"Don't do anything, don't
touch anything, Sci-fi rule number 1: you start messing with the past, you end up with monkeys ruling the future."
Want to go back in time
to stop your parents from losing their retirement money in the Dotcom crash? Save a loved one from a fatal accident? Nudge a closet a little to the left to avoid hitting your toe
? In some universes, you're not just going to run into You Can't Fight Fate
, but into Finagle's Law
on a grand scale: the Butterfly of Doom. Any and every change made in the past will always
have an unintended and horrible side effect.
Much like a temporal Monkey's Paw
, you might succeed at changing the thing you intended, but at a terrible cost. Telling your parents to move their money elsewhere gets them arrested for insider trading; the loved one you saved develops a wasting terminal cancer; the closet you moved is now on a weak floorboard and crashes through it, destroying your house. To repair the damage, it's usually necessary to travel in time again to Set Right What Once Went Wrong
— more specifically, to set right what you
made go wrong.
A Fantastic Aesop
, the Butterfly of Doom is intended to drive home that any attempt to change history will be met with the wrath of Fate itself. As a subtrope of For Want of a Nail
, it can overlap with Wonderful Life
, in which the butterfly is you. Godwin's Law of Time Travel
is a subtrope in which the thing that you change leads to Hitler winning World War II
This is one of the techniques that writers use to ensure that Time Travel
doesn't interfere with Status Quo Is God
. Others are that Time Travel
creates Alternate Universes
, that creating a Temporal Paradox obliterates reality
or unleashes the Clock Roaches
to eat offenders, and that Time is resilient and can absorb
changes without breaking.
See also Finagle's Law
, Hitler's Time Travel Exemption Act
, Schrödinger's Butterfly
, Rube Goldberg Device
, Rube Goldberg Hates Your Guts
, Necro Non Sequitur
, For Want of a Nail
and Ripple-Effect-Proof Memory
. Contrast Save This Person, Save the World
and Merged Reality
. Unrelated to Butterfly of Transformation
or its subtropes.
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Anime & Manga
- Almost the entire point of all events in Xxx Holic. Interesting that Yuuko's symbol is the butterfly, though that falls under another butterfly trope.
- In an episode of Penguin Musume, Kujira learns that she confessed her love to Sakura when they were both young girls (Kujira was raised as a boy.) Embarrassed into action, Kujira takes the Time-Penguin-X1 (yeah, you heard me) back to prevent herself from confessing. After older-Kujira realizes she's made a horrid mess, she works to repair the timeline, causing her younger self to instead make a marriage vow. Hilarity Ensues.
- The Girl Who Leapt Through Time. Though Makoto never tries to change anything particularly big (she uses it for stuff like repeating a karaoke session over and over for several hours), once or twice she changes something small that has massive and unexpected repercussions. After several failed attempts at matching a friend with a girl who who likes him by leaping back in time, she finally gets it right. He borrows Makoto's bike, the brakes snap and both he and the girl die in a train accident that Makoto herself only narrowly avoided earlier. Fortunately, Chiaki was around to fix things.
- Perhaps not even needing a mention, Steins;Gate relies much on the butterfly effect theory. In fact the visual novel (and anime to a lesser extent) analyze much of the science after everything had Gone Horribly Wrong.
- This is practically the premise of Ore ga Doutei wo Sutetara Shinu Ken ni Tsuite (How I'll die if I lose my virginity) where the protagonist goes back in time after his best friend kills him when he was 32 years old.
- In Fairy Tail, this is the Defense Minister's argument against using the Eclipse Gate to travel back in time to kill Zeref. Since Zeref is such a huge part of their history, killing him in the past could have drastic consequences.
- Berserk: In The Reveal, it turns out that the entire plot has been carefully constructed by the Idea of Evil. It has, in its time, created demons, assemble the Godhand (its demigod-like emissaries), controlled human history and eventually shattered the boundary between fantasy and reality to disastrous effect. How? It distributed Behelits to just the right people at just the right times; human nature and the laws of physics (down to the last detail) took care of the rest.
- In All-Star Squadron, the robot Mekanique is sent back from the future by the evil scientist Rotwang to prevent a car accident that will kill a small girl and a naval officer. Somehow, this change will prevent the rise of the rebel leader Maria in Rotwang's future who leads a slave rebellion that threatens to overthrow the ruling elite.
- Mentioned, though not actually applicable in the Runaways time-travel arc:
As usual, you're missing the bigger issue. What you should be worried about is the Butterfly Effect
Chase: Dude, I'm totally on top of the Butterfly Effect! (aside, to Molly) What were they, like, bigger?
- 52 has a literal example. Big Bad Mr. Mind transforms into its adult stage as an Eldritch Abomination Hyperfly that devours time and space. His feeding frenzy across the Multiverse changes the originally identical other universes into full blown Alternate Universes. Okay, so maybe he's a Moth of Doom instead.
- Pinky and the Brain (Yes, this is a comic story instead of a cartoon) once went back in time a few hours to prevent their past selves from opening a savings account at a bank that would be robbed afterwards. (They had a time machine that Brain planned to use to go to the future to get the money plus interest) When they returned to their own time, they found the world being ruled by ostriches. (No, really)
- Flashpoint involves The Flash suddenly awakening in a Crapsack World and trying to figure out what caused the change to the timeline. It turns out that it was all caused by The Flash going back in time and saving his mother's life. Somehow this resulted in such changes as Bruce Wayne having been shot by the mugger while his parents are still alive, Wonder Woman and Aquaman being murderous dictators, and Frankenstein killing Hitler.
- Marvel Comics' 2013 event Age of Ultron features an alternate universe in which the sentient robot Ultron has annihilated mankind and taken control of the entire planet. Wolverine goes back in time in order to kill Ultron's creator, Hank Pym, only to discover that in the new timeline, the murder of Hank Pym caused the Avengers to disband, which somehow caused Asgard to lose the Asgardian/Latverian War, which led to a present in which sorceress Morgan le Fay conquered most of Earth, and Iron Man leads a resistance of broken heroes trying to keep New York from falling into Morgan's hands. Apparently, this is worse than a universe in which humankind was completely annihilated by a sentient evil robot, as stated by the characters in the book.
- In Justice League Elite, Manchester Black tries to use the reality-warper Eve to alter history so that Superman was killed before his powers developed, but she claims that there is no way for her to make such a drastic change to the universe without tearing reality itself apart.
- Usually Subverted in Paperinik New Adventures, as time pirates are Genre Savvy enough to limit themselves to steal treasures due the danger of this. That said, they did try and alter the timeline in three occasions... And every time it was somewhat 'strange':
- the first time the Raider came in the present to assemble and activate a device made purposefully to change the timeline without risking that the alteration would backfire;
- the second time the Organization sends their best agent, the aforementioned Raider, and Paperinik forward in time to prevent the creation of a bubble of nothingness that would erase the entire space-time continuum. Except that their intervention causes the experiment that would create the bubble to start early, and they personally make it go awry and nearly create the bubble (they stop it just in time). It's also implied that the Organization had already tried to stop the experiment due the risk, and their agent actually made it go awry the first time;
- the third time the Organization sent the Gryphon (their best agent after the Raider's death) in the past to neutralize Paperinik. He's successful, and somehow his actions gets the Time Police replaced by a front of the Organization completely by accident, before another intervention saves the Raider and restores the timeline.
- The reboot played it straight, with a group of Evronians getting their hands on Kronin's Time Machine and using it to prevent the creation of their enemies the Guardians of the Galaxy. Then they return to the present, and, to their horror, find out that preventing the creation of the Guardians also caused the Evronians to become a peaceful race, at which point an amused Kronin explains that this is the reason he never tried something like that.
- The Card Captor Sakura fic Shadow of the Dragon features such an example in chapter 8; Sakura uses the Time Card to travel back in time by one day to save Tomoyo's mother from dying in a car crash courtesy of a drunk driver, but as a result, her classmate Reiko Ichimai is hit by said drunk driver instead. According to Cerberus/Kero and Yue, regardless of what Sakura tried to do, someone was going to die that day, and her interference just changed who died and when.
- The Worm fic Security subverts this trope, as the SI uses Contessa's power (Path to Victory) to ensure that any changes he makes to the timeline due to his mucking about with his future knowledge don't cause any major unintended side effects.
- Hans Von Hozel's Doctor Who fic has a time travel related accident with a feather duster which causes the world's population to turn into dinosaurs... who eat the Doctor... and conquer the world...
- Final Fantasy VII fic The Fifth Act has this when Cloud accidentally time travels to Crisis Core. It starts with Cloud curing Genesis of his degeneration which results in him getting a new lease on life and not defecting. Which results in Sephiroth never going crazy because he still had his friends... and results in Angeal defecting and betraying Cloud due to suffering degeneration alone and becaming desperate for a cure. Which results in Cloud falling to madness and getting possessed by Jenova.
- The majority of the first Back to the Future movie is Marty trying to reverse the effect of his having saved his father from being hit by a car.
- Over the course of the trilogy, changing the past has nothing but positive effects for most of the characters. But not intentionally. In fact, almost all of Marty's intended timeline changes end up nearly erasing him from existence. All the positive changes came from unintentional changes — most notably his "Darth Vader from the planet Vulcan" schtick, intended to spook his teenage dad into asking for a date, instead gave him confidence to become a professional science-fiction author.
- Part 2 has an ideal example with the Timeline-Altering MacGuffin. Marty buys it to make a fortune in sports betting. Doc finds out and throws the almanac away, Biff from 2015 finds it. Old Biff then steals the time machine and gives it to himself in 1955. This then causes Biff to become the richest and most powerful man in the country, single-handedly legalizing gambling, ensuring Nixon's re-election for multiple terms, and turning Hill Valley into a Crapsack World where biker gangs rule the streets and armed thugs ride around on tanks. Then there's the part where Biff married Marty's mom and killed Marty's dad!
- In a deleted scene, where Old Biff brings the DeLorean back to 2015, he fades out himself. Presumably, Lorraine finally got up the courage to off him sometime after 1985. So the "stuff you do on purpose turns out badly for you" rule still holds.
- you could also say that this movie averts this trope. While some of the things he does ends up with a bad outcome, other smaller things that should create a terrible effect by the trope's standards end up making life better for them in the future, meaning the old future wasn't necessarily the "right one."
- "Timewaves" are the result of the change in history in the very loose film adaptation of A Sound of Thunder.
- The Butterfly Effect, named for the effect that names this trope.
- The Butterfly Effect is also notable for the protagonist not only learning that messing with time can have disastrous consequences, but also realizing that he himself is the product of someone tinkering with fate. The world cannot be righted unless he does not exist. Only in the director's cut, not the original theatrical release ending.
- This is played with in Donnie Darko; the setup is the same, and the plague of strange events that follow lead him to return in time and allow himself to be in bed when an airplane engine crashes into his house, thus saving his girlfriend's life in a roundabout way. A subversion: in the original timeline bad things happened ''without'' Donnie around to stop them.
- More than that, the DVD commentary says that Donnie's purpose was to give the plane engine a reason for existing, preventing the collapse of the universe.
- Inverted in 2002's movie adaptation of The Time Machine, wherein Alexander Hartdegen's repeated attempts to go back in time to save his fiancée Emma inevitably go wrong. Later, the Uber-Morlock explains that the reason he cannot save Emma is that her death was his prime motivation for building the time machine.
- In the film Frequency, a shortwave radio and the Northern Lights allow the main character to communicate with his father thirty years back in time. Their conversations accidentally lead to the protagonist's mother (a nurse) saving the life of a serial killer who, in the original timeline, received a fatal overdose of medicine in the hospital. Since the murderer already had an obsession with nurses, and realizes she saved his life, this has worrisome consequences.
- Dennis Quaid's character actually lampshades this trope during the film. However, Frequency is an interesting example, because it's a case where the Butterfly of Doom comes into play, but the movie otherwise plays out like a country-western song played backwards. Rather than a cautionary story about the dangers of time travel, it's a movie about how time travel can make everything better forever.
- The movie Sliding Doors had a non-time travel variation. The movie follows the events following the protagonist either missing the subway or getting on just in time, and then some...
- The film Mr. Destiny starring Jim Belushi as Larry Burrows, an unhappy middle aged office employed loser. He blames the state of his life on the moment he struck out in a high school baseball game. A guardian angel like figure named Mike (played by Michael Caine) changes the past so that he hit the ball. Larry is now the president of the sporting goods company he worked and married to the owner's daughter. However, he soon learns that his alternate self's other decisions have a number of problems: his father is now divorced (on "his" advice, no less), he's having an affair with an Ax-Crazy worker, his best friend is now afraid of him, he's been involved in some shady schemes with the other executives who are now plotting to get rid of him after noting his "change of heart" and his wife from the original timeline is now married to someone else.
- In the Stargate Verse film Stargate Continuum, Ba'al has gone back in time and stopped the Stargate from reaching the United States in WWII, also killing Mitchell's great-grandfather, who was also transporting the Stargate to the US. This is made more interesting when the main characters, who know about the normal timeline, ask to be allowed to fix things, only to be told by General Landry that the people in this timeline don't want to be involved in big intergalactic wars. They like things just fine the way they are.
- He also points out that by restoring the timeline, the lives of everyone in the altered timeline are changed, and many will cease to exist — like Jack's son, Charlie, who is alive in the alternate timeline.
- Perhaps the Aesop of Lola Rennt is that it's all just a crapshoot. Any given ripple of influence from a chance passing could be a Butterfly of Doom — or a miraculous windfall — for Lola or anyone she brushes with. The opener alone establishes that fighting fate is just a game.
- Fish Story is one big butterfly effect, tracing from the initial recording of a before-its-time and rapidly forgotten musical number to how that particular bit of music sets in motion a chain of events that saves the world.
- Invoked in the Terminator franchise — in that it is the machines' plan to alter their present by meddling with the past. Yet curiously averted in that they kill a whole bunch of people other than Sarah or John seemingly without affecting anything. note
- In the third movie, several of John Connor's lieutenants were killed by the Terminator. We find out in the fourth film that their places were taken by other people who were just as effective lieutenants... which unfortunately undermines the idea that one man can be the central linchpin of history that is central to the Terminator story.
- Not necessarily. These people would be the officers that would make John Connor immediate leader of the resistance. Their deaths, including John's father-in-law's, caused some very incompetent officers to take their places, and turn John into a mere foot soldier, not to mention ignore his many warnings and suggestions. So yeah, Connor is meant to be a big leader against the Machines, but only because of a Stable Time Loop he himself created, where he would know everything that would happen and be ready, but also have people who would stand by him and take his word for things. What T-X did was to ensure that even if she failed her mission(Like the last two did), Connor still would be diminished as a threat. And Skynet's plan was so good that she came closer to killing Connor in the fourth movie than any of the Terminators sent to the past.
- In Hot Tub Time Machine, in which the protagonists are transported from 2010 to The Eighties in a hot tub, they are Genre Savvy enough to attempt this. They even reference the butterfly effect. They set out to do everything their '80s selves would've done in the same way they would've done it.
- The archetypal example — from which the trope name descends — would be Ray Bradbury's 1952 short story A Sound of Thunder. There is a "Time Safari" where you can go back in time and hunt any animal. It is a Defied Trope here because they specifically look for animals who are going to die and go back in time to just before they do, and have an anti-gravity path to shoot the animal from. Naturally, something goes wrong: the cocky Eckels is scared as heck when he sees his T-Rex, and runs off the path. When they go back to the present, the Hitler-esque Deutscher wins the Presidential election instead of Keith. There is also a different alphabet. And all because, you guessed it, Eckels accidentally stepped on and killed a butterfly. This is a Trope Namer; the other Trope Namers drew inspiration from this one.
- Similarly, the science-fiction story "Aristotle and the Gun" by L. Sprague de Camp has an arrogant time traveler trying to change history, and achieving the exact opposite of what he intends.
- Both the novel and the film Millennium conclude with a runway "timequake" obliterating the future, because of an accidental change made to the timeline in the present.
- An Animorphs Super Special dealt with a villain changing time. Some things were better, some things were worse; World War II, of course, was one of the affected areas. Much of the conflict of the book is over whether to restore the world or keep it the new way, and what justifies preserving bad pieces of history.
- There was also another storyline where we find out what would have happened if the main characters hadn't run into the alien who gave them superpowers and warned them about an alien invasion.
- In fact, Cassie's history teacher Ms. Paloma makes a reference to the butterfly thing in Book 7, The Stranger. See here.
- The Green Futures of Tycho by William Sleator involves a time traveler teenager making repeated trips into the future. Each time he discovers a bad future, and tries to fix it in the present or past. Each time, his actions only make it worse. He eventually realizes the reason ( In all futures, he has the time machine and he's using it to control events), but not before he gets his time-traveling Evil Overlord future self chasing him to stop himself from messing up the past (present for the teenager) that lead to his present (future).
- Isaac Asimov's novel The End of Eternity. Only in this case, the constant changing of the potential timelines by a secret trans-temporal time agency resulted not in unpredictable chaos but in a static history, because the time agency tried to erase, with the best intentions, every invention, trend or development that they regarded a danger to Mankind and human life in general... erasing wars, but also deliberately killing all attempts at space exploration throughout the various milennia. In the end, only the destruction of the time agency itself allowed the restoration of Mankind's original timeline: a life full of risks in search of the Unknown, but also with the potential to colonize the galaxy and survive into the distant future after the Earth's sun had gone nova.
- This was subverted in Terry Pratchett's The Last Continent. When the faculty of the Unseen University find themselves trapped centuries or even millennia before they were born, Ponder Stibbons invokes the ever-popular "kill your own grandfather" example of why you shouldn't muck around with the past. Arch-chancellor Ridcully dismisses Ponder's concerns with a logical "whatever happens stays happened" attitude. He points out that having killed one's own grandfather and ceased to exist, no-one would exist to step on the ant, meaning your grandfather was never killed. This creates a circular paradox; doing something makes you unable to do it. He also observes that he is unlikely to kill his own grandfather, as he "rather liked the chap." Therefore, since they are in the past, they were clearly there once already (i.e. now), and therefore any ants that are stepped on, are vitally important in their capacity for being stepped on. The Bursar later attempts to take this to heart by jumping around on ants in between walking into trees.
- This subversion of the Butterfly of Doom theory is itself a well-respected alternate theory of how time travel might work; in a real sense Ridcully is simply the Discworld inventor of an idea that many writers of time travel stories already accept in our world.
- Directly parodied with the Quantum Weather Butterfly, flocks of which played a big part in Interesting Times. The Quantum Weather Butterfly uses its ability to affect localized weather phenomenon as a form of self-defense, and possibly a way of attracting mates. "Hey baby, look at this thunderstorm!" (And of course, Pratchett Shows His Work by pointing out that the fractal nature of the edge of the Quantum Weather Butterfly's wing makes it quite finite in area, but nearly infinite in perimeter, which is one of the seeming paradoxes of fractal surfaces in real life.)
- Alas, no. While probably a deliberate 'error' attributed to Discworld logicians, the statement in the book is actually less mathematically sound:
And therefore, if their edges are infinitely long, the wings must logically be infinitely big.
They may look about the right size for a butterfly's wings, but that's only because human beings have always preferred common sense to logic.
- Pterry plays with theories of time travel/the Butterfly Effect a lot. A good example is Night Watch, where despite the fact that when John Keel, an important figure in the storyline, is killed because Vimes turns up 30 years in the past, Vimes ends up taking his place more-or-less seamlessly. Lu-Tze, the history monk, muses on the nature of time:
Lu-Tze: We're learning a lot, though! For a perfectly logical chain of reasons Vimes ended up back in time even looking rather like Keel! Eyepatch and scar! Is that Narrative Causality, or Historical Imperative, or Just Plain Weird? Are we back to the old theory of the self-correcting history? Is there no such thing as an accident, as the abbot says? I'd love to find out!
- and later...
Vimes: I mean, doesn't it change history if you tread on an ant?
Qu: For the ant, certainly.
Lu-Tze: I told you, Mister Vimes. History finds a way. It's like a shipwreck. You're swimming to the shore. The waves will break whatever you do. Is it not written, "The big sea does not care which way the little fishes swim"?
- Madeleine L'Engle's A Swiftly Tilting Planet: Mad Dog Branzillo will succeed in nuking the earth unless Charles Wallace goes back in time and changes the Might-Have-Beens in humanity's history. Thus, Branzillo's very distant ancestors never waged a fratricidal war; his blue-eyed ancestor Zylle was never hanged as a witch; the descendants of the two brothers married, and "Mad Dog" Branzillo was instead born El Zarco, "the Blue-Eyed".
- In the third book of The Pendragon Adventure, The Never War, the characters at first think that to make the turning point go correctly, they must stop the destruction of the Hindenburg. However, they ask the Traveler from Third Earth (the far future) to analyze what would happen if they did it. It turns out that the world would be destroyed if they went through with it. After a rather huge misunderstanding because one character didn't get that last bit of info, they manage to let time go on its proper course.
- And then, in the later books, Mark brings incredibly advanced technology into the past, jump-starting the computer industry and advancing technology's development. Of course, also thanks to Mark, we also get the future dystopia seen in Raven Rise because of a stupid decision he made in 1939.
- In Marge Piercy's Woman on the Edge of Time, it's implied that the apparently futile actions of a single patient in a mental institution will affect whether the future holds a sustainable, egalitarian utopia or a polluted colony of virtual prisoners and sex-slaves.
- Alfred Bester's The Men Who Murdered Mohammed plays around with this. A scientist attempts to erase his wife's existence after he finds her cheating on him. He whips up a time machine, and goes back in time to kill her grandfather. The catch? It doesn't work. So, he works bigger, rampaging through time, killing more and more famous people with absolutely no effect on the present until, finally, he meets a fellow time traveler who explains that the past he's killing is his own, and he's unhinged himself from reality because of his actions.
- The Children of the Lamp series has a non time traveling example. Philipa (a djinni) grants an innocent wish of removing all foie gras from New York city. But it takes a horrible turn in that through an unusual series of events it destroys her mother's body in a volcanic eruption. Fortunately her mother is a djinni thus she was able to survive and a friend had earlier been in an accident that had left that friend brain dead.
- A literal example of this shows up in a Philip K Dick story, where traveling to the future causes hordes of blue winged, acid secreting butterflies to show up and kill everything.
- Invoked in a small way, along with Failure Is the Only Option, as part of a brutally satirical short story in Stanislaw Lem's Memoirs of a Space Traveller: The Further Reminiscences of Ijon Tichy. Attempts to correct problems in history and create a better world fail spectacularly due to a combination of mishap, incompetence, and malice, resulting in a thoroughly fouled-up world —- the one we currently live in.
- Hilariously lampshaded/satirized in William Tenn's short story "Brooklyn Project", which opens with the acting secretary to the executive assistant on press relations explaining to a group of journalists that the project to send a probe four billion years into Earth's past — and then two billion, and then one billion and so forth — is perfectly safe, that nothing that happens in the past can change the present. In brief vignettes we see the probe condensing moisture on its outer surface, the probe destroying microorganisms with its weight, the probe crushing tiny trilobites... and the story ends with "the thing that had been the acting secretary to the executive assistant on press relations" spreading his tentacles and explaining that as they can all see, nothing has changed.
- Directly referenced in the fist chapter of the first Code Lyoko novel, "The Butterfly at the Bottom of the Sea". The butterfly is the minuscule disturbance of a cable deep beneath the Sea of Japan, and the end result is XANA's revival and Aelita's memory loss.
- Invoked in Scorpion Shards, where Dillon intentionally searches for the proverbial butterflies he can kill to cause huge catastrophes.
- In The Wise Man's Fear the Cthaeh, an entity unable to leave a single tree, has perfect knowledge of all possible futures, and whenever it speaks to someone, it manipulates them into causing the greatest possible harm with just a few words. Policy on handling those who speak to it is to shoot them dead from half a mile away, leave the body to decompose, and if a crow descends to eat the body, shoot the crow.
- The historians in Connie Willis's time-travel novels are afraid of this happening, because although for many years they've believed that the laws of time-travel physics don't allow anyone to travel if their presence will change history, this isn't borne out by their own experiences — while they can't visit "divergence points" (for example, the battle of Waterloo, or anywhere near Hitler) they can alter minor events, and then have no way of knowing whether this has had a significant effect. The plot of To Say Nothing of the Dog balances on whether two individuals will marry each other instead of the people that they're required to marry so that their descendants exist in the future in order to play historical roles. In Blackout it's posited that a novice time-traveler bumping into a woman and making her drop her handbag may cause the Allies to lose WWII. However, in both novels, the continuum appears either to self-correct, or to have "required" the presence of the time-travelers — in other words, the things they do have always happened and don't change the overall outcome of events.
- In the short story "You're Another" a hapless man finds that all of his troubles are caused by people from the future who alter the past, over and over again, and then film it as entertainment. When asked if changing the past doesn't change their time in the future, they explain that it doesn't, saying "What happens to a dog when you cut off its mother's tail?" He is not happy when he finds out his part in all this, and why he's constantly falling into holes, having paint drop on him and being cheated on by his girlfriend. Their explanation: "comic relief".
- Played with in 11/22/63. While changing the past does have major negative effects, some of them are the result of the timestream shattering. For example, saving Kennedy leads to a massive Los Angeles earthquake the same week, which could not possibly have been a direct result.
- Averted with Larry Niven's "Hanville Svetz" series. The time traveling agents of the Institute For Temporal Research do not realize that time travel is nothing more than a fantasy, so when they go backwards in time (forward time travel being impossible because the future does not exist yet), they always end up in some fantasy world. In "Flight of the Horse", for example, Hanville Svetz is sent back in time to retrieve a horse (long extinct in his time) for the government-run zoo . . . and brings back a unicorn.
- In "Because a Little Bug Went Ka-Choo!", by Rosetta Stone (aka Dr. Seuss), a bug sneezes, setting off a series of larger and larger consequences, in the end nearly sending a whole town into chaos.
- Time Riders is centred around stopping people from a seemingly hopeless future from changing the past. Only the odd book has no massive effect on the future due to something being changed in the past as its main plot.
- In TimeRiders, Kramer tries to lead Hitler to victory and grab some glory for himself too. Kramer eventually goes insane and starts a nuclear war, leaving nothing but savage mutants on the planet.
- In Day of the Predator, an assassin (later proven to be a Hitman with a Heart when he doesn't kill Chan) is sent to kill young Edward Chan, one of the biggest contributors to the invention of time travel. Thankfully, we see very little of the Bad Future that would occur.
- In Doomsday Code, Liam finds himself in the middle of a History-changing battle. Time is in a state of flux until the battle is over.
- In Eternal War, the Eternal War in question is the result of Abraham Lincoln not being around to win the American civil war.
- In Gates of Rome, the Project Exodus team tries to overthrow the Roman Empire. Instead, everyone but Rashim is killed and Emperor Caligula uses the support units the team had as his personal bodyguards, leaving him to rule for far too long.
- In City of Shadows, the team run into Jack the Ripper and figure out that they have to let him get away with his murders; he is actually an aristocrat, and the discovery of that would leave London in ruins.
Live Action TV
- Blackadder Back and Forth is a brilliant example of this trope. In the story, Baldrick (accidentally, Blackadder meaning it as a scam to win a bet with his guests) invents a working time machine. They're sent on a dare to use it and to bring back a catalogue of different items including a centurion's helmet and the Duke of Wellington's boots. After Blackadder succeeds, it emerges that he has changed the course of history as a result: After finally arriving at the battle of Waterloo, he squashes the Duke of Wellington with his time machine just before the battle begins, steals his famous boots and causes the French to win the fight. As a result, Blackadder returns to an alternate-reality Britain which has been ruled by the French for 200 years - as a result of his tampering - following Napoleon Bonaparte's victory at Waterloo, and just in time for garlic pudding. He becomes especially disconcerted when he sees Archdeacon Darling wearing a tutu and exclaims "We've got to save Britain!" before going back in time to try and rectify everything. He also has a run-in with William Shakespeare, earlier on in the story, whom he attacks for the interminable suffering of school pupils that would happen for the next 400 years as a result of having to study his plays at length, leaving William completely discouraged as a playwright but dropping his ballpoint pen in the process. Later on, in the alternate reality, William Shakespeare is revealed to have been known only for "inventing the ballpoint pen."
- Subverted in an episode of Scrubs appropriately entitled "My Butterfly", where a butterfly affects the events of the day, ending in the death of a patient. When the butterfly changes where it lands, the episode features an alternate future, but the patient that J.D., Dr. Cox, and Turk are involved with still dies on the table.
- Another fine example of how one man's repeated attempts at changing the past to find the "perfect" timeline are leading to ever more disastrous consequences is the two-parter episode "Year of Hell" from the 4th season of Star Trek: Voyager. Things are spiraling out of control, precisely because the timeship is based on the idea of Laplace's Demon which is contradicted by both Quantum Mechanics and Chaos Theory. In the end the original timeline can only be restored by destruction of the timeship (which had existed "outside time" while aboard centuries of subjective time passed), which Captain Janeway brings about by ramming it with the Voyager, destroying both ships in the process and "resetting" the timeline back one year.
- Both mocked and utilized in Star Trek by Q in "Tapestry". While changing the past would certainly alter one man's future, it's incredibly self-centered to think that changing one person would change everything.
- In what is widely considered to be the best episode of Star Trek (TOS), "The City on the Edge of Forever", the world falls to Nazi Germany and Starfleet never forms because one woman didn't die when she was supposed to.
- Played with in the MST3K episode, Time Chasers, a nerdy scientist invents a time machine, and then has to go back in time and prevent an earlier version of himself from giving it to a Corrupt Corporate Executive. The original versions of the scientist and his girlfriend end up dying while the "earlier" versions of them manage to keep the time machine from falling into evil hands.
- The host segments also play around with this trope, with Crow going back in time to prevent Mike from getting shot into space. Unfortunately, Mike dies in this alternate fate-line and his Jerkass older brother Eddie ends up on the SOL instead. Crow goes back in time again to tell the earlier version of himself not to warn Mike, and, as a result, the earlier version of himself gets stuck in the past where he will presumably remain, as an employee of the cheese factory where Young Mike worked.
- There is a sort of this in Seven Days. It's stated that simply backstepping (Going back in time one week) already changes the timeline because the Sphere materializes and changes air currents, causing airplanes to land a bit sooner/later and the like. Of course, it was never explained further than that.
- Hysterically parodied in a The Whitest Kids U Know sketch. Every time Trevor and Sam try to change history, random things happen (because that's how physics works). They go back in time and kill Hitler; JFK turns into a panda bear. They stop two Godzilla-esque monsters from attacking each other and cause the Vietnam War. After preventing 9/11, one of the character's sister starts to disappear from a picture (a parody of Back to the Future). In response, they scream "We have go back and save 9/11!" Seems the maker of the show didn't know anyone close to the attack.
- A big part of Heroes, where time travel (mainly by Hiro Nakamura, and later Peter Petrelli) and precognition are used to fix, worsen, and then repair the future many times. Featured most prominently in the episode, "The Butterfly Effect", where Future Peter screws up the past so badly, that he leaves things for Present Peter to fix since he had "stepped on too many butterflies."
- Possibly subverted, or at least morphed into You Can't Fight Fate, during Volume 4 where all of the things that happened in the "averted" future are happening anyway (Sylar can heal and shapeshift, Nathan has turned on the mutants, Sylar-As-Nathan is gunning for president, etc..
- Heavily subverted with Charlie. Through Hiro's intervention, she is saved from her brain tumor and Sylar's murder-spree. But she is kidnapped and stranded in the 1940's in order to manipulate Hiro. Before she went, she was an insatiable reader and had the super-power of 100% perfect memory - someone with enormous potential to alter history for good or evil. Yet she does...nothing, instead choosing to work a factory job and settle down.
- Supernatural covers this in two different episodes, although they aren't played straight. In one, Dean is tricked into believing a Djin has taken him to an Alternate Universe where his mom never died, and none of his family members became Hunters. Everyone's living happily, but as a consequence, his relationship with Sam is estranged because of their lack of time together, and all the people he saved as a Hunter died in their "accidents" without the brothers there to prevent them. Luckily, it was All Just a Dream. In the second episode, Dean is actually taken back into time by Castiel, who warns him that any attempt to save his mother will inevitably result in the death of the innocents he has saved. Subverted in that no matter what Dean did, things ended up going exactly the same way anyway.
- In a non-time travel related version, when Dean becomes Death for a day and fails to reap a twelve-year-old-girl, the butterfly ensures that things go badly for everyone near her. For example, a nurse gets off early because her help wasn't needed and dies in a car crash. His husband sees her die and attempts suicide by car accident. Presumably, this kind of thing would continue forever.
- In Smallville, Clark goes back in time to save Lana's life. However, in preventing the accident, his dad, no longer having a reason to stay and console Clark, goes straight to his meeting with Lionel Luthor. The scuffle that ensues causes him to have a heart attack, ultimately killing him.
- Several alternate universe/timeline episodes of Stargate SG-1 feature worlds where it seems like only one small thing has changed, but often, that leads to something even more horrible happening. A good example is "2010", where contact with one group of aliens leads to the slow but inevitable destruction of Earth's human population.
- Doctor Who:
- In the episode "The Shakespeare Code", the Doctor lampshades this to put Martha at ease in her first time time-traveling.
Martha: But, isn't it dangerous? You know, like you step on a butterfly and the future's completely changed because of it?
The Doctor: Well... I tell you what then: don't step on any butterflies. What have they ever done to you?
- While the show is mostly immune to this trope, with characters messing through time willy-nilly, it is used occasionally. The episode "Turn Left" is probably the most striking example, with an It's a Wonderful Plot twist.
- "The Fires of Pompeii" both plays this straight and subverts it. Donna asks the Doctor why he can't warn the city of the impending volcanic eruption, only for him to say that it's a fixed point in time that must not be tampered with. At the end, as the volcano is erupting, Donna pleads with the Doctor to help, so he rescues one family (the one they've gotten to know throughout the episode) and puts them outside of the city with what appears to be no consequences.
- The Doctor has mellowed a bit when it comes to messing around with history. The First Doctor story "An Unearthly Child" has him so paranoid about the possible ramifications of this trope that he is convinced that the mere idea that a device such as the TARDIS exists could irreparably change the course of human history.
- In the episode "Father's Day", Rose goes back in time to visit her father before his death but ends up saving him from his fatal accident. The resulting tear in the fabric of reality lets through a host of aliens who feed off time energy and kill a lot of people.
- In the series 6 finale, River Song tries to subvert reality by not killing the Doctor. The result of this is that all of time and space coexist in the same eternal instant, with anything unable to happen until the proper events of the timeline are carried through.
- In the series 5 episode, "The Pandorica Opens", it happens in a big way when the TARDIS explodes and rips up time, so much so that every star in the universe is never born and he only reason life exist on Earth is that the TARDIS is exploding at all points in time. To fix it, the Doctor has to take the Pandorica to the TARDIS and have it explode, sending all the atoms of the old universe everywhere in every point of time, effectively Big Bang 2, but he will be stuck on the other side of rip. He gets better, though.
- Used in the UK series Misfits, where Curtis uses his time-travelling ability to go back to the night he and his girlfriend Sam were arrested for drug possession. His initial attempts to change things only make things worse (such as Sam ending up stabbed by the dealer), but he eventually manages to change things enough that neither of them is killed or arrested and "jumps" back to the present, where it looks initially like an inversion; he's back to being an Olympic athlete and Sam is alive. Then he realises that without him there to save them, almost the entire main cast were murdered back in the first episode.
- A continuing theme of the Cut Short series Odyssey 5. Five astronauts who survived the destruction of Earth are sent back in time five years to try and avert the xenocide. Although they agree not to try and change their own personal lives none of them can resist trying to tinker with events, with varying results.
- The Kamen Rider 40th anniversary movie Let's Go Kamen Rider is all about this. OOO and Den-O chase a monster back to the era of the original Kamen Rider and accidentally leave behind an O Medal. When they return to 2011, that single Medal has allowed villain organization Shocker to Take Over the World and put four decades' worth of Kamen Riders on the ropes.
- Fringe: In a roundabout way, the show reveals in bits and pieces that the entire plot of the series and the fate of multiple universes all pivoted on a single inadvertent action by a time traveler: an Observer's presence distracting the red universe's Walter Bishop from discovering a cure for his son Peter's illness. This miniscule action caused Walter's blue universe counterpart to bridge their two universes to save Peter, and then kidnap him to be a Replacement Goldfish for his own Peter. This dimensional mess destabilized the physical laws of both universes and jeopardized the timeline that would spawn the time-travelers in the first place, forcing them to take a direct role in correcting the original mistake.
- The Community episode "Remedial Chaos Theory" is all about this. It's decided that a roll of the dice will dictate who has to leave and pick up a pizza, so the one rolling the dice will be creating six different universes, all based around what the characters would or (or in some cases, wouldn't) be doing in the two or three minutes that the pizza is getting picked up. All outcomes except for one involve the group somehow creating a conflict in these couple minutes. In the real (best) outcome, Abed stops the dice from falling, Jeff goes to get the pizza, and the group gets along fine while he's gone. In the "Dark" outcome where Troy leaves to pick up the pizza, Pierce dies, Annie goes insane and Shirley becomes an alcoholic because of Pierce's death, Jeff loses an arm, and Troy loses his larynx. Abed acknowledges that it's the darkest timeline, and makes everyone felt goatees so they can all be "evil" versions of themselves.
- Angel. In "Birthday" the demon Skip shows Cordelia (with the help of Monday Night Football replay and onscreen graphics) how her life could have been different if she'd just moved in one direction as opposed to the other during a party in the series premiere and met a Hollywood talent agent instead of the series protagonist, becoming the famous star of a comedy television series instead of a Fainting Seer whose visions are killing her.
- Mr. Young: "Mr. First Impression". Adam going back in time to make a better first impression on Echo leads firstly to his getting fired, then to Echo dumping him for a criminal kingpin, and finally to elephants beating humans in a war for control of the Earth.
- Invoked in the 2014 Cosmos series. Neil deGrasse Tyson uses three butterflies in a cloud of white moths to represent the concentration of carbon dioxide in the atmosphere because the variations needed to radically change the climate are so mathematically small—no butterflies, and the Earth freezes, three more butterflies and it heats up. He also mentions the "butterfly effect" of chaos theory (tiny changes in starting conditions lead to entirely different results) when explaining the difference between weather (chaotic) and climate (not).
- Ray Bradbury's radio drama version of A Sound of Thunder virtually has the same plot as the short story, butterfly included.
- In Big Finish Doctor Who, the Seventh Doctor gently tells Ace that it's "just a story we tell the butterflies", and that she should stop looking for one single moment in her life that will magically change everything.
- Averted in Feng Shui, where the universe actively resists attempts to change it. To illustrate it, the sourcebook gives the classic example of a man going back in time to kill his own grandfather. If Johnny Fong goes back in time and kills his grandfather, he returns to the present to find that his name is Johnny Wong now, but nothing else has changed. In Feng Shui, world history bows to the whims of the people in control of the world's feng shui sites, and anything done by insignificant time travelers just gets corrected.
- Prince of Persia: Warrior Within actually uses this trope, but with a twist — instead of unexpected consequences, there is an actual guardian of time that hunts the Prince in order to restore time to its original flow.
- Time Hollow. The player makes small changes to the past and watches the subsequent results.
- This is also the plot for the PS2 game Shadow Of Memories which was written by the same maker of Time Hollow. Dude loves his time travel.
- The basis for the Red Alert series. The whole thing started when Einstein went back in time to kill Hitler, resulting in WWII taking place between the Soviets and the Western Allies.
- And in Command & Conquer: Red Alert 3, the Soviets go back in time to erase Einstein in order to save the Soviet Union, weakening both the Aliies and the Soviets(no nukes) and creating the Empire of The Rising Sun, resulting in a three-way world war.
- BlazBlue. Six words: The Wheel of Fate is Turning.
- Achron allows for rather odd situations involving chronoporters (time-teleporters) and battles. For example, by sending units back in time to fight alongside themselves, if the original units are damaged in the ensuing battle, the future versions will be also damaged when the next timewave comes by. Eventually, this can resolve into a much weaker army than was originally used. Also, these sorts of time-manipulation tricks can allow for armies to go back to attack economic or production structures to disrupt opponents. For example, killing that one marine who built all the resource processors that made the construction of the army that's harassing you in the future even possible. So, by killing one marine, you defeated an entire army. note It should be noted that much of the game is built on these sorts of tactics.
- It should also be noted that it's not segregated to the story: you can play with these temporal shenanigans yourself. In multiplayer.
- Averted by Chrono Trigger in that, while major changes to the timeline (such as the entire plot of killing Lavos) will, of course, have major effects, minor things, such as opening a treasure chest in the past, will, at most, have the effect of making the corresponding treasure chest empty in the future, yet you can get the future chests, then go back in time and open the past ones with no consequence... Killing monsters doesn't do a thing; they'll even reappear when you enter the area.
- Played straight with Porre, at least if you accept Chrono Cross as canon. Remember the small country whose people you told not to be selfish? They destroy Guardia with the help of Dalton, are implied to have killed Crono and Marle, and gain a strong influence on Zenan.
- Played straight in Chrono Cross, although most of it is just Serge.
- Once you sort through Chrono Cross's labyrinthine plot, it retroactively applies it to Chrono Trigger in a huge way. In a nutshell, after Crono and friends defeat Lavos and create a good future, Lavos in the past - in an attempt to avert its own destruction - pulls a supercomputer called FATE from the newly created future back in time, to fight with an organic computer that the planet has called in from an alternate future where Lavos never landed on the planet. FATE wins and, in an attempt to make sure that its current existence doesn't prevent its future creation and, thus, create a time paradox, it starts guiding human events to make sure everything happens according to plan. The Lavos that was defeated by Crono, meanwhile, has merged with Schala and formed into a being that is attempting to devour all of spacetime. Schala, for reasons that aren't really clear, winds up altering spacetime herself in order to save an infant Serge from a panther demon, causing Serge to mess up FATE's plan and suddenly become the centrepiece to approximately two dozen people's schemes for saving, destroying, or conquering the world. Basically, Crono altering the future by killing Lavos causes a dozen or so beings with the ability to manipulate time to immediately launch into an elaborate web of overlapping gambit schemes to try and ensure that the new future does or does not come to pass. And that's the ''short'' version!
- Mortal Kombat 9. By doing some minor things to avert a Bad Future, Raiden ends up making his and Earthrealm's future doomed. For instance, preventing Motaro from killing Johnny Cage causes Shao Kahn to kill Shang Tsung and empower Sindel; Sindel subsequently slaughters nearly all of Earthrealm's warriors. Similarly, when Raiden prevents the Lin Kuei from turning Smoke into a cyborg, they grab Sub-Zero instead.
- Used for a joke in Metal Gear Solid 3: Snake Eater where there's a point in the game where you can kill the young version of future turncoat agent Ocelot. Doing so ends the game instantly, with the game telling you that you created a time paradox.
- If you do this in the HD Rerelease you also get a trophy stating that all the problems in the series are solved, thus it's over. You still get a Game Over though.
- TimeSplitters: Future Perfect subverts this trope with Cortez causing countless paradoxes and shooting up everything. After all, he is cleaning up the mess of the actual villain. By the end, he manages to destroy the Timesplitters that had made a mess of the timeline, fixing up his own future. It's possible that all his deeds were always meant to happen or were simply erased from existence.
- Also subverted in Onimusha 3: Demon's Siege. Samanoske is stuck in present day and can therefore not affect events in the timeline, but Jaques in ancient Japan can and has to due to the Genma mucking around with time travel and causing the current mess in the first place. The two end up being time janitors, in a way.
- In Ghost Trick, Sissel is the Butterfly of Doom who can travel back in time and manipulate minor events—and he uses this power to save people rather than to destroy.
- Although the Legacy of Kain series generally runs on You Can't Fight Fate this trope occurs in Blood Omen when Kain goes back in time to kill William the Just before he becomes the Nemesis, thereby causing the sequence of events that leads to the genocide of Nosgoth's vampire population by the Sarafan. However, the events are not the result of vengeance on the part of the timestream itself but it was precisely calculated by Moebius the Timestreamer.
- In The Journeyman Project, the Temporal Security Agency works to prevent this trope from happening, and each Agent - including Gage Blackwood, Agent 5 - is tasked with reversing any changes that some other time traveler would have done to the past.
- Ironically, The TSA made their own change to the past by hiding its Historical Log disc in 200 million BC, though it's lampshaded in that the area it's situated in will inevitably be destroyed by a volcanic eruption.
- Invoked in Discworld, where Rincewind must use a literal Butterfly of Doom to progress the plot. Rincewind must catch a Butterfly in the past (about twelve hours ago) in the park then release it near a lamppost to solve a puzzle. This is later lampshaded in an Easter Egg in the sequel where past Rincewind asks current Rincewind to explain the thing about Butterflies and lampposts to him.
- Used Star Trek Online. During the "Ghosts" Featured Episode, your character and his team must go back in time to Drozana Station of the 23rd to stop the Devidians from causing havoc with the time stream. One of your crew members will make sure you invoke the Temporal Prime Directive, meaning you can't go around and muck with the time stream all willy-nilly. The first time you go back in time, you don't have much of a choice to muck with the time stream when you end up encounter Dr. McCoy - saving lives from the Devidians takes priority over everything else and you help pioneer a way to counteract the Devidians' absorptions. The second time, after you destroy a comet the Devidians were using to perform their time travel shenanigans, the Black Ops group you're aiding says they'll make sure everything you've done is kept off the books.
- It's done again in the finale of the Federation's "Klingon War" storyline. You chase Ambassador B'Vat through the Guardian of Forever and learn that his arrival had changed history with the original Enterprise destroyed. You arrived just in time to stop that and you go on to rescue Miral Paris.
- The developers of Until Dawn refer to the mechanic behind the game's branching storyline as the butterfly system, with a butterfly motif appearing in the trailers. And sure enough, given that this is a Survival Horror game, some changes can end in doom, making this a case of the Butterfly of Doom being enacted on the player.
- In Super Robot Wars Reversal, Raul and Fiona Graydon attempt to not use this trope when they and their friends are tossed back five years into the past. When they get to a crucial point in history (the Grand Finale of Zambot 3 and Mobile Suit Gundam Wing Endless Waltz), they suffer a Heroic BSOD before deciding to Screw Destiny and make sure things happen differently. Things get even worse as you find out that the mechanics found designs of future units such as the Nu Gundam and the Black Serena and have built them five years before they should and allowing you to defeat the Big Bad. When you return to their normal time, they learn that their changes brought about good futures.
- The Alternate History Forum, home of Look to the West and Decades of Darkness among others, is divided on the issue. There are purists ("step on a butterfly and everything changes") and non-purists ("consequences of an event ought to follow on logically: things take a while to change, and sequences of reasons can be made"). People who don't include any "ripple" of changes are laughed at. To quote veteran member Jared "In 1618, Australia will be discovered on time and the effects [of a sedentary yam-farming aboriginal civilization] will spread. Anyone asking "Great! How does this changed Australia affect World War 2?" will be fed to the blobfish."
- This is parodied in Reds, where the alternate history version of the Alternate History Forum appears, and the members discuss the alternate timeline... and the exact same kinds of arguments crop up.
- However, a key general note: the 'of doom' aspect is avoided in all but deliberately dystopic timelines (things change, often without directly described causal relations to the original point of divergence — but the changed things are often a mix of good and bad).
- Played with, and ultimately subverted, in Red vs. Blue: Church gets transported a thousand years into the past and then uses the time to come up with plans to prevent the accident that caused him to travel through time in the first place. The loop repeats dozens of times but everything he tries never changes anything.
- The sixth season of Sonic For Hire involves the Butterfly Effect. Some examples include there not being such of a thing as sliced bread, but it is called "chopped with your hands bread" instead.
- Time Squad: Planet of the Flies, a parody of Planet of the Apes. Tudrussel squashes a fly in the Stone Age, altering history so that the world is ruled by giant flies. Complete with a ruined Statue of Liberty scene. "You maniacs! You blew it all up!"
- Phineas and Ferb: "Phineas and Ferb's Quantum Boogaloo" featured an adult Candace going back in time to bust Phineas and Ferb for the rollercoaster and returning to her own time to learn it was now a Bad Future. As it turns out, her effort to bust her brothers not only created a wave of child-proofing hysteria, but it caused Perry the Platypus to get injured by Dr. Doofenshmirtz's evil scheme backfiring, instead of Doofenshmirtz like in the original timeline. This allowed Doofenshmirtz to ride the wave of hysteria and take over the Tri-State Area, turning it into a ruined industrial dystopia where fun and creativity are outlawed, kids are kept in People Jars until they reach adulthood, and everyone is forced to change their name to "Joe".
- In the Simpsons Treehouse of Horror segment "Time and Punishment", a malfunctioning toaster transports Homer to the prehistoric past. He remembers some Genre Savvy advice Grandpa gave him regarding this very trope, then instantly forgets it to squash a bug. When he returns to the present, Flanders has taken over the world. His attempts to fix the timeline cause alternate futures that range from even worse to just plain weird. When one of his sneezes causes all of the dinosaurs to drop dead, he moans, "That's gonna cost me." Homer eventually snaps and just starts whacking everything with a baseball bat, creating a future that's actually pretty near normal, except everyone has weird, elongated, lizard-like tongues.
- One of the alternate futures seems perfect for him: his sisters-in-laws are dead, his family is rich, the children are polite… but then he learns that donuts apparently don't exist in this timeline when he uses the word and nobody knows what he's talking about. He disappears into the past to try again, before we see that it rains donuts in this future.
- In Futurama's first movie, "Bender's Big Score", time travel plays a huge role in the plot. There's even mention of a failsafe in the universe itself that erases impossibilities created by time travel, like the same person meeting themselves, that prevents the Butterfly effect from having a dangerous effect. It comes up again in an episode where the Professor makes a time machine that only travels forward in time resulting in seeing the big bang twice as the universe resets itself and squashing the current timeline versions of themselves, stopping a paradox.
- In "Roswell That Ends Well", they go back in time to become the Roswell Incident. When Professor Farnsworth finds out that Fry's grandfather is there he gives him the classic advice for people going back in time: "Don't do anything that will change history. Unless, you're supposed to do it, in which case, for the love of God, don't not do it." Of course he does by killing his grandfather but the effects are minimal because he realizes that he is not vanishing so his grandfather can't really be his ancestor. He then sleeps with his grandmother and becomes his own grandfather. Farnsworth gets fed up after this incident and decides to just attack Roswell and steal their ship back. "Screw history! Let's just get the hell out of here!" When that plan actually works the Professor triumphantly shouts "Choke on THAT, causality!"
- The Invader Zim episode "Bad, Bad Rubber Piggy" starts out with Professor Membrane explaining on his show that, as tempting as it sounds, purposely changing the past would create more problems than it solves (Such as a giant fish in a bear-suit rampaging). Zim, of course, plans to do just that to get rid of Dib, but his attempts to destroy Dib's younger self eventually go from 'make him more decrepit' to 'gives him more super weapons from the professor.'
- In the Lilo & Stitch: The Series episode "Melty", the duo use Jumba's time machine to attempt to simultaneously capture the experiment and impress Lilo's crush Kioni, but after experimenting different methods it becomes apparent that each iteration causes something to go horribly wrong, often by setting off a Rube Goldberg-esque chain of events (one involving an actual butterfly.) In one case, they accidentally go forward instead and are met by an apocalyptic world directly stemming from their actions on that day.
- Invoked in a Robot Chicken episode when a kid says that a butterfly's wings flapping can cause storms etc. The other kid smashes the butterfly, causing an earthquake in Japan. The geisha quickly steps on another butterfly, causing an erupting volcano which melts one of the kids. The remaining kid rips a third butterfly in half, and Godzilla appears to burn the geisha's house.
- In the episode "Sword of Righteousness", Earthworm Jim uses said sword to go back in time and shave Abraham Lincoln's beard at the Gettysburg Adress ("Well, that's a big goodbye to my credibility.") to see if his face on the penny will change. When he gets back, he finds Peter Puppy dressed like Colonel Sanders:
Alt!Peter: What are y'all doin' now, Earthworm Bubba?
Jim: (Sheepish) I think the training is going well...aside from changing the course of history and all...
Sword: Listen to me! You will go and put Lincoln's beard back! And then no more time-travel for you, young worm!
- Brian in Family Guy goes back several years in time with Stewie to see where he had buried a ball. Stewie warns Brian not to touch anything or to talk to anyone, for doing so could alter their present time. Once the duo returns to their original time, Stewie discovers that Brian had told his past self about the September 11th terrorist attacks, which caused his past self to stop the attacks from ever happening. Sounds good, right? Sure, the lives of 3000+ people were saved, but the action caused George W. Bush to lose his reelection for U.S. President in 2004, which motivates him to have all the southern states secede from the rest of the country and declare a second civil war, but with nukes being used and causing the death of over a million people. Whoops.