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Spanner in the Works

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"A common mistake people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools."

They are the bane of the Clock King. They are the undoing of the overconfident Smug Snake. They are the worst nightmare of Manipulative Bastards everywhere. They are the monster in the closet that haunts The Chessmaster's every waking moment. They are the impending doom for the untouchable Magnificent Bastard. Their very presence causes even David Xanatos himself to freeze in utter terror, who can only watch as his master plan crumbles down into dust.

They are the Spanner in the Works.

Whether it's The Ditz, The Fool, Inspector Oblivious, or a monkey Geddit?, the Spanner in the Works is the miscreant capable of derailing the most ironclad of plans by unknowingly taking an option that the planner hadn't even considered. They ruin the implausible Gambit Roulettes by exploiting their one, intrinsic flaw: their reliance on Contrived Coincidences, rigid patterns, and the assumption that nobody would be stupid enough to actually push the Big Red Button or fight the apparently unstoppable robot.

How can they outdo the master at his own game with nothing but stupidity and clumsiness? It's precisely because these characters are the fools and tools of fate that they are uniquely placed to derail these schemes with the gentleness of a butterfly flapping its wings... of doom!

Put another way, the Spanner is an author's walking deconstruction or Lampshade Hanging of the Theory of Narrative Causality: as easily as a plan or plot can come together, it can be pulled apart even easier with the tiniest, most ridiculous thing.

When the character ruins a protagonist's plans by unknowingly doing something small but crucial, he becomes an Unwitting Instigator of Doom. When the Spanner can trigger a series of coincidences, it's Disaster Dominoes. When the plan is screwed and the character is also aware that he will screw the plan, and doesn't care, he becomes a Leeroy Jenkins. Occasionally, may be Mistaken for Badass. If the focus isn't on them, they're often an Unknown Character.

Compare Finagle's Law, It Began with a Twist of Fate, Nice Job Fixing It, Villain, Outside-Context Problem, Remembered Too Late.

Opposite of the Unwitting Pawn, often is the Unwitting Pawn until the final crucial moment. This is the main cause of Didn't See That Coming, this trope being the "that". Quite often an Achievement In Ignorance. Inverse of Unintentional Backup Plan, where a character accidentally completes an imperfect plan that would have otherwise failed. Compare with Out-Gambitted, where someone's plan is (or could have been) successful but ineffective against a better-thought-out plan. Compare Too Dumb to Fool, where the character is too stupid even to be baffled by explanations. Also, compare Evil Cannot Comprehend Good, where the flaw is that the villain can't see someone being generous or brave or honest enough to foul up his plan.

The specialty of The Fool. See also Immune to Fate, for characters that manage to be this to Fate itself.

The trope is reputedly named for the Industrial Revolution-era practice of disgruntled workers throwing a spanner into a machine, either because of fears that machines would put them out of work, or as a bargaining chip for better working conditions (and often because they were the only ones who knew how to repair the machines as well). Disgruntled French workers also did this by throwing sabots (wooden-soled clogs) into machinery — giving us the word sabotage.

(Note for Americans reading this: "Spanner" is the British English word for what you would call a "wrench". It has nothing to do with a Long Runner in development. The equivalent American phrase specifically involves a monkey wrench, known in the UK as a gas grip — "He really threw a monkey wrench into my plans.")

Incidentally, the word "spanner" is also a British slang word for "moron", which is rather fitting.

Often an ending trope, spoilers may be ahead.

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  • "Victory by Computer": Lex Luthor's plan to force Superman into releasing him by trapping Supergirl fails because the Tandy Computer Whiz Kids, a group of sixth-grade computer students, manage to find information about the place where Kara has been trapped and pass it on both cousins.
    Supergirl: ''"Naturally, I didn't tell him how I escaped— He has years behind bars to wonder about that! Even if I told him the truth...He'd probably never believe his scheme was done in by a class of sixth graders...who gained a victory with the help of microcomputers!"

    Comic Strips 
  • Subverted in the Dan Dare series Reign of the Robots, wherein the only person that the Mekon paralyses after capturing the group is Dare's bumbling aide Digby, on the grounds that "he has no brain, therefore there is no predicting his actions".
  • In one week-long FoxTrot series, Jason finds it impossible to beat one guardian monster in a video game, as it instantly squashes his character every time he tries. Paige, who almost never plays video games, takes the controller and gets by the guardian by simply walking around him.

    Fairy Tales 
  • "The Three Snake Leaves": The princess' husband-murdering ploy could have worked if it were not for the prince's loyal servant witnessing the murder. Swiftly, he got into a boat, hauled the prince out of the water, used the snake-leaves to bring him back to life, and took him back to the king before the princess had the chance to feed her father one lie.

    Films — Animation 
  • Aladdin: Jafar's plan to steal the lamp and leave Aladdin behind in the cave would have worked if Aladdin's pet monkey Abu hadn't picked his pocket and then given the lamp to Aladdin. Though Jafar kind of did this to himself as well as Abu wouldn't have done so if Jafar hadn't attempted to kill Aladdin.
  • The Bad Guys (2022): Marmalade's plan to frame the Bad Guys for his own heist via their Falsely Reformed Villain scheme is exposed because of Diane, who figured out his scheme and broke the group out of jail. Her managing to cause Wolf to Heel–Face Turn for real also consequently leads him to chain off the rest of the group's turn later on, saving him and Diane from Marmalade and destroying his operation from the inside out. Additionally, it is Diane's stolen ring that fully ruins Marmalade and gets him framed as the Crimson Paw.
  • Barbie: Princess Charm School: Dame Devin's plan to kill the royal family, have her daughter Delancy be crowned as ruler and act as Devin's puppet queen would've gone off without a hitch, had it not been for Emily Willows entering her sister Blair's name into the Princess Charm School lottery. Blair gets picked and Devin repeatedly attempted to get Blair out of the way, which causes Blair and even her daughter Delancy to get suspicious; Delancy subsequently delays things enough to put the magical crown on Blair, who is revealed as the thought-dead Princess Sophia and Devin rants about her plan in front of everyone, resulting in her arrest.
  • Beavis and Butt-Head Do America has two of them:
    • The first are the crooks who break in and steal the two's TV. This is what prompts them to search for it (or a suitable replacement) and making their way to Muddy Grimes, who drunkenly mistaken them for the two crooks and sends them to "do" (re: kill) his wife.
    • Beavis and Butt-Head are the other spanner. Dallas Grimes uses the boys' libido to get them to go to Washington, DC, hiding a deadly virus in Beavis' pants. Instead, their crazy road trip separates the two from Dallas, leading to her and Muddy getting arrested and the virus back in the hands of the US Government.
  • A Bug's Life: Dot overheard the grasshoppers' plan to squish the queen and flew back to the circus wagon to get Flik and company to return to save the colony.
  • In Home (2015), Pig the cat's presence spare Tip from being abducted with the rest of the humans. When the Boov are collecting the humans, Pig panics and clings to Tip's head. The scanner detects Pig instead of Tip and disregards them both, causing Lucy to be taken alone. Were it not for this twist of fate, Earth and the Boov would likely have been destroyed.
  • The Lion King (1994): Timon and Pumbaa inadvertently save Simba while scaring off buzzards, and raise him into his adult years. Without them, Simba would've likely died in the desert and Scar would've driven the Pride Lands further into irreparable doom.
  • The Little Mermaid (1989): Scuttle is the recurrent reason Ursula's con on Ariel fails and the film doesn't have the same Downer Ending as the original fairy tale. Not only does he catch Ursula gloating about her plan in her disguise and warn Ariel she has been duped, he arranges the other ocean creatures to stall her wedding with Eric, as well as smashing Ursula's conch to grant Ariel back her voice and break Eric from his hypnotic state so he could pull a Big Damn Heroes.
  • Monsters, Inc.: Mike forgetting to file his paperwork, and Sulley volunteering to get it for him, end up causing a chain of events that exposed Randall and Waternoose's plan. Roz gives them credit for exposing the scandal when she reveals her own true colors.
    Roz: Two and a half years of undercover work were almost wasted when you intercepted that child, Mr. Sullivan. Of course, without your help, I never would have known that this went all the way up to Waternoose.
  • My Little Pony: Equestria Girls
  • My Little Pony: The Movie (2017): When Tempest sends the orb to petrify Twilight, two different pegasi dash in with the aim of saving Twilight. Rainbow Dash saves her, while Derpy Hooves Takes The Bullet and the resulting distraction buys the Mane Six their chance to get away.
  • Ratatouille: Émile's first time bringing over his friends to eat Gusteau's food is how Rémy finds out that Linguini is the true heir.
  • Lord Farquaad in Shrek. By sending the fairy tale creatures to Shrek's swamp, he is the reason Shrek sets out to find him in the first place. He sent Shrek to get Fiona so Farquaad could become king in exchange for his swamp leading to Shrek and Fiona meeting. Fiona falls in love with and marries Shrek, which foils the plans of every subsequent villain in the seriesnote .
  • The Super Mario Bros. Movie: Mario and Luigi ruin Bowser's plans of marriage and conquest when nobody else can:
    • Mario's arrival in the Mushroom Kingdom kickstarts a series of events which lead to Bowser's defeat. His determination to find and rescue Luigi impresses Peach enough that she allows him to accompany her on her journey to the Kong Kingdom to recruit Cranky and his army. Mario fights and beats Donkey Kong, the champion and Cranky's son, earning Peach another ally against Bowser. Even when the Kongs are captured by Bowser, and it seems that Mario and Donkey Kong have died, the pair escape the Maw-Ray which swallowed them and begin an assault on Bowser's army, disrupting his wedding and rescuing Luigi and the prisoners. Mario then proceeds to save the Mushroom Kingdom from being blown up when Bowser launches a Bomber Bill. And to add further insult to Bowser's injury, it is possible that Mario may have unknowingly garnered some romantic attention from Peach.
    • Luigi may have been chased, captured and tortured the moment he arrives in the Mushroom Kingdom, but he still plays a significant part in Bowser’s downfall. In the climax, Bowser is dangerously close to winning: Donkey Kong is incapacitated and all Peach can do whilst restrained is knock the Super Star towards Mario with a Koopa shell. In a last ditch attempt to prevent Mario from getting said Star, Bowser shoots a stream of fire breath at him. It's Luigi who ruins Bowser's chances of victory by way of shielding Mario and himself with a manhole cover. This action buys the Bros enough time to grab the Super Star and save Brooklyn.
  • Teen Titans Go! To the Movies: Slade-as-Jade made sure every superhero was distracted by them having their own movie, even The Challengers Of The Unknown. What he didn't count on were the Titans, who had no movie and therefore were the only ones who confronted Slade at S.T.A.R. Labs, and he really didn't count on them being competent enough to grab the MacGuffin away from him, countering his moves. This drives "Jade" to try to distract the Titans by Divide and Conquer while making the Robin movie the main vector for his Mind-Control Device.
  • Woody, Chatter Telephone and Chuckles turn out to be the keys to dissolving Lotso's reign over Sunnyside in Toy Story 3. With Chatter's help, Woody breaks out all of his friends and escapes with them out the trash chute (a feat rarely done without being broken), sends Lotso into a Villainous Breakdown by presenting him with Daisy's locket (which Chuckles saved) and ultimately gets him banished to the dump, freeing Sunnyside from his corruptive influence.
  • Up: Dug's obliviousness ends up endangering the heroes in at least two separate occasions:
    • When Carl, Russell and Kevin are taking the house to Paradise Falls, Dug receives a call from Alpha and sheepishly says he has taken the bird as a prisoner. This leads the pack to track them down, kidnap the two humans and lead them to Muntz' blimp, presumably to be executed.
    • When Russell and Carl are transporting an injured Kevin to her babies, Dug gives away their location because he forgets (or doesn't know) that Muntz can track their position by monitoring his collar. This results in Kevin being captured by the mad old man, with Carl's house almost being destroyed in the process.
  • The title character of Wreck-It Ralph. His desire to gain the fame and respect his rival, Fix-It Felix, Jr., had, even unwittingly, lead to Sugar Rush's King Candy being exposed as the thought-dead Turbo and the restoration of glitch character Vanellope Von Schweetz.

    Films — Live-Action 
  • Abbott and Costello in the Foreign Legion: When Lou accidentally buys a lot of six slave girls, the lead girl — actually a French spy — is not amused, since Lou accidentally bid against the man she wanted to win so she could infiltrate his house.
  • The Adjustment Bureau tries to contain this kind of incidents. But they are not above random chance and unexpected behavior.
  • In American Animals, the first attempt at the robbery gets abandoned because there are multiple librarians in the rare book room, and the gang has no contingency for dealing with this.
  • In Andhadhun, Mrs. D'Sa witnessing the comings and goings at the Sinhas' apartment and telling the police results in both Simi and Manohar's plan (simply framing an innocent man and then moving on) and Akash's plan (feigning ignorance to avoid putting himself in danger) being thrown off course. Simi's attempts to course-correct further complicate matters.
  • In And Then There Were None (1945), the killer has, as in the book, meticulously designed a Batman Gambit based on the psychologies of the people invited to the island. It didn't occur to him that somone might have claimed the invitation under false pretences, and neither have a murderous past they want to hush up, nor react to the situation in the same way the real person would have.
  • In The A-Team, Face's plan would have gone off smoothly if not for Pike having a SMAW.
    Pike: Here's what I think of your best laid plans!
    [Pike fires the SMAW into the ship's hull]
  • The Atomic Brain: The main plot for the villain Miss Marsh is for her to have her brain swapped with the prettiest girl of three chosen. That gets ruined when the homeliest of the three, who has had her brain swapped with a cat's, gouges her eye out. Miss Marsh's companion tries to double-cross her, killing her and letting the remaining girl take her money, but Marsh kills him. The scientist, Dr. Otto Frank, pulls one by placing Miss Marsh's brain with the cat's, revealing that he wanted to keep her locked away in the cat so he could use her money to continue his research on reviving the dead. Miss March responds by locking him in the revival chamber and setting the dial to "Frag the entire house".
  • The Avengers (2012):
    • Had Thor not been there to keep the Hulk at bay, the Helicarrier would have crashed, and Loki's plan would have more than likely been successful.
    • The arc reactor in Tony Stark's chest. It prevents Loki from mind-controlling him and turning him against his allies, which would have derailed everything just as much as the Hulk's potential rampage.
  • Beetlejuice would have succeeded in marrying Lydia and be able to stay in the world of the living forever, if it wasn't for the Maitlands. Adam manages to drive a miniature car into Betelgeuse's foot, which distracted Betelgeuse, while Barbara comes into the house, riding on a sand worm that ends up eating Betelgeuse stopping the wedding from happening.
  • In Big Game, the villains' meticulously though-out plan is derailed by Oskari. If he didn't find the escape pod with president in, the only thing to do would be to open the door and pull the trigger. As it is, they end up chasing the two of them throughout Finland and fail.
  • In The Butchers, JB's original plan was to resurrect the six Serial Killers and then kill them so he could absorb their power. What he didn't count on was a busload of tourists being stranded in the Ghost Town on the day he planned his ritual, or two of those tourists triggering the ritual early. The end of the film implies that Satan, in the guise of the bus driver, deliberately led the tourists there to thwart JB's scheme.
  • Carlito's Way ends in a similar fashion. After outsmarting all his enemies by the skin of his teeth Carlito ends up getting killed by some random lowlife he mistreated earlier in the film.
  • In Cast a Deadly Spell, the Evil Necromancer's plan to summon Cthulhu is thwarted when it turns out his daughter was no longer a virgin due to the idiot cute cop nobody had been paying much attention to.
  • Con Air features the Ax-Crazy Cyrus the Virus, who plans to take over the Fairchild C-123 plane Jailbird before it drops him off to a new Supermax prison and has several very dangerous criminals willing to help him. Too bad that one of the passengers just happens to be a guy on parole named Cameron Poe, an ex-Army Ranger who takes absolutely no shit from anyone and will do anything in his power to stop Cyrus and Co. so he can go home to his family.
  • The Dark Knight Trilogy:
    • In Batman Begins, Batman himself is the Spanner towards Ra's al Ghul and the Scarecrow's plan to destroy Gotham.
    • In the same movie, Joe Chill is revealed to have been one. The League of Shadows caused Gotham's depression in order to get the city to collapse, creating the circumstances that led to Chill's stickup. But then Chill's murder of the Waynes caused the city to wake up for a moment, realize the hellhole it had let itself become, and was inspired enough by their deaths to pull itself out and limp along until Ra's next scheme. Plus, you know, the whole "creating Batman" thing.
    • By refusing to sacrifice each other, the passengers on the two boats end up being this for The Joker in The Dark Knight, in that his social experiment in proving that anyone could be corrupted ends in failure.
    • And in The Dark Knight Rises, Catwoman serves as one when she saves Batman from Bane in the climax.
  • In Day of the Wolves, #1's plan for Taking Over the Town was masterfully planned and executed. The one thing he could not have foreseen was that Chief of Police Pete Anderson would have been fired the day before the plan was executed, and therefore was at home instead of at the police station with the other officers.
  • Deep Rising: The cruise ship's owner had intended to fake a pirate take-over by hiring mercenaries to rob the passengers, force them into the lifeboats, and then sinking the ship so he could collect the insurance money. He (nor anyone else for that matter) certainly didn't count on the cruise ship being attacked by a hungry Sea Monster before the mercenaries arrived.
  • The scheming husband in Dial M for Murder is undone because he underestimates the intelligence of Swann/Lesgate, the thug he hired to kill his wife. Swann puts the key right back after using it, rather than keeping it, as his employer expected.
  • Die Hard: Cowboy Cop John McClane's real job. When terrorists are confidently moving chess pieces behind the scenes, he knows that all he has to do is look for something sensitive and start whaling on it.
    • He even invokes this in all but name in the first film when Hans Gruber demands to know who he is.
      McClane: Just a fly in the ointment, Hans. The monkey in the wrench. The pain in the ass.
    • In Die Hard with a Vengeance, it surprisingly isn't McClane as the villain deliberately got him involved. It's actually a juvenile delinquent who gives McClane his "Eureka!" Moment.
    • In A Good Day to Die Hard, Komarov has convinced long-time rival Chagarin that Komarov has a file on all of Chagarin's evil plans. Komarov intends for Chagarin to free him and then use his resources to steal uranium stockpiled at Chernobyl. The first spanner is that Komarov didn't expect the CIA (also believing the file to be real) to break him out of prison before Chagarin could. And the second spanner is, of course, McClane who's come to Moscow to help out his son John and ends up ruining everything.
  • Lara Lee in Django Unchained is the one who first notices Hildy's tension with Django, and it's her lighthearted jest about it that draws Stephen's attention to them enough for him to work out the rest. It's possible that the plan would have gone off without a hitch had she not noticed or not chosen to joke about it.
  • In the 1932 sci-fi mystery film Doctor X the Mad Scientist Serial Killer manages to not only trick the other characters into believing he is innocent but also manipulates them into physically restraining themselves so he can slaughter them at his leisure. Unfortunately he forgot about the Plucky Comic Relief Intrepid Reporter, who manages to dispatch him in a terrified and bumbling fashion at the last minute.
  • This concept drives the entire plot for Dumb and Dumber. Lloyd sees Mary "forget" her briefcase while going through the airport, and, desperate to win her affection, races through the airport to snag the briefcase and return it to her: the briefcase is the drop for a ransom, containing millions, left there to be picked up by a few hired thugs. The entire plot also runs because the crooks think that Harry and Lloyd are merely Obfuscating Stupidity, never understanding that no, they are actually that dumb, but happen to thwart the criminals at every turn.
  • In A Few Good Men, it becomes apparent that the Department of the Navy very much wants the case of United States v. Dawson & Downey to be quietly resolved by a Plea Bargain so as to prevent incident from causing too much embarrassment to the Marine Corps. This plan is undone by the dual spanners of Galloway and Dawson; Galloway, because she senses something isn't right, and goads Kaffee in doing his due diligence for once instead of rushing to a Plea Bargain. Dawson, meanwhile, is too hardcore of a jarhead to willingly accept a dishonorable discharge because it'd be easier for him, telling Kaffee to take his plea bargain and shove it.
  • Forrest Gump calls to complain that he can't sleep because of people playing with flashlights in the next building over, and so blows the lid on Watergate.
  • In Godzilla vs. Destoroyah, Godzilla spends days suffering a nuclear heart attack without even realizing it.
    • Godzilla vs. Kong: Team Godzilla. Unlike Team Kong, whose actions are essential in moving the plot forward, Team Godzilla's only role up until the Final Battle against Mechagodzilla is discovering the conspiracy behind Apex. While important for the audience's sake, it's technically inconsequential in the grand scheme of things — until they manage to sabotage Mechagodzilla's remote control panel at a pivotal moment, giving Kong and Godzilla enough breathing room to finish it off. If they hadn't been there, Mechagodzilla would've killed both Godzilla and Kong before going on to destroy what was left of Hong Kong and likely the rest of the world.
  • Goosebumps (2015): Usually whenever one of the Goosebumps manuscripts is unlocked and a monster escapes, Stine manages to capture it and he and his daughter are forced to move. When Zach releases the Abominable Snowman, however, the bookcase collapses and Slappy escapes as well. Slappy then proceeds to release every monster R.L. Stine ever created and burns the manuscripts for good measure.
  • Grand Slam: Only when the Caper Crew is preparing their break-in do they discover that the diamond company has installed the new "Grand Slam 70" safe system: an alarm triggered by any sound detected near the safe room by means of a sensitive microphone listens for sounds while the safe and its environs are secured. This happened after Anders left Rio, so he could not have known about it.
  • Two occur to upset the carefully planned Bank Robbery in The Great St. Louis Bank Robbery. first, Egan swaps the Getaway Driver role from George to Willy, and Willy didn't know that he was supposed to bring along a police-frequency scanner. Secondly, the bank has relocated a switchboard from the lobby to the basement that morning, which the gang is unaware of. Seeing the old switchboard unattended, they assume they no longer have to take the switchboard out of commission. Combined, these two factors allow the bank staff to trip the alarm, and leave the robbers unaware that the police are on their way.
  • Nicely played with in Hold-up and Quick Change (both are based off the same book). Grimm (Jean-Paul Belmondo in the former and Bill Murray in the latter) has carefully planned out a complex Bank Robbery and it goes off without a hitch. He correctly anticipated just how the cops would react, how the hostages would behave and the exit strategy perfect. Grimm is just as confident the trio's plan to get through airport security and flee the country will also work. Sadly, Grimm never considers that getting to the airport is going to turn into a disaster...
    • For Hold-up, former prison comrade of Grimm Lasky has been stalking Grimm for a while, knows his gang robbed the bank and chases them relentlessly after the heist. In addition, it turns out Lise (the girlfriend of Grimm's friend and accomplice Georges, played by Kim Cattrall) doesn't love Georges and grew feelings for Grimm. Grimm didn't expect this, and it becomes a thorn on the side of their getaway from the heist over time (what Grimm calls "the human factor").
    • For Quick Change, the first problem is Grimm not knowing that the signs to a key expressway were removed during construction, leading to the trio getting lost in Brooklyn. From there, they're robbed themselves, a fire truck pushes their escape van down a hill, they run afoul of a mafioso and it just gets worse after that point. Amazingly, they do manage to escape but it's more sheer blind luck than anything they could have planned for.
  • In How to Rob a Bank, Simon's carefully planned Bank Robbery goes to hell when Simon, The Everyman who only came in to complain about ATM fees, locks himself in the vault, accidentally taking the crew's computer expert hostage in the process.
  • In The Hunt (2020), Crystal ends up derailing the entire hunt simply by being more competent than pretty much everyone else save Athena. Towards the end, it's revealed that this is because they kidnapped the wrong woman. Instead of a school dropout with dead druggie parents who was on welfare and bounced from job to job, they ended up taking a person who happened to be an ex-soldier that served in Afghanistan, who just happened to have a similar name to their true target.
  • In Jurassic Park, Nedry has a very well-thought out plan to steal the dino embryos and whisk them to a waiting boat. He's plotted a perfect 18-minute window to be back before anyone knows it with a minor computer glitch to hide the theft. But a hurricane suddenly changing course to hit the island was never in his plans. It leaves Nedry racing and driving in the rain to get lost and eventually to his death.
  • In The Caper film The Killing, a band of criminals pull off an elaborate robbery of a racetrack. Even though the most of the criminals kill each other off fighting amongst themselves, the Anti-Hero and his Love Interest manage to escape to the airport and prepare to board a plane out of the country with all the loot. However, all their plans are foiled when a dog runs out in front of the luggage train, causing it to crash and spill the loot all over the runway for all to see.
  • In Kingsman: The Secret Service, Valentine's plan would have gone off without a hitch if Harry hadn't pulled Eggsy to his place to yell at him, allowing Eggsy to watch the video transmission of the church events. This directly led to Eggsy realizing that Arthur was compromised and allowed him, Merlin and Roxy to take Valentine down before the evil plan was completed.
  • There were multiple spanners in Knives Out:
    • Ransom was the one to anonymously hire Blanc, assuming that his investigation will lead to Marta's incarceration as he was the one to tamper with Marta's medical bag hoping that it will result in Harlan's new will being nullified.
    • Marta ends up being this to Ransom's plan, as she was able to correctly identify the right medicine and never gave Harlan the fatal morphine dose.
    • Then there was Harlan himself who rather than let Marta get wrongfully indicted, constructs a complex plot to give her an alibi, forcing Ransom to adjust his plans.
    • Great-Nana is a spanner to Ransom and Marta's plans since she was the one to spot both of them climbing down the trellis on the night of Harlan's murder.
    • In the end, Blanc himself is the ultimate spanner, as he was the one to figure out that being anonymously hired to solve what appeared to be a suicide would be Too Good to Be True. In fact, the client would have to have ulterior motives when a large inheritance is on the line. He decides to take the time to solve the case and was able to discover the murderer.
  • In The Lady Vanishes, an oblivious Iris manages to completely destroy a Nazi conspiracy just because she won't give up insisting that the eponymous lady exists.
  • The ending of Layer Cake has the protagonist outclassed not by dumb luck, but by being shot. Because while he was really successful in tricking clever criminals in his Batman Gambit, he ends up shot (and possibly killed, it's a little vague) by a guy whose girlfriend he stole and whom he considered of little importance.
  • Convinced that everything is one giant reality-tv roleplaying game, Wallace in The Man Who Knew Too Little ends up convincing a veteran assassin to retire and dismantles a covert international plan to escalate the Cold War, saving god knows how many people in the process.
  • Mythica: The Iron Crown: Three different gangs of villains are chasing after the heroes, and any one of them could have succeeded if the others did not keep on getting in the way.
    1. Demons raised by the Big Bad Szorlok, who wants an item that the party have.
    2. Mercenaries hired by someone who thinks that he could do a better job than the party at keeping the item out of Szorlok's hands.
    3. A group of Sky Pirates led by The Admiral, who is just pissed off that the party stole her stuff and prevented her quiet enjoyment of her sex slaves.
  • Before both above films, you have New Jack City, where drug kingpin, Nino Brown, is able to fast talk his way out of serious prison time, only to get killed by an old war veteran he didn't take seriously during the film.
  • In Ocean's 11, all it takes is Anthony Burgdorf's widow deciding to have his funeral in Las Vegas for Operation Pine Box to go to hell.
  • Official Secrets: The Observer's front-page story revealing the US-British plot to influence the UN vote on the Iraq War is spoiled because a copyediting intern ran the story, including the reproduced memo, through spell-check, changing the American English spellings to British English. This is pretty close to what actually happened.
  • In One Foot in Hell, Mitch's plan to kill Dan and Julie probably would have worked if Dan hadn't disobeyed Mitch's orders and gone to town to tell Mitch that he and Julie had fallen in love. Because of this, he is at the sheriff's office when the Posse arrives back with the bodies of Stu and Ivers and immediately realises that Mitch has double-crossed them.
  • The Pink Panther
    • In The Pink Panther 2, it seems like Inspector Clouseau, a seemingly Inspector Oblivious, is one of these until the very end, where he reveals that he was a Chessmaster after all.
    • According to Peter Sellers, the original Clouseau qualified as well, but he knew he was a buffoon deep down.
    • The Pink Panther Strikes Again had killers from all over the world come after him. He bends over to tie his shoes at the exact right moment... Likewise in the film's Dénouement, Clouseau is unwittingly catapulted onto Dreyfus' Death Ray, destroying it and killing Dreyfus in the process.
  • All throughout Pirates of the Caribbean: The Curse of the Black Pearl, Jack repeatedly plots for the most favorable outcome (for himself), but stubborn fool Will Turner and arrogant jerkass Captain Barbossa assume they know best how to get things done, and nearly screw themselves out of their goals frequently. If Barbossa had wanted to cut Elizabeth's throat instead of her hand, Will would've been too late to save her on his own, and if Will had died like he should've when Barbossa ordered the Interceptor scuttled with Will trapped below, Barbossa would never have gotten Will's blood to pay Bill Turner's debt. Near the end of the film before the climactic battle, Jack has everybody where he wants them, but because Barbossa and Norrington don't trust him at all, his plans almost fall apart.
    • In the second movie, Dead Man's Chest, James Norrington of all people serves as this. Jack and his crew encountered him by chance on Tortuga and enlisted him to help in their quest to find Davy Jones's chest that contains his heart. Norrington didn't even believe in its existence at first until Jack actually finds it, and after finding out that Elizabeth has a letter of pardon from Lord Cutler Beckett on the condition that she brings him what he seeks, Norrington puts the two and two together and correctly deduces that Beckett wanted Davy Jones's heart, so he steals it right under everyone's noses and makes his escape back to Port Royal to present Beckett with the heart, earning his pardon and all of his titles back and becoming the unlikely winner of the entire film.
    • From the third movie, At World's End, it's Jack's turn to act as the Spanner which disrupts the East India Company's plan to wipe out the pirates at Shipwreck Cove. Faced with the imminent threat, the Brethren Court has gathered to choose a new pirate king; it's mentioned that this has happened many times in the past, but no king is ever chosen because every pirate inevitably votes for themselves, leaving the results tied at a single vote for everyone, preventing a new king from being chosen. Sure enough, as the vote goes around the table, every pirate puts in a vote for themselves...until Jack Sparrow casually votes for Elizabeth Swann, giving her two votes and thus the role of pirate king. As a result of her leadership, the East India Company (who came in expecting to massacre a bunch of unorganized pirates) instead found themselves facing an actual organized resistance.
  • James Bond tends to function as one of these in his movies. He may not excel at the more subtle spy work, but throw him into a supervillain's operations and he'll disrupt them immediately and decisively. He's often described in the films and Ian Fleming's original work as a necessary blunt instrument aimed at particular hazards.
  • In Murder on Flight 502, the killer left a letter addressed to Donaldson in the TWA passenger lounge, telling him about the murders to committed on Flight 502. The killer intended the letter to be delivered to Donaldson the next day when it would be too late to prevent the killers. However, Millard Kensington sets off a smoke bomb in the lounge as a prank, causing the letter to be discovered earlier and to Donaldson reading it before the murders have occurred.
  • The Downer Ending of The Pledge is triggered because some random idiot crashed with the car that the Serial Killer was driving to get to the trap the Cowboy Cop had set for him, killing him instantly. As a result, the killer is legally a Karma Houdini (until his own wife admits to his acts on a Deathbed Confession many years later) and the cop's life falls apart when his manipulations to set the trap are revealed.
  • The Raid (1954): The raid is about to go ahead when two Union platoons ride into St.Albans in their way to Plattsburgh, and the Confederates have to hurriedly postpone the riad until they ride out on Monday.
  • Scream:
    • In the first film, Gale shows up at the front door and threatens the killers, which distracts them long enough for Sidney to escape and turn the tides on them.
    • Gale does something similar in Scream 4, arriving in Sidney's ICU room right before Jill kills her, and she distracts Jill long enough for Sidney to sneak up and knock her out via defibrillator.
    • Scream VI:
      • Kirby's presence definitely threw a wrench into the killers' plans. Knowing that a trained, armed agent is a threat if the group completely trusts her, Bailey has to resort to lying to Sam about Kirby no longer be in the bureau to keep them on their toes until he arrives to gun her down for the big finale. After Bailey knocks Kirby unconscious by shooting her, she awakens just in time to fire back at him and give Sam and Tara (who were surrounded by the killers) an opening to escape, and later she kills Ethan when he rises up for one last scare.
      • Gale actually inverts the trope this time around, as her discovery of the shrine actually makes Bailey's plan slightly easier. He doesn't have to go out of his way to trap Sam there, since Sam already learned about the place from Gale.
  • In Shock, two things threaten to expose Dr. Cross' impulsive murder of his wife. One is Janet Stewart; a "Rear Window" Witness to the crime. The other is an unconnected assault and robbery in the area where he disposed of his wife's body, which causes the local authorities to exhume her body to see if the cases are connected.
  • Star Trek
    • Sulu in Star Trek (2009). By "leaving the parking brake on", he delays the Enterprise's warp to Vulcan, sparing the ship from the Narada's assault. And indirectly, saving Earth.
    • Kirk in Star Trek Into Darkness. By threatening Harrison and offering him a chance to surrender, rather than killing him from afar as ordered, he single-handedly and accidentally derails all of Admiral Marcus' plans. And Spock, who drove him toward that decision.
  • Star Wars has a few examples:
    • Believe it or not, Valorum is this since before the films even chronologically began. Despite him being an ineffective leader, he was still a man with good intentions, and when the Senate didn't listen to him for too long, he decided to send the Jedi to negotiate with the Trade Federation without consulting with the Senate, thus unwittingly planting the seeds for Palpatine's downfall.
    • The Ewoks in Return of the Jedi are the one tiny overlooked factor that brings the Emperor's entire grand scheme crashing down.
    • The Expanded Universe has the entire Imperial Fleet artificially boosted by the Emperor's force powers. The Emperor's death ended up causing the imperial officers to lose control of the situation, preventing them from shooting down the Millennium Falcon before it could destroy the Death Star 2.
    • There's also Jar Jar Binks, whose clumsiness is more than a match for several tanks.
    • There are about a dozen ways the Rebels lucked into the plans for the Death Star in the expanded universe. By now you'd think they had enough plans to spare.
    • Anakin Skywalker's destroying the Trade Federation's droid control station in the first prequel was a massive stroke of luck. To the extent that not even he realized what was happening. He just hid in an unmanned Naboo fighter and stuff happened.
    • Finn in The Force Awakens; his defection set the chain of events that would stop the First Order's plans. He frees Poe from them, finds Rey and BB-8, and helps them get off Jakku and meet up with the Resistance.
  • Strange Brew has Bob and Doug McKenzie, a couple of drunken idiots who inadvertently stumble into a mind-control plot by a crazed brewmeister and derail it — without even realizing what's going on.
  • In Sudden Death, Foss has a great plan to use Game 7 of the Stanley Cup Finals to hold the Vice-President of the United States and others hostage to demand hundreds of millions of dollars in ransom. He's got bombs set around the arena, his men around it, explosives set to keep the cops at bay and the head of the Secret Service unit handling this is secretly on his side. All it takes for things to go awry is for the fire marshal's daughter to walk off and his trying to find her causing him to stumble onto the whole plot and fight the terrorists on his own.
  • Towards the end of Sunset Limousine, Alan decides to escape from the bad guys by blending in to a funeral procession at Inglewood Park Cemetery. As he and Julie are trying to figure out where in the chapel to hide from said bad guys, Alan accidentally triggers the incineration of the deceased, causing the mourners to file in. Luckily, the bad guys take the opportunity to flee the cemetery. Unluckily, they decide to do it in Alan's limo.
  • S.W.A.T. (2003): Alex Montel kills his uncle Martin Gascoigne for sticking his hand in The Syndicate's till, then takes Gascoigne's car to the airport to catch his flight home. On the way, he's pulled over by a motorcycle policeman because he has a taillight out. The officer then discovers there's an arrest warrant linked to the license plate and detains Montel "until we can verify who you are." Lampshaded by an FBI agent after Montel's identity is discovered:
    "We've been lookin' for this guy a long time. Busted taillight brings him down? That's amazing."
    • This type of thing is very much Truth in Television, many real criminals are caught because of insignificant things that shouldn't have happened. One notable example is Timothy McVeigh, who was also caught when he was pulled over by a state trooper.
  • Sweeney Todd: The Demon Barber of Fleet Street: Sweeney Todd would have killed Judge Turpin and ended the movie right there and then in the middle had Anthony, who had recently talked to Sweeney about his plan to elope with Johanna in order to get her away from Turpin, not busted into his shop with the judge right there in the room in order to inform Sweeney that he has found Johanna and that she has agreed to the plan. Needless to say, this ends up blowing both the aforementioned plan and Sweeney's attempt to kill Turpin straight to hell.
  • In Thir13en Ghosts the housekeeper Maggie ends up discovering the mechanisms that run the "Ocularis Infernum" machine and begins hitting every switch she can grab, not only freeing the ghosts from the musical wail that imprisoned them, but also destroying the machine with the overloading.
  • The Hood's scheme in the infamous live-action Thunderbirds movie — to trap the Tracy family aboard the damaged Thunderbird 5 in orbit, invade Tracy Island to hijack the Thunderbird craft and then rob the biggest banks in the world, leaving International Rescue responsible — would've gone off without a hitch, had it not been for the presence of three kids (Alan Tracy, the youngest Tracy brother, Brains' son Fermat and Tin-Tin, the daughter of the housekeepers, and the Hood's niece), who then proceed to rescue the Tracys and help stop the Hood's plan.
  • In Tiger House, Kelly presence in the house was the one thing the gang had not bargained for.
  • In Under Siege, the bad guys have a brilliant plan to take over a battleship and sell its missiles on the black market. They neutralize the crew, have the Pentagon at bay and in total control. How were they supposed to know the cook was a highly trained NAVY Seal and the most capable warrior on the entire ship?
    • Likewise, in the sequel, Dane's entire plan would have worked out perfectly had he not chosen to use the exact same train Ryback just happened to be on.
  • Badass Bystander Gina in Unknown (2011). Despite just being his cab driver, she saves Dr. Harris' life at the beginning of the movie and twice afterwards, killing Mooks and the Big Bad in the process, which also allows Harris to stop the plan of the Big Bad.
  • The terrorists from Vantage Point might have gotten away with it, had it not been for a little girl.
  • The bank robbery in Violent Saturday probably would have gone off with a hitch if the robbers had picked anyone except Shelley's car to carjack.
  • In The Young Poisoner's Handbook, Graham's final mass poisoning attempt falls apart because management replaces the staff's individual mugs with a new set of identical ones, and Graham cannot keep track of whose mug is whose. And the irony here? Management got rid of the old mugs because Graham's previous poisonings made them think there was an infectious agent in the factory, and they were getting rid of possible sources.

  • This joke. A software tester walks into a bar and does very extensive testing — so crawling into the bar, flying into the bar, dancing into the bar, jumping into the bar, and ordering 99999999 beers, a lizard in a beer glass, -1 beers, and so on — to make sure everything works to try and make sure the bar doesn't catastrophically fail if the bar takes an unexpected order or if the user enters in an unexpected way. When a real customer walks in, they ask where the washrooms are. The bar goes up in flames.

  • Invoked, if only as pastiche (which Morrissey adores, as we know) in The Smiths' title track "The Queen is Dead":
    So I broke into the Palace
    With a sponge and a rusty spanner
    • ...referencing a peculiar event—long forgotten by most, perhaps — though the unlikelihood of Michael Fagin's misadventure conveys this trope's inherent flavor of the unexpected. In the BBC's retrospective, we learn "[t]he Queen was only able to raise the alarm when he asked for a cigarette." In more security-conscious days, who'd imagine such a Royal contretemps could occur at all?

    Myths & Religion 
  • A conspiracy by Sejanus and Herod Antipas to overthrow High Priest Caiaphas and install Herod as King of Judea (a plot not mentioned in The Bible at all due to damnatio memoriae being inflicted on Sejanus), using Jesus of Nazareth as their pawn, ended in failure when Sejanus was brought up on murder and treason charges before the Roman Senate and sentenced to death by the garrote (resulting in the aforementioned damnatio memoriae), which resulted in everyone with even a remote connection feeling more vulnerable than ever, setting in motion the events leading up to Jesus's crucifixion.

  • The Black Jack Justice episode "Justice For Some" features a client of Jack's planning to steal his wife's heirloom necklace during an event and invite known thieves to be fall guys for Jack to catch. The plan fails because one had legitimately reformed, another was on a whole other floor casing the joint's artwork, and Jack managed to grab the third when the lights went out to facilitate the robbery. This leaves the client the only person in any position to have performed the act.
  • The Cool Kids Table Harry Potter-themed game Hogwarts: The New Class is built on this. The plan was to bring four American muggle-borns to Hogwarts and teach them magic in order to expand the wizarding community. Unfortunately, the four picked were four cloud-cuckoolanders who ignore almost all advice given to them and go out of their way to poke holes in every rule of wizarding society, causing McGonagall to quickly grow exasperated.
  • The Contention Boys in Pretending to Be People have little-to-no idea of what's going on, and have been known to fail so horribly that they wind up sitting on the ground, sobbing. They still managed to take out the head of one of the most powerful organizations in the series.

    Pro Wrestling 
  • In TNA, Taylor Wilde and Lauren Brooke derailed Dr. Stevie's attempts to turn Abyss into his puppet. Despite using drugs, physical abuse, and mind games to keep him in line, Dr. Stevie didn't count on Abyss falling in love with Lauren. Then, when he ordered Abyss to attack Wilde, he didn't count on her being Lauren's best friend...
  • Donovan Dijak was most responsible for bringing an end to The House Of Truth's second Ring of Honor run, the very same Dijak Truth Martini took in to prevent him from challenging for Jay Lethal's television title belt. He was paired with Joey Daddiego and redirected at the Tag Team titles of War Machine, but when he refused to use the Book Of Truth for an illegal advantage, Martini barred him from the group...and got kicked in the head as a result of this, allowing Prince Nana plenty of time to turn Dijak towards his own designs. Daddiego and Taeler Hendrix then went after Dijak and Nana in revenge, leaving Lethal basically on his own regarding Bullet Club, who swiftly positioned Adam Cole to take his last title belt.

  • It's extremely rare for this to not happen at least once per game in Comic Fury Werewolf. It also happens intentionally a surprising amount, considering.

    Tabletop Games 
  • In the Champions (5th edition) universe, the centuries-long, multi-dimensional, wheels-within-wheels master plan of DEMON's secret master involves in its final stages a literal Spanner in the Works. The precise timing that underlies the multiverse needs to be off just slightly for the rest of his plan to work and as such he has positioned a minion in the metaphysical boiler room of creation with a $10 hardware store spanner. Now he just needs the stars to align....
  • In Chrononauts, new players are the spanner. Plans in the game range from Gambit Roulette to "I win next turn as long as no one makes a minor change in 1914". New players will often meddle with history (even starting World War III), steal random historical artifacts, or kill the makers of said artifacts, to "see what happens".
  • Dungeons & Dragons:
    • In just about any D&D module, the adventurers are the Spanner. And any good GM has to be able to handle a Spanner, as the PCs can be expected to do the one thing the GM hasn't anticipated.
    • A mediocre GM can do this to players. When the players have a good plan which bypasses the intended challenge handily or solves a challenge with minimal fuss, a good GM may let the players have their moment in the sun and save those encounter notes to recycle them with new window dressing. A mediocre GM will have the players' plans fail for increasingly implausible reasons. A poor one will have a deer in headlights look as soon as the players are Off the Rails. Probably a good example of this is this story, where a player completely and utterly derailed a cynical GM's Crapsack World with Incorruptible Pure Pureness: in a game that had a Corruption Points mechanic representing how evil characters had become, his character singlehandedly defeated the Big Bad, took his Artifact of Doom, and used it on himself. Said artifact turned the user into a god at the cost of multiplying Corruption Points by 100. The GM declared he was now the new Big Bad, but the player revealed he had accumulated no corruption points at all, and 0 times anything is still 0. His character became a God of Good whose influence slowly made the Crapsack World less crappy over time.
    • Example: Give the PCs the Eye of Vecna, you get some fun people fighting over it. However, one of the PCs sacrificing the Eye of Vecna to THE GOD OF JUSTICE? Not so expected.
  • In Exalted, beings that exist outside of fate are the ultimate Spanners from the perspective of the Sidereals. Since they cannot be detected, manipulated, or predicted by fate and fate-based powers, one of these beings can derail centuries of careful planning before the Sidereals realize that anything's amiss.
  • In Unknown Armies, you can become an Avatar of an archetype by mimicking that archetype's classical behavior. One of those is The Fool, who can pull this off easily and walk away unscathed.
  • In Vampire: The Requiem, the Circle of the Crone has the position of The Fool, whose sole purpose is acting as this. When the Circle needs something stopped they send in The Fool and watch stuff blow up. Basically it's like "so, you're a rather spirited walking corpse, eh? Say, could you go check out what that Invictus bastard is doing downtown? Just do whatever feels natural, I'm sure it'll be a blast." Fools who survive long enough to gain some measure of respectability might make it to the rank of Trickster, for whom the purpose is basically the same except the Trickster actually has some idea of what he is doing.
  • Warhammer 40,000:
    • A common meme in Warhammer and Warhammer 40,000 is to label the defeat of Tzeentchian and Eldar forces as "Not as Planned"; as the smug bastards claim any victory is "Just as Planned". Of course, claiming the defeat was just as planned is a meme in itself...
    • During the 40K "Gathering Storm" event, Kairos Fateweaver succeeded in capturing the newly revived Roboutte Guilliman and his army as they made their way back to Terra, with the Lord of Change intending to torture the Primarch into crossing the Despair Event Horizon and joining Chaos. Before Kairos could really get started, though, the prison Guilliman and his forces were being held in was attacked by a massive horde of Khorne daemons led by Skarbrand, the Bloodthirster hoping to take Guilliman's head as an offering to the Blood God. The resulting Mêlée à Trois gave Guilliman enough time to rally his troops and escape to Terra.
  • In Eos games' Weapons of the Gods , one of the background stories has an invincible martial artist invade the heavens, easily curbstomping all the gods in his quest for immortality. But the fighter's disciple complained that he was getting hungry, so the martial artist decided that it'd be alright to take a lunch break. The master sends his disciple off to go herb hunting, while he slaughters some divine cattle. The disciple finds some chili peppers from the fields of the sun god, and makes a beef hotpot with the meat from the divine cattle. Unfortunately, the peppers burned with the force of the sun, causing the master to run around screaming from the burning, eventually falling from the heavens.

  • Cyrano de Bergerac: Played hilariously straight: This play (a farce) has a lot of Gambit Pileup orchestrated by Cyrano, Roxane and De Guiche, but no one of them is capable of being an Unwitting Pawn for long.
    • Cyrano: Lampshaded by himself at Act II Scene VI: Unaware of it, he destroys De Guiche plan to set an arranged marriage with Roxane and De Valvert when he manipulates De Valvert to a duel.
      Cyrano: [bowing to Roxane]
      Then I fought, happy chance! sweet lady, not
      For my ill favor—but your favors fair!
    • De Guiche: When you apply Fridge Logic, you see that De Guiche was the Unwitting Instigator of Doom in his own plan to bully Roxane into a marriage with De Valvert at Act I Scene IV: When De Guiche makes a Dare to Be Badass to De Valvert, it’s only a small act, but it’s crucial because it sets a Disaster Dominoes scenario that ends with De Valvert being touched by Cyrano and so unable to marry Roxane. He also destroys his own plan to Buy Them Off Cyrano when he mentions that his uncle Richelieu could correct a line or two from Cyrano’s work.
  • The Yeomen of the Guard: Colonel Fairfax has been falsely accused of sorcery. In order to prevent his accusers from inheriting his property he marries Elsie Maynard so that she will inherit instead. When a plot to secretly rescue him succeeds he is honor bound to remain in the vicinity as he is now married.

    Visual Novels 
  • Ace Attorney:
    • The Big Bad's ultimate scheme in Apollo Justice: Ace Attorney ends up being exposed this way. Kristoph Gavin's scheme was meant to be the murder of Vera Misham via a poisoned postage stamp depicting the magician act Troupe Gramarye. However, the girl is such a huge fan of the Troupe that she saves the stamp for seven years; her father eventually uses the stamp instead and dies. The flaws in Gavin's plans run deeper than this, but this is his only apparent mistake; everything else is because of Phoenix Wright's meddling.
    • Larry Butz also counts, owing to his tendency to do unreasonable things that end with him stumbling onto vital evidence or just doing anything in general related to the case which usually winds up being the sole reason Phoenix and Edgeworth were able to win their cases. In the first game, he was coincidentally returning a boat he had been using at precisely the right time to overhear a gunshot, in the third he shirked his work as a security guard when the villain's plan relied on him being at his post so that he would hear the noise of a panic button, rush into the room and arrest the wrong person and then in a later case his choice to wander around at night in the cold leads to him witnessing a number of things he wasn't meant to. Lampshaded in the fourth case of the first game, when Edgeworth remarks that this is the first time von Karma has had to deal with a witness he hasn't questioned in advance, which gives them the opportunity they need to find the truth.
    • The bonus 5th case was likely intended to frame Edgeworth (again), as the victim's body was discovered in his car and stabbed by his knife. However, lunch vendor Angel Starr happened to be in the parking lot in time to witness Lana Skye stab the victim, leading to Edgeworth not being considered a suspect in the case. Lana didn't do it either, as she was just being blackmailed by the culprit. When she was arrested, her sister trusted her enough to hire Phoenix in her defense, allowing him to expose the real killer.
    • Case 2-2 has Maya's little cousin, Pearl, who manages to undermine the real killer's alibi and retrieve important evidence simply by running around doing kid stuff, and the victim himself, who didn't die immediately upon being stabbed and managed to get one shot off at his killer. The shot missed, but the bullet holes left help Phoenix nail down what really happened.
    • The whole reason Phoenix gets involved in Justice for All's forth case is that Adrien Andrews was the first on the scene of the crime and rearranged it to frame Matt Engarde. Matt had hired Shelly de Killer to murder the victim. Shelly prides himself on professionalism and protecting his client (and himself had left no evidence that could directly trace back to Matt), so when Matt is arrested anyway (thanks to Adrien Framing the Guilty Party), he kidnaps Maya to force Phoenix to take the case and get Matt aquited. This leads to the complete mess that is case 2-4, but it also means that Phoenix finds evidence that Matt actually was guilty (and, more importantly, that he'd planned on betraying de Killer), something that never would have happened if de Killer had simply killed the victim and got away like he'd planned.
    • Also in the fourth case of Justice For All, the lead that helps Gumshoe and company track down Shelly de Killer is, of all things living and not living, Matt Engarde's cat, who meows at the end of a transmission from de Killer.
    • In the third case of Justice For All, Acro's plan to murder Regina was to call her to a specific point where he would drop a heavy weight on her head. Problem is, the note he secretly planted on Regina began with "To the murderer...". Due to Regina being very naive, she didn't think the note was for her, and posted it on the circus's bulletin board, where her father saw it and responded to it in Regina's place. Then you realize that Acro wanted to kill her because her naivete led to his brother being put into a coma, so he really should have known that she would never realize the note was meant for her...
    • In Trials and Tribulations, Furio Tigre's plan to use Glen Elg's MC Bomber virus, worth several million dollars, to pay off his own million-dollar debt was annihilated because the moment the exchange was about to happen, Elg miraculously wins half a million in the lottery. The half-million is enough to just pay Elg's debt normally, which Elg then did, leaving Furio with half the money he needed, resulting in Furio killing him to steal the virus..
    • In the final case of Ace Attorney Investigations, the shenanigans of Larry Butz and Wendy Oldbag, of all people end up helping Miles Edgeworth put away the seemingly untouchable Big Bad. Larry, by accidentally breaking the Samurai Spear, forces the staff to have the Steel Samurai use a different move instead, thus enabling Edgeworth to realize that Alba was not at the Steel Samurai show while he was killing Manny Coachen. Wendy Oldbag takes the box of "Rising Sun Dogs" thinking they were some sort of limited-edition Samurai Dogs, when they were actually a perfectly normal box of Samurai Dogs with a drop of Alba's blood on it, and combined with Alba's wound, proves that he was injured while killing Coachen.
    • Larry gets to do this again in the manga. Simply by being arrested on suspicion of killing Bright Bonds (based on calling him and demanding that he get out of his ex-girlfriend's life), he derails the killer's plan to use him as an alibi, because she gets called in to prove his alibi, and through contradictions in her testimony, gets implicated as the murderer.
    • Phoenix Wright: Ace Attorney – Dual Destinies has one in the first case that only pays dividends in the last: Ted Tonate, a bomb disposal specialist who noticed that the bomb involved with a murder he himself had just committed had been rearmed, and warned everyone in court to evacuate before it exploded. The phantom had secretly rearmed the bomb in order to blow up evidence against him. Not only does Tonate's testimony alert Phoenix to the fact an outside party was involved, two of the people in the courtroom at the time of the bombing (and thus potential casualties) are Athena Cykes and Simon Blackquill, who end up being crucial witnesses when the Phantom is eventually dragged to court.
    • Phineas Filch ends up as one in Dual Destinies' second case. Florent L'Belle's entire scheme — a plot which took months of planning, backstabbing, manipulation, blackmail, threats, and outright murder, one so complicated that it's lampshaded how insanely complicated it all is by Apollo Justice — was all to have unrestricted access to the Forbidden Chamber in Nine-Tails Vale to steal a gold ingot supposedly contained inside of the Chamber. Filch, on the other hand, snuck into the Forbidden Chamber on a whim in fifteen minutes because he was bored. By doing so, Filch spooked Jinxie Tenma, which forced L'Belle to improvise a few things, proving to be his downfall in court.
    • Phoenix Wright: Ace Attorney – Spirit of Justice: In the game's second case, there's the equally complex plot enacted by Roger thirteen years in the making. His plan of framing Trucy Wright as revenge against her family for shaming him over his true colors involved a very meticulous setup during one of Trucy's magic shows. After conning Trucy into agreeing to pay out a ransom money over the show's cancellation, Retinz roped all three of Trucy's fellow actors, Manov Mistree and the de Famme twins, into playing a prank on Trucy that involved Mistree faking his death upon exiting a coffin that Trucy had just stabbed. Retinz then deceived Mistree and the de Famme twins by dragging Mistree up via pulley to be impaled by a sword planted on the nearby catwalk, then staged the scene to make it look like Trucy had accidentally killed Mistree. What he couldn't foresee was one of the de Famme twins accidentally positioning a prop on the wrong side on the stage, thus causing Trucy to stab the coffin at the same irregular angle - when Retinz later learned about this, he returned to the scene in a desperate attempt to switch the coffin panels so the facts would line up again, inadventently sealing his fate in the process. Not helping that fact was that, also unbeknownst to Retinz, Apollo Justice was himself a Gramarye descendant who was able to see through every single one of his elaborate illusions.
    • Additionally, the DLC case shows that Larry Butz's still got it; thanks to messily sneaking into a wedding reception because he was hopelessly infatuated with the bride, he not only screwed with the whole "time travel" theme and coverup that was attempted, his general interference also forced the culprit to enact his plan and murder his accomplice much earlier than intended, completely derailing everything and making it possible for the culprit to get caught.
    • In The Great Ace Attorney, Kazuma Asogi convinces Ryunosuke Naruhodo to accompany him on his study trip to London. However, Asogi ends up dying while on the ship, so Naruhodo takes a crash course in British law and becomes a lawyer in his stead. This throws a big spanner in Mael Stronghart's scheme, which was to have an assassin pose as an exchange student so they could benefit from Diplomatic Immunity. Now that another student showed up in Asogi's place and proved himself worthy of being on the study tour, Stronghart can't just send him back and look for another assassin without seeming very suspicious.
      • The killer of case 2-1 helped with that by murdering Jezaille Brett back in Japan after she said a few too many racist slurs. Jezaille Brett was the other assassin in the exchange program, and the back-up plot in case Kazuma failed. She would've probably killed Inspector Gregson in his place if she'd made it back to England... but just before she was due to be deported, she pissed off Raiten Menimemo, a Japanese journalist who'd just so happened to have stolen a sample of rare and extremely toxic alkaloids. Raiten then spiked her drink with the poison, leaving her dead and the Reaper conspiracy lacking both assassins, meaning that Jigoku had to murder Gregson himself, which is what eventually leads to the conspiracy being unraveled.
      • Also invoked ad verbatim in the second game's third case by the engineer Enoch Drebber. The plan involved destroying his room with a time bomb set in plain sight, while he's concealed inside an impenetrable safe: should anyone happen to enter the room, they would normally run away in panic. The room would blow up with no one else in it, and thus the bomb would dispose of vital evidence while simultaneously hiding Drebber's presence. This entire scheme backfires when, upon the police's arrival at the scene, Great Detective Herlock Sholmes instead mistakes it for an antigravity device and spends several minutes performing a complex deduction with the help of Naruhodo to locate Drebber within the room, completely foiling his plan. They do also risk their lives in the process, with Herlock realizing that the bomb is primed when it's just about to explode and defusing it with only 7 seconds left on the clock.
  • Danganronpa:
    • In Danganronpa: Trigger Happy Havoc, the entire triumph of hope over despair on Earth hinges on a poorly-fitting bathroom door that gets stuck in the doorframe, which forces the killer to go back to his room to retrieve a screwdriver to open the door, providing a bit of decisive evidence. A door which, because of Naegi's Ultimate-level luck (which manifests as seemingly-bad luck that turns out to be good luck in disguise), gives him an alibi for a crime he would otherwise have been framed and executed for. Given how important Naegi would go on to be to the future of humanity, it's no exaggeration to say that that was the moment that the mastermind's fate was well and truly sealed. Even worse, it's implied that the mastermind deliberately gave him the crappy door just because they thought the idea of the Ultimate Lucky Student being the only one with a crappy door was funny.
    • Naegi's luck is even referred to as a "spanner in the works" verbatim by the mastermind; no matter how Crazy-Prepared they are for every possible scenario, Naegi's luck is totally unpredictable and can throw everything off on a dime. As the mastermind has such an analytical mind that they can essentially predict the future, causing them to suffer from constant crippling boredom and leading them to become obsessed with the emotion of despair because it causes people to behave in unpredictable (and therefore not boring) ways, this has caused them to develop a similar obsession with Naegi as well.
    • In the game's first case, the murder's plot is more or less derailed by the fact that Aoi happens to be sitting in the dining hall at a certain time, and as a result realizes that there's only one person who could've possibly retrieved the murder weapon from the kitchen. Sure, the murder's plot ended up backfiring and getting them killed by their intended victim, but that particular piece of evidence is integral in figuring out what really happened and identifying the killer.
    • Downplayed in Chapter 2 (since that murder was a spur of the moment deal), but Chihiro's murderer would've gotten away with it if Celeste hadn't happened to be in the storage room and saw Chihiro before the murder.
    • Kiyotaka avenges his own murder in Chapter 3 with his obsession with timeliness; when he's found dead, Kyoko notices that his watch was broken at a certain time. As he'd loudly announced the time from his watch the previous night, she's able to prove that the watch was broken in the struggle that killed him, thus proving that his murder didn't happen when the killer wanted people to think it did, which helped blow the lid on the Frame-Up against Hagakure.
    • Sakura Ogami also manages this. In the fourth chapter, she commits suicide, but before she did this she broke the lock on the Headmaster's Office (breaking down doors was against school rules, so no student who wanted to live would do it- but since Sakura was already planning to kill herself, she broke it without fear) to get posthumous revenge on Monokuma. Not only does her suicide help Makoto rally the students against Monokuma, the Headmaster's office being open allows Kyoko to grab Mukuro Ikusaba's student profile and a master key that allowed her to access every room in the school, which ultimately leads to the Mastermind's unmasking.
    • It's later mentioned that Sayaka Maizono was one, as the Mastermind wanted Sakura, as their mole, to kickstart the killing game. Sayaka snapping and resorting to murder so quickly (and Leon killing her after she failed to kill him) meant that Sakura was spared for her own moment discussed above.
    • In the fourth chapter of Danganronpa 2: Goodbye Despair, Hajime is able to figure out who committed that chapter's murder because Fuyuhiko happened to wake up during the night and saw the victim heading downstairs, then sat down in the lounge and spaced out for a while. Fuyuhiko's presence in the lounge prevented the killer from returning to their room after carrying out their plan, and thus they couldn't secure their alibi of being fast asleep when their time-delayed murder method went off. Instead, the killer had to pretend they had left their room along with everyone else to investigate the ringing alarm clock in the lounge, which is proof they weren't in their room in the first place since they had one of the Deluxe rooms, which were completely soundproof.
  • In Hatoful Boyfriend's True Ending storyline, Dr Iwamine had won. Ryouta was mindless and implanted with the Charon Virus, Sakuya was emotionally broken, Yuuya and Hiyoko were both dead, and Kazuaki and Anghel were trapped. It takes two spanners to fix this. The first is Okosan, who snaps Sakuya out of his grief just in time to stop Anghel and Kazuaki from dying to nerve gas. This leads directly into the second — and most important — spanner, which is Anghel using his hallucinogenic pheromones to put Ryouta into a mental state where he could be talked down and prevented from wiping out humanity, thus unravelling everything Shuu had done up to that point. Needless to say, it's best not to fuck with the Joke Characters.
  • In Higurashi: When They Cry, 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 "Groundhog Day" Loop.
  • In Shall We Date?: Ninja Shadow, Makoto's route has his Anti-Villain brother Toru deploying an Evil Plan where he frames Makoto for murder to disband the Nagasaki Vigilantes, isolate his younger brother and force him to join his rebel cause. It works scaringly well despite Saori's efforts, until... Ukyo decides to call the Edo Vigilante group and ask them for help. The moment Kinshirou and Wakasa from the Edo group step in is the moment they start working hard to learn what's going on, leading to them clearing Makoto's name and giving him and Saori the chance to confront, fight and capture Toru.
  • True Love Junai Monogatari:
    • The Player Character can potentially become this if following Ryouko Shimazaki's route. Ryouko is actually an Idol Singer (under the identity of Sonoko Takahashi) and has apparently retired, much to the sadness of her fans and the profit of her sponsors. Her manager and brother/parent figure, Tadaaki, actually had her fake her retirement to pique the interest of the fandom, then make the greatest come back ever — and since Ryouko is both his younger sister and his ward, she cannot stop him no matter how badly she wants to lead a life of her own. But after she befriends the MC, he inspires her to try speaking up and being her own self, leading her to rebel against the stage brother who controls her life and actions.
    • Also, if the PC pursues either Mayumi Kamijou or Yumi Matsumiya (who can't be romanced if at least a good part of Mayumi's path isn't unlocked first), he will also ruin Mikazaki's plan to blackmail Mayumi into sex and will give Yumi enough proof to get Mikazaki himself humiliated and kicked out of the school.
  • Tyrion Cuthbert: Attorney of the Arcane:
    • The defendant in case 2, Wallace Nightgrave, was framed by accident. The culprit intended to frame a different student for the murder, except:
      • An academy staff member who found the victim's body attempted to heal her with magic, which concealed the fatal wound and left traces of necromancy on her body, throwing suspicion on Wallace because he was the only known necromancer at the academy.
      • The bloody murder weapon was supposed to be left in Miriam Frega's locker to implicate her, but Wallace's locker ID had been swapped with Miriam's as a prank by other students, and the Animated Armor tasked with the deed couldn't tell the difference.
    • In case 4, Beatrice Frega wouldn't have come under suspicion for murder if a stolen Anti-Magic sword used in the crime hadn't been found in her old bedroom. Her sister's wolf familiar had been hiding in said room, and retrieved the sword from elsewhere believing it to be a large stick.
    • In case 5, Eris Illmater's master plan revolves around forcing Celeste McCoy to sign a Deal with the Devil and murder Garrick Pierce, which goes off the rails when Pierce realizes that he's been marked for death and kills himself out of spite, making the terms of the contract impossible to fulfill. The mastermind spends the rest of the case trying to cover up their mistake and make it look as if the plan had been carried out as intended.

    Web Animation 
  • In the Homestar Runner holiday toon "A Death-Defying Decemberween", Homestar announces to one and all that he's going to sled down the Steep Deep — a vertical cliff face — and Strong Bad catches The Cheat surreptitiously helping Homestar bury a mattress at the foot of the alleged slope. Of course, Strong Bad being Strong Bad, he moves the mattress expecting Homestar to maim himself on impact...but the next day, when Homestar sleds down the Steep Deep, he makes a perfect landing. As it turned out, the mattress was full of "hammers, broken glass and candy canes sucked down 'til they're all pointy"; the whole thing was a ridiculously elaborate (and painful) scheme for Homestar to get out of having to spend Christmas with his girlfriend Marzipan's parents, one that Strong Bad successfully sabotaged (even if the end result wasn't quite what he had been expecting).
    • The Strong Bad Email "do-over" involves Strong Bad attempting to re-do past emails that didn't go the way he wanted them to. However, in summoning The Cheat for help, he gets Homestar badly pretending to be the cheat, which ends up causing Strong Bad's re-dos to go even worse than the originals; he subsequently re-dos the current email. (An easter egg shows the Cheat on a date with Marzipan dressed as Homestar, implying they'd swapped roles for whatever reason.)
  • Red vs. Blue:
    • In Episode 100 of the Blood Gulch Chronicles (Seasons 1-5), Omega the evil AI has apparently won; He's repossessed Tex, captured Junior, Tucker's alien son, and has a ship to escape Blood Gulch with. What stops the computerized personification of rage from possessing Junior and using him to eventually take control of the aliens from within? The Red Team planting Andy the Bomb on the ship. This was originally done in an attempt to defeat the Blues, but Andy's presence allows them to blast Tex and Omega out of the sky, allowing Junior to escape in the chaos. On a smaller scale, Tucker finding the alien sword makes him immune to Agent Wyoming's time-rewinder, allowing him to remember the events of each iteration and eventually figure out how to stop the bounty hunter for good.
    • The Space Pirates from the Chorus Trilogy (Seasons 11-13) had a pretty good False Flag Operation; their leaders would play two rival factions on the planet against one another, fueling them with reversed engineered alien technology and special weapons from ships they forced to crash into Chorus using their tractor beam until both sides killed each other off, allowing their employers to take full control of the planet and all the alien relics therein. However, their last attempt was foiled when the ship tried to change course, jump to slipspace, and power down simultaneously, causing it to break apart on entry and leave some of its passengers alive. Said passengers are the Blood Gulch Crew, who not only complicated the attempted crash in the first place (purely by accident) but would also end up outing the Space Pirates scheme to Chorus and eventually the rest of the UNSC.
    • In Season 14, we learn how the Blood Gulch outposts were formed. Project Freelancer were going to use the place to hide the Alpha AI, so Agent Florida purposely assembled the worst soldiers from both the Red and Blue armies to fill the ranks, and even had a computerized personality (Vic) act as Command and keep both sides at a stalemate. Vic even had a roster of other Freelancers to recruit if anything happened to Florida. So what causes a perfectly orchestrated Forever War to spiral out of control, and eventually lead to the Project's destruction? Florida tripping over one of Vic's cables, then dying in a Stable Time Loop (Church tried to prevent his death by giving him aspirin, which he was allergic to). This scrambled Vic's systems and replaced the agents who were supposed to be sent to the teams with Caboose and Donut, whose Snipe Hunts (wait for an inspector with different armor than the Blue team and go to a store and get some elbow grease, respectively) end up with Donut running off with the Blue Flag. This caused Tex's appearance, Church's death, and ultimately the entire series.

  • Fighter of 8-Bit Theater is the living embodiment of this trope, as he's too stupid to know whether he's supposed to fall for a crazy plan or not. He bends the Theory of Narrative Causality by his very existence.
  • Antihero for Hire's Wizard lays it out cold for would-be Chessmaster Hector:
    You always overthink things. The reason your plans keep failing is not because your enemies are geniuses. It's because they are idiots. A plan is only truly foolproof if you consider the fool.
  • One of the characters in the Blip is this to God's master plan.
  • Obi-Wan and Qui-Gon end up doing this to Darth Maul in Darths & Droids. In a clever little inversion, this whole scenario is actually made up on the spot by the DM, after the events took place in which the players apparently screwed up everything by going Off the Rails. The author suggests this technique as a way of getting back at players who mess with your established scenario too much.
  • In Dead of Summer, the Big Bad's backup plan to blow everyone up with a Time Bomb was thwarted because Tito and Otis saved Panther, who proceeded to disarm the bomb and save everyone.
  • The majority of the plot of Demonology101 consists of Raven and her friends following this trope.
  • The main cast of Drowtales are Manipulative Bastards and Chessmasters whose plans often wind up crashing into each other, but so far the biggest example of this trope is Ragini, a child slave who survived the massacre at the Val'Sharess tower and was able to keep said Queen alive for a year, and then later become host to her aura and escape. If it weren't for her things in the story would be much, much different, and the full extent of her spanning potential is just beginning.
    • The Big Bad, Snadhya'rune, is implied to consider Ariel a key part of her plans. This results in the Big Bad's "Well Done, Son" Guy attacking Ariel out of jealousy, ensuring Ariel will never trust the Big Bad.
  • El Goonish Shive: Sirleck's plans were carefully calculated, but he never anticipated that Ellen would be conscious whilst he puppeteered her body — which gave Magus the time he needed to dispose of him.
  • Gunnerkrigg Court: Trickster God Coyote should by nature be used to chaos, but in Chapter 90 "Coyote Knew This Would Happen", it turns out even he couldn't predict Lana would fall in love with Loup (both in his Jerrek disguise and out of it) and seduce him, disrupting his plan to make him Star-Crossed Lovers with Annie.
  • I Don't Want This Kind of Hero: From Baek Morae's perspective, Haze ruined everything. Haze was a random trespasser who saved Raptor's younger brother, Stell, and uncovered the truth behind Baek Morae murdering all of her friends, therefore utterly destroying their relationship in the span of about a day. To rub salt in the wound, in the present day, he's the one who ended up with her.
  • Misfile: It turns out Rumisiel managed to throw a huge monkey wrench into a plot to destroy the Celestial Bureaucracy and remake the world and humanity by taking the key to his wing of the filing system with him when he got exiled, keeping it out of the wrong hands.
  • The Order of the Stick:
    • Roy Greenhilt qualifies for this in one early instance, despite being a very intelligent person, simply because he does something so very unexpected. Xykon honestly doesn't expect the heroes to stop him (and rightly so, as he has an army of monsters, 10 or more levels on the strongest PC, and a monster strong enough to send Paladins flying by LIGHTLY TAPPING THEM). He has three characters immobilized, two more being stalled by monsters, and he had JUST shattered the leader's ancestral sword. Confident that the battle is as good as over, he starts to call out the aforementioned monster to finish the heroes off. And then Roy goes and tosses his bony ass into a body-destroying Gate that holds an Eldritch Abomination at bay. The Big Bad is out of commission.
    • Elan is one of these for both the good and bad guys. Daigo at one point wonders if he's more useful the less he knows what's going on, and Durkon suggests that "He has Ignorance as a class power source." In 691, Roy lets him wander around the desert in the hopes that he'll stumble over something. WHICH HE DOES!
    • The unnamed Cleric of Loki restored Belkar exclusively because it would help him leave safely, which he immediately did. He had no interest in what Belkar did next.
    • The Monster In The Dark has as of #1041 taken to secretly hindering Team Evil's search for the final Gate. Lampshaded by the page's title, "Value of an Independent Variable".
    • When the Order planned an ambush for Xykon, they end up getting derailed by Serini, who believed that it was for the best to prevent them from stopping Xykon. By the time the Order convinces her otherwise, they are informed by Blackwing that Xykon has come out and they've missed their window of opportunity, causing Roy to actually lose his cool and go into a Cluster F-Bomb.
  • Rusty and Co.: Zar the Psion gives his agents as little information as possible in order to avoid derailing his own prophecies. However, the Rhyming Devils are under no such limitations and Anti-Madeline's theft of an Artifact of Doom marks a major break from the future he'd foreseen, so the Princess convinces Zar to give up on his original predictions and help them out properly.
    Zar: This definitely didn't happen before. Something is... wrong.
  • Schlock Mercenary: In Book 15 Schlock ends up derailing a Staged Populist Uprising simply by drawing the attention of a police officer who was unwittingly carrying a bomb that was supposed to blow up the heads of the popularly elected legislature, providing the pretext for the fake revolt. And there was a second spanner — most of the police force was supposed to have their personalities overwritten as part of the uprising, it just that one of them was hijacked by a different party.
    • Schlock does this a lot, really, crowning it off in Book 20 by accidentally boarding a Pa'anuri warship with a powerful enough AI implanted in his head for Petey to gain the means to stop the Pa'anuri invasion.
  • Sleepless Domain: Chapter 13 focuses on Rue fighting a monster, almost getting killed until Zoe steps in, choosing to battle for the very first time to save her. The chapter concludes with the reveal that the attack was staged by "The Purple One", the Big Bad of the story who has control over the monsters. The Purple One shows frustration that the attack failed even without the active interference of "The Golden One", who has occasionally led magical girls to places where they might be of aid. Zoe just happened to pick the right time to become brave.
  • In the Sluggy Freelance story arc "GOFOTRON Champion of the Universe," Zorgon Gola has a pretty nice Gambit set up where he pretends to be an Omnicidal Maniac, so that the heroes will sacrifice themselves trying to prevent a chain reaction that would destroy the universe, leaving him free to take over the Punyverse after their deaths. What he didn't count on was Torg, Riff, and Bun-Bun accidentally teleporting themselves into the Punyverse. They end up hijacking a vital piece of the heroes' Combining Mecha (the crotch). Without this, the heroes have no way of pulling off their Heroic Sacrifice, and Zorgon Gola, along with the rest of the Punyverse, is blown up. Oops.
  • In Season 9 of Survivor: Fan Characters, Prescilla/Bonnie has been controlling the entire game and has managed to take the two weakest players to the finals with her while tricking everybody into believing that she's just a sweet, innocent girl who couldn't POSSIBLY be an evil mastermind and gloats about how she has a 100% chance of winning the day just before the final Tribal Council. Then Cherman, the little robot who has been a Butt-Monkey for most of the game, reveals that he has a recorder he used to record Bonnie's Evil Gloating about how her only regret is that she didn't do more to hurt others. Your reign was nice while it lasted, Bonnie.
  • Quentyn Quinn in Tales of the Questor is a subversion. Instead of stupidity, it is a sense of honor and desire to help that make him accept quests which almost always indirectly monkey-wrench SOMEONE'S plans, generally without even knowing it. Examples:
    • A simple lack of knowledge led him to believe (and say) that human coins were forged. A politician's Oh, Crap! moment led a guard to realize they were indeed fakes — and who was behind it.
    • His very decision to become a Questor — paired with the discovery of an old contract — puts his home village in peril. The contract stated that the previous Questor was to retrieve some artifacts in exchange for land on which to build a village. The problem: the old Questor failed to do so, and now that there's a new Questor, a political faction intends to use that contract to get Freeman Downs repossessed and thus out of the picture. Quentyn's decision is to bravely attempt to retrieve those artifacts himself, putting his own life at risk to do so. This puts the faction at the end of a Morton's Fork — if Quentyn dies in the attempt, the law ensures that the contract ends with Quentyn, and the faction's scheme will fail. But if Quentyn succeeds, the faction will have no legal standing to get Freeman Downs repossessed, and the faction's scheme will fail. Quentyn knows nothing about the true scheme at work, and the faction has a Mass "Oh, Crap!" as they realize what this could mean, having no idea what to do about him. The legal counsel sent to deliver the bad news summed it up thus:
    • Quentyn's desire to help a human village ended with Quentyn screwing over an evil member of The Fair Folk, again without knowing of the true nature of what's going on in the background. The fae in question calls a Wild Hunt on Quentyn, promising a wish if he survives. Quentyn barely manages to win, but it's only then that the fae realizes Quentyn is not only part of a race that's protected from the Hunt, but also under the protection of another being which doubly prohibits him from being Hunted. As punishment, the fae now has to grant three wishes instead of one. The first two wishes are used to deprive the fae of everything he has. The third wish is that the fae must permanently leave, with an additional clause that forbids the fae from ever calling a Wild Hunt on that plane of existence ever again.

    Web Original 
  • Boomer, a Mad Bomber from the SCP Foundation storyline "Game Day", tends to carelessly leave dangerous explosives in random places around his hideout, to the point that it's not really possible to plan a safe approach to it.
    Boomer was the type to leave loads of bombs, traps and other assorted goodies laying around in a nightmare combination of cunning and blind, absentminded stupidity. You could plan around a smart enemy, a dumb one was prone to blowing your intelligent, well-planned ass off at random.
  • In the Whateley Universe, this is Jade's purpose in life. She's screwed over at least four plans, simply by being there. See "It's Good to be the don", "Christmas Elves", "Christmas Crisis", and Ayla 7-6.

    Web Videos 
  • The "Heist" episodes of Achievement Hunter's Let's Play Grand Theft Auto V always have one that ruin their well thought-out robbery plans towards (usually) a convenience store.
    • The first episode "(Geoff's) Heist" gets derailed when their explosions causes their wanted level to hit 3-star, bringing in a helicopter.
    • "Gavin's Heist" goes bad when the explosives on the tanker truck they were using despawned due to distance.
    • "Ryan's Heist" got derailed due to just how much trouble the gang was having trying to get the Cargobob to the armored truck.
    • "Michael's Heist" hits a minor snag when he realizes that he can't rob banks yet (Rockstar hadn't added that in just yet), but recovers spectacularly.
    • "Jack's Heist" gets hit because of the escape jet they were using — they couldn't escape cleanly in traffic and later roasts Michael, who had the money.
    • "Ray's Heist" goes belly up because of a locked armored car door.
    • "The Grand Heist" stumbles at the finish line because the Titan stalled.
  • Dragon Ball Z Abridged:
    • An odd variation occurs when Dende uses the last wish on Porunga to wish everyone off of Namek save for Frieza and Goku. Not only did this screw Frieza out of his immortality like in canon, but this was the same exact plan King Kai was going to use, only Dende beat King Kai to the punch and did it solely to piss off Frieza.
    • Earlier on, before Vegeta makes his way to Namek to gather its Dragon Balls, Cui tells him that Freeza heard about Vegeta's plans whilst he was on Earth, because the scouter was on the entire time. Vegeta is shocked at this, claiming the transmitter was off the entire time, but then he realises that Nappa was with him and probably forgot to turn off his scouter...
  • Double subverted during the Centralis battle in the Noob novels and webseries. Fantöm's plan was to distract Amaras simply by his unexpected presence to keep him away from the Coalition frontlines, depsite being much weaker than him. Amaras doesn't fall for it, but this is the time Spectre chooses to confirm the rumors about him being Back in the Saddle. The major difference is that Spectre is strong enough to give Amaras trouble and wants the Empire to win enough to keep him busy so it will have a chance. The novel version of scene mentions the trope by name.
  • The first episode in the Persona Memeverse series ended with Haru completely trashing Atlus' headquarters because they wouldn't give her more screen time. The third episode reveals that FEMC used this to her advantage to escape the company's clutches, delaying their plans and kicking the series' plot into motion.
  • In Ten Little Roosters, Chris just can't die, preventing Burnie from getting the killer four times in a row because he keeps acting like Boromir.
  • When Tipping Forties LP'd Tales of Symphonia, they managed to go about 90 videos without using Presea, who they perceived as The Scrappy. The point was they hated the flatness of the character and refused to involve themselves with how stupid that part of the game was. Of course, they forgot the game was stupid (for that one instance, at least) and a scripted event forced them to use her. It nearly brought them to tears. Laser-Guided Karma.
  • Stampy's Lovely World:
    • If the Easter Bunny hadn't set up the annual egg hunt in Episode 291, "Egg Hunt", Stampy would have never realized Hit The Target had kidnapped his dogs (the only reason he went to the Doghouse that episode was because the clue for the next egg hinted it might be there). By the time he would have figured it out (presumably the next episode), Hit The Target would have already been gone with the dogs, and the Hotel of Dreams would most likely be completely destroyed.
    • William Beaver was this to Hit The Target and Veeva Dash's plan to unleash a Wither to destroy the Lovely World in Episode 355, "Friends and Foes", having persistently kept an eye on them and Stampy since he secretly settled in the World and charging in to help Stampy fight off the Wither after it's spawned. Veeva Dash lampshades this on Twitter after the episode.
      Veeva Dash: (tweeting) You ruined everything @William_Beaver! We have been planning for so long!
  • In Yu Yu Hakusho Abridged:
    Kurama: I believe Hiei's superior speed would be the best choice for this fight.
    Hiei: Well Kurama, your plan sounds good except for one fatal flaw.
    Kurama: What? What are you talking about? My plan is foolproof!
    Kuwabara: [screen-shift] Here kitty kitty!
    Kurama: I stand corrected.


Video Example(s):


"Where Did History Go Wrong?"

At first, it seemed that Zim's plan to eliminate Dib using a time machine to change the past with rubber pigs worked. Unfortunately, due to unexpected events in the past, his attempt ends up making Dib a more dangerous threat than ever.

How well does it match the trope?

5 (39 votes)

Example of:

Main / GoneHorriblyWrong

Media sources: