History SpannerInTheWorks / AnimeAndManga

** Ironically, Lelouch could count as ''his own'' Spanner: on multiple occasions, his attachment to his friends (mostly Suzaku or Shirley, but '''''especially''''' his sister Nunnally) have caused him to make moves that jeopardize his plans or even ''the entire rebellion'' he leads. The first occurrence in R1 is where he [[spoiler: lets Villetta live, because he thought she was no danger to him]]. When was that? Second episode. The big ones are where he [[spoiler: ignores his own unstable Geass, leading to the death of Euphemia as he geasses her into becoming a GenocidalManiac and then has to shoot her dead to stop her]], and where he abandoned his followers for his kidnapped sister shortly afterward which ''greatly'' weakened their position, his trait continued on in R2. This came to the logical conclusion [[spoiler:when his RoaringRampageOfRevenge for the murder of Shirley, carried out against a cult whose members included scientists and children, which ended up being a large part of Prince Schneizel's efforts to turn the Black Knights against him -- the centerpiece being the fact that their beloved leader possesses a MindControl eye and quite possibly forced them all into obedience (he didn't, probably because he's smart enough not to misuse a power that only works once).]]
** Suzaku Kururugi is both this and an UnwittingPawn. When [[spoiler:Marianne brought him to the Sword of Akasha (possibly thinking he'd side with her out of love for her stepdaughter Euphemia, or because of his friendship with her "vessel" Anya Alstreim)... he sided with ''Lelouch'' instead.]] Not only that, but he messes up Schneizel's plans, as well: [[spoiler: Schneizel was planning to eventually kill off his father and become Emperor, but Suzaku realised this and volunteered to help... right in front of several subordinates who were very worried about doing something like that, including Cornelia (who had never considered such a thing, but went along with the idea anyway)... and Gino Weinberg aka Knight of Three, who's highly loyal to the Emperor. Who escaped with his mecha and told Bismarck Waldstein, the Emperor's personal sword.]] This made Schneizel's attempt to blame it on Lelouch or the Black Knights completely impossible.

** The Princess has a habit of messing up the plans of both the Demon King and the Hero in her quest for a good night's sleep while in captivity. She will frequently steal and/or damage items meant to be used or found in the course of the Hero's quest, rendering them completely useless. In one instance, the Demon King and his generals are discussing a series of items, tools, and weapons they plan to dispatch against the Hero, only for the Princess to be shown ruining each and every item they describe, and in one cast its ''guard'', in the course of washing her bedsheets.

*** Vegeta ends up being a spanner at the climax of the Cell Saga. While Gohan is in a beam struggle with Cell, all of the other fighters seem helpless to even budge Cell, and it seems that Cell is set to kill Gohan. But Vegeta hits Cell with a blast from behind that's just strong enough to make Cell briefly lose his footing, distracting him. This allows Gohan to unleash all of his remaining power, destroying Cell down to the atomic level and finally getting rid of him[[note]]The Z-Fighter's unsuccessful beam attack on Cell was [[{{Filler}} anime-only]] as Vegeta was the only one to hit Cell in the manga[[/note]].

*** Vegeta ends up being a spanner at the climax of the Cell Saga. While Gohan is in a beam struggle with Cell, all of the other fighters seem helpless to even budge Cell, and it seems that Cell is set to kill Gohan. But Vegeta hits Cell with a blast from behind that's just strong enough to make Cell briefly lose his footing, distracting him. This allows Gohan to unleash all of his remaining power, destroying Cell down to the atomic level and finally getting rid of him.

* In ''VisualNovel/HigurashiWhenTheyCry,'' [[spoiler:the only arcs in which the village is safe are Watanagashi and Meakashi because Shion kills Rika in secret, and so the mass gassing can't take place within the time that it would take for the virus to incubate, and by the time they did figure out that Rika was dead, oops, it doesn't look like the villagers are going to kill each other after all]]. This doesn't really make things better for the main characters, though. After all, most of them are still dead. It does, however, clue a mysterious third party in on what's going on; the one aware of the GroundhogDayLoop.

** ''Manga/DiamondIsUnbreakable'': First, [[spoiler:Shigechi]] gives a DyingClue to lead everyone to Yoshikage Kira. Then Hayato trails Kira, [[spoiler:who has impersonated his father]] around, which gets noticed by Rohan during his investigation and ends up leading the team to Kira's location.
** [[spoiler:Polnareff]] in ''Manga/GoldenWind''. During the time he was recuperating from his injuries, he accidentally discovered [[spoiler:the method of awakening the power of Requiem]], something that Stand Users weren't aware even existed, and ultimately decides to share this information with the heroes to help them defeat Diavolo.

* ''Manga/Overlord2012'':

*** Bewear of the ''Sun and Moon'' series usually evacuates Team Rocket just as they're about to get their ass kicked, though on some occasions it cuts in just as they're about to defeat the twerps. In some instances they become savvy to this, and one time even leave a distraction for Bewear so they have time to finish a more elaborate scheme.

* In ''LightNovel/{{Baccano}}'''s Flying Pussyfoot arc, it seems like everyone is this for everyone else, in a plot that was already capable of being summed up in one word: "clusterfuck." [[spoiler:Long story short: the [[{{Cult}} Lemures]] plan to hold the train passengers hostage in return for Huey Laforet's release from prison. [[AxCrazy Ladd Russo]] and his [[TheMafia buddies]] plan to kill a bunch of people ForTheEvulz. Czeslaw Meyer plans to smuggle explosives into New York and sell them. Jacuzzi Splot and his gang of delinquents plan to steal Czeslaw's explosives and sell them. [[OutlawCouple Isaac and Miria]] have already pulled off a robbery and plan to use the train to make their getaway into New York City. [[InformationBroker Daily Days]] agent [[BadassBystander Rachel]] just wants to [[RailEnthusiast hitch a ride]]. And [[SociopathicHero Rail Tracer]] ''does not approve of all these shenanigans going down on his train''.]] All of these plans disrupt one another in spectacular fashion and end in varying levels of success based -- with one or two notable exceptions -- on how sympathetic the characters involved are.

* In ''LightNovel/ACertainMagicalIndex'', Touma often derails the complex plans of any character by simply showing up and kicking the crap out of every bad guy in sight. Subverted in that Laura Stewart and Aleister Crowley are {{Magnificent Bastard}}s and can factor him into their schemes. Later, Aleister has a VillainousBreakdown when [[spoiler: Shiage defeats Meltdowner]], raging that it's impossible and ordering his death in an effort to stop him from derailing his calculations any further.

* In ''LightNovel/{{Durarara}}'', one of the main reasons [[ManipulativeBastard Izaya]] hates Shizuo so much is because his emotional volatility, TooDumbToFool nature, and firmly sustained belief that Izaya is responsible for 99.9% of everything that goes wrong in Ikebukuro makes him liable to become one at any moment -- because all of it makes him immune to Izaya's manipulations. [[spoiler:Shizuo ends up doing exactly this in Volume 6, when Izaya's attempt to frame Shizuo and get him out of the way for the moment doesn't go quite as planned and instead brings even ''worse'' people down on Izaya's head]].

* ''LightNovel/FullMetalPanic'': Though not a [[TheDitz ditz]] or stupid like some of the other examples, kidnapping OrdinaryHighSchoolStudent Kaname means that you've instantly lost, because [[IndyPloy she tends to figure out ways to screw up your best laid plans]]. Not to mention the whole "bodyguard with HumongousMecha" thing she has going, and how said bodyguard is the most hardcore BadassNormal the world has ever seen and such.

* ''LightNovel/RebuildWorld'': After the protagonist Akira finally gets his own vehicle after having found a TreasureMap, his efforts to scavenge untouched ruins, thus striking it rich, get foiled by idiot hunters (scavengers/PrivateMilitaryContractors) repeatedly:

** In the OVA continuity, because Mihoshi is a descendant of Washu, she and her whole family have the ability to subconsciously alter probability around them. Being a Spanner is *literally* her super power.

* In ''Manga/{{Basilisk}}'', Princess Oboro may not be able to fight, but she derails [[spoiler: BigBad Tenzen]]'s plans ''thrice''. First, [[spoiler: she tries to interrupt a fight between Koushirou and Gennosuke but accidentally causes Koushirou to [[EyeScream blind himself with his own powers]], limiting Tenzen's physical actions since Koushirou is his NumberTwo]]. Second, [[spoiler: she seals her own [[AntiMagic Piercing Eyes]] to avert using her incredibly lethal powers against her clansmen again, but ''also'' preventing Tenzen from using said powers for his sole benefit.]] And third, [[spoiler: her eyes are unsealed when ''Tenzen is reviving himself after Gennosuke kills him'', which allows her to undo Tenzen's {{Immortality}} and kills him for good]]. And in the end she also [[spoiler: derails Ofuku's plans via commiting a HeroicSuicide instead of killing a completely defenseless Gennosuke, sending her into a ''huge'' VillainousBreakdown.]]

* ''Manga/CaseClosed:''

** Teru Mikami screwed up by going for his notebook when Kiyomi Takada was kidnapped by Mello, which lead Near to the notebook ... If it hadn't been for this one mistake, which allowed Near to successfully replace the notebook with a fake, Light would have won. Unusually for a Spanner, this wasn't a result of stupidity but of Mikami thinking ''too much'' like Light: he did exactly what Light would've done in his situation, with the limited information available. In the manga, Light even acknowledges this. The missing information, of course, was that LIGHT HAD HIS OWN NOTEBOOK HE ALREADY USED!

*** An earlier example would be at the end of the first Dragon Ball hunt. Pilaf has summoned the Dragon and is about to wish for world domination, but he never expects one of the good guys to escape from their prison and change the wish...like Oolong did.

*** And afterwards, preparing to kill the heroes for their interference, Pilaf's palace is destroyed by Goku, having turned into a giant monkey monster.
** ''Anime/DragonBallZ''

*** Vegeta ends up being a spanner at the climax of the Cell Games arc. While Gohan is in a beam struggle with Cell, all of the other fighters seem helpless to even budge Cell, and it seems that Cell is set to kill Gohan. But, Vegeta hits Cell with a blast from behind that's just strong enough to make Cell briefly lose his footing, distracting him. This allows Gohan to unleash all of his remaining power, destroying Cell down to the atomic level, finally getting rid of him.
*** King Yenma and Fortuneteller Baba are this in the Buu arc. Had they not brought back Vegeta to fight Super Buu, Goku wouldn't have anyone to [[FusionDance fuse with]], and would have remained completely outclassed by Super Buu.

* In the Battle of Fairy Tail arc of ''[[Manga/FairyTail Fairy Tail]]'', Erza's false eye is this. Its existence halves the effect of any ocular magic used on her. When Erza is petrified by Evergreen using an ocular attack, the eye allows her to break free and defeat Evergreen.
* ''Manga/FullmetalAlchemist''
** It turns out '''[[spoiler:Scar's older brother]]''' was the first to figure out Father's AncientConspiracy (more exactly: [[spoiler: he was the first person to notice the transmutation circle around the country and began piecing together what's going on; the raid on his country confirmed his suspicions, and he quickly devised countermeasures for it).]] And he did this '''before the series even starts'''! [[spoiler: He may have died to save his younger brother before he could execute the plan but he played a major role in defeating Father, by allowing the heroes to fight back.]] And even more: [[spoiler: by transmuting his own arm to a mutilated Scar ''plus'' imbibing it with the right kind of alchemy, he not only saved his younger brother's life (at the high price of further damaging his mind and soul), but helped him become the one who ultimately took down Fuhrer Bradley aka Wrath, one of the most dangerous Homunculus.]]

** ''Manga/DiamondIsUnbreakable'': First, [[spoiler:Shigechi]] gives a DyingClue to lead everyone to Yoshikage Kira. Then Hayato, who trails Kira, [[spoiler:who has impersonated his father]] around, which gets noticed by Rohan during his investigation and ends up leading the team to Kira's location.
** [[spoiler:Polnareff]] in ''Manga/GoldenWind''. During the time he was recuperating from his injuries, he accidentally discovered [[spoiler:the method of awakening the power of Requiem]]. Something that Stand Users weren't aware even existed, and ultimately decides to share this information with the heroes to help them defeat Diavolo.

* ''Anime/LupinIIIPart5'' has Lupin's ploy to [[spoiler: [[FakingTheDead fake his death]]]] to get away from assassins nearly fall apart due to [[spoiler: [[TheOnlyOneAllowedToDefeatYou Zenigata running up and "rescuing" him.]]]] If it wasn't for this, Lupin would have successfully pulled his plan off right there and then, but instead is forced to trek across the desert and have both of them, as well as [[SixthRanger Ami]], nearly die of thirst. (He does successfully manage to pull of the plan eventually, though, after some improvisation.)

** Killer Bee also threw a spanner in Akatsuki's plans, when he faked his own capture to ''go on a vacation''. He does it again, when he foils Kisame's attempt to capture him, helped with Kisame's sword betraying him and Killer Bee's brother [[BigDamnHeroes turning up to save him]]. However, it later turns out that Kisame throwing away the fight was all part of the plan.

** [[spoiler:Ironically, Tobi himself became a spanner in Black Zetsu's plans with his reluctance to resurrect Madara and a wish to take control of the Moon’s Eye Plan since Black Zetsu wanted Indra in place of Madara in order to complete the plan, forcing him to use Kabuto to revive Madara as a zombie in the first place. Also his HeelFaceTurn and his wish help Team 7, becoming a spanner to Kaguya's plan to get rid of them and ultimately becomes the cause of her defeat and re-sealment.]]

** Most importantly, [[spoiler: Mireille's mother Odette's LastRequest was... for Kirika, ''her own soon to be killer'' and later Mireille's aforementioned partner, to take care of Mireille. A last wish that, many years later, Kirika would ultimately follow to the letter -- ruining Altena's desire for a Chloe/Kirika Noir match.]]

** ''Anime/PrettyCureAllStars''

* ''Anime/{{Rune Soldier|Louie}}'': The idiotic sorcerer Louie ruins the SecretWeapon when he takes a leak in an unusual spot. After that he punches his way through a impenetrable barrier ruining Plan B as well.

* In ''Manga/TalesOfWeddingRings'', the Gisaras Empire has arranged a marriage between one of its princes and Princess Krystal of Nokanatika, keeper of the legendary [[RingOfPower Rings of Light]]. This marriage would grant the prince the title and powers of the Ring King, which the Empire would use to bring yet more lands into their fold. They were not expecting Krystal's childhood friend, a Japanese high school student named Satou, to follow her back to her world and disrupt the wedding ceremony, or that Krystal would take the opportunity to {{elope|ment}} with Satou and make ''him'' the Ring King instead.

** In the WholeEpisodeFlashback of manga Chapters 921-924, Shinichi himself was one of these ''at the age of four''. In his attempts to befriend a just as young Ran in his new daycare, he briefly caught [[NightmareFace a weird]] [[OhCrap expression]] in the face of the daycare worker in charge. He mentioned that as well as other details in front of his parents in what seemed to be just a display of childish jealousy... this but allowed his GuileHero dad Yusaku to realize that [[spoiler:the teacher and his IllGirl wife were planning to kidnap Ran and raise her as the ReplacementGoldfish of their runaway daughter]]. Yusaku alerted the police (including Ran's ActionDad Kogoro), had [[spoiler:the wife and her brother/accomplice arrested]], convinced [[spoiler:the teacher to turn himself in willingly in exchange for being reunited with the missing daughter, and Ran was ultimately saved]] -- all because [[ChildProdigy Shinichi]] made his first deductions right in the perfect moment.

*** The [[ArmiesAreEvil Red Ribbon Army]] is a worldwide military organisation planning to use the [[MacGuffin Dragon Balls]] to TakeOverTheWorld. Too bad they didn't expect to be dealing with a [[KidHero 12-year-old boy]] [[SimpleStaff with a stick]] after the [[OrphansPlotTrinket Four Star Dragon Ball]] left to him by his deceased grandfather. In fact, Goku may not have been inclined to attack the Red Ribbon Army's headquarters... until they sent the hitman Tao Pai Pai to kill the guy who ''happened'' to have the ball Goku wanted. This meant Goku had to make amends to the guy's son, and that meant he now had to get ''all'' the balls to revive the dude... including the ones the Red Ribbons had already collected. ''[[OhCrap Their base is now a target.]]''

** [[spoiler:The Second Greed]] to Father, who certainly wasn't expecting him to [[spoiler:regain his old memories and betray him a second time]]. Not only does [[spoiler:Greed betray Father]] but he also [[spoiler:joins the heroes to fight against him]]. [[spoiler:Greed]] managed to weaken Wrath (greatly helping Scar) and helped the Briggs soldiers hold the Central fort. He was also crucial in the final battle as he managed to [[spoiler:absorb some of Father's souls and distracted him long enough for the heroes to make him use up his Philosopher's Stone shield]]. Most importantly, after [[spoiler:being [[TheAssimilator absorbed]] by Father (who at this point, still couldn't die due to his regeneration abilities), Greed '''greatly''' [[AssimilationBackfire damages him]] by using his carbonization powers to turn Father's shell into [[MadeOfPlasticine charcoal]], thereby rendering Father unable to regenerate. All that was needed left to destroy Father afterwards was a single punch from Edward]].

* Although the events of ''Manga/CardcaptorSakura, Manga/TsubasaReservoirChronicle'', and ''Manga/XxxHoLic'' are among the most complex and [[GambitPileup densely gambited]] known to man, ''none'' of the respective [[TheChessmaster chessmasters]] of the former two expected Yukito to fall in love with Touya instead of Sakura. The gambit ruling the latter one ''did'' anticipate the YaoiGuys -- but apparently failed to anticipate a ''heterosexual crush'' from one of them.

* ''Manga/OnePiece'':
** The Straw Hat Pirates in general:
*** Luffy and his crew have a tendency to do this wherever they go. Captain Kuro, Crocodile, Eneru, [=CP9=], Shiki (from ''[[Anime/OnePieceFilmStrongWorld Strong World]]''), and Z (from ''[[Anime/OnePieceFilmZ Film Z]]'') all had very elaborate plans that were a stone's throw away from fruition, but then along came Luffy and crew. All of the above made the mistake of underestimating them, and paid dearly for it.
*** They also (unsurprisingly) stumbled upon the villainous plot for Fishman Island on their way to the New World, and thwarted that one as well. It helped that BigBad Hody Jones, in spite of knowing everything that the Straw Hats had done before their hiatus, dismissed the nine of them as no threat and used EvilGloating to outright provoke them. With exactly ''one'' ally joining the nine Straw Hats to fight, Hody and his army of 100,000 found themselves on the receiving end of what may be the most devastating CurbStompBattle in the series as a result.
** Monkey D. Luffy in particular:
*** [[IdiotHero Luffy]] honestly doesn't care about the [[TheGovernment World Government's]] rule, or for that matter any of the {{Big Bad}}s he faces. He just won't let anyone he cares about get hurt and will go to any lengths to protect his TrueCompanions. Hence his beating three of the [[PsychoForHire Seven Warlords of the Sea]] (and earning the respect or allegiance of the other four, ''and'' allying with yet another who proved to be TheMole after more were added to the roster), the destruction of Enies Lobby, and the assault upon the [[AristocratsAreEvil most powerful jerkasses]] in the world. Soon afterwards we add [[spoiler:the first successful mass-jail break from [[TheAlcatraz Impel Down]] and his assault upon the Marine HQ, just to save his big brother from being executed.]] The surrounding politics and larger conflict don't enter his mind at all.
*** Luffy's proficiencies to this trope have been lampshaded during the Impel Down arc, when the jailers have to deal with two simultaneous riots on top of Blackbeard's invasion, both as a result of Luffy sneaking in.
---->'''Magellan:''' Nothing is going our way! How could one intruder spark so much mayhem?!
** Sanji:
*** Luffy may be the biggest spanner among the Straw Hat Pirates, but Sanji deserves special mention as well; his skills as a tactician often prove to be the linchpin to the Straw Hats' success. Enies Lobby shows his shrewdness in this ''twice''. First, he lures a bunch of Marines and Agents into the back of the train Puffing Tom, then slips past them while they're distracted and ''detaches their cars behind him,'' stranding them and dealing with almost all of the remaining Mooks and one OneManArmy without having to fight them. Then, when the Buster Call arrives at Enies Lobby, he disappears for a while. When he returns, it's revealed he'd been looking for the controls to the Gates of Justice so he can ''close them and throw the Buster Call ships into disarray.''
*** Much earlier, he shows off his skills in the Alabasta saga. First, all the way back in Little Garden, he happens to intercept a call from Mr. 0 and, pretending to be Mr. 3, tricks Baroque Works into thinking Vivi and the Straw Hats are all dead, meaning they don't have to worry about constant pursuit for a while; plus he intercepts an Eternal Pose to Alabasta, meaning the Straw Hats could leave right away rather than wait a year for the Log Pose to reset. Later, in Alabasta itself, all of the other Straw Hats except Chopper have been captured by Crocodile and trapped in a room that will soon be submerged. He uses a bit of trickery to lure Crocodile and his Dragon out of the building and lure them far enough away to give him time to sneak in and set all of them free. He even taunts Crocodile with a note saying "Mr. Prince was here" for when he comes back and discovers that he's been outsmarted.
*** In Skypeia, the first time Eneru shows any real shock was when he discovers Luffy's rubber body is [[NoSell shockproof]]. The ''second'' time, though, was after he KO's Sanji, but his PartingFromConsciousnessWords hint he's still ruined Eneru's day...by sabotaging the ''Ark Maxim''!
*** As of 862, Sanji might have performed his ''biggest'' spanner act ever... [[spoiler: simply by calling his bride Pudding's ThirdEye [[FreakinessShame "beau]][[FreakyIsCool tiful"]]. Up until then, the AxCrazy BitchInSheepsClothing Pudding was fully willing to shoot him dead with a HandCannon... but since she had been bullied all of her life for that same ThirdEye, Sanji's kind phrase shook her to the core and sent her in a sobbing VillainousBreakdown. This meant: she couldn't bring herself to kill him, Sanji managed to perceive and dodge additional threats in their surroundings (like an attack from Pudding's '''very''' badass ColdSniper older brother Katakuri)... and then Luffy (and some clones of his) got the ''perfect'' opening to [[WeddingSmashers begin crashing the wedding]], undo Big Mom's KillEmAll plans regarding Sanji's family, '''and''' put the plan to ''assassinate'' Big Mom herself in movement.]]
** Marineford:
*** In the Assault of Marineford Arc, [[spoiler:Little Oars, Jr.]] caused the Marines strategy for fighting Whitebeard to backfire when his body blocked a piece of a huge siege wall they were trying to activate from rising.
*** Buggy the Clown also qualifies in that same arc. His desire to grandstand and show off to a world audience led him to capture a video Transponder Snail, meaning that the World Government didn't have total control over what information was getting out of Marineford when they started slaughtering the pirates mercilessly with the Pacifistas, or when Blackbeard betrayed the World Government, indelibly humiliating them in the process.
** Punk Hazard:
*** At the beginning of their journey into the New World, the Straw Hats evade Smoker this way. They were originally planning to go to Raijin island, and Smoker knew they were going there because it was the most dangerous of the New World's first three islands, fitting Luffy's adventurous personality and reckless tendencies. However, due to a timely distress call and pure happenstance, they end up going to an island the Log Pose ''didn't even register''. Thus began the Punk Hazard arc, where the crew accidentally stumbled upon ''another'' long term villainous plot and GovernmentConspiracy, that they inevitably wreck. [[HereWeGoAgain Again]]. And this time, they have a live audience to witness it all over the New World.
*** Going to Punk Hazard destroyed many villains' ongoing plans. It not only derails Doflamingo's 10 year rule, but also devastated Big Mom's, Shogun Orochi's as well as Kaido's plans. Big Mom could never have [[spoiler:laid hands on Sanji]] if not for the trip to Dressrosa, which in turn [[spoiler:bolstered Luffy's own reputation as a prospective Emperor]] when Luffy went charging in to the rescue. Orochi and Kaido's enemies were there in Punk Hazard itself. As they rescued Kin'emon and Momonosuke, they also [[spoiler:revitalized Wano's resistance movement against the tyrannical Orochi, and Momo himself is revealed to be the son of Oden, the transcriptor of the ''Roger Pirates'']]. Also they accidentally saved Zou from being destroyed by Jack, only because Kin'emon and Momo stated it as their destination. The red Poneglyph in Zou in turn provided the most important clue to the route to Laugh Tale. It's safe enough to say both Wano's resistance and Luffy's quest would have failed [[UnintentionallyUnwinnable completely by accident]] if Luffy didn't decide to step on the most dangerous island to report on the distress call.
*** Smoker's obsession with catching Luffy has made him into a spanner for a quite number of villains as well. The moment where the Straw Hats evaded him upon entry into the New World led to Smoker following them to Punk Hazard. The presence of both him and Tashigi later proved to be pivotal to the Straw Hats and Law taking down Caesar Clown, as it was Smoker who got Law his heart back from [[spoiler:Vergo]], while his own heart was used to trick Caesar into accidentally killing his subordinate Monet, right before she was about to blow up the island to kill everyone except for Caesar, who, being a Gas Logia, would've been the only survivor. [[spoiler:He also proved to be a spanner for the World Government's propaganda practices. He was absolutely disgusted by the MedalOfDishonor situation issued to him and Tashigi at Alabasta, and confessed as much to the newly conscripted Admiral Fujitora, whose goal/dream is to one day end the Warlord system, admitting the only reason he didn't reveal the truth is because he lacked the power and influence to make people believe him. This inspired Fujitora to delay his report after Doflamingo's defeat and expose to the surrounding islands both Dressrosa's current state and their true saviors, the Straw Hat Pirates and Law, preventing his superiors from trying to cover it up]]. And that, [[spoiler: led to [[NothingIsTheSameAnymore the abolishment of the Seven Warlords System]].]]
** Dressrosa:
*** In the Dressrosa arc, Donquixote Doflamingo hatches what looks like the perfect trap to destroy the Straw Hats with. See, this guy isn't your average villain; not only is he an extremely skilled and powerful [[TheChessmaster Chessmaster]] and ManipulativeBastard, he's also smart enough to know that underestimating Luffy's crew would be a fatal mistake. However, outside factor after outside factor helps the Straw Hat Pirates out, rendering it all moot. The Tontattas, whose people were enslaved by the Donquixote Family, provide intel on the location of the Smile Factory and the identity of the power-user maintaining control over the country's LivingToys. A familiar face from the past shows up at the colosseum, and he probably wouldn't have without the tournament Doflamingo created to trap Luffy, to switch places with Luffy, allowing him to attack Doflamingo's castle undetected. But the biggest spanners came from Doffy's own crew: his officer Violet, who maintained a façade of loyalty since the time she was blackmailed into joining, falls for Sanji's chivalry and switches sides. Giolla, on the tail-end of her capturing the ''Thousand Sunny'', lets her guard down long enough for Brook to pull a YouAreAlreadyDead. Bellamy helps Luffy escape the colosseum because Doffy decided to have him killed. And most of all, there's Sugar, the one turning people into toys. Her being knocked unconscious is the only way for the guise over Dressrosa to be lifted, but no one can get near her. Usopp is captured, but instead of turning him into a toy like the others, she feeds him a grape she believed to be poisoned... which was actually hellishly spicy, and the resulting JumpScare / NightmareFace causes her to faint in shock. Consequently, Doflamingo's precious {{Masquerade}} is shattered, the country sees him for the evil person he truly is, and he's forced to take the most drastic measures that he can.
*** There's also the fact that in the resulting battle, five of the eleven remaining [[OneManArmy One-Man Armies]] in his crew are taken down thanks to pirates that came to the colosseum due to the tournament.
*** It turned out that Sugar herself commited quite the mistake regarding her plan... Due to how her powers work, once she makes somone into a member of the LivingToys group, Sugar must manually create a contract with the victims, forcing them to follow every order given at that point, against their will. She did ''not'' do that with her first victim... who turned out to be the son-in-law of the former King, the ''extremely'' badass gladiator Kyros. As a result Kyros, now the toy Thunder Soldier, managed to retain his free will and do what he could to raise his not-turned daughter Rebecca, became the leader of an underground movement of rebels against Doflamingo's rule, and helped out the Straw Hats to overthrow Doflamingo.
** Trafalgar Law:
*** In a non-Straw Hat example, there's Trafalgar Law. The Dressrosa arc, which escalated to involve nearly every major power in the world in some form -- the Seven Warlords of the Sea, the Four Emperors, the Marines, the World Government, and the Revolutionary Army -- wouldn't have even ''happened'' if it weren't for him in the first place. His alliance with Luffy really did "shake the world" as the papers said, as it put the Straw Hats in the path of the Donquixote Family, leading to all of the above, and the gradual destruction of Donquixote Doflamingo's criminal empire. The thing is, Law, much like Luffy in that regard, doesn't care about ''any'' of it. The ultimate purpose of all his actions, including continuing to live to this very day, for the last ''thirteen years'', has been '''to kill Donquixote Doflamingo'''. If the world has to spiral into chaos just so he can kill the man who murdered the most important person in his life, then so be it... though it's revealed in some chapters that he also seems to want the aftershock he knows will follow Doffy's defeat. Luffy grants his wish for the most part: [[BreakTheHaughty Doffy's not dead, but he's clearly ruined]]. So when the government kicks him out of the Warlords and puts him and Luffy on equal footing, he shrugs it all off as if to say, "SoLongSuckers"
*** The aforementioned "most important person" in Law's life, [[spoiler: Doflamingo's younger brother]] Rocinante, aka Corazon, not only allowed Law to become a spanner in Doffy's plans, but ''also'' was a spanner in his own right. By treating Law with sincere kindness [[BecauseYouWereNiceToMe when no one else would]], Corazon reached for him and became his BigBrotherMentor, beating Law's potential EvilMentor Doflamingo to the punch and restoring Law's lost humanity. Later, [[spoiler: when Doflamingo obtained an ''incredibly'' powerful Devil Fruit (the Op-Op Fruit) Corazon [[ForceFeeding forcibly fed it to Law instead]], curing him from his lethal illness ''and'' [[SuperpowerLottery granting him other VERY good skills]].]] True, [[spoiler: Corazon was shot dead by Doflamingo for that (and for being TheMole for the Marines)]], but ultimately he had a spectacular last laugh since, as said above, Law ultimately became Doflamingo's biggest nemesis.
** Lola from Thriller Bark. During Thriller Bark, she supplies Luffy with the shadows that allow him to pummel the giant zombie Oars, and though that doesn't destroy Oars, it does weaken him enough for the Straw Hats to finish him off. Then, before they part, she gives Nami a Vivre Card that apparently belongs to her mother. [[spoiler: In Totland, it's shown that ''Big Mom'' is Lola's mother, and that card is full of Big Mom's SoulPower, allowing Nami to control the {{Animate Inanimate Object}}s also created by Big Mom. In fact, by leaving Big Mom's territory, ''Lola disrupted an ArrangedMarriage that would have allowed Big Mom to become Pirate Queen!'']]
** In a larger scale, there's a woman named Sora. She foiled the plans of [[spoiler: her husband Judge]] to [[spoiler: experiment with their quadruplet sons, ''that she was still pregnant with'']], by taking a dangerous drug that [[spoiler: undid gene modifications]]. While [[spoiler: only one of the boys was spared being modified]] ''and'' [[spoiler: [[IllGirl her health was damaged beyond repair]], which later [[MissingMom killed her]]]], it turns out [[spoiler: the son that she ''did'' manage to save eventually escaped from his BigScrewedUpFamily and grew into... none other than Vinsmoke ''Sanji'', one of Luffy's TrueCompanions, who's been helping Luffy become a bonafide example of this trope.]]
** The DarkestHour in the Wano arc comes when Shogun Orochi manages to head off the heroes' attempts to covertly build up a rebellion and raid Kaido's island base, Onigashima, by sinking all the ships they had planned to use to travel by water and the bridges they would have used to go by land the night before they were all set to gather. This happened due to the actions of a traitor in the good guys' midst passing along every scrap of information they could, including a last minute change of plans orchestrated by an ally just before his execution. What results is the Ninja-Pirate-Mink-Samurai Alliance arriving at their planned rendezvous, finding no one there, and the traitor revealing themselves in order to [[spoiler:abduct Momonosuke]]. However, it's then revealed that [[spoiler:the message that brought the main allies to this place meant something completely different. The meeting place was different than indicated and, because of the differences in distance between where they were and where everyone else was, everyone else was already in position long before the ships and bridges were demolished]]. Kin'emon, the leader of the samurai, is praised for such a brilliant piece of tactical misdirection, which exposed the traitor, prevented their actions from derailing their plans, and guaranteed the raid on Onigashima could proceed. The thing is, [[spoiler:the only reason the allies were in the wrong place was because Kin'emon misinterpreted the message that changed their plans while everyone else ''didn't''. Upon realizing this, Kin'emon can only stand there stone-faced as he realizes basically "Oh, ''that's'' what that meant..."]]
** Kaido's Beast Pirates crew is particularly fearsome for one big reason: the artificially produced SMILE fruits grant them the biggest Zoan army in the whole world with over ''five hundred'' devil fruits user among them. It's gotta be hard to defeat such a force right? Well, that would be the case if not for [[AdorablyPrecociousChild Tama]], who's Kibi-Kibi no Mi allows her to take control of any beast that eats her Kibi Dango, and unfortunately for Kaido's the nature of the SMILE fruits makes his underlings [[ElementalRockPaperScissors sensible to this very specific power]].

** Akira fights his way through the entrance of the most important building of the Mihazono ruin, an ancient city where robots and factories constantly replace themselves and goods to loot, serving as a good place to train up hunters. After Akira runs inside after killing the previously untouchable defenses of the Sarenthal building, dozens of hunters hear the commotion and enter after him. The spanner: A jumpy hunter puts a bullet in the ProjectedMan little girl that represents the building's A.I., which causes it to activate emergency protocols and flood the city with tank drones creating chain reaction leading to a BigBadassBattleSequence of hunters trying to save defeated hunter squads.

** [[spoiler:Polnareff]] in ''Manga/VentoAureo''. During the time he was recuperating from his injuries, he accidentally discovered [[spoiler:the method of awakening the power of Requiem]]. Something that Stand Users weren't aware even existed, and ultimately decides to share this information with the heroes to help them defeat Diavolo.

* ''Manga/DetectiveConan:''
** Heroic Gambit Example: Between them, Heiji Hattori and Ai Haibara screw up a plan Conan had worked out to get information on the Men in Black. Haibara, despite being an otherwise intelligent and calculating person, felt enough of an obligation to Conan that it made her insistent on going to him. She showed up just as the plan was going his way, and her presence opened the door for everything to get shot to hell. Heiji's role in the Spannering was in deliberately leaving Haibara the means to locate Conan in the first place in case she chose to do exactly what she did.
** Another, more indirect, example has an assassination attempt by the Men in Black foiled because of a little boy who kept "Ding-Dong-Ditching" one of the operatives' homes. This act ultimately put Conan in a position to foil the plot.
** The fifteenth movie has Touma Tachihara, a boy who wakes up from his years-long ConvenientComa at the worst moment possible for the BigBad because he's the only person able to identify him... since he witnessed the murder he committed in the past. Pretty much the whole movie's plot relies on whether Touma's TraumaInducedAmnesia will be undone or not.
** The Mystery Train arc has [[spoiler:the Kaito Kid]] forcibly drafted into this role by Conan in a plot to convince the Organization that [[spoiler:they killed Haibara]]. When everything's over, the only one in the Organization to realize they were duped is also the only one who was guaranteed to keep quiet about it.
** In the WholeEpisodeFlashback of manga Chapters 921-924, Shinichi himself was one of these ''at the age of four''. In his attempts to befriend a just as young Ran in his new daycare, he briefly caught [[NightmareFace a weird]] [[OhCrap expression]] in the face of the daycare worker in charge. He mentioned that as well as other details in front of his parents in what seemed to be just a display of childish jealousy... this but allowed his GuileHero dad Yusaku to realize that [[spoiler:the teacher and his IllGirl wife were planning to kidnap Ran and raise her as the ReplacementGoldfish of their runaway daughter]]. Yusaku alerted the police (including Ran's ActionDad Kogoro), had [[spoiler:the wife and her brother/accomplice arrested]], convinced [[spoiler:the teacher to turn himself in willingly in exchange for being reunited with the missing daughter, and Ran was ultimately saved]] -- all because [[ChildProdigy Shinichi]] made his first deductions right in the perfect moment.

* ''Franchise/PrettyCure'':

*** Going to Punk Hazard destroyed many villains' ongoing plans. It not only derails Doflamingo's 10 year rule, but also devastated Big Mom's, Shogun Orochi's as well as Kaido's plans. Big Mom could never have [[spoiler:laid hands on Sanji]] if not for the trip to Dressrosa, which in turn [[spoiler:bolstered Luffy's own reputation as a prospective Emperor]] when Luffy went charging in to the rescue. Orochi and Kaido's enemies were there in Punk Hazard itself. As they rescued Kin'emon and Momonosuke, they also [[spoiler:revitalized Wano's resistance movement against the tyrannical Orochi, and Momo himself is revealed to be the son of Oden, the transcriptor of the ''Roger Pirates'']]. Also they accidentally saved Zou from being destroyed by Jack, only because Kin'emon and Momo stated it as their destination. The red Poneglyph in Zou in turn provided the most important clue to the route to Laugh Tale. It's safe enough to say both Wano's resistance and Luffy's quest would have failed [[UnwinnableByMistake completely by accident]] if Luffy didn't decide to step on the most dangerous island to report on the distress call.

** ''Anime/{{Pokemon}}'':

* ''Manga/RosarioToVampire'': In his first appearance, Gin tried to set Tsukune up to take the fall for Gin's own perversions in an effort to have Moka all to himself. The only reason it failed is because Kurumu was about to comfort Tsukune just as Gin intercepted him. Kurumu followed them and stumbled across [[{{Frameup}} a certain episode behind the school involving a digital camera and the girls' locker room]]. Afterwards, she rescued Tsukune from the vengeful locker room girls, confronted Gin on the roof, and presented a testimony that confirmed Moka's already-growing doubts about Tsukune's role in the incident.