[[quoteright:350:[[VideoGame/{{Utawarerumono}} http://static.tvtropes.org/pmwiki/pub/images/Dark_vs_Light_4579.png]]]]

Two forces exist within the same '{{verse}}. Both of them are unbreakable absolutes. And they are diametric opposites.

Naturally, this raises one question in everyone's mind: What happens when they fight? Sometimes the story itself will depict the fight, sometimes characters will simply speculate about the fight, and sometimes the story won't address the issue at all, leaving the fans to debate amongst themselves what the outcome would be.

There are several possible outcomes:
* One or both of these forces proves less absolute than advertised:
** Yin is stronger and defeats Yang (or vice-versa).
** Yin and yang both destroy each other simultaneously, an outcome that's both a win and a loss for both sides.
* The two forces are completely evenly matched, so [[SealedEvilInADuel they clash forever]] or until some outside force intervenes.
* Both of the forces are absolute, so [[RealityBreakingParadox the logical contradiction of their fight destroys the universe]].

In the West, the UnstoppableForceMeetsImmovableObject conundrum is the most famous version of this, enough so that it's become a StockPhrase. The Eastern equivalent is the unstoppable sword and unbreakable shield (see Folklore, below)--the Chinese word for "contradiction" is derived from this.

'''Please note:''' This is for actual, absolute forces. See UnstoppableForceMeetsImmovableObject for the use of that particular stock phrase to refer to objects or people who aren't absolutes.

Compare BalanceBetweenGoodAndEvil, which may be represented with this. If the two characters are not life and death personified as absolutes but have these as motifs anyway, that's LifeDeathJuxtaposition. Contrast YinYangBomb when someone sniffs at the idea of opposing yin-yang sides and points out that the two actually complement each other -- in a powerful way.



[[folder:Anime & Manga]]
%%Removed a Anime/TengenToppaGurrenLagann example, WordCruft and ExamplesAreNotArguable.
* According to Creator/GoNagai (making it half WordOfGod, half WordOfSaintPaul), [[Manga/GetterRobo Shin Getter]] and Anime/{{Mazinkaiser}} are equals, Shin Getter possessing [[GlassCannon the ultimate offensive power]], and Mazinkaiser possessing [[StoneWall the ultimate defense]]. When they appear in crossovers like ''VideoGame/SuperRobotWars'', it's popular to have them fight each other or at least show up around the same time.
* In ''LightNovel/{{Katanagatari}}'', two of the Twelve Deviant Blades are a sword that is supposedly unbreakable and a sword that supposedly can cut through anything. Shichika briefly wonders what would happen if the swords clashed. Togame guesses that the sword that can cut through anything would defeat the other since it was a later creation of the UltimateBlacksmith who forged all of the Deviant Blades and thus was forged with greater skill and knowledge. [[spoiler:This foreshadows the end of the series, when Shichika, whose fighting style and bloodline are the thirteenth Deviant Blade, easily shatters the "unbreakable" sword.]]
* In ''LightNovel/HighSchoolDXD'', this is the relationship between Boosted Gear and Divine Dividing. Issei's Boosted Gear doubles his power every ten seconds, while Vali's Divine Dividing halves its opponent's power every ten seconds, resulting in a zero sum game. This stalemate is broken the first time when [[spoiler:Issei incorporates a fragment of Divine Dividing into his Boosted Gear armor, by conscious abusing the fact [[AchievementsInIgnorance he doesn't understand how utterly impossible it should be]], giving him an arm that can punch Vali and nullify Divine Dividing's effect]].
* ''LightNovel/ACertainMagicalIndex'': Touma Kamijou's Imagine Breaker ability, housed in his right hand, represents the hope to change the world back to normal. As a result, it is a powerful AntiMagic and PowerNullifier that even works on RealityWarper powers. Kakeru Kamisato's World Rejecter ability, also housed in his right hand and specifically stated to be Imagine Breaker's opposite, represents the hope to escape the current world. As a result, it has the power to create new worlds and exile anyone and anything into them. When the two fight, [[spoiler:Touma's hand gets ripped off and exiled to another world, but the "Invisible Thing" sealed within Touma emerges and injures Kakeru, forcing him to retreat as Touma's hand regenerates.]]

[[folder:Comic Books]]
* The ComicBook/{{X-Men}} foes Blob and Juggernaut are sometimes portrayed as this. (Juggernaut's superpowers boil down to being an Unstoppable Force, and The Blob's powers boil down to being an Immovable Object.) Though other comics have stated that The Juggernaut would simply win. (Blob is telekinetically bonded to the ground, but the Juggernaut could dislodge him, plus a substantial amount of the ground, as a single unit.)
** The other comics that depict Juggs the winner go with the fact that he's a mystically-empowered human, and not a mutant like the Blob. So it's more/less "mystic powers vs. mutant abilities".
** The Marvel Comic RPG says that Juggernaut could just force the ground The Blob is on to move and thus beating him. However, they do mention that this method would be moot if they were on a planet of Adamantium (though they didn't state what'd happen then).
* This is invoked by name in a ''Franchise/{{Superman}}'' comic in which Superboy travels forward in time -- Superman is the irresistible force, Superboy the immovable object. The result is that Superboy gets sent back to his home time.
** Another example comes courtesy of Grant Morrison's ''ComicBook/AllStarSuperman''. His solution? "They surrender."
* The finale of Alan Moore's Comicbook/SwampThing story arc "American Gothic" ends like this. A group of male witches awaken "The Great Evil Beast," perhaps the ultimate EldritchAbomination, as it is the complete and total absence of God's light, with the intention of destroying not only the universe but ''heaven itself.'' As it slowly moves forward, ComicBook/{{Etrigan}}, ComicBook/TheSpectre, and ComicBook/DoctorFate all try and fail to defeat it. Finally, [[spoiler: the Hand of God Itself descends down. Everyone is preparing for the universe to end. . . but their hands clasp each other and "run together," showing that Good and Evil cannot exist without each other.]] If that sounds like a massive MindScrew, it's because it is.

* ''Film/TheMatrix'': Neo vs. Agent Smith.
* In ''Film/TheAvengers2012'', Thor's hammer (the most powerful weapon in the Franchise/MarvelCinematicUniverse) is [[DropTheHammer dropped]] on Captain America's shield (the most indestructible defense in the Marvel Cinematic Universe). The result? '''[[KungFuSonicBoom BOOM]]'''.
* In ''Film/LittleShopOfHorrors'', DepravedDentist Orin Scrivello (played by Creator/SteveMartin) meets his match in [[TooKinkyToTorture masochistic patient]] Arthur Denton (played by Creator/BillMurray). After trying in vain to make Denton suffer, Scrivello kicks him out of the office in disgust after realizing that Denton is actually ''enjoying'' everything Scrivello is throwing at him. (Fun fact: This scene is based on a similar scene in [[Film/LittleShopOfHorrors the original 1960 film]], in which the masochistic patient is played by a young Creator/JackNicholson.)

* A classic example comes from the Han Feizi. A merchant selling spears and shields claims that his spears can pierce anything and his shields can't be broken. When someone asks him what would happen if he were to strike the shield with the spear, he is unable to answer.

* Peter Crowther's "The Eternal Altercation" features a train in which the (identical looking) embodiments of Hope and Despair are locked in eternal combat. The train operator's job is to jerk the train if either of them gain too much ground.
* ForgottenRealms [[SideStoryBonusArt spin-a-yarn story]] "[[https://ww2.wizards.com/Books/mirrorstone/Article.aspx?doc=fr_spinayarn2004main The Night Tymora Sneezed]]" had a codpiece that "awakens battle-lusts and... lusts in general" and a chastity that aids "[...] in resisting the distractions of the flesh and dedicating themselves wholly to the clear-headed vigilance the Supreme Guardian demands". HilarityEnsues, of course.
* ''Literature/TheWheelOfTime'' plays with this a lot. One of the key icons of the series is the yin-yang symbol, though with the dots removed. One of the central conflicts of the story is not only the eternal struggle between the Light and the Shadow, but the one between men and women, best encapsulated by the [[GenderRestrictedAbility gender-striated magic system]]. The general conclusion is that harmony between the sexes produces the best results.
* ''Literature/TheTenetsOfFutilism'' features the mythology of the titular cult. Its members believe in a god of fortune named Crescis who is opposed to the god of misfortune, Decrescis. The cult's system is even a yin-yang symbol, only jagged and uneven at places.
* The world of ''Literature/MistbornTheOriginalTrilogy'' was created by the gods of Preservation and Ruin working in concert during a one-off truce. Their vying over the fate of the world they made causes the conflict in the story, and ultimately [[spoiler: the protagonist takes on the mantle of Preservation and uses it to annihilate Ruin, destroying both of them]].
* "The Chronicles of Amber" Has the Patern and Logrus, representing order and chaos respectively. The Unicorn and Serpent also.

[[folder:Live-Action TV]]
* In ''Series/TheFlash2014'', Captain Cold's freeze ray is designed to project Absolute Zero and Heat Wave's flamethrower is designed to project Klein Temperature or "Absolute Hot". When Flash tricks the two into blasting him at the same time, the blasts cancel each other out and blows everybody back.

[[folder:Mythology and Religion]]
* In Myth/ClassicalMythology, Amphitryon once sent Laelaps, a hound that can catch anything, after the Teumessian Fox, which can never be caught. Zeus's resolution to the paradox was [[TakenForGranite to turn both animals to stone]] and cast them into the sky as the constellations Canis Major (the hound) and Canis Minor (the fox).
* Actually ''[[InvertedTrope inverted]]'' according to original UsefulNotes/{{Taoism}}, where Yin and Yang are not opposites, but complements of each other. What is perceived as a "conflict" or "struggle" to keep the forces balanced is actually the two of them working in harmony. Furthermore, the clash of Yin and Yang, if it can be called that, is actually a ''good'' thing, as the [[YouCannotGraspTheTrueForm ineffable]] Tao is formed and supported by the two absolutes working with each other.

[[folder:Tabletop Games]]
* ''TabletopGame/DungeonsAndDragons'':
** The [[EvilVersusEvil Blood War]] is a conflict between [[OurDemonsAreDifferent the devils and the demons]] to resolve which is the superior force in the multiverse, [[OrderVersusChaos Chaos or Law]]. The demons, representing ChaoticEvil, have a theoretically infinite number of soldiers to call upon and some of those soldiers can be truly formidable individual combatants, but they rarely give consideration to advanced strategies and tactics, and they spend as much time [[WeAreStrugglingTogether fighting amongst themselves as they do trying to bring down the devils]]. The devils, representing LawfulEvil, have well-disciplined, well-trained soldiers and leaders who are ruthless tacticians to make up for the fact that they are frequently outnumbered. Both sides have fought each other to a stalemate for as long as the conflict has gone on.
** 3rd edition actually has a lesser known rule that solves this problem if you look at as the "spear/shield" version. In D&D specific trumps general, and thus the spear that can break any shield (specific power to break shields) trumps the shield that can't be broken (general power to be unbreakable).
* Since ''TabletopGame/{{Exalted}}'' contains a lot of 'irresistible' and 'invincible' powers, they have a rule for this: a perfect defense always wins, even against a perfect attack.
** Several second-edition books written by freelancers with a poor understanding of the game's mechanics occasionally created "transperfect" attacks which trump this balance. This prompted the creators of the main game line -- fearful of a LensmanArmsRace of transperfect attacks and transperfect defenses [[SerialEscalation followed by trans-transperfects and so on]] -- to state definitively that nothing can ever defeat a perfect defense, even if the thing itself says it can.

[[folder:Video Games]]
* Shield and Sword from ''VideoGame/{{Suikoden}}'': Shield can withstand anything, and Sword can destroy anything.
* One mini-boss in ''VideoGame/TheLegendOfZeldaOracleGames'' is defeated this way. You have to trick it into hitting its unbreakable shield with its unbreakable sword to destroy both.
* The Iron Clefts in ''VideoGame/PaperMarioTheThousandYearDoor'' claim that their bodies can withstand any attack and their spikes can pierce anything. To defeat them, you have to knock them into each other with Yoshi's Gulp attack.
* In ''VideoGame/PokemonRubyAndSapphire'', it's Groudon (representing the land) vs. Kyogre (the sea). Rayquaza the sky dragon needs to step in to break them up. (When pitting the two against one another in actual gameplay, Kyogre has [[ElementalRockPaperScissors a clear type advantage]], but Groudon has an ability and movepool that's potentially well-equipped to deal with water-types.)
** ''VideoGame/PokemonBlackAndWhite'' takes this a step further: the version mascots [[PlayingWithFire Reshiram]] and [[ShockAndAwe Zekrom]] are ''literal embodiments of yang and yin''. They are this whenever they meet each other in battle, so much so that [[spoiler:when one uses their signature attack, Fusion Flare/Bolt, the other will be forced to respond with a powered up Bolt/Flare. The faster one will have the weaker attack which is why N's legendary is two levels above yours.]] This also makes it so that the side that wins is dependent upon version (Yang wins in Black, Yin for White.)
*** It reaches the point where, instead of a ThirdOptionAdaptation, Generation V had [[VideoGame/PokemonBlack2AndWhite2 two sequel games]], each of which give version mascot [[AnIcePerson Kyurem]] mutually exclusive forms based on Yin and Yang.
* ''VideoGame/WorldOfWarcraft'' Involves the following player spells, The Warlock's "Chaos Bolt" A spell that's stated to go through everything and anything and in fact, ''does''. Then there is the Paladins "Divine Shield" which is simply put, "You cannot be damaged for the duration of this spell". The result: Chaos Bolt bounces of Divine shield due to the exact nature of the mechanics involved.
** The current version of chaos bolt had this ability removed to make up for the fact that it is now usable every 3 seconds or so.
** ''VideoGame/WarCraftIII'' had the opposite effects when a "Divine" armor type unit takes "Chaos" damage where the damage goes through the armor.
* ''VideoGame/AsurasWrath'' has [[spoiler: [[AttackOfThe50FootWhatever Asura]], [[OneWingedAngel The]] [[HumongousMecha Destructor]] vs. [[TrueFinalBoss Chakravartin]], [[HumanoidAbomination The]] [[{{God}} Creator]].]]
* In ''VideoGame/FinalFantasyVII'', the heroes have to stop the ultimate Black Magic, Meteor, by way of defeating the BigBad, who's holding back the power of the ultimate White Magic, Holy.

[[folder:Visual Novels]]
* The Han Feizi story is retold in ''VisualNovel/PhoenixWrightAceAttorney''. The "King of Prosecutors" trophy is a broken shield and knife, showing the result of the truth being pursued to its conclusion.
* In ''VisualNovel/FateStayNight'', Lancer's ultimate attack uses his cursed spear Gáe Bolg to pierce his opponent's heart without fail ''before he even starts the attack''. In the ''Unlimited Blade Works'' route, he ''throws'' the spear at Archer for even greater power. Archer responds with Rho Aias, a legendary shield that no spear was ever to pierce. [[spoiler:Rho Aias successfully halts Gáe Bolg but is destroyed in the process, consuming a large chunk of Archer's power and shredding one of his arms. Lancer is completely dumbfounded.]]
** A similar showdown occurs in ''VisualNovel/FateHollowAtaraxia'', where Lancer's Gáe Bolg is pitted against Fragarach. Gáe Bolg functions by reversing causality, with the cause being 'the opponent's heart is struck' and the effect is 'Lancer throws Gáe Bolg', while Fragarach reverses time and kills its opponent before their attack is made. The resulting pretzel of causality [[spoiler: results in a double kill.]]
* ''VisualNovel/UminekoWhenTheyCry'' has a WizardDuel in which an 'Unstoppable Spear' and an 'Unbreakable Shield' are summoned. [[spoiler:They both vanish right before they can contact each other.]]
* In ''VisualNovel/HerTearsWereMyLight'', the very existence of Space, who creates, contradicts the existence of [[spoiler:Nil]], who erases. In the true ending, Time's goal is to resolve the conflict between them without letting one of them disappear.

* ''Webcomic/EightBitTheater'' gives us a scene in which Black Mage is hyped up on the absorbed power of the five greatest evils in the world: Kary, Lich, Kraken, Muffins, and ''[[ScrewYourself himself]]''. Fighter has already demonstrated the ability to block ''anything''; Black Mage decides to put it to the test, and ''[[TheCuckoolanderWasRight Fighter is not wrong]]''. Let's let Black Mage explain it better:
-->'''Black Mage:''' I'm saying we're ''Fighter and Black Mage!'' Are we really going out on a superpowered duel? You [Fighter] can block ''anything'' and I'm basically a god. Our fight would raze the earth for miles ''and'' we'd solve nothing.
* ''Webcomic/BrawlInTheFamily'' [[http://brawlinthefamily.keenspot.com/2008/05/15/15-pac-man/ shows us what happens]] when Franchise/{{Kirby}} and VideoGame/PacMan both try to eat each other. [[spoiler:They both disappear, by the way.]]
* ''Webcomic/GrrlPower'': A minor supervillain claims to have both impenetrable skin and claws that can cut through anything in [[http://www.grrlpowercomic.com/archives/1331 this strip.]] As Sydney points out, "Clearly one of those statements was false."

[[folder:Web Original]]
* Wiki/{{Uncyclopedia}}: Both Creator/MrT and Creator/ChuckNorris are depicted as {{Memetic Badass}}es. According to one article (which has since been deleted or edited into oblivion) the fight between the two of them resulted in the Big Bang and the creation of the universe.
* Accordingly, some people joke that the biggest reason cloning should be outlawed is because cloning ''[insert name of your favorite MemeticBadass here]'' would make one of these possible.
* The winner of the [[http://www.irtc.org/irtc/irtc?_n&pg=PriorRound&id=Animations_October-January2002 October 2002 Animation round]] of The Internet Ray Tracing Competition (topic: Force) had some fun with the concept.
* Encyclopedia Dramatica: Longcat vs. Tacgnol.
* The Wiki/SCPFoundation deconstructs it with [[http://scp-wiki.wikidot.com/scp-225 SCP-225]], a pair of objects, one unstoppable, the other immovable, both indestructible. The Foundation has no idea what would happen if they collided (though a multi-gigaton explosion has been speculated), and they ''really'' don't want to find out. Worse, they have no known way to prevent such a collision if it were going to occur, since neither object can be affected by anything.
-->Since all tests thus far have shown that neither SCP-225-1 nor SCP-225-2 can be damaged or moved by any means known, the possibility also exists that neither object would be annihilated, halted, or altered from their course even by contact with the other. If this is true, then a collision between SCP-225-1 and SCP-225-2 has the potential to [[[TheseAreThingsManWasNotMeantToKnow DATA EXPUNGED]]].
-->In this circumstance [[RealityBreakingParadox planetary evacuation may not be sufficient]]
* In ''Literature/FineStructure'', Anne Poole is immortal and indestructible. Dropping her into a black hole makes physics break down and the Imprisoning God go into failure mode.

[[folder:Western Animation]]
* In an episode of ''WesternAnimation/StarWarsTheCloneWars'' the [[GodOfEvil Son]] and the [[GodOfGood Daughter]], [[AnthropomorphicPersonification embodiments]] of the [[SiblingYinYang Dark and Light sides of the Force]] clashed, when the Son attempted to turn [[TheChosenOne Anakin]] to his side, and the Daughter tried to stop him. Their battle was cut short, when the Father, embodiment of the Balance of the Force, intervened.
* In an episode of ''WesternAnimation/TheFairlyOddParents'', Timmy wishes for both of his parents to be the best surfer ever, forgetting that two people can't be simultaneously better than each other at something. The resulting paradox traps them in a limbo.
* ''WesternAnimation/TheLegendOfKorra'' brings us Raava and Vaatu, two powerful spirits on the opposite sides of the same coin. Raava (colored [[HeavenlyBlue blue]]/[[GoldAndWhiteAreDivine white]]) is the female spirit of order and peace, while Vaatu ([[RedAndBlackAndEvilAllOver red/black]]) is the male spirit of darkness and chaos. They battle every 10,000 years for the fate of the world, equal in power unless the balance is disturbed. In addition, neither one can ever truly destroy the other, for even if one spirit ''is'' destroyed, it will be fully restored by the next 10,000 year cycle.