[[quoteright:204:http://static.tvtropes.org/pmwiki/pub/images/the_butterfly_effect_001_45.jpg]]

'''''The Butterfly Effect''''' is a 2004 American ScienceFiction PsychologicalThriller film starring Ashton Kutcher, Amy Smart, Eric Stoltz and others, directed and written by Eric Bress and J. Mackye Gruber and distributed by New Line Cinema.

It's about Evan Treborn, a guy who can travel back in time by reading his journals and change what happened then, and uses this ability to try to undo various traumatic events he and his friends suffered as children. Despite his best intentions, the results aren't always good for everyone. What's more, his own brain suffers from trying to assimilate all the new memories from these consequences.

The title is a reference to the [[ButterflyOfDoom butterfly effect]], which theorizes that a change in something seemingly small and innocuous, such as a flap of a butterfly's wings, may have unexpected larger consequences in the future, such as the path a hurricane will travel.

It was followed by two [[InNameOnly largely unrelated]] DirectToDVD sequels, ''2'' and ''3: Revelations''.
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!!This film provides examples of:

* AbusiveDad: George Miller
* AllJustADream: [[spoiler:Subverted. At one point near the end of the film, it looks like the story is gonna go out with a TwistEnding. As Evan's doctor explains that there are no journals, he asserts that everything that we've apparently seen so far is a delusion that Evan created to cope with the guilt of killing Kayleigh, describing alternate universes with colleges, prisons and paraplegia. Then it turns out that the mental time travel ''was'' real when Evan goes back one last time]].
* AnAesop: Similar to that of ''[[Film/TheTimeMachine2002 The Time Machine]]'' remake. Attempting to undo the mistakes of the past is futile; sometimes, you just have to accept things the way they are.
** Which is [[BrokenAesop broken]] by Evan's final decision by [[spoiler:making sure Kayleigh stays out of his life, which makes things all the better for everyone in the end]]. So yeah, it's more like the Aesop gets twisted into "You'll only be okay if you never find true love."
* BeardOfSorrow: It's subtle, but there. In the futures that Evan loses Kayleigh in, he's always grown out a full beard. When he's still with her in the "frat-boy" future, he's shaved it down to a goatee, but it isn't until [[spoiler:the very end of the movie, when he's put her being a part of his life behind him]] that he's clean-shaven.
* BigBad: Tommy and Kayleigh's pedophile father, who is directly or indirectly responsible for everything bad that happens to the characters.
* BittersweetEnding: The theatrical cut. [[spoiler:Evan makes sure that he and Kayleigh never become friends by being mean to her when he travels back in time to their first meeting. Kayleigh and Tommy live a happy life away from their abusive father, and Evan and Lenny remain lifelong friends. Evan runs into Kayleigh in a downtown street in New York, but he ignores her after hesitating for a moment.]]
* BreakHerHeartToSaveHer: In the theatrical cut, [[spoiler:Evan finally decides that the best course of action is to go back to where he and Kayleigh first meet and be mean to her, so she never befriends him, moves away with her mother and avoids the sexual abuse by her father which ultimately leads to her suicide.]]
* ButterflyOfDoom
* BlessedWithSuck
* BlofeldPloy: Tommy beats the shit out of a random kid in a movie theater after he sees Evan kissing Kayleigh.
* BlondGuysAreEvil: Tommy. Even in a reality where he turns out alright, his hair is brown.
** Lenny, also depending on the reality.
* BrokenAesop: The lesson that you can't possibly undo all of your past mistakes and that you have to accept them for what they are is broken by both of the endings, as Evan does precisely that by [[spoiler:removing himself from Kayleigh's life entirely. The real mistake he had to fix was meeting her in the first place (theatrical cut) or ''being born at all'' (director's cut).]]
* BurnBabyBurn: Turns out this is what originally happened with the dynamite. Also [[spoiler:the ending (although that was hinted at throughout)]].
* ButtMonkey: Taken to the extreme.
* CrapsackWorld: It starts here and gets ''worse''.
** And worse, and worse, and worse...
* CreepyChild: Tommy, who is a total sociopath.
** Except when he's not, and then he's arguably MORE creepy. He's more of a creepy adult then, though.
* DeathIsTheOnlyOption: The director's cut ending invokes this trope. [[spoiler:Evan strangles himself with the umbilical cord in his mother's womb to make life better for the people he knew.]]
* DidNotGetTheGirl: [[spoiler:This is the least sad part about the ending]].
* DownerEnding: The director's cut. [[spoiler:Evan realizes that he's the reason why everyone else's lives are so miserable, so he travels back to when he was still in his mother's womb and suffocates himself.]]
* DrivenToSuicide
* ExactWords: "Here, take this [[BuffySpeak rusty spiky thing]]. You've got to stop Tommy! Cut the rope!" Too bad Lenny took that to mean [[spoiler:''Tommy's spinal cord'']].
* ExpositoryHairstyleChange: Kayley's hair color changes depending on how happy she is in whatever timeline. It's brown and mousy in the timelines where she's miserable and it's blonde when she's happy. [[spoiler:Her hair is blonde at the end]]. Likewise, Lenny has long hair in all the timelines in which his life turned out halfway decent.
* {{Foreshadowing}}: [[spoiler:You have no life-line. No soul. You were never meant to be.]]
* ForWantOfANail: A rusty, spiky nail, in all likelihood.
* FromBadToWorse: Evan endures a lot of pain in just the first half-hour of the movie, which chronicle his childhood and adolescence. Then he starts time-traveling, and things get ''really'' bad. In various alternate timelines, he winds up [[spoiler: imprisoned for murder and left with no arms, while Kayleigh winds up as a drug-addicted prostitute in one timeline, and Lenny winds up permanently doped up in a psychiatric ward]].
* GrandfatherParadox: No matter what ending you watch (or what ending you want to prefer), the plot is resolved in a manner that would make it impossible and/or unnecessary for Evan to ever travel back in time and influence past events, which means he never traveled back in time and changed the timeline, which means Evan went back in time and changed the timeline, which means he never traveled back in time, which means he did, which means he never did, which means he did...
* GroundhogPeggySue
* HairOfGoldHeartOfGold: In several realities, Kayley, especially while still a child.
* HeelFaceDoorSlam: Tommy in one reality. [[spoiler:Evan manages to convince him not to kill his dog and invoke his BigBrotherInstinct...only for Lenny to stab him from behind]].
* HeelFaithTurn: Tommy in an alternate timeline.
* HeroicBSOD: Lenny has this after the [[spoiler:dynamite incident]].
* HeroicSacrifice: [[spoiler:'''Strangling yourself as a fetus?!''']]
* HeroicSuicide: [[spoiler:Evan]] in the director's cut.
* HookerWithAHeartOfGold: Deconstructed.
* HollywoodLaw: Evan wouldn't go to a regular prison, but county lockup, since he hadn't even been tried. The filmmakers knew this; [[RuleOfCool it was cooler filming in a prison, though]].
* InSpiteOfANail: Evan goes back in time just to [[{{Squick}} stab his own hands]] on the teacher's spiky desktop notepad in second grade so he can re-live his whole life, land up in the same jail about to be raped by the same prison gang, and prove to his cellmate that he has magical powers in the form of [[WhatDoYouMeanItsNotSymbolic stigmata]].
** As if the movie wasn't enough of a MindScrew, every single other time Evan changed the past, no one else noticed ANYTHING different, but that ONE time his cell mate suddenly notices the "new" scars that should have been there the whole time from his [=PoV=].
* IncestSubtext: Tommy made a rather un-brotherly remark towards his sister Kayleigh in one timeline.
* ImpaledPalm: Evan does this to ''himself'', to get stigmata-like scars on his hands as a little kid, as a part of a complex plan to get his religious present-day cellmate to believe him. (TimeTravel is involved.)
* InstantWinCondition
* ItsAWonderfulPlot: The plot of this film is one of the most famous (and ''cruelest'') subversions/{{deconstruction}}s of this trope. The protagonist's life has been really depressing, and all his friends are worse off than before he met them. He uses his MentalTimeTravel abilities to correct his past mistakes, but they each end up making things worse for them and/or himself. [[spoiler:Accepting that they really are better off without him, he eventually decides that the only way to make them all happy is to remove his presence from their lives entirely. The director's cut was even worse; in that version, he travels back ''so he dies in his mother's womb'', just so his loved ones can live their lives without his damaging influence.]]
* IWantMyBelovedToBeHappy
* KavorkaMan: Evan's roommate Thumper, who's seen making out with an array of hot girls despite being an obese guy in {{goth}} clothing.
* KidsAreCruel
* MeaningfulName: "Evan Treborn" = "event reborn", alluding to Evan's [[spoiler:and his father's]] power.
** His name was originally going to be "Chris Treborn," but the writers feared the wrath of religious groups.
* MentalTimeTravel
* MindScrew
* MySisterIsOffLimits
* NextSundayAD: The epilogue takes place eight years in the future, which would be 2010.
* NiceJobBreakingItHero: Every single goddamn time he goes back to "fix" something. The first time, he seems to get it right and has the perfect life when he gets back to the present. But then [[spoiler:he manages to screw it up by murdering his girlfriend's psychotic brother and getting put in prison]]. Brilliant.
* NightmareFuelStationAttendant: Subverted, but still disturbing.
* NotQuiteTheRightThing: The reason things go downhill. Any time Evan tries to go back and do what seems to be the right thing. ''Any'' time.
* ParentalIncest: Kayleigh was molested by her father. He molested Tommmy instead in another timeline.
* PlotHole:
** [[TimeyWimeyBall Time travel inconsistencies]] aside, there's no mention of Evan ever having a trial before being sent to prison after he [[spoiler:kills Tommy]] nor is there any mention about why he didn't [[spoiler:plead self-defense]] when the murder was clearly witnessed as such and could have avoided any kind of stay in jail.
** The "stigmata" sequence is also frequently called out for this. When in prison, Evan briefly time-travels back to his grade-school classroom to puncture his hands with metal spikes, hoping that the resultant scars will convince his religious cellmate that he has a mystical connection to God. Not only does this not change the timeline in any way (Evan's still in prison when he comes back), the cellmate acts like the scars have spontaneously appeared on Evan's palms--even though, from his perspective, he should have had them all along.
* PrisonRape: A very brutal example.
* RelationshipResetButton: The ending.
* RetGone: [[spoiler:Evan nullifying his own existence in the director's cut]].
* RevisedEnding
* RewritingReality
* RippleEffectProofMemory: Memories from the "new" timeline hit Evan in a rush, giving him a nosebleed...caused by [[MySkullRunnethOver brain hemorrhaging]].
* SetRightWhatOnceWentWrong: '''Very''' subverted.
* StarCrossedLovers: At least in the director's cut, [[spoiler:Evan]] and [[spoiler:Kayleigh]] just aren't meant to be together.
* TapOnTheHead: Done quite realistically.
* TimeIsDangerous: The director's cut reveals that Evan suffers minor brain damage every time he majorly changes the past, resulting in severe migraines and nosebleeds as he gets the extra memories (often 20 years worth) burnt onto his existing ones. On the other hand, he's GenreSavvy enough to realize that repeated time travel might ultimately kill him, causing him to intentionally think through what he wants to change before each trip.
* TimeyWimeyBall: The events of roughly half of Evan's blackouts are caused by his older self [[MentalTimeTravel going back to them]], while the other half were normal initially, but could be changed by his older self. One blackout even has examples of both. Also, it is established early on that Evan is the only who has any memory of the old timelines, but at one point another character notices a change in the timeline for no apparent reason.
* TookALevelInBadass: Evan, after dealing with the thugs in prison.
* TrainStationGoodbye
* WhenSheSmiles: Evan has this reaction to Kayleigh in the first alternate reality. He's seen her sad and messed-up so many times that, when he sees her smile, he's convinced he wants to marry her.
* WhereItAllBegan
* WoobieDestroyerOfWorlds: Evan unintentionally becomes one of these.
* WorldHalfEmpty
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