You TimeTravel into the past; something happens as a result of your time travel, and [[ButterflyOfDoom somebody dies]]. Somebody important and probably even famous, who you ''know'' stayed alive until after this date. What can you do to close the StableTimeLoop, SetRightWhatOnceWentWrong, or at least [[TrickedOutTime trick out time]] so you can end up back in a CloseEnoughTimeline to your own? Why, impersonate them, of course!

Usually, for added [[RuleOfDrama drama]], the person you're replacing is supposed to die in some other way in order to trigger a significant event, meaning that you expect replacing them to lead to a HeroicSacrifice. This is not to say that it actually does, though; you can often find a [[TakeAThirdOption third option]] besides dying nobly in the past and screwing up the timeline.

There is also a variation in which the time traveller doesn't cause the historical figure's death, but instead discovers that the historical figure ''never actually existed''; the time traveller then has to impersonate the historical figure in order to [[StableTimeLoop create the history he remembers]].

Compare and contrast TimeTravelEscape; in particular, the third option in the more-dramatic version often involves pulling something like a TimeTravelEscape. Also compare BeethovenWasAnAlienSpy, which is a supertrope to at least the StableTimeLoop version of this, and EmergencyImpersonation, a very similar plot that doesn't require time travel.
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!!Examples:

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[[folder: Audio Play ]]

* In the tremendously funny AudioPlay/BigFinishDoctorWho episode ''[[Recap/BigFinishDoctorWho081TheKingmaker The Kingmaker]]'', Creator/WilliamShakespeare manages to [[spoiler: get into a tiff with Richard III]] through a very complicated time travel mishap, ends up [[spoiler: on the Battle of Bosworth Field]] and promptly [[spoiler:gets mistaken for Richard III (very long story) and dies]]. Once the Doctor is past the initial shock, he wearily realises he's now got to [[spoiler:train Richard III in how to be Shakespeare]].

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[[folder: Anime And Manga ]]

* One of the primary plot points in ''LightNovel/OdaNobunaNoYabou'', the main character--Yoshiharu Sagara--is deposited in the UsefulNotes/SengokuJidai without warning. Upon his arrival--in the middle of a battlefield--his life is saved by a young soldier, who's actions result in his own death. Asking the man's name, Yoshiharu is startled to discover the man is none other than UsefulNotes/ToyotomiHideyoshi. In the aftermath of the battle, he becomes a favorite of UsefulNotes/{{Oda|Nobunaga}} [[GenderFlip Nobuna]], and serves has her sandal-bearer, eventually taking Hideyoshi's place in this deviation of history altogether.
* ''Anime/SengokuOtome'' has a similar case to ''Nobuna'' above. OrdinaryHighSchoolStudent [[PunnyName Hide Yoshino]] ends up in another world, much resembling the UsefulNotes/SengokuJidai - except everyone in her textbook is a woman. She is found by UsefulNotes/OdaNobunaga and UsefulNotes/AkechiMitsuhide, introduces herself as Hideyoshi, and ends up taking [[UsefulNotes/ToyotomiHideyoshi that role]]. [[spoiler:Turns out her teacher Date-sensei is also in this world, and is currently masquerading as "hick samurai from Oshu" UsefulNotes/DateMasamune.]]
* ''Anime/NobunagaConcerto'' has high school student Saburou sent back in time and encountering a sickly Oda Nobunaga. When Nobunaga realizes how similar the two look, he asks Saburou to serve as his replacement [[spoiler:and later serves him as UsefulNotes/AkechiMitsuhide]]. An interesting depiction, as Saburou was not a particularly good student and only has a vague understanding of history, so the StableTimeLoop is more often than not one that occurs naturally rather than one he deliberately takes.

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[[folder: Comic Books ]]

* Applies to the ([[CrisisOnInfiniteEarths Pre-Crisis version of]]) DCComics' heroine Superwoman. She was a time traveling researcher who came to the present from the 29th century in order to try to find Superwoman's secret identity, the only superhero whose secrets were never discovered. She ends up realizing that ''she'' was supposed to be her. At first she only visited the past when recorded history said Superwoman appeared, but a time travel accident left her stuck there with amnesia for years. She eventually returned to her home time, however.
* This sort of happens in issue #5 of the original run on ''Comicbook/FantasticFour'', in which Dr. Doom (his first appearance) sends the foursome back in time and The Thing, who has always been a fan of stories of Blackbeard, ends up ''becoming'' Blackbeard.

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[[folder: Literature ]]

* In ''Discworld/NightWatch'', Vimes spends almost the entire novel impersonating his own mentor John Keel.
* Happens several times in the ''Literature/TimeWars'' series:
** In ''The Pimpernel Plot'', a time traveller's action causes the death of Sir Percy Blakeney, a.k.a. the Scarlet Pimpernel. One of the Time Commandos is assigned to replace Sir Percy to ensure that the events described in ''Literature/TheScarletPimpernel'' play out as they should. At the end of the mission, another agent is assigned to take over and live out the rest of Sir Percy's life.
** In ''The Zenda Vendetta'', the villains murder [[ThePrisonerOfZenda Rudolf Rassendyll]], again obliging one of the Time Commandos to take his place.
** In ''The Ivanhoe Gambit'', [[Literature/{{Ivanhoe}} Sir Wilfred of Ivanhoe]] isn't dead -- the heroes deliberately kidnap him so that one of their number can impersonate him as cover -- but the timing means that the impersonator does end up having to do all the stuff that Ivanhoe is remembered for (meanwhile, in a subplot, a supporting character becomes King UsefulNotes/RichardTheLionheart after the real Richard is killed by the villain).
** Perhaps because this imposes a restriction on the plotting, the other ''Time Wars'' novels just have the heroes befriending historical figures, not replacing them.
* In Creator/IsaacAsimov's ''Literature/TheEndOfEternity'', someone is sent back in time by the leaders of Eternity, a centuries-spanning time-traveling organization, to explain the workings of time travel to its purported inventor, thus completing a StableTimeLoop. The inventor dies, however, and the person from the future ends up replacing him and "inventing" time travel himself. Or rather, this was the plan of the leaders of Eternity, based on secret information about what had happened in the previous iteration of the loop, but in the end of the book [[spoiler:the StableTimeLoop gets broken, bringing about the eponymous "End of Eternity"]]. Probably the trope maker, and at minimum the trope codifier: pretty much every other example on this page traces back to Asimov and many directly allude to it.
* In Creator/TimPowers' ''Literature/TheAnubisGates'', the main character, expert in the study of a (fictional) Victorian poet, travels back in time and ends up being said poet in the past. This is the variant version mentioned in the description, as the poet in question didn't die and need replacing. He'd ''always been'' the time traveller, product of a StableTimeLoop with no discernible origin. [[TemporalParadox Nobody ever composed his poems, either]], which worries the protagonist more than the actual replacement does.
* ''Behold the Man'' by Creator/MichaelMoorcock. You can probably figure out the subject in question from the [[http://en.wikipedia.org/wiki/Ecce_Homo title]].
* In one of Creator/PoulAnderson's ''Literature/TimePatrol'' short stories, a time-traveler gets pressed into taking the place of an assassinated Persian royalty; history remembers him as Cyrus the Great.
** Another story in the same series, which has the magnificently awesome title "The Sorrow of Odin the Goth", has a time-travelling anthropologist trying to find the source of a particular legend involving the god Odin. He visits a dark-ages Goth community several times over the course of decades, and the locals, noting that he never seems to age (among other reasons), decide he is Odin. At the end he has to close the ''StableTimeLoop'' by doing what Odin is described as doing in the legend, even though it means killing two of his grandsons.
* The variety where the famous person never existed appears in at least two writings of Creator/StanislawLem.
* The protagonist of Creator/ManlyWadeWellman's ''Twice in Time'' travels back to Renaissance Florence to meet LeonardoDaVinci and to leave a mark on the back of the Mona Lisa to prove he made the trip. He eventually ''becomes'' Leonardo da Vinci and paints the Mona Lisa itself as proof of his trip. Of course, the time traveler's name was [[{{Foreshadowing}} Leonard]] to begin with.
* In the ''Found'' series by Margaret Peterson Haddix, this is combined with TimeTravelEscape. A group of children who are adopted, but cannot find their birth parents. They find out they are long lost children of the past (such as Anastasia or Virginia Dare of the Roanoake Colony) that were taken by time travelers from the distant future. Unfortunately, the time machine went wrong and ended up at an airport in the 90s. In the second book, ''Sent'', this trope is almost played straight when Chip and Alex are found to be missing medieval princes who are meant to be killed.
* In ''The Door Into Summer'' by Creator/RobertAHeinlein, a professor who's invented a faulty form of time travel talks about how one of his students took the risk and went back in time. His name? [[LeonardoDaVinci Leonard Vincent]]. While he never appears in the story, so we never find out if he really is da Vinci, the protagonist wonders if Leonard, trapped in the past, drew plans for flying machines and such because he was hopelessly trying to recreate things he'd seen in the 20th century. He also quietly mourns for the man, talking about how incredibly impressively difficult it would have been for him to travel across fifteenth century, pre-Columbian America and wrangle his way to Europe, and pitying him as a FishOutOfTemporalWater either way.
** The protagonist himself fulfills the trope, [[spoiler: first by revolutionizing robotics and then, when he's betrayed by his business partner and fiancee and forced into suspended animation, uses the professor's time travel apparatus to return to the past with knowledge of future designs, set up a rival company, and drive his former partners out of business.]]
* ''[[http://www.gutenberg.org/catalog/world/readfile?fk_files=1563580 A Knyght Ther Was]]'' had Tom Mallory, a time thief. A particularly nasty rival sabotages his time machine, landing him in the 15th century--when ''Le Morte d'Arthur'' was written (or compiled) by Sir Thomas Malory

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[[folder: Live Action TV ]]

* ''Franchise/StarTrek'':
** In the ''Series/StarTrekDeepSpaceNine'' two-parter "Past Tense", Sisko ends up in [[TwentyMinutesIntoTheFuture the 21st century]] as the result of a [[NegativeSpaceWedgie transporter accident]], where he has to impersonate the soon-to-be martyr Gabriel Bell after accidentally causing his death in a food line. At the end of the episode Starfleet Command has some questions to ask about why the picture of Gabriel Bell in the history books resembles him so closely; it gets {{Lampshaded}} again in a later episode when Nog is looking at a historical database and comments that Gabriel Bell looks an awful lot like Sisko.
** In an [[WhatCouldHaveBeen early draft]] of the ''Series/StarTrekTheNextGeneration'' episode "Yesterday's Enterprise", Surak was accidentally killed by time-travelers, and Sarek had to take his place in order to bring logic to Vulcan. The actual episode is a borderline example. Tasha ends up going back in time with the ''Enterprise-C'' after she dies, but it's not to fool anyone into thinking she's anyone important -- it's just that they need somebody to manage tactical station on the ship.
** ''[[Series/StarTrekDeepSpaceNine Deep Space Nine]]'' also has a strange example with a short timeframe. In "Visionary", O'Brien is time-jumping uncontrollably, and he sees the station blow up in the future. To prevent this, he decides to force a time-jump, find out how the disaster happens, and come back. Unfortunately, the device that makes this possible emits deadly radiation, and O'Brien overestimates his endurance; when it's time to go back, he realizes he won't survive the return trip. Solution? He gives his future self the device and sends ''him'' back. The disaster is averted, and at the end of the day there's still just one O'Brien, but he can't help wondering if he's really the same man.
* In ''TheTwilightZone'' (the 80s version), the episode "Profile in Silver" has this as a plot. An academic from the future travels back in time and ends up saving JFK from the assassin's bullet. As a result, this creates an alternate timeline where the extinction of the human race via nuclear war is inevitable. Kennedy is informed of this and offers to go back to be assassinated in order to restore the timeline, only for the academic to send him to the future instead while he takes Kennedy's place in the limo and dies. We then see Kennedy in the future, giving a university lecture praising the sacrifice of heroes like the professor.
** Another episode of the '80s ''TheTwilightZone'' qualifies as well. In "The Once and Future King", an Elvis impersonator goes back in time and meets the younger Elvis, who mistakes him for his brother. The impersonator is frustrated when Elvis shows no interest in becoming a rock singer, which eventually lead to a struggle that leads to Elvis' death. The impersonator ends up taking Elvis' place.
* In ''Series/RedDwarf'', the crew go back in time and accidentally kill Lee Harvey Oswald, preventing the Kennedy assassination. After the usual time travel shenanigans, eventually they convince a JFK from later in the time line to take the place of the assassin, firing from the grassy knoll.
* In ''Series/{{Heroes}}'', Hiro goes to 17th century Japan to find that his childhood idol, Takezo Kensei, doesn't even come close to meeting his expectations. While not actually doing (some of) the amazing things that Kensei would be credited for, Hiro definitely plays a part in the making of history. In fact, the writers actually try and fake out the audience to think this is what Hiro is going to do after [[spoiler: Kensei dies]]. However [[spoiler: it is revealed shortly afterward that he is a "Special" and his wounds heal]].
* There's a TV-movie (read: PoorlyDisguisedPilot) that involves a NY cop being hunted by time-travellers from the past, to prevent him from realising his destiny -- to go ''back'' in time to become... wait for it... [[http://www.imdb.com/title/tt0207631/maindetails Nostradamus]]. Unlike most examples, the StableTimeLoop is averted, except for a woman with RippleEffectProofMemory.
* A key plot point in ''Series/BabylonFive'' involves Sinclair going back in time one thousand years to intervene in the previous war against the Shadows [[spoiler: and become the Minbari cultural hero/religious figure Valen in the process]].
* ''Series/{{Farscape}}'': Aeryn tries this in "Different Destinations" to save the life of a bumbling cook who clearly had no place in a battle. He doesn't let her, though, and dies like he's "supposed" to. Still doesn't fix the timeline, though...
* In ''Series/DoctorWho'', Vicki decides to leave the TARDIS when she falls in love with Troilus, becoming the Cressida of Greek mythology.
* In the final season episode "Mokey Then and Now" of ''Series/FraggleRock'', Mokey, Wembley, and Boober accidentally [[TimeTravelEpisode get sent back in time]] after triggering some mysterious magic. They're sent back to a time in the distant past that Mokey identified as being before the arrival of a figure called the Great and Wondrous Blunding. It turns out that the Great and Wondrous Blunding was none other than Mokey Fraggle, who teaches the ancient Fraggles the "Dance Your Cares Away" song, promotes having hair, and encourages freedom over following a leader.

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[[folder: Tabletop Games ]]

* The Thespians in ''TabletopGame/{{Continuum}}'' have this as a big part of their schtick. The subject doesn't necessarily have to be dead, either, just unavailable for their historic moment.

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[[folder: Video Games ]]

* In ''[[http://www.adventuregamers.com/newsitem.php?id=1970 Gamelet]]'', a currently-in-development video game, you play a time traveler who ends up having to act out the plot of ''{{Hamlet}}'', impersonating the title character.
* ''VideoGame/{{Jigsaw}}'' forces you to be the instigator of some of the twentieth century's worst disasters, starting with [[UsefulNotes/WorldWarI assassinating Archduke Franz Ferdinand]]. You end up doing as much good as harm, though.

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[[folder: Western Animation ]]

* In ''WesternAnimation/{{Futurama}}'', Fry travels back in time and accidentally kills his own grandfather before his father could be conceived. When Fry doesn't cease to exist, he correctly assumes the man he thought was his grandfather wasn't really his grandfather. He then incorrectly assumes the woman he thought was his grandmother isn't either, and sleeps with her. Afterward, his friends have to explain to him that in doing so, he effectively [[MyOwnGrampa became his own grandfather]].
* In ''WesternAnimation/FamilyGuy'', Stewie discovers LeonardoDaVinci was his ancestor, and his archnemesis travels back in time to kill him, therefore eliminating Stewie's existence. In the end, Leo dies, so Stewie must continue living in the 16th Century as him [[MyOwnGrandpa until he can pass his progeny forward]], after that, he built a cryogeny chamber and froze himself until the present day.

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[[TheStinger ...and]] [[Franchise/{{Terminator}} I'll be]] [[IncrediblyLamePun Bach]].