whatever environment he's in, such as growing gills while underwater.
** ''Film/XMenDaysOfFuturePast'': The Sentinels in the BadFuture have the ability to adapt their structure, powers and strategy to counter the mutants, allowing them to win in almost any scenario. They got the ability from 50 years of research on Mystique's DNA. The only way to beat them is using time travel to prevent their creation.
* In ''Film/ShinGodzilla'', Godzilla quickly mutates to counteract new challenges, acclimating to consume radioactive waste, "evolving" stronger legs to walk on land, and [[spoiler: gaining a BeamSpam attack to defend itself]].

* In ''Literature/{{Worm}}'' the villain Crawler has this power. Whenever he suffers an injury, he regenerates and becomes slightly more resistant to that type of injury as well as more dangerous overall. He obsessively seeks powerful enemies to deal damage to him so that he can grow stronger.
* Titan from ''Literature/SuperPowereds''. His power responded to frustration so that not only would he become tougher if he was ever actually hurt by a physical attack, but he would also become stronger if he ever failed to overcome a physical challenge like lifting a heavy object. He also reveals that [[spoiler:his son Hershel inherited a different version of the same power. When kids were bullying him in school, Hershel's power manifested as his SuperpoweredAlterEgo Roy, who is stronger, more muscular, taller, and more social than Hershel. Everyone thinks that Hershel is just a shifter, until Titan reveals that Roy is a manifestation of Hershel's ideal self. This comes up, when Roy hits his physical limit, unable to lift 800 lb weights no matter how many times he's able to lift 750 lb weights. Titan explains that Hershel needs to start pushing himself in training as well, allowing his adaptive ability to raise Roy's {{Cap}}]]. For Titan, this also applies to superpowers. Certain abilities no longer affect him (as much) after the first exposure. For example, when Aether tries to phase him through a wall, it doesn't work, because Titan once fought a criminal super with a similar power, so his body adapted to counter it. He ''could'' temporarily disable it, but he has to constantly focus on it. HealingHands also don't work on him for the same reason, but he has a limited HealingFactor to compensate. He specifically told the government to keep a certain super on-hand with the power to cause fatal brain aneurysms in order to take Titan down, if he ever turned rogue. It would only work once, though, as a botched attempt would make him immune.
* In ''Literature/MySistersKeeper'', this reason is used to explain why none of the treatments for Kate's leukemia work more than once.
* In the ''Literature/SwordOfTruth'' series, [[spoiler:the beast from the underworld]] is said to adapt to prevent one strategy from working on it more than once. Ironically this works to its detriment--while a given strategy only works once, as a creature of chaos its methods and weaknesses are totally ''random''. On at least one occasion, it had the heroes entirely dead to rights, but for the fact [[DeusExMachina its current form dissolved in water, discovered just as it starts to rain]].
* In the novel ''Literature/{{Meg}}'', blinding the giant shark made it deadlier, as its other senses compensated for its blindness and now it could hunt during the day.
* In ''Literature/LastAndFirstMen'', the Martians do this while fighting the Second Men. [[SciFiWritersHaveNoSenseOfScale Over the course of several thousand years, naturally]].
** The shorter timescale is partly down to the Martians' very unusual biology and partly due to the fact that [[ScienceMarchesOn genetics was very poorly understood when the novel was written.]] The structure of DNA wouldn't be identified for another quarter century, for example.
* In Creator/GregEgan's ''Teranesia'', an evolving organism is apparently able to anticipate future challenges and develop appropriately.
* In Stephen King's ''Literature/TheStand'', what made the superflu different from the normal flu (and much deadlier) is its ability to change to fight the antibodies the human organism generates to fight the virus, until your defenses can't stand anymore.
* This trope is played for tragedy and to kill all remaining hope in the sci-fi novella ''With Folded Hands...''. A man creates a perfect race of robots to cater to humanity and stop them from killing each other after his home planet was wiped out by civil war. It works too well and the robots begin stripping humanity of its freedom, planet by planet. A man uses rhodomagnetics, the force discovered by the creator and what allows the robots their highly advanced functions, to slip under their radar and attempts to assassinate the creator for dooming mankind. He's stopped, and the creator [[MyGodWhatHaveIDone only then realizes what the robots are doing]]. He jumps from colony to colony, staying ahead of his creation while attempting to create a weapon that will destroy his lifeless homeworld, where the central network is located. He finishes and fires the weapon, only for it to fail. Robots arrive at his residence and inform him that after the assassin, they engineered a way to detect and neutralize rhodomagnetics applied against them, effectively shielding the planet from the weapon. [[DownerEnding This dashes mankind's only hope to free itself from the robots.]]
* The Vord in ''Literature/CodexAlera'' definitely qualify. When we first run into them, they're a bunch of creepy spiders who spin wax instead of webs. Then there are big warrior beetles, and little spiders that can [[PuppeteerParasite take over your brain,]]. And that was back before they got scary. They could quickly create entire new species and [[ExplosiveBreeder generate massive numbers]] of them. They see human knights in armor? Suddenly there are heavily armored humanoids with swords to fight them. Make a wall of shields? Now there are enormous mantises with [[SinisterScythe sickle-arms]] that can reach over the shields and disembowel you. Oh, you can fly with magic? How about warriors with [[WingedHumanoid dragonfly wings]]. Team up with huge wolf-men? That's okay, we've got a [[LightningBruiser vord]] for that too. Build a massive wall just to keep us out? How about a Vord the size of a ''[[AttackOfThe50FootWhatever Gothic cathedral]]'' smashing into your wall! Wow, good thing you have that amazing magic that we can't quite seem to get hold of... [[OhCrap oh]]. [[AwesomenessByAnalysis Nevermind]].
** And to make matters worse, they're [[AbsoluteXenophobe obsessively xenophobic]], want to TakeOverTheWorld, aren't fussed about whether they do it by [[AssimilationPlot assimilating us]], [[KillEmAll slaughtering us]], or [[ImAHumanitarian sticking us in wax to digest to death]], and are [[HiveMind controlled]] by a Queen who's the [[UncannyValley stuff of]] nightmares [[PsychopathicManChild all by]] [[AGodAmI herself.]]
* The Inhibitors in Creator/AlastairReynolds' Literature/RevelationSpace Verse have this ability, there's some interesting character speculation about whether they are really adapting or whether they're downloading countermeasures from an extant database whenever they encounter a new weapon
* In ''Literature/{{Dune}}'', the Bene Gesserit (and those trained in their methods like Paul Atreides) have the ability to change their internal chemistry. This makes them immune to poisoning, as they will simply change the composition of the poison to something that is not lethal.
* The sword of Gryffindor in ''Literature/HarryPotter'' can't be destroyed; as a weapon made with goblins' special magic and metalwork, it simply takes in the power of whatever it encounters. For example, when in ''The Chamber of Secrets'' [[spoiler:Harry uses it to kill the basilisk, it becomes imbued with basilisk venom]].
* The Vlagh and its creatures in Creator/DavidEddings' Dreamers. They adapted to every trick the protagonists use in the previous battles... only to have them devise more. They also forage the battlefield for dropped weapons. Eventually they evolved to the point they had [[spoiler:eight arms on some of the creatures... each carrying four bows]]. This caused the protagonists some anxiety. [[spoiler: [[TooDumbToLive At least until they saw the creatures using the bows...as maces.]]]]
* This is the effect of Mobium in ''Literature/SuperheroesAnonymous''.
* In ''LightNovel/ACertainMagicalIndex'', Fraulein Kreutune has a brain that rapidly absorbs information from her surrounding environment, causing her body to change in response.
* ''Literature/ReleaseThatWitch'': The more witches use their magic, the more magical energy they can store within their bodies, and the more they comprehend the world around them and how their magic feeds into it, the more powerful their abilities become. For instance, after Anna understands how heat works at an atomic level, she gains the ability to form her "flames" into any shape she wants, including planes, lines and other geometric shapes.

[[folder:Live-Action TV]]
* The Borg from ''Series/StarTrekTheNextGeneration'' are explicitly described as being able to adapt to anything used against them, so most weapons will only work two or three times before they're useless.
** [[RockBeatsLaser Melee attacks have a better chance of succeeding]], but you're still fighting a cyborg with super-strength. Worf and Data do fine, but a RedShirt tried to [[PistolWhip rifle butt]] a drone and got trounced. Data rampaging in Engineering also got him thrown behind a forcefield eventually, if only because the Queen was in the room.
** Also note that in ''Elite Force'', Seven came up with the [=IMod=] (Infinity Modulation Weapon), a weapon with infinite, random energy signatures that change after every shot to take out the Borg.
*** The [=IMod=] only works because it unleashes devastating energy in a single burst (at least against the Borg), and also automatically changes energy signatures. Normal phasers and phase rifles can do the same thing as the [=IMod=], but must be manually changed to new frequencies, and are limited in power. Human (and alien) imagination being what it is, it's not possible to keep coming up with random frequencies.
*** Except maybe by randomly punching keys.
*** In the first mission of the sequel (taking place in parallel with the GrandFinale of ''Series/StarTrekVoyager''), the Borg aboard the sphere come up with a counter to the I-MOD by generating an interference field that disables the weapon, forcing you to rely on other weapons and use them sparingly.
* The Federation itself is a milder example than the Borg, but they have been somewhat accurately compared to the Borg before, in both the assimilation aspect and the adaptation. Admittedly, they are never the villains of the show from a normal perspective. [[spoiler:Except for Section 31.]]
** Whenever they are faced with a cloaking device that actually cloaks a ship from their sensors, the Federation quickly begins work on adapting sensors.
** When the USS ''Odyssey'' is destroyed and the ''Defiant'' later disabled easily by mere Jem'hadar fighters (that later on become little more than cannon fodder) using "some kind of phased polaron beam", the [[Series/StarTrekDeepSpaceNine DS9]] crew sets about developing countermeasures. Sure enough, without any further fights with the Jem'hadar, the ''Defiant''[='=]s shields have been adapted by O'Brien and his teams to block the phased polaron fire, if only for a few shots. After "[[Recap/StarTrekDeepSpaceNineS05E02TheShip The Ship]]", the polaron beams are no longer any more effective than phasers or disruptors.
** The Breen energy-dampening weapon can easily disable Romulan, Klingon, or Starfleet ships even with shield and ablative armor. For a while the only defense is a modification to the tritium intermix of the warp core--but only Klingon ships have one. At most two episodes after Kira, Odo, Garak, and [[spoiler:Damar]] steal a Jem'hadar fighter being retrofitted with the energy-dampening weapon in "[[Recap/StarTrekDeepSpaceNineS07E22TackingIntoTheWind Tacking Into the Wind]]", Starfleet engineers have worked out how to completely counteract the weapon for Federation and Romulan ships.
** The entirety of the Federation's fight/contingency against the Borg after [[Recap/StarTrekTheNextGenerationS3E26S4E1TheBestOfBothWorlds the Battle of Wolf 359]] is a massive quest to adapt their technology to be able to effectively fight the Borg, adapt their weapons and shields in combat just as the Borg do, and generally out-adapt the Borg just enough to survive and win the day, with overkill being happily accepted.
* The Cybermen of ''Series/DoctorWho'' have always had traits of TheAssimilator, but this aspect gets focused on in the incarnation introduced in "Nightmare in Silver" (apparently, a fusion of the original Mondasian Cybermen and the newer Cybus Cybermen). Sometimes you'll take a few of them down before they adapt - others, it won't cost them a single unit.
* An episode of ''Series/TheOuterLimits1995'', "The New Breed", had a man infested with {{Nanomachines}} programmed to heal and protect his body, which they did [[LiteralGenie mindlessly and efficiently]]-- he nearly drowns and grows gills, he gets beaten up and grows extra layers of bone, and his skin develops poison glands like a jellyfish, so ''no one can touch him''. They also, for some reason, decide that having a limited field of view is a flaw, so they grow an extra pair of eyes on the back of his head.
* ''Series/{{Smallville}}'''s version of Doomsday, like his comic counterpart, has this ability; as his "mother" Faora put it, "What kills you makes you stronger".
* The Replicators from ''Series/StargateSG1'' have essentially the same adaptability level as the Borg from ''Franchise/StarTrek''; they, too, cannot seem to adapt to [[KineticWeaponsAreJustBetter being shot with a machine gun]], until Season 5...Viva La Evolution!
** Ditto for their cousins the Asurans in ''Series/StargateAtlantis'', although they are already in humanoid form when they encounter the Atlantis team. In one episode, dozens of Asurans throw themselves at a shield that disintegrates them, until, finally, the rest adapt and are able to pass.
* ''Series/UltramanMax'' had an extreme version: IF is a monster that can counter anything with itself. Max blew it apart with the Max Shot, it regenerated instantly and fired it right back at him! He never defeated it..
* ''Series/MightyMorphinPowerRangers''
** The War Zord Cyclopsis acted like this after it was rebuilt by Lokar. In a bit of a subversion, that "evolution" disappeared after the Rangers retreated and when they came back to fight, they knew how to overcome it (rapidly switching tactics). "Overload! Overload! Too many changes!"
** Hatchasarus was repeatedly destroyed and would reassemble with more bling (though not necessarily directly related to what had killed him before.) He can't be taken down for good until Cardiatron (the giant, floating ''heart'' that is its central computer) is destroyed.

[[folder: MultipleMedia]]
* Reidak from the ''Toys/{{Bionicle}}'' series. Specifically, any power used to defeat him will be ineffective for the next go around (i.e. he gets knocked down by a giant fist of earth and won't feel a thing if it happens again, even if the fist of earth is twice as big). However, the power seems to have a "reset" function after a battle, and unlike [[Creator/DCComics Doomsday]], he won't be coming back from something that actually ''kills'' him.

[[folder:Other Sites]]
* ''Wiki/SCPFoundation''
** [[http://scp-wiki.wikidot.com/scp-682 SCP-682 ("Hard-to-Destroy Reptile")]] of the ''Wiki/SCPFoundation'' is a reptilian [[HealingFactor regenerating]] OmnicidalManiac who also possesses this power. They try to shoot out its eyes, it grows several new sets covered in armor plating. They try to poison it, it starts spraying out jets of high-pressure blood to get the poison out. Thankfully, the adaptations wear off after a short while. This is the main reason they refuse to use [[NukeEm nuclear weapons]] on it: if it survives, it'll be immune to pretty much ''anything.'' The Foundation once tried to kill it by using an [=SCP=] with the [[RealityWarper power to change the universal constants of physics within its boundaries]]. 682 not only adapted to survive as it always does, it found the experience ''fun''.
** [[http://www.scp-wiki.net/scp-1550 SCP-1550 ("Dr. Wondertainment's Custom-Pets™")]]. When their eggs (called Adapto-Eggs) are placed in a certain environment, they will hatch into a creature suited for that environment, e.g. putting one in water will cause it to develop gills and flipper-like tails. Although putting the eggs somewhere inhospitable (e.g. a vat of molten iron) will destroy them.

* Parodied by the Haggunenons in ''Radio/TheHitchhikersGuideToTheGalaxy'', who would shapeshift into seemingly random "adaptations" because they have "the most impatient chromosomes in the Galaxy".

[[folder:Tabletop Games]]
* The epic level [[TabletopGame/DungeonsAndDragons D&D]] monster, the Infernal, has this as a specific power, only able to be affected by a spell once from the same spellcaster.
** At lower level there is the skindancer, which has pretty good resistance to the last weapon type that struck it, and the last magical energy type that affected it.
** In the red box edition, the master's level book described the Adapters, who develop a temporary immunity when struck by an elemental attack.
** In 4th edition, all demon type enemies gain the ability to immediately become resistant to any elemental energy type attack (acid, cold, fire, lightning, thunder) after you hit them with it once. So something that doesn't put them down on the first hit will be much weaker against them the second time.
* ''TabletopGame/{{Warhammer 40000}}'' has the Tyranids:
-->"We fought them the first day, and our guns tore through them with ease. We fought them the second day and saw our missiles bounce of a thickened skin they seemed now to bear, so we turned our lances on them. We fought them the third day, and no cursed thing worked!"
** Even worse: Not just one of them, but at least ''that entire fleet'' you are fighting can get that characteristic.
** The Tau were able to exploit this: by getting their Kroot allies to take on Tyranids in forests, particularly agile but also rather fragile Gaunts were produced that had adapted extremely well to fighting arboreal warriors...then they drew the 'Nids out of the forests and opened up with their usual array of {{BFG}}s.
** This is also believed, both in-universe and out, to be how some Tyranid lifeforms came to be. The psyker-like Zoanthropes are thought to be derived from Eldar psykers, and the extremely resilient Tyrant Guard may have been cultivated from Space Marines.
* ''Mechanon'' is a standard recurring (and overarching) BigBad from ''TabletopGame/{{Champions}}''. Each time he is defeated (even if destroyed, he's rebuilt), he returns immune to the last attack that killed him, and often with weapons to which his prior nemesis is particularly vulnerable. If fought long enough, he truly becomes unbeatable.
* Unsurprisingly, ''TabletopGame/MutantsAndMasterminds'' features a power or two for this. "Adaptation" works like it says. Then there's "Nemesis"- every round you pick one person to be your nemesis, and you get X points worth of powers suited to fighting them (X being based on your power rank). The catch is that while you are free to suggest things, the GM has final say on what you get, and can distribute things however he likes (he could give you one strong useful power, 2 medium-strength, fairly useful powers, 10 weak powers of varying helpfulness...)
* In ''TabletopGame/{{Exalted}}'', one Charm the Lunar have allows them to render themselves immune to the first weapon classification to hit them in a scene. This is somewhat mechanically awkward because weapons aren't classified in a way that makes this make sense as it's written[[note]]according to some readings, a punch could render you immune to all bludgeoning weapons, or to all martial arts weapons, or to all non-artifact martial arts weapons and so on[[/note]], but it's the thought that counts.

[[folder: Video Games]]
* ''VideoGame/ResidentEvil6'' introduces a new species of [=B.O.W=] called the J'avo that can do this, with about a dozen different mutations that can occur depending on if you've been targeting their arm, legs, torso or head. Plus, multiple mutations can occur on the same J'avo, so you can give them two different arm mutations, a head mutation, a torso mutation, and legs mutation. Plus, there's a rare chance of them cocooning themselves to undergo a "Complete Mutation", emerging as a coherent but much tougher variant of [=B.O.W=], with several different outcomes, ranging from the armor-plated LightningBruiser Napad to the dart-throwing, {{wall crawl}}ing Strelat.
* Pringer X, the ultimate bonus boss in the remake of ''VideoGame/{{Disgaea 2|Cursed Memories}}'' and ''VideoGame/{{Disgaea 4| A Promise Unforgotten}}'' possesses an ability that makes it completely immune to whatever special attack it was hit by for the rest of the battle. Made more complicated by the fact that when you fight more then one of them at the same time later on, all of them become immune to the attack.
* Cubia from the first four ''[[Franchise/DotHack .hack//]]'' [=PS2=] games.
* Most [=RPGs=] have at least one boss that adapts to the elements you attack them with, resulting in a literal ElementalRockPaperScissors as you try to switch the elements of your attacks to be the opposite of your last one or whatever it has shifted to. Can be frustrating if you misstep, because the wrong element will usually fully heal the boss.
** The Tetramorph in ''VideoGame/FinalFantasyX''.
** At least one monster in every other ''Franchise/FinalFantasy'' game as well.
** Most ''Franchise/FinalFantasy'' bosses are actually a variant: they're weak against one specific element and absorb all others, but can randomly change the element they're weak against. This is usually called "Wall Change" or "Element Change" or something similar.
** ''VideoGame/BreathOfFireIII'' has a lot of these as well.
** The Golem in ''VideoGame/ChronoTrigger'' not only defends against the attack type used on it, but begins attacking using that type. This trait makes it very dangerous to the unprepared, it also makes it one of the easiest bosses to beat. With the right equipment and the right attacks, it's very easy to force the Golem to use attacks that are very inefficient against you. In a NewGamePlus, it's stupidly easy to force Golem to use attacks that ''heal'' you. Alternatively, if you have a full range of elemental attacks, the Golem can simply be forced into an endless pattern of elemental charging so long as you never use the same element in succession (assuming you can keep up with the MP cost).
* ''Franchise/{{Pokemon}}'' has two: the Porygon series and Kecleon.
** More specifically, [=Porygon2=]'s [=Conversion2=] move and Kecleon's Color Change ability. [=Conversion2=] is rather more limited, since the nature of Pokémon's ElementalRockPaperScissors means that the type it changes to is randomly chosen from the types that resist the last attack. Color Change is a more typical example.
** Ironically, since Ghost and Dragon-types are weak against themselves, using such a move on Kecleon actually makes it weaker to these attacks then it was before (It starts off respectively immune and neutral to them). Oops.
** Variations of the glitch [[TheMissingno MissingNo.]] had no [[ElementalRockPaperScissors type]] themselves, and therefore took the type of the last Pokemon loaded.
** There's also an ability called Adaptability, but it only powers up move of the same type (more than usual).
** The ability Download boosts the attack stat of the Pokemon based on which of the defense stats of the opponents is lower.
** Sometimes invoked by players in the more random battle facilities in the series - Battle Tower, Battle Frontier, Battle Subway and Battle Maison - as part of the AI. Jossed by RNG-researching hackers who assert that opponents' sets do not take player Pokémon into account. Some players go well beyond streaks of 50, 100 or 200 victories to attain 1,000 or more wins in a row.
* The fallen Levant's (OneWingedAngel?) monster form in ''Jade Cocoon 2'': he occasionally gains immunity to the element of the side of the [=BeastAmulet=] that's been used to attack him. When this happens, he summons a pair of lesser Divine Beasts of the same element he just immunized himself against and they prevent you from attacking him by becoming the only available targets. Attacks with any other element will damage him as normal, [[ElementalRockPaperScissors and attacks of the opposite element are particularly effective]], but a few turns after the lesser Beasts have both been killed, the cycle repeats. So the fight continues until you've defeated him.
* ''VideoGame/WarningForever'' has this as its main mechanic: a time attack boss rush where the boss repeatedly comes back stronger in a way that seeks to counter how the player destroyed it in the last round. For example, if it was defeated by having its rear armor destroyed, its next form will have more armor on its rear. It also changes which weapons it adds depending on how effective they were (e.g. if it killed the player using lasers frequently in one round, expect it to have a lot more lasers in the next round).
* Warlock Nether Protection and Death Knight Acclimation talents in ''VideoGame/WorldOfWarcraft'' work somewhat like this. They have a chance to reduce the damage taken from the school of the last spell that hit you.
** There's also some creatures, notably certain types of Voidwalkers, with an ability like this. Hit them long enough with one spell school and they not only gain an immunity for that type of damage, but can now use an [=AoE=] spell of that type.
* Arcueid from ''VisualNovel/{{Tsukihime}}'' claims such an ability. She was immune to conventional weapons to begin with, and gained immunities to conceptual weapons as they were used to fight her. When Shiki killed her, she was sure he used some obscure far eastern conceptual weapon. In a slight subversion, she can't become immune to that particular ability, either.
** The manga adaptation gives the same ability to Roa, a vampire (accidentally) created by Arcueid. He demonstrates it in his battle against Ciel - by the end of the fight, her signature Black Key swords have become so ineffective that being impaled by several dozen at once barely phases him.
* In ''[[VideoGame/NexusWar Nexus Clash]]'', Nexus Champions can do this with their aptly named Tattoo of Adaptation, requiring their would-be killers to bring more than one kind of weapon - or some friends.
* In ''Videogame/{{Nethack}}'', you. If you manage to kill a red dragon, eat his corpse, and you're immune to fire. The next red dragon's fire breath might damage your equipment, but will not do much damage to you. Same goes for several immunities.
* This is pretty much the point of the Zerg in ''VideoGame/StarCraft''. Notably, their upgrade building is called the "Evolution Chamber," in which the Overmind pits hundreds of zerg warriors against each other and only keeps the strong, and is also the fluff explanation for the origin of Banelings.
** In the campaign of ''VideoGame/StarcraftIIHeartOfTheSwarm'' approximately half the evolution missions involve zerg exposed to various environmental hazards (acid pools, lava, [[NuclearNasty experimental nukes]]...) in order to grant them new abilities. In the other half the zerg absorb DNA from creatures they [[CannibalismSuperpower consume]].
* Berserker from ''VisualNovel/FateStayNight'' must be "killed" 12 times to make the death stick. What's worse is that after he's died once, he is then permanently immune to whatever it was that killed him. Given how [[NighInvulnerability hard it is to kill him even once]], this makes him one hell of TheJuggernaut. On the other hand, extraordinarily powerful attacks are capable of taking away multiple "lives" in one blow, though such attacks are both rare and difficult in the extreme to perform, even for Servants.
* In ''Videogame/{{Spore}}'' you edit your creature throughout the cell and creature stages to give them the highest chance of survival.
* Story-wise, there is a promotional ITEM for ''VideoGame/DragonAgeII'' that does this; The Belt of Hindsight. The trailer for this belt says that it analyzes the deaths of its wearers, and develops magic defenses to slightly protect future wearers against what it was unable to block before. Current resistances when obtained by Hawke include Fire, Poison, Stabs, and Witches. Don't ask, just read the obituary on the leather, magically scrawled in lyrium ink.
* Mockingbird's power in ''VideoGame/MarvelAvengersAlliance'' is to [[TacticalRockPaperScissors switch to the opposing class]] of any classed character that attacks her.
* This trope is the true source of VideoGame/MegaManX's "Limitless Potential"; he was revolutionary in robotics as he had the ability to learn and grow in strength when [[VideoGame/MegaManClassic previous robots]] had their minds and power levels pre-determined by their creators. [[BigBad Sigma]] takes interest in his potential, and decides to instigate a reploid revolution in order to [[EvilutionaryBiologist evolve reploids to their fullest potential]].
* Jr. Troopa in ''VideoGame/PaperMario'' is a minor version. He starts off pretty incompetent. As the game goes on, however, he will acquire new powers to counter abilities Mario uses against him, combining them together late into the game. That being said, he remains rather incompetent throughout the whole game, as while he can adapt to limit Mario's ability to fight him, Mario keeps gaining ''more'' techniques that render him a joke again.
* In ''Enemy Infestation'', the entire gameplay is based on the fact that the aliens mutate so fast that every mission, the effects of the weapons ([[RockBeatsLaser except for two]]) on them are completely unpredictable. Last mission, they dropped from a raygun shot. This mission, the raygun causes the aliens to split in two or grow, while what kills them is pointing a remote at them and clicking. Next mission, the remote does nothing and they need to knocked out by a bug spray... well, you get the idea.
* ''Franchise/MassEffect'':
** Mechanically, the geth. When a platform is destroyed, the runtimes operating it will return to the main collective if there is a comm buoy in range [[spoiler:(hence why Legion can get killed in the Suicide Mission; he tries that but there are no buoys in range)]]. Extrapolating, any info on new tactics and weapons will be returned too, so while they may not have instant immunity like the Borg, they will develop countermeasures much more quickly than any other race [[spoiler: which is the crux of the Quarian's problems come the attempt to retake Rannoch; the Geth adapt to their hacking attempts far too quickly to be effective until Admiral Xen makes a breakthrough]].
** Biologically, the vorcha. Roughly humanoid aliens with no abundance of intellect, their bodies contain numerous pockets of undifferentiated cells, allowing each individual vorcha to adapt to new environmental influences. For instance, vorcha that land on higher-gravity worlds will develop stronger bones and muscles to compensate. When the Reapers invade, vorcha prove difficult for them to subdue, as they can adapt to ignore poisoned water supplies, or even [[MoreThanMindControl Indoctrination]].
* In ''VideoGame/DevilSurvivor2 Record Breaker'', the Triangulum Spica has several bodies. Each time one is destroyed, the rest of them become immune to whatever element killed it.
* Exploited in ''VideoGame/PathOfExile''. The ''Elemental Equilibrium'' passive skill causes enemies hit with elemental damage to gain moderate increased resistance to that element but have their resistances to the [[FireIceLightning other two elements]] reduced by twice as much.
* In ''Videogame/{{Warframe}}'', there's the Sentient faction whose units can adapt to four damage types, which technically give them near immunity (95%) to those damage types. [[spoiler:This can be nullified by the Operator's Void Beam, resetting all their resistances. Good luck figuring this out by yourself, however, because not only [[GuideDangIt you're not informed of the beam's property anywhere in the game]], but switching from your fully armored and combat-ready warframe to your squishy human form in the face of a LightningBruiser enemy [[ViolationOfCommonSense sounds like a bad idea through and through]]!]]
* In ''VideoGame/{{XCOM 2}}: War of the Chosen'', the eponymous villains gain new abilities in response to what XCOM uses against them.

[[folder:Web Comics]]
* Oberon from the Webcomic ''Killroy and Tina'' would always come back with the properties of whatever "killed" him. The only way to permanently kill him is to throw him into a black hole (so he comes back as nothing). Unfortunately, he [[OhCrap falls into a star instead]]. Just think, if the series hadn't been [[OrphanedSeries cruelly abandoned]], something ''might'' have come of it.
** There are the ArcWords "illumination goes boom".
* Aylee from ''Webcomic/SluggyFreelance'' (although her adaptations may involve spending months in a cocoon).

[[folder:Web Original]]
* In the ''Roleplay/GlobalGuardiansPBEMUniverse'', Mexican superhero Evolucion, is a FlyingBrick with "reactive evolution" powers. He gains those defensive and sensory powers he needs depending on the situation he finds himself in (he gains night vision in darkness, he grows gills if he's underwater, fireproof skin if he's in a fire, and so on).
** The {{Super Robot|Genre}} Omega, from the same setting, is programmed to redesign himself after ever defeat so he cannot be defeated by the same method twice.
* In ''Literature/{{Worm}}'', Crawler of the Slaughterhouse Nine combines this with a massive HealingFactor, one which lets him fully regenerate within seconds of being harmed. He deliberately throws himself into harm's way in order to become stronger. At one point, he's exposed to a nanothorn attack that takes most of his body apart on a molecular scale...which causes the destroyed portion of his body to grow back with ''biological nanomachines that can disintegrate anything he touches.'' [[spoiler:The heroes only manage to kill him by carpet bombing the area he's in with [[TheSparkOfGenius super]][[MadBomber -villain]] [[HavingABlast made]] bombs which [[TakenforGranite turn him into glass.]]]]
* ''Literature/{{Brennus}}'' has Desolation-In-Light and her sister Gloom Glimmer have the power to posses several superpowers appropriate to the situation.
* In ''Literature/{{Twig}}'', the protagonist, Sylvester, is regularly injected with a cocktail of venoms and toxins which have this effect on his brain by boosting his brain plasticity, effectively enabling him to rapidly increase his skills in an area he focuses on at the cost of long-term memory loss and deterioration in areas he doesn't focus on. He uses it to adapt his skillset to fill the role he needs to fill in his team, most frequently as TheSocialExpert.

[[folder:Western Animation]]
* The android Amazo in ''WesternAnimation/JusticeLeague''. [[AGodAmI Eventually gets so many powers he doesn't know what to do with them and decides to become a philosopher]]. Doomsday to a lesser extent as per his comic counterpart. Try to lobotomize him with heat vision? His skull thickens in time for the next fight.
* Shane "Goose" Gooseman from ''WesternAnimation/AdventuresOfTheGalaxyRangers'' had this power combined with his {{Shapeshifting}}, due to being a genetically engineered SuperSoldier with a [[UpgradeArtifact Series Five Implant]] that also acted as a RestrainingBolt if need be.
* In the third ''WesternAnimation/JimmyTimmyPowerHour'', the two create their own supervillain to fight, but accidentally gives him this power because of a typo.
-->'''Timmy''': [[NeverMyFault You should've checked]] [[BookDumb my spelling!]]

[[folder:Real Life]]
* Your own immune system adapts to infections. A vaccine is a weakened sample of a virus, your immune system uses it to learn how to combat the non-weakened version. As a result, you are unlikely to get any particular virus more than once. Chicken pox is a classic example, and since it's much more dangerous to adults, it's recommended to expose kids (or, better, to vaccinate them) to reduce the chance that they'll get it after they grow up. But this also works the other way, since some diseases evolve too quickly for immunity to last very long. This is why new flu shots are issued each year to keep up with new strains.
** Inverted by the [[http://en.wikipedia.org/wiki/Original_antigenic_sin original antigenic sin]] where a prior mismatched infection makes the future related infection significantly worse.
* Other parts of our body respond to damage by rebuilding the affected tissues and structures with greater strength. Repeatedly damaged skin forms calluses. Exercise causes muscle damage and stress, so the muscles rebuild with greater strength. Damaged bone will rebuild itself with greater density.
** Some martial artists train themselves by striking at hard things. This will damage their bones, which rebuild. This leads to people who can smash bricks with their heads and have skeletons visibly different. Serious Muay Thai kickboxers kick trees.
*** Overdoing it tends to leave the practitioner with serious health problems later in life, as the body simply cannot cope with the stress. However, with no stress on bones and muscles at all (such as happens without gravity) leads to them turning brittle, weak and ultimately non-serviceable. Like all things, best utilized in moderation.
* Any population of organisms evolve. The word "evolution" is older than the concept of biological evolution. This is slow, noticeable changes to the environment usually take several generations at least.
** Bacteria reproduce quickly, and evolve quickly as a result. Biologists study bacterial evolution in a lab because they don't have to wait too long for the results. Bacteria can also develop resistance to antibiotics quickly -- which is why doctors tell you to finish your entire antibiotics prescription instead of stopping when you feel better. If you finish it all, there's a good chance you've wiped all the bacteria out. If you don't finish the prescription, the bacteria remaining may have evolved a degree of resistance and the next course won't be as effective.
*** So when you're taking antibiotics, think of the bacteria as your typical shonen hero, and antibiotics as your signature move. Wipe them out before they can learn to counter your signature move.
*** More to the point, [[BondVillainStupidity don't stop to gloat when you've got them on the ropes]] -- just kill them.
** Sex is essentially an adaptive ability; it is believed to have evolved as a trait because it enhances variation and makes species much more robust. While wholly asexual organisms, like bacteria, avoid the inconvenience of having to mate, organisms that can both reproduce asexually and sexually will always evolve faster through sex. Asexual species can only evolve by mutating during a single generation or by errors during replication, while sexual species have the mutations/replication errors of all the parents, plus the randomized factor of which gametes are brought into the new generation. The fact that asexuality pretty much doesn't exist beyond a certain level of complexity (mammals and birds are incapable of it, it is very rare in fish and amphibians/reptiles and only as an emergency backup plan to stabilize a population, and even most plants and protists prefer sexual reproduction if they can get it) supports the benefits of this approach.
** Viruses, to the degree that they qualify as 'organisms', evolve even faster than bacteria. The seasonal flu is essentially an endless game of cat-and-mouse between flu outbreaks and the adaptive immune system (with pharmacy and flu vaccines having recently joined the fight on our side), with the flu evolving new strains in order to re-infect those who have grown immune to last year's strain.
* Humanity itself is also like this, compared to most other animals: Due to a human's ability to figure out what to use and construct whatever is necessary to survive, the ability to change an environment to make living easier, and the unique accumulation of knowledge and instructions between individuals and across generations, humans have been able to live in a greater variety of environments and subdue a greater number of other animal species than almost anything else on Earth, and anything with even more cosmopolitan distribution achieved it through human actions.