"What happens if Bobo causes one of those weird numbers where he goes back into the past and steps on a butterfly or something, and because of that mammals as we know them never evolve, and because of that mankind never invents slot machines, and my favorite hobby goes straight down the toity, huh?!"A story in which one small change has a ripple effect, resulting in massive changes. Derives from a proverb-turned-poem which traces its origins as far back as the 14th century (making this Older Than Print). Probably the most well-known version is the one which appeared in Benjamin Franklin's Poor Richard's Almanac:
— Pearl, Mystery Science Theater 3000
For want of a nail, the shoe was lost;A Deal with the Devil will often have the "nail" as a price, something of seemingly small consequence, that is in fact huge. In a series of Disaster Dominoes, the first domino often falls when the "nail" that props it up suddenly goes missing. Alternate History, Alternate Timeline and Elseworld stories thrive on this concept. A Sub-Trope of What If?, and often a Sub-Trope of Make Wrong What Once Went Right. A Super Trope of Close Enough Timeline. If the originals meet their alternates, may result in Other Me Annoys Me or Future Me Scares Me. The It's a Wonderful Plot trope is a Sub-Trope of this itself. Often overlaps with In Spite of a Nail, because many stories wouldn't be that interesting if everything was different. Compare It Began with a Twist of Fate and Contrived Coincidence.
For want of a shoe, the horse was lost;
For want of a horse, the rider was lost;
For want of a rider, the message was lost;
For want of the message, the battle was lost;
For want of a battle, the kingdom was lost,
And all for the want of a horseshoe nail.
For want of a shoe, the horse was lost;
For want of a horse, the rider was lost;
For want of a rider, the message was lost;
For want of the message, the battle was lost;
For want of a battle, the kingdom was lost,
And all for the want of a horseshoe nail.
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- A Staples Business Depot TV commercial from the '90s, directly references the trope with a different scenario.
For want of a paperclip, a page was lost.
For want of a page, a contract was lost.
For want of a contract, a deal was lost.
For want of a deal, a factory was lost.
For want of a factory, a company was lost.
All for the want of a paperclip.
- Toshiba Electronics commercials depict this inside the mind of the CEO, leading him to hold back on releasing the product to make sure it has all the features it needs, regardless of the cost. For example, adding shock-proof hard drives to their PC's. He imagines an electrician dropping his laptop, picking it up and plugging it into an outlet at a relay substation, which causes a spark that knocks out the power. This leads to a person's roommate opening the refrigerator, sniffing some milk, noticing it's spoiled but drinks it anyway, immediately turns into a zombie, and unleashes the Zombie Apocalypse on the world.
- An ad series for DirecTV starts with a customer experiencing some flaw associated with digital cable, which cascades into random scenarios like waking up in a roadside ditch, selling your hair to a wig shop, or re-enacting scenes from Platoon with Charlie Sheen.
- Imagine a World Without Hate, an ad by the Anti-Defamation League which shows how some people, like Yitzhak Rabin and Martin Luther King, could have changed the world had they not been assassinated, to the tune of John Lennon's Imagine.
Anime & Manga
- For want of Raye Penber, Death Note lasted much shorter than it could.
- Even earlier than that, the human who picked up Ryuk's fallen Note happening to be both crazy enough and smart enough to use it constantly without getting caught initially.
- The basis for the plot of Dual! Parallel Trouble Adventure is that reality splits depending on whether a construction worker on site when Lost Technology is found takes a sample home when his crew's ordered to destroy the evidence. The Hero, Kazuki is at first able to see into the other reality, and eventually crosses over.
- The reboot of the Rozen Maiden manga features Jun, the protagonist of the original manga, who decided to take the blue pill path instead, resulting in him not meeting the dolls and remaining a hikikomori for the remainder of his mid school duration. We meet him as a disgruntled college student with a bad side job, and frequently being laughed at due to his past status as a hikikomori. That is, until Shinku and the other dolls from the original continuity appear in his continuity...
- One of the recurring themes in Legend of Galactic Heroes, where seemingly minor events cause a huge impact on history. What if Kircheis had been armed during Ansbach's assassination attempt and survived instead of died? What if the supply depot Muller attacked had fought back instead of surrendering, so that he couldn't rescue Reinhard? What if Hilde hadn't persuaded Mittermeyer to attack Heinessen to force a ceasefire, or if Yang ignored said ceasefire? What if Yang hadn't allowed the "Imperial escorts" on his ship so that they couldn't assassinate him?
- In the Mai-Otome manga, Sergay is not Nina's father and Nagi, while not a very good person, is not the main antagonist. As a result, Nina stays on the heroes' side for the entire story.
- On a lesser scale, Sergay is not anonymously paying for Arika's education in the manga, forcing her to take on several side jobs and leaving her no time to study, at one point putting her in danger of failing and dropping out.
- In Dragon Ball Z, the main timeline ends up being VERY different than the one Trunks comes from. For example, Androids #17 and #18 are much more powerful in the main timeline but not really all that evil (they do initially intend to kill Goku out of boredom but don't really go out of their way to hurt anyone else) whereas in the future timeline, since Goku was already dead, they were made explicitly for world domination but were far less powerful to account for a Super Saiayn. Android #19 didn't exist in the Trunks' timeline nor did Android #20 (Dr. Gero had never turned himself into an Android). Goku also got sick MUCH later than he did in Trunks' timeline.
The difference in strength between the main and alternate timeline versions of #17 & #18 was explained differently in the manga. In the "Trunks: The Story" chapter when Gohan was fighting #17 & #18, immediately before #17 kills Gohan, #17 tells him that he'd been using no more than half of his power. After a short timeskip we see Bulma & Trunks debating the need for a time machine. Trunks thinks he's already gotten strong enough to defeat 17 & 18, while Bulma thinks he's too naïve since he was only at about Gohan's level and Gohan was still killed. After this we see Trunks leave to fight them and the next panel we see they've put him in the hospital. There is no actual proof that the full magnitude of 17's power (and possibly also 18's) was revealed to Trunks before he went back in time. Assuming that Trunks was unaware of 17 & 18's full power in his timeline, it would explain his surprise at their power in the main timeline. This would also indicate that the androids from the main timeline were actually just as strong as those in the alternate timelines and that Trunks was simply unaware of that fact. However, one thing remains consistent in both timelines: Goku dies.
- In Blood+, Saya and Diva are twin sisters. Joel raised Saya like a daughter, whereas Amshel kept Diva locked in a tower, treating her like an experiment. When Saya receives this history lesson, she can't help but sympathize with her sister, knowing full well that they could just as easily wound up with their roles switched.
- As revealed in Mobile Suit Gundam Unicorn, just about everything that's happened in the Universal Century, from the Earth Federation's MO to the One Year War and beyond, could be traced in some form or another to the Laplace incident in UC 0001.
- Puella Magi Madoka Magica: During Episode 5, Sayaka laments not contracting earlier, wondering aloud if doing so would have saved Mami's life. The Different Story reveals that yes, it would have. However, this is not necessarily a good thing.
- All the events of Tokyo Marble Chocolate would never have happened if the pet store hadn't mixed up the delivery of the pet animal Yuudai intended to give to Chizuru; instead Chizuru would have broken up with Yuudai right at the beginning.
- Ranpo Kitan: Game of Laplace It's the driving plot device behind the events.
- The prequel arc of The Irregular at Magic High School reveals that nigh everything that happened in the main story is the result of Tatsuya smiling at some friends he happened to meet while guarding Miyuki, his sister. This makes Miyuki realize that 1: her brother has emotions and is in fact a human being just like her (although their family considers him The Unfavourite), and 2: he has never, ever smiled like that at her. He's closer with those people than he is with his own family. And then Miyuki starts to really question why that is, and to realize how bigoted her family is. This starts the chain reaction that led to her and Tatsuya becoming friends and (successfully) rebelling against their clan, who are a major national power. And none of that would have happened if Tatsuya hadn't smiled, or Miyuki hadn't seen him do it, or his friends hadn't attended that party, or if their elitism had overwhelmed their affection for him.
Films — Animation
- Shrek Forever After: Rules Lawyer and borderline Jerkass Genie Rumpelstiltskin offers Shrek a Deal with the Devil. Shrek gets one day as a lawless ogre in exchange for one day from his past. Rumpelstiltskin takes the day Shrek was born, thus creating a world in which Shrek never existed. One of the biggest changes is the fate of Fiona, who without anyone to save her from the tower chose to Screw Destiny and simply escaped by herself. In addition, in this universe Far Far Away is a dystopia ruled by Rumple- since Shrek wasn't alive to rescue Fiona in the nick of time, the king and queen were tricked into signing their kingdom to Rumple.
- In Monsters, Inc., Mike forgets to file his paperwork on time, and can't get it in himself because he has a date. Because of this, he sends his friend Sulley to get it. Sulley then finds a door to the human world that shouldn't be there, and through that door comes a little girl. Sulley and Mike hide her in their apartment, and their attempts to get her back uncover a conspiracy by Monsters Inc. CEO Waternoose to kidnap children to solve the city's energy crisis.
- In Toy Story 3, as when Andy grew up and was about to go to college, he put all his toys (save Woody) inside a bag to store them in the attic. However, Andy's mom mistook the bag for garbage and put it next to the garbage cans, leading to all the toys except Woody into thinking that Andy outright tried to get rid of them and so they wanted to stay at Sunnyside Daycare Center, where new children will play with them and the leader there Lotso appeared friendly and welcoming. However, later on Andy's toys are assigned to dangerous infants who play rough and Lotso turns out to be a sadistic bully who wants them to be tortured, if not broken to death.
- In The Simpsons Movie, there literally is a nail involved, as Homer was working to hammer down a nail on the roof. The entire plot wouldn't have happened if Bart didn't laugh at Homer lodging the hammer's claw into his eye. Angered at how his own son would dare laugh at this, this led to Bart trying to rationalize his laughing out of Homer's signature strangling of Bart's neck, which led to Homer daring Bart to skate naked to Krusty Burger, which led to Homer finding a pig at Krusty Burger, which led to Homer keeping the pig as a pet and choosing to dump the pig's wastes into a lake, leading to a catastrophe where the head of Environmental Protection Agency and film's villain, Russ Cargill, tried to destroy Springfield. At the end, Homer and Bart are not only back to square one, but now they have to rebuild their entire house, not just repair the roof.
Films — Live-Action
- Lola rennt (a.k.a. Run, Lola, Run): the wildly variant endings of Lola's twenty-minute "Groundhog Day" Loop can all be traced back to Lola's reaction to the boy with the dog on the staircase.
- Sliding Doors has catching/not catching a train as the "nail" and ends with dramatically different versions of the protagonist. The 'nail' moment was marked with music and later in the film when the protagonist had to make a decision the music was played again. Although we didn't follow this 'split' it implied that there were more points where a single decision would be important.
- In the movie Frequency, a son manages to send a message back in time and save his firefighter father's life. However, because of this change, his mother, who was a nurse, never left the hospital to make funeral arrangements and so was on duty to save the life of a man who would've died. This man turns out to be a serial killer who kills the mother and is now still at large in the present of the son.
- The vast majority of Brazil's plot occurs because of a swatted fly that fell into a typewriter, causing an arrest warrant for Harry Tuttle to instead be made out for Harry Buttle.
- The whole "Pottersville" sequence in It's a Wonderful Life is an example of this. George's having never been born turns out to have an indelible effect on the lives of pretty much everyone he's ever known in real life. (Of course, the whole idea of the movie is how much one man can make a difference.)
- The Back to the Future film trilogy is a series of nails showing what would have happened if a certain event did or didn't occur:
- In the first movie, Marty McFly's father was a wimp who couldn't stand up to the bully Biff Tannen, but after Marty changed events concerning his father in 1955, he becomes a more confident man who has Biff eating out of his hand, and Marty's family life has also improved.
- Also in the second movie, an automobile accident that would have happened in the third movie when Marty was racing with his friend Needles was the nail that caused Marty's future history to go down the toilet by 2015, eventually resulting in him being fired from the company he and Needles were working for. When the accident was avoided in the third movie, the YOU'RE FIRED message that Marty's girlfriend/future wife Jennifer Parker had received from the future was erased, meaning that their future could potentially become a better one.
- Pointed out by the scriptwriters in the Audio Commentary of Pirates of the Caribbean: The Curse of the Black Pearl. The entire plot is basically kicked off by a corset being laced too tightly.
- The Gods Must Be Crazy: Because a pilot throws an empty Coca-Cola bottle out of an airplane... a primitive tribe abruptly discovers civilization.
- Star Trek:
- The Narada being sent back through time causes a divergence, creating a brand new timeline in the 2009 Star Trek reboot. James Kirk's father dies by suicide-charging his ship into it, James himself is born in space rather than Iowa, he and Spock do not meet on the best of terms, and Vulcan is completely destroyed.
- This continues into Star Trek Into Darkness, where Khan/John Harrison is found and awakened almost a decade before he was originally, and Starfleet is in no condition for the coming war with the Klingons (when the emergency is called, only about a dozen captains and their Number Ones are present at the meeting). It's also implied that the Praxis incident happened much earlier than expected, possibly due to misuse of technology obtained from studying the Narada.
- ...and on into Star Trek Beyond where due to one species not accepting a peace offering from another and forcing Kirk to keep the artifact in question, the Enterprise (NCC-1701) is destroyed some 22 years before it did in the original timeline and the Enterprise (NCC-1701-A) is commissioned roughly over 20 years sooner as well.
- In The Adjustment Bureau small things make big ripples in fate's plan.
- Invoked by Al Pacino's character in Any Given Sunday to light some fire in his players at half-time (see the quotes page).
- The Lord of the Rings, as is mostly canonically adapted from the books (though occasionally not), bounces the outcome of its story backwards and forwards through the many separate applications of this trope within its work. Here are the lost nails, in numerical order:
- 1. Sauron, with his left hand firmly holding the Idiot Ball (as well as his mace), extends his right hand — the one carrying the Ring of Power — out to Isildur.
- 2. Isildur, apparently catching the Ball as Sauron throws it, keeps the Ring.
- 3. Deagol finds the Ring while fishing.
- 4. Smeagol loses the Ring, allowing Bilbo to steal it.
- 5. Merry and Pippin, having stolen produce from Farmor Maggot, bump into Frodo and Sam as they run.
- 6. Frodo decides to travel through Moria instead of scaling Calahdras.
- 7. Merry and Pippin disinterestedly disturb the waters outside the entrance to Moria.
- 8. Pippin knocks a skeleton down a well within Moria.
- 9. Galadriel gives the Fellowship several gifts.
- 10. Aragorn advises Theoden to spare Grima Wormtongue.
- 11. Smeagol dips in the Forbidden Pool.
- 12. Pippin finds one of the Lost Seeing Stones at the foot of the Tower of Orthanc.
- 13. Orcs argue about the distribution of Frodo's possessions.
- X-Men Film Series:
- X-Men: Days of Future Past: The Bad Future faced by the cast of the original trilogy all came about due to the assassination of Dr. Bolivar Trask in 1973.
- X-Men: Apocalypse: Because of the changes to the original timeline, the public is aware of mutants nearly three decades earlier. This leads to En Sabah Nur gaining a cult, Agent Moira MacTaggert investigating it, and the ancient mutant waking up when he otherwise didn't.
- A petty argument about a character's choice of decoration snowballs into a full-blown race riot in Do the Right Thing.
- In 2009: Lost Memories, Korea and Japan's (and by extension, much of Asia's) future hinges on the survival or assassination of Ito Hirobumi in 1909. In the Alternate Timeline most of the movie takes place in, Hirobumi survives, Japan goes on to retain most of its colonial holdings (including Korea), and becomes an ally instead of an enemy to the Allied Powers in World War II — which results in the nuclear bombs being detonated in Berlin instead of Hiroshima and Nagasaki.
- The major conflict of the second half of Project Almanac. When they first fired up the machine, it blew the power on the street which caused the school's star basketball player to get run over and get his leg broken. Since he was benched, the team never made it to the championship, and those that would have attended went elsewhere instead. One particular parent was a pilot, who ends up crashing a plane and killing a lot of people as a result. David's frantic attempts to correct for this only further makes a mess of things.
- Retroactive: Karen keeps having to travel back through the time machine to stop Frank from murdering his wife, because each loop keeps getting worse. She goes back 20 minutes and ends up in the same place each time in Frank's car after he picked her up, but her different attempts to stop him (warning the Sheriff, stealing Frank's gun, etc.) only result in Frank going on an even bigger killing spree. She eventually decides to go back to before she got in Frank's car, which results in Frank turning on his partner and getting shot by Rayanne.
- Alexander and the Terrible, Horrible, No Good, Very Bad Day: Alexander drops his brother Trevor's pacifier in the sink, Ben accidentally turns on the garbage chute that destroys it, causing Trevor to cry all night, forcing Emily to rehearse for her play in the cold car, making her extremely sick; forgetting to turn the lights off which drains the car of its battery and making Kelly late for work the next day. And Ben being forced to look after an extremely unhappy Trevor makes his day and job interview a nightmare and he embarrasses himself at a Japanese restaurant meeting. Only Anthony's next day was not directly affected by the pacifier accident; instead this was tied to an argument with Alexander that led to a miscommunication with his girlfriend, causing them to nearly break up and him getting detention, failing his driver's test and wrecking the family car trying to fix things up. Also, he gets a zit.
- The Final Destination films each involve premonitions allowing people to escape a mass disaster, only for Death to come after everyone who should have died according to "Death's design". The second film leans heavily on this trope; it's revealed halfway through that the first film's characters avoiding the Flight 180 crash created ripple effects as Death hunted them down, allowing others to escape their fates. (For example, one character in the first film is hit by a bus, which means that one of the passengers on that bus doesn't make it to the hotel she was planning on staying in that night, which means she survives when a gas leak suffocates everyone else in the hotel) It's implied (and was explicit in the original script) that the highway pile-up in the second film was arranged by Death to take out a number of these 'ripple survivors' in one go.
- In the final film of the series, the final scene reveals that the film is a prequel, and that the Flight 180 disaster was a means of catching up to two survivors of an earlier bridge collapse, meaning that if those survivors had been a little bit slower escaping the bridge, the first two movies wouldn't have happened.
- However, the fourth film (and the most recent events in universe) reveal that actually this isn't a result of this trope but was in fact Death's plan for each person all along. The premonitions were Death's way of making sure that the protagonists survived long enough to reach their intended deaths.
- In Hot Tub Time Machine, the bar bet turns into a nightmare for Lou. The squirrel that was vomited on in an earlier scene changes the history of the NFL playoff game as it disrupts John Elway's pass on the field.
- The beginning of Tajomaru's story in Rashomon starts like this: he was drifting off to sleep in a forest, but is awakened by the sound of hoofbeats and opens his eyes to see the samurai and his veiled wife passing by. He initially isn't interested, and drifts off again when a breeze stirs his hair and lifts the veil of the woman, causing him to want her, and from there, the events snowball into a murder which results in the trial. He blames the whole incident on the breeze revealing the woman's face and rousing him to view the face. Admittedly if the samurai hadn't stopped to inspect this strange, half-clothed man reclining by a tree at the edge of the forest road and kept moving, the breeze would have arrived later and Tajomaru wouldn't have given the couple a second thought.
- At the start of The Shawshank Redemption, Andy Dufresne contemplates murdering his wife and her lover, but instead throws his gun away after sobering up and deciding not murder them. They're murdered by someone else and Andy is charged. Andy's only defense is he couldn't have done it because he threw his gun in the river. Had he not thrown away his gun, the bullets recovered from their bodies would have proven his gun was not used to commit the crime. This is actually pointed out by the District Attorney.
- In Money for Nothing, Joey, while being driven home by his friend when there was not enough work at the docks, sees a metal bin that would make a nice toolbox and has his friend stop. The bin turns out to be from an armoured car and contains two canvas bags with $1.2 million meant for a casino. Joey takes the bags and leaves bin. Had he also taken the bin, the police would never have found out where and how the money left the truck and thus been unable to question the two kids who the saw everything, including the make and colour of Joey's friend's car, and likely would never find Joey. However, the ending states the real Joey was acquitted on a plea of temporary insanity, so he wasn't thinking right.
- In Spider-Man this idea is particularly strong. If Peter Parker had not had a crush on Mary Jane Watson for most of his life, he wouldn't have had to work up the nerve to talk to her at Columbia's science lab (sowing the seeds of later friendship and romance,) which also means he wouldn't have lingered long enough to be bitten by the GM spider. He wouldn't have had his conflict with Ben or the fight with Flash Thompson, he wouldn't have gone out for the wrestling show, he wouldn't have let the thief go, and Uncle Ben would not have been killed. Despite the upside of the Parker family not losing Ben, the seminal events of Spider-Man's origin would never have happened, leaving New York without its most iconic superhero. This potentially means that Norman Osborn would still have become the Green Goblin, but there would have been nobody capable of stopping him. (Not as important, but he also never would have gained the confidence he needed to confess his feelings to MJ as Peter or save her life and catch her eye as Spider-Man , and however dragged out, they wouldn't have gotten together.)
- Much of the above applies to The Amazing Spider-Man with the added wrinkle that if Peter had never worked with Curt Connors in recreating the OO formula, Connors would never have been able to turn himself into the Lizard. Had Peter still become Spider-Man, this means the defining moment where he goes from vigilante to hero would never have occurred (though he might have succeeded in catching Ben's killer.) Interestingly, while Captain Stacy's death by impalement at the claws of the Lizard never would have happened, his profession meant that there could always have benn another day he didn't make it home to his family.
- The verses to "It's All Who You Know" by the Newsboys are two scenarios of this trope.
- In the first verse, a slip-up in an actor's facelift leads to the failure of the show that would have saved a TV network.
- In the second verse, an dogsled racer forgets to take a cough drop and loses his voice. He and his dogs freeze to death when "the sled got snowbound."
- Tom Waits' song "Misery Is the River of the World" from Blood Money even includes a line from the trope namer.
For want of a bird
The sky was lost
For want of a nail
A shoe was lost
For want of a life
A life was lost
For want of a toy
A child was lost
- The video for "Has It Come To This?" by The Streets features a split-screen of two possible day-in-the-life situations of Mike Skinner.
- "The Want of a Nail" by Todd Rundgren.
- The whole point of Jay-Z's American Gangster is basically showing the mirror universe where Sean Carter kept on selling drugs instead of going into music.
- Bowling for Soup's "Almost"'s verses each have chain of events that might have happened, if not for the first event in the chain only "almost" happening:
- Verse 1: "I almost got drunk at school at 14 / and I almost made out with the Homecoming Queen / who almost went on to be Miss Texas / but lost to a slut with much bigger breastes / who almost dropped out to move to L.A. / and was almost famous for almost a day"
- Verse 2: "I almost held up a grocery store / where I almost did five years and then seven more / 'cause I almost caught for a fight with a thug / who almost made off with a bunch of the drugs / that I almost got hooked on when you ran away / and I wish I could've had the nerve to ask you to stay"
- Verse 3: "And I almost wrote a song about you today / but I tore it all up / and then I threw it away"
- While the lyrics themselves have nothing to do with it, the video for Relient K's song "Who I Am Hates Who I've Been" fits here. Apparently, where on the sidewalk you step can stop someone across the street from getting hit by a car.
Myths & Religon
- In Norse Mythology, Freyr is doomed to lose the fight to Surtur at Ragnarok because he gave his good sword away to Skirnir.
- In Big Finish Doctor Who The Mutant Phase the Doctor and Nyssa arriving draws a Dalek over. This Dalek getting stung by a genetically-modified wasp nearly destroys the Universe. It is revealed to be a Stable Time Loop caused by Daleks from an alternate timeline, whose attempt to draw the TARDIS into the future caused it to land and create the alternate timeline, though the time loop was further made by the Dalek Emperor travelling back to prevent this.
- The current default setting for GURPS is based on mixing this idea with The Multiverse to produce an infinite number of worlds. There's at least one canon parody of the concept with the world "Enigma" in which the only difference is the band The Clash never formed (and then
the planetall humans on the planet disappeared without a trace in 1982).
- During Magic: The Gathering's Time Spiral block, the middle set (representing the present) featured "alternate universe" versions of certain cards, primarily reprinting older cards into other colors that would best represent them if various mechanics hadn't been assigned as they were. Keeping in the spirit of "What if?", the flavor text on a good portion of the cards give quick looks at an entire subplot that revolved around what would've happened if Mirri had slain Selenia before Crovax had a chance to, thus fulfilling the terms of a family curse, turning her into a vampire instead of him.
- In a nice scenario for a Dr Who style RPG the player's TARDIS comes to rest in the car park of a film studio. This causes John Wayne to have to find another spot so he is late and angry for his meeting to discuss playing Genghis Khan. Instead Ronald Reagan gets the role and cancer inducing radiation dose. President Wayne's foreign policy isn't a great success either.
- John Wayne was a very heavy smoker throughout his life (at one point up to six packs of cigarettes a day!) and in 1964 nearly died of lung cancer (one lung was removed and The Duke needed supplemental oxygen for the rest of his life). Any contamination he might have received from the set of The Conquerer was likely just The Last Straw given what he'd already done to himself.
- This is actually a means to become 'fragged' or disassociated from the right timeline in the time-travel RPG Continuum. You can destroy a time traveler by introducing a few of these little changes into his perceived timeline. "Replacing the nail" is a defense. Did an enemy time-traveler realize you sat in a coffee shop and read a book on Saturday, July 8th, 1995? He can frag you by doing something as simple as stealing the book out of your bag. You can reverse it by replacing a near-identical copy into your bag before "past you" notices the change. Screwing over a major historical event could bring down the wrath of any number of time travelers, all of whom find themselves affected by the change.
- The true turning point of Clockwork And Chivalry's timeline is a Battle of Naseby that does not fall under this trope, differing from the real battle in almost every significant particular and ultimately ending in a bloody stalemate that leaves thousands dead and no clear victor, along with Fairfax MIA and presumed dead... but one of the most important changes to the battle and the course of history does fit this trope — The Earl of Carnwath is killed by cannon shrapnel, and is unable to prevent King Charles from engaging in his suicidal charge of the enemy forces, leading to his being captured and executed a full 3 years early following a trial that was even more swift and blatantly stacked against him than the real one, with both the lead-up to this and the aftermath of it leading to numerous changes in the course of history.
- A major plot point in Harry Potter and the Cursed Child. Harry's youngest son Albus and Draco's son Scorpius get their hands on a Time Turner capable of traveling back years into the past rather than mere hours. They want to use it to save Cedric Diggory from dying at the hands of Voldemort. Their meddling in history results in two alternate timelines:
- The first timeline is caused when Albus and Scorpius disguise themselves as Durmstrang students to sabotage Cedrics attempt at the First Task of the Triwizard Tournament. Hermione spots them and suspects Viktor Krum of cheating, resulting in her not accepting his request to dance at the Yule Ball, going with Ron instead. Because of this, Ron never experiences any romantic jealousy over Hermione and never throws a fit about it towards her either. Instead, he continues to see her as a friend rather than a potential love interest. He does find love in Padma Patil and ultimately marries her, with the both of them conceiving a son named Panju. This makes Hermione an embittered woman who in her adult live becomes a Sadist Teacher at Hogwarts, venting her romantic frustrations at the students. Unfortunately for Albus and Scorpius, the changes to the timeline did not result in Cedric surviving, as his humiliation at the first task made him more determined at the other tasks.
- The second timeline is caused when Albus and Scorpius successfully sabotage the Second Task of the Tournament. The humiliation of losing becomes too much for Cedric, resulting in him enlisting into Voldemort's Death Eaters. At the Battle of Hogwarts, Cedric manages to kill Neville Longbottom, who, in the original timeline, managed to destroy Nagini, Voldemort's final Horcrux. Because Neville was killed before destroying Nagini, Harry failed in his mission to kill Voldemort, resulting in Voldemort gaining absolute power. In this timeline, Harry was killed by Voldemort so Albus is never born. Also, Draco Malfoy has become the head of the magical law enforcement, with his son Scorpius being a somewhat important figure maintaining a reign of terror at Hogwarts, ran by Dolores Umbridge as headmistress. Also, Hermione runs an underground resistance movement with Ron and Severus Snape as members.
- The Bad Future in Clock Zero would never have happened had Nadeshiko, or rather, her alternate self, never been hit by that car at age 13 thanks to Rain's manipulations. Or better yet, had she not spoken to Rain at all in the first place in that timeline, the accident would never have happened in the first place.
- Higurashi: When They Cry has a bad case of this; every arc it's something else in the initial factors—minor things like a man moving into the village or even Keiichi giving someone a doll—that sets off a completely different scenario of bloody tragedy.
- In Umineko: When They Cry we have Lion, who appears in a fragment where Natsuhi accepted the baby that Kinzo gave her and didn't throw him/her over the cliff, therefore letting Lion lead a well-adjusted life and not growing up to be Yasu. Though ultimately subverted in that Lion is still murdered during the massacre...or so Bernkastel claims.
- A subversion is mentioned in the Ep 8 manga where it is mentioned that even if Battler would have kept his promise to Shannon/Yasu, Yasu would have still thought him/herself as furniture and so it still wouldn't have saved him/her.
- A large number of 'nails' exist in Nine Hours, Nine Persons, Nine Doors. Every possible choice- from Junpei's travel partners to whether or not you take a bookmark- influences your fate. Akane is watching them all unfold, to find the best fate for her to follow.
- A little toy doll, of all things, ends up playing a pivotal role in Akane's backstory. While escaping the first Deadly Game with Seven, she dropped it and ran back to get it...which led to her getting caught by the murderous Zero and getting thrown in the incinerator room...which led to her Traumatic Superpower Awakening...which allowed her to establish a psychic connection with Future!Junpei...which saved her life...which meant that, several years later, she had to trap Junpei, herself, and eight others in a similar Deadly Game so Junpei could connect psychically with Akane's past self, fulfil the paradox, and ensure her survival. If not for that one important item falling at that one crucial moment, the entire game's events could have been averted.
- Nails eventually decide which of the three routes you take in the opening of Fate/stay night. The best example is probably the choice leading to "Unlimited Blade Works": If Shirou recalls Saber before she slashes Archer, Archer is left unharmed and capable of participating in the Grail War at full strength. This in turn boosts Rin's position in the war, making her a competitor to Shirou instead of someone forced to rely on him as an ally (and also makes Ilya not notice Shirou). Thus, "Fate" and "Heaven's Feel" get locked out because everything begins snowballing from that decision
- Steins;Gate features a device that can send a text message into the past. While for the most part the characters make big, sweeping changes to the timeline, Ruka simply uses it to tell his mother to eat lots of vegetables during her pregnancy. This results in Ruka being born a girl, just like she wanted.
- Red vs. Blue:
- Averted during Season 3. Church is blown back into the past and realizes that he can stop everything from happening. Instead, he just creates an army of Churches as he realizes that everything is set in stone. Because it was all his fault.
- Season 10 goes to show that if Carolina had kept Sigma, her assigned AI and learned to realize that she wouldn't ever be able to beat Tex, Project Freelancer would have been spared a lot of pain and misery. Maine wouldn't be reborn as the Meta, as Sigma wouldn't be able to influence him; she wouldn't request both Eta and Iota as AI, which means that Wash would never have received Epsilon and learned the truth behind everything, and South wouldn't have gone Cain and Abel on her twin brother.
- Erfworld Book 1 starts with this trope. The narrated opening scene shows the world's creators dropping one extra gem into a resource spot, which pays for an extra squad of units to go to field against Gobwin Knob's army, which is just enough to tip the balances in a heated battle, which means that Gobwin Knob's chief warlord gets an arrow between the eyes, which means that Gobwin Knob needs a new chief warlord before The Alliance shows up on their doorstep, which means that Wanda Firebaugh's bad day is about to get a lot worse. And then Parson blows up a volcano. Judging from the way the story is going, this was just the start.
- In a time-travel example: the Schlock Mercenary time-travel plotline in Book 6 invokes this trope, but isn't itself an example.
- Parodied here on Chainsawsuit.
- Homestuck has innumerable offshoot timelines which all create elements necessary for the existence of the primary timeline. In one of those offshoot timelines, Karkat never runs the Mobius Double Reacharound virus. Without the virus (or some effect the virus had, such as possibly the deaths of the lusii), Gamzee does his From Nobody to Nightmare transformation much earlier than he was supposed to, and succeeds in murdering all of the trolls minus Aradia.
- This also applies to the Alpha timeline; especially notable is the chain of events starting with Gamzee placing a harlequin doll in John's bedroom on Prospit, which ultimately leads to Jack Noir destroying the Kids' universe.
- In General Protection Fault, the Nega-Verse is what would happen if Nick and Ki were evil and acted on Nick's fantasy of taking over the world that was discussed in a brief arc early on. There are smaller examples, such as Nega-Trudy being as selfish as Trudy Prime until her mother's request for her to finde her sister (something Trudy Prime didn't hear about until after her Evil Plan failed) changed her for the better.
- Parodied in this strip of Tom the Dancing Bug. Percival Dunwoody wonders if he caused the people of 2012 to turn into fly-men when he stepped on a twig in the Paleozoic; it turns out that he actually did it by killing off all the humans in 2011 and injecting flies with human DNA.
- This Subnormality strip. If you look closely enough, the last panel nearly spells out this trope.
- One plotline of Stand Still, Stay Silent can be traced back to Emil throwing a wing mirror he had broken off the Cat-Tank a little too hard. The mirror landed on the head of a guy that was labelling crates and ended up swapping the labels of two crates in the confusion before passing out. One of the crates was food for the main cast's expedition, the other was full of candles. The swap is not discovered before they are in an isolated area and have gone past a Point of No Return. Mission Control gets a merchant ship to deliver them some new food. Aboard said merchant ship is a sheltered sheep herder who really, really wants to see the world and has just realized that getting hired as an unpaid kitchen aid on a merchant ship was not working towards this objective as well as he hoped. Said sheltered sheep herder then notices two food crates being prepared for delivery and has a lightbulb moment. Due to not being immune to the illness that is a very serious threat in the area the main cast is exploring, they can't just send him back and end up having to watch him on top of their existing duties.
- Squigly calls a butterfly a murderer for producing such effects, and then imagines his own effects.
- Squigly predicts this for a cocoon, who thinks "Cool!". Later Buddha fixed it, though.
- In Freefall, they blame Sam rather than a butterfly.
- Fate/Nuovo Guerra has at least two so far, being an Alternate Universe story and all. More obviously, the destruction of Fuyuki City caused the Einzberns to pack up and move operations to Lucca, where the next Holy Grail War takes place. Less obviously, the lack of a living Shirou results in Luvia getting killed while fighting a Dead Apostle Ancestor by herself, as well as the very existence of the Edelfelt Sisters Lumi and Lempi.
- According to Plumbing the Death Star's "Why Is the Death Star Spherical?", putting a friendlier management on the Death Star and renaming it the "Love Sphere" would make the Stormtroopers more open about the Death Star's structural problems; this would allow the Empire to cover up the exhaust port, allowing them to destroy Alderaan, the Rebellion, and Luke while derailing the entire Star Wars saga.
- Decades of Darkness has president Thomas Jefferson dying of a heart attack. His bumbling successor James Madison manages to anger the New England states enough so they leave the union and defend themselves successfully in a war, splitting the USA forever. The slave states get the majority and transform the rest into an expansionist slave-holding empire.
- Look to the West's very different world (Steam Punk revolutionary France, a divided India, French Australia, loyalist America) all stems from George II tripping on the carpet at his coronation in 1727.
- We'll Meet Again's truly Crapsack World solely emanates from the butterflies of a letter lost in the mail...
- The 4chan imageboard /co/ had a thread that speculated what would happen if Bruce Wayne's parents never died. The result? Bruce and a certain fellow named "Jack Napier" end up becoming best friends, Gotham City goes through a golden age, and the readers cried manly tears.
- 4chan's /tg/ board does this as well, some of the more recent ones, the crusades are won in the third crusade, the slew of changes involve a massive Kingdom of Jerusalem, The Library of Baghdad still stands, the reconquista never happened to its fullest extent, and the rising heresies move the reformation in a very different direction (Cathars, Flagellants and Waldensians rather than Anglicans, Calvinists, and Lutherans.) And these are the most normal things to come from it.
- In the Chaos Timeline, Genghis Khan dying from a minor accident in 1200 prevents the unification of the Mongol tribes and their subsequent global conquests. The world becomes very different...
- No Spanish Civil War in 1936 sees a (non-Stalinist) leftist Republican Spain not only survive the attempted coup in 1936 (with Francisco Franco critical to the thwarting of that plot), but become a junior partner of the Allies when World War II rolls along, having an anarchist (Buenaventura Durruti) for a president, and great advances in Spanish influence in the arts of the mid-20th Century, all because Casares answered a letter from Franco that didn't go answered in real life.
- The Union and Liberty timeline begins with a small change in Andrew Jackson's 1828 campaign platform and changing a few words in a John Calhoun speech.
- 1983: Doomsday starts off with a certain Soviet Air Defense forces officer being assigned to a different bunker in September 1983. The officer who takes his place mistakes a false alarm for an American nuclear attack, leading to World War III.
- A More Personal Union begins when a young man recovers from a mid-autumn cold. The young man is the king of France, and the cold would have killed him; instead he lives for another seven years, and his continued reign brings very big changes to France.
- In Counter Monkey, Spoony recounts the "Leaping Wizards" incident wherein he was serving as DM for a Dungeons & Dragons module for the RPGA. Reading through the module, he found a particularly pathetic ambush by three wizards, each with a single spell. Knowing the encounter would be a cakewalk, he altered each wizard's spell so that, rather than each having the default Magic Missile, it was a variety of Sleep, Charm, and Ray of Enfeeblement. Through a combination of this change and some lucky rolls, the vastly outclassed wizards killed two party members before going down... much to the displeasure of the RPGA, as the module was intentionally weak to prevent player deaths.
- A Giant Sucking Sound: Ross Perot is able to win the 1992 election first by not withdrawing in August, and by choosing Jerry Brown as his running mate.
- Pokemon Digimon Mon Wars is based on Digimon Adventure if Tai had choose the Agumon card, leading the group to the Pokémon world right after the Kanto season.
- Rage by Guy Collins Animation starts with a butterfly extinguishing a man's last match, which triggers a chain of rage-inducing events that ends with an Earth-Shattering Kaboom.
- Ad Astra Per Aspera has Senator Edmund G. Ross vote to acquit Andrew Johnson, leading to his impeachment in 1886. This leads to the events of three interstellar superpowers waging a galactic war in the 28th century.
- This Macworld article warns that solid-state drives are sometimes not all they're cracked up to be, as they can be even more unstable than hard disk drives at times. Each data cell in an SSD can only be written to so many times before it gives out, and most of the time that takes years, but the author admits his Macbook Air crapped out after only a month because of this very issue, which is why he wrote the article (he had no backup at the time). Basically, solid-state drives sort of know that their cells can give out for any reason, and so 10-20% of the cells included in an SSD are meant as remedy cells for use when others give out... but once that remedial supply is gone, any further cell failures are totally gone too. He writes that once this happens, the drive can simply refuse to boot up at all, meaning that if you want any shot at fixing the drive, you have to format it... losing everything on it forever. You can't retrieve data from an SSD the same way you can from an HD, because on the latter the data is not really deleted once you move to delete it, but on an SSD for data to be recognized as deleted it has to actually be deleted.