History Main / TemporalMutability

** This is explicitly the case for the Abramsverse / Kelvin Timeline, presumably to preserve the main continuity. An accident sends both Nero and the original Spock over a hundred years into the past, radically altering certain events. While Spock Prime doesn't have to worry about paradoxes, he's also unable to return home.
** The non-canon ''Countdown'' comic shows events still occurring after Spock and Nero travel to the past, meaning the old timeline still exists.

[[folder:Fanfiction]]
* ''FanFic/SplitSecondMyLittlePony'' has this, although the gods are the exception. For them, any changes overwrite their own pasts.

[[folder:Fanfiction]]

[[folder:Fanfiction]]

* The original Marvel UK comics run of ''ComicBook/TheTransformers'' had this approach, with time-hopping characters from the future causing (both directly and indirectly) horrific effects to the timestream that result in the catastrophic "Time Wars" and numerous other paradoxes. The situation is eventually contained - barely - but the 'future' is no longer set, and indeed takes a wildly different path.

* In Disney Duck Comics, the fact that there are various authors with different opinions and nobody to control, if you search long enough, you'll most certainly find examples of all the sub-tropes, ''and'' a few original ideas.

[[folder:FanWorks]]

* According to its creators, this is what Einstein's use of the HitlersTimeTravelExemptionAct in ''VideoGame/CommandAndConquerRedAlert'' boiled down to. When he {{Ret Gone}}d Hitler from history to prevent the original World War 2, all he did was create an alternate timeline in which several {{Weird Historical War}}s replaced it. The original Einstein from our history (kinda) returned to his laboratory in Trinity. Which makes it even more sad in a way. He didn't really undo the genocide of the Jews, and [[UnwittingInstigatorOfDoom he unknowingly condemned]] an alternate universe to even more mayhem, in which his AlternateSelf ends up getting {{Ret Gone}}d too.

* According to its creators, this is what Einstein's use of the HitlersTimeTravelExemptionAct in ''VideoGame/CommandAndConquerRedAlert'' boiled down to. When he {{Ret Gone}}d Hitler from history to prevent the original World War 2, all he did was create an alternate timeline in which several {{Weird Historical War}}s replaced it. The original Einstein from our history (sorta) returned to his laboratory in Trinity. Which makes it even more sad in a way. He didn't really undo the genocide of the Jews, and [[UnwittingInstigatorOfDoom he unknowingly condemned]] an alternate universe to even more mayhem.

* The final season of ''Series/AgentsOfSHIELD'' has the team travel back in time in a chase after the [[AlienInvasion Chronicoms]], who are trying to dismantle S.H.I.E.L.D. before it has a chance to become strong enough to stop them. Theoretically they could have succeeded in stopping the Chronicoms and preserving their original timeline, however the team's butting heads over whether they should try to improve their own futures as well causes enough ripples to [[spoiler: cause the Malick family to all survive into the 70s and Nathaniel to copy Daisy's powers, get Mack and his brother orphaned as children, get Daisy's mom killed but sparing her sister, and destroy a majority of S.H.I.E.L.D. anyway.]]

** Xanatos learns how to properly take advantage of this by using a coin meant to be sent to his past self a thousand years later. the coin wasn't worth much for it's time, but would now go for the 20 grand he would ultimately use to kickstart his fortune. He also made sure to write a letter that would be sent to himself a week before these events occurred, so he would know the instructions for how to pull it off.

* ''VideoGame/LegacyOfKain'' takes an axe to all of this and more. ''Blood Omen'' has Kain altering the past, only to [[spoiler: create a future where vampires are all hunted down and killed by [[MadOracle Moebius the Timestreamer's]] mercenary army.]] However, ''Soul Reaver'' has Kain insisting that [[YouCantFightFate all events are preordained]], and that everyone plays out the part written for them by fate. But immediately afterwards, in ''Soul Reaver 2'' and ''Defiance'', we find out that [[spoiler: Raziel is the only being capable of changing fate, which Kain structures his entire [[XanatosSpeedChess Xanatos]] GambitRoulette of [[ScrewDestiny defying fate]] around and disrupting the GambitPileup created by his, Moebius', the Elder God's, and Hash'ak'gik's manipulations throughout Nosgoth's history.]] And that's not even getting into the many, time-derailing paradoxes present throughout the series, most of which revolve around the incredibly complicated existence of the [[SoulCuttingBlade Soul Reaver]]. In short, the rules of time travel in ''Legacy of Kain'' depend on and act to the advantage who is on top of of giant GambitPileup, which results in XanatosSpeedChess from many different sides, and where the effects of defying fate can either result in events already predestined or happen, or completely alternate futures that deviate entirely from the timeline, such as seen in ''Blood Omen 2''.

* ''Fanfic/ChildOfTheStorm'' mostly has this kind of time travel. You don't necessarily ''have'' to change things, but the Butterfly Effect can still ensue. Moreover, the series' primary MagnificentBastard, Doctor Strange a.k.a. [[spoiler: Taliesin, student of Merlin and Court Physician/Bard of Camelot]] uses his powerful abilities as a {{Seer}} and skills at Time Magic to outright ''exploit'' the Butterfly Effect with (almost) perfect precision, and steadily manipulate the timeline to where he wants it to be. Why? He's preparing the Earth to face off against Thanos.

#'''YouAlreadyChangedThePast:''' AKA [[http://en.wikipedia.org/wiki/Block_time Block time]] or Eternalism. Past, present, and future are an immutable whole. YouCantFightFate. You can't change history. [[Series/DoctorWho Not one line.]] Consequently all time travel to the past results in the creation of a StableTimeLoop, by virtue of the fact that the past -- ''including the interference'' of all those time travelers -- already happened. Any attempt to change the past is not merely futile but vulnerable to a variation of the SelfFulfillingProphecy: an effort to Set Right What Once Went Wrong may be tragically revealed as the ''reason'' it went wrong. Alternately, an accidental involvement in something that Once Went Right might be the ''reason'' [[WaybackTrip it went right]] (that was probably left out of the history books).

* ''FanFic/SplitSecond'' has this, although the gods are the exception. For them, any changes overwrite their own pasts.

[[folder:Video Games]]
* In ''VideoGame/TheLegendOfZeldaOcarinaOfTime'', time-travel shenanigans (or, rather, mental time travel shenanigans) cause the timeline to split into three branches, with one point of divergence known [[note]]the ending, where Zelda sends Link's mind back in time to prevent his removing the Master Sword from its pedestal[[/note]], and the other previously [[EpilepticTrees only theorized]][[note]]the final boss fight, depending on if Link wins or loses[[/note]].

* ''VideoGame/KingdomHeartsIII'' applies WrongContextMagic to MagicAIsMagicA in regards to the time travel rules from ''VideoGame/KingdomHearts3DDreamDropDistance'' mentioned above under Type 1, first as a HandWave to some EarlyInstallmentWeirdness and next as a plot point, which becomes especially relevant in the ''Re:Mind'' DLC. First we have [[spoiler:Dark Riku]] in [[WesternAnimation/BigHero6 San Fransokyo]] offhandedly mentioning that he had to play by the rules to time travel, unlike “[[WesternAnimation/TheSwordInTheStone a certain wizard]]” the heroes know (presumably in reference to the [[WesternAnimation/ClassicDisneyShorts Timeless River]] world from ''VideoGame/KingdomHeartsII''). The more plot-relevant example comes in the final battle when [[spoiler:the heroes die and Sora has to journey through the Final World to retrieve their hearts from the Lich]]. After breaking one set of universal rules (regarding the power of waking), Sora then proceeds to break the rules of heart time travel by [[spoiler:sending his friends’ hearts to the past to a point before they all died and replacing the original history with a new one where they survive]]. The ''Re:Mind'' scenario has Chirithy explain to Sora that doing this caused a TimeCrash, and that since he shouldn’t try to change the past anymore than he already has, he’ll have to use that space-time rift he created to visit both of the contradictory events now occupying the same timeline for this adventure. Chirithy’s warning edges closer to “Enforced Immutability” category than before, as AllThereInTheManual indicates that Sora breaking the rules of time travel to accomplish this all this resulted in [[spoiler:him vanishing from existence during the ending]].

* ''VideoGame/KingdomHeartsIII'' applies WrongContextMagic to MagicAIsMagicA in regards to the time travel rules mentioned above under Type 1, first as a HandWave to some EarlyInstallmentWeirdness and next as a plot point, which becomes especially relevant in the ''Re:Mind'' DLC. First we have [[spoiler:Dark Riku]] in [[WesternAnimation/BigHero6 San Fransokyo]] offhandedly mentioning that he had to play by the rules to time travel, unlike “[[WesternAnimation/TheSwordInTheStone a certain wizard]]” the heroes know (presumably in reference to the [[WesternAnimation/ClassicDisneyShorts Timeless River]] world from ''VideoGame/KingdomHeartsII''). The more plot-relevant example comes in the final battle when [[spoiler:the heroes die and Sora has to journey through the Final World to retrieve their hearts from the Lich]]. After breaking one set of universal rules (regarding the power of waking), Sora then proceeds to break the rules of heart time travel by [[spoiler:sending his friends’ hearts to the past to a point before they all died and replacing the original history with a new one where they survive]]. The ''Re:Mind'' scenario has Chirithy explain to Sora that doing this caused a TimeCrash, and that since he shouldn’t try to change the past anymore than he already has, he’ll have to use that space-time rift he created to visit both of the contradictory events now occupying the same timeline for this adventure. Chirithy’s warning edges closer to “Enforced Immutability” category than before, as AllThereInTheManual indicates that Sora breaking the rules of time travel to accomplish this all this resulted in [[spoiler:him vanishing from existence during the ending]].

** ''VideoGame/KingdomHeartsIII'' applies WrongContextMagic to MagicAIsMagicA in regards to its time travel rules, first as a HandWave to some EarlyInstallmentWeirdness and next as a plot point, which becomes especially relevant in the Re:Mind DLC. First we have [[spoiler:Dark Riku]] in [[WesternAnimation/BigHero6 San Fransokyo]] offhandedly mentioning that he had to play by the rules to time travel, unlike “[[WesternAnimation/TheSwordInTheStone a certain wizard]]” the heroes know (presumably in reference to the [[WesternAnimation/ClassicDisneyShorts Timeless River]] world from VideoGame/KingdomHeartsII).

#'''YouAlreadyChangedThePast:''' AKA [[http://en.wikipedia.org/wiki/Block_time Block time]] or Eternalism. Past, present, and future are an immutable whole. YouCantFightFate. You can't change history. [[Series/DoctorWho Not one line.]] Consequently all time travel to the past results in the creation of a StableTimeLoop, by virtue of the fact that the past -- ''including the interference'' of all those time travelers -- already happened. Any attempt to change the past is not merely futile but vulnerable to a tragic variation of the ProphecyTwist: an effort to Set Right What Once Went Wrong may be revealed as the ''reason'' it went wrong. Remember that [[WaybackTrip the history books do not tell the whole story]]! Needless to say, don't try to [[HitlersTimeTravelExemptionAct assassinate Hitler]]: you are liable to lend crucial support to the tyrant's rise to power.

#'''YouAlreadyChangedThePast:''' AKA [[http://en.wikipedia.org/wiki/Block_time Block time]] or Eternalism. Past, present, and future are an immutable whole. You can't change history. [[Series/DoctorWho Not one line.]] Consequently all time travel to the past results in the creation of a StableTimeLoop, by virtue of the fact that the past — ''including the interference of all those time travelers'' — already happened. Changing the past [[YouCantFightFate is out of the question]] — but there is the possibility that [[WaybackTrip the history books don't tell the whole story]]. Even so, your attempt to travel back to 1930 and assassinate Hitler [[HitlersTimeTravelExemptionAct is almost certainly doomed]].

* As detailed in ''Discworld/NightWatch'', this seems to be the case on Discworld. When Sam Vimes and a convict he's chasing both get sent back in time, the convict kills Vimes' mentor, and Vimes is thereafter given the chance to fulfill that mentor's role in history (although he ''does'' need to have this all explained to him by the History Monks). In the end, both versions of history converge on the same present day.

* Rip Hunter in ''ComicBook/BoosterGold'' states that the future is in flux but major events in the past (called "solidified time") are immutable. This strange time scheme hinging on the present is particularly odd when you consider Booster is ''from the future himself'' making the present ''his past'', and Rip spent most of his time in the future ([[spoiler:and is also Booster's future son]]).

** Xanatos learns how to properly take advantage of this using a coin meant to be sent to his past self a thousand years later. the coin wasn't worth much for it's time, but would now go for the 20 grand he would ultimately use to kickstart his fortune. He also made sure to write a letter that would be sent to himself a week before these events occurred, so he would know the instructions for how to pull it off.

[[folder:Tabletop Games]]
* In ''TabletopGame/FengShui'', trying to change history without capturing any Feng Shui sites will inevitably result in this. Big world events happen with the perpetrators having different names and everything eventually comes around to something resembling the present day. But once you start capturing Feng Shui sites, you can start making changes stick, and can even bring about a Critical Shift if enough sites are in your power.
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* ''WesternAnmiation/MiloMurphysLaw'' has this. There's a time travel organization that sends its agents into the past to deliberately alter certain events, with the two agents seen most often (Cavendish and Dakota) tasked with making sure the pistachio nut doesn't go extinct. The episode "Missing Milo" also has the duo unintentionally set up a StableTimeLoop involving a peach, while the main character plans to do the same when his friends discover a note from the 1960s that is addressed by him but that he never wrote.