History Main / TheConstant

If the time traveled was too short, there may be so many Constants that it's unremarkable. For example, it's not uncommon for the entire cast from the past to switch to FutureBadass versions of themselves in the future. On the other hand, there is no minimum time difference -- a city may be reduced to an unrecognizable place overnight by a terrible weapon, except for The Constant proving it was there. Or as Nena would say, "If I could find a souvenir / Just to prove the world was here."

If the Constant in question ends up being destroyed in real life (e.g. the World Trade Center), can result in a FunnyAneurysmMoment.

* The TropeNamer is an episode of ''Series/{{Lost}}'' ("The Constant") in which Desmond is undergoing rapid MentalTimeTravel between two times in his life and must find a Constant in the two times in order to avoid insanity and death. It's [[spoiler:his girlfriend Penelope]].
** On the same show, Daniel Faraday uses [[spoiler:Desmond]] as his Constant.

** Elrond Half-Elven serves as the Constant for the stories, born in the last days of the First Age in ''Literature/TheSilmarillion'' and being a character in ''Literature/TheHobbit'' and ''Literature/TheLordOfTheRings''. Technically, Galadriel was around for longer, but Elrond appeared in more works.

* Creator/RobertRankin's Brentford series has Professor Slocombe, who is implied to have been Merlin and have worked with Sherlock Holmes. Also, the Flying Swan, which shows up on 15th century maps. Ironically, the real-life pub the Flying Swan is based on, the Bricklayer's Arms, has since been closed and turned into housing.

* In the GeorgePal version of ''[[Film/TheTimeMachine1960 The Time Machine]]'', the protagonist finds a couple of constants during his early trips into the near future, including his friend Filby, and a shop near his laboratory that is featured in the time-travel montage whipping through a succession of window displays (later spoofed in the Literature/{{Discworld}} series, as described below). However, on his main excursion into the distant future he finds that everything has changed.

* In ''Webcomic/{{Homestuck}}'', [[spoiler: Dad is pretty much the same guy in both the original universe and the post-Scratch universe.]]
** As well, Caliborn's home [[spoiler: is the troll's meteor and his planet is Earth, ''littered'' with Statues of Liberties.]]

** Lampshaded in ''Discworld/WyrdSisters''. The biggest expense of TimeTravel is finding a fashion store that will remain open for 50 years in the exact same place, keeping the same mannequin in the display window.
** [[InvertedTrope Inverted]] in ''Discworld/NightWatch''. Sam Vimes ends up in the past after a magical accident, and has to keep things on-track while a criminal who went with him is messing everything up. Right when he's most despairing of ever getting back to where he belongs, [[spoiler: a History Monk brings him his silver cigar case, a gift from the wife he doesn't have yet and a reminder that his "future" is real and has already happened.]] On the other hand, many of the important cast members' past selves feature in the story: Fred Colon, M(r)s. Palm, Young Vimes, [[spoiler: Vetinari]]...

* The American Flag in ''ComicBook/TheUltimates''. The newly thawed out Captain America is despondent over how different things are. Technology has advanced massively, his high school friends, fiance and army buddies are in their 80s and modern morality is completely different than the 1940s. That is until Nick Fury points out the American flag over a cemetery and comments that one thing hasn't changed. (Well, except those two extra stars from 1959.)

If everything inexplicably survives in a slightly distressed state, it's a case of RagnarokProofing.

* The GrandFinal of Series/KamenRiderZiO reveals that every world has at least one Kamen Rider to represent it. Without one, the world would be lead to ruin. [[spoiler:Even as the BigBad who's destroying worlds to save his learns of this, he decides to keep destroying worlds anyway.]]

** In "Vanishing Act", Trevor [=McPhee=] travels forward in time to 1960, 1970, 1980 and 1990. He meets his wife Theresa, who eventually divorces him due to his unavoidable absences, in every time period. Trevor also meets Theresa's new husband Ray Carter in 1960, 1970 and 1980. As Ray died in 1986, he only sees a video recording of him in 1990. Trevor's son Mark, who was conceived during his brief sojourn in 1960, is present from 1970 onwards.

* In ''Series/AshesToAshes'' [[spoiler:which does not involve Time Travel]] Gene Hunt is Alex's constant because he was present in Sam Tyler's world in ''Series/{{Life On Mars|2006}}''. This is of great importance to Alex as it could mean that she is inhabiting the same world as Sam Tyler, Thus disproving her original theory that she was in a coma. [[spoiler:In the end, it is revealed that Alex is in purgatory.]]

** Nelson the Bartender from ''Series/{{Life On Mars|2006}}'' also appears at the end of ''Series/AshesToAshes'' becuase [[spoiler: he is a holy power and is accepting Alex, Shaz, Chris and Ray into heaven.]]
** A few minor characters (notably DCI Litton) from ''Series/{{Life On Mars|2006}}'' appear in ''Series/AshesToAshes'' but because Alex never read of these characters [[ItMakesSenseInContext from Sam Tyler's Notes]], she can not ascertain if they are constants or figments. This is only revealed in the series finale.

* In ''Film/MenInBlack3'', a alien criminal travels back in time to kill Agent Kay several decades in the past and changing the present, leaving the Earth vulnerable to an invasion from said criminal's people (that was originally fended off due to a device created by Kay to protect Earth). His partner Agent Jay is somehow unaffected by this change in time and must also go back to the past to save Kay and prevent Earth's invasion. Turns out there is a reason why he remembered everything when the timeline was rewritten: [[spoiler:he was always [[StableTimeLoop meant to go back in time and save Kay]]]].

** In the old series, there was only one actor who crossed the tenures of more than two Doctors: TheBrigadier. Even TheMaster and Davros changed actors. But Creator/NicholasCourtney was there as Brigadier Alistair Gordon Lethbridge-Stewart from the Second Doctor, to the Seventh, making his final appearance in ''Series/TheSarahJaneAdventures''. Companions changed, and the Doctor regenerated, but the Brigadier stood there throughout it all, always taking TheSlowPath, and always ready to [[CrowningMomentOfAwesome do the best he can.]] And that's what makes it so [[TearJerker heartbreaking]] when you find out he has died by the time of the Eleventh Doctor.

** And when Jack [[CrowningMomentOfHeartwarming finally finds]] [[TearJerker his homeland.]]

** The same idea occurs with all the other series of ''Franchise/StarTrek'' as well, with a character from a preceding series showing up in the first episode of the new series (Picard in ''[[Series/StarTrekDeepSpaceNine Deep Space Nine]]'', Quark in ''[[Series/StarTrekVoyager Voyager]]'', Spock (and a reference to an Admiral Archer) in [[Film/StarTrek the reboot]]. ''[[Series/StarTrekEnterprise Enterprise]]'', due to taking place earliest in the continuity, used Zefram Cochrane from ''Film/StarTrekFirstContact''.

** There's a ShoutOut to ''Film/PlanetOfTheApes1968'' in an episode where Fry, Bender, and the Professor travel forward in time to the year 10000. Fry, walking through the ruins of the city of New New York, sees a tilted, half-buried Statue of Liberty and laments "They blew it up! (pan to an identical statue of a gorilla) ... and then the apes blew up their society too!" (pan to another statue with a bird's head) "And then birds took over and ruined ''their'' society!" (pan to yet another statue) "And then cows ..." (pan again) "and ... I don't know ... is that a slug maybe? [[BigNo NOOOOOO!]]"
** Also Fry's boyhood home. When they find it in the ruins of Old New York it's a ruin and Bender even comments on time has been cruel to the house. They then switch to the 1990's to find it was in that condition even then.

[[folder: Anime and Manga]]

[[folder: Comic Books]]

[[folder: Film]]
* The Christopher Reeve movie ''Film/SomewhereInTime'' features an elderly hotel employee who recognizes the hero from his childhood - much to the hero's confusion, because from his perspective that event hasn't happened yet (he later goes back in time and meets a boy in the lobby who is clearly the same guy).
* In ''Film/{{Inception}}'', the folks who enter dreams carry a "totem", a small personal item that they alone know the exact size and weight of, to help them remember if they are in reality or dream state if need be. For instance, lead protagonist Dom carries a top that will spin endlessly in a dream, but topple in reality. Growers of EpilepticTrees may find some fertilizer in the observation that [[spoiler:the viewer does not see it topple before the movie cuts to credits]].
** [[spoiler:Although WordOfGod states that eventually it does.]]

* Inverted in the James Garner film, ''ThirtySixHours1965''. The existence of something that should have vanished in a few days, [[spoiler: a paper cut]], is what convinces Maj. Pike, that he ''hasn't'' spent the last few years in a fugue state, as his German interrogators are trying to convince him he has in order to extract information from him.
* In Film/{{Idiocracy}} a "Fuddrucker's" restaurant serves as the constant. After 500 years of increasing stupidity the name has gradually changed to "Buttfucker's." Oddly, it retains its status as a family restaurant, while Starbucks, H&R Block, and several other businesses have become brothels.

[[folder: Literature]]

* Literature/{{Discworld}}:

** [[InvertedTrope Inverted]] in ''Discworld/NightWatch''. Sam Vimes ends up in the past after a magical accident, and has to keep things on-track while a criminal who went with him is messing everything up. Right when he's most despairing of ever getting back to where he belongs, [[spoiler: a History Monk brings him his silver cigar case, a gift from the wife he doesn't have yet and a reminder that his 'future' is real and has already happened.]] On the other hand, many of the important cast members' past selves feature in the story: Fred Colon, M(r)s. Palm, Young Vimes, [[spoiler: Vetinari]]...

* For Creator/MichaelMoorcock, the constant throughout every conceivable phase of the {{Multiverse}} is the Eternal Champion - originally [[TheElricSaga Elric]], but his incarnation is ''everywhere'', often accompanied by the Companion to Champions, the Love Interest, and the Eternal Enemy.
* Hoid in ''Literature/TheCosmere''. On every world and in every era, he appears in some way. His role varies wildly from story to story - HeroOfAnotherStory, AllPowerfulBystander, TheTrickster, GreaterScopeParagon, [[GreaterScopeVillain Greater-Scope]] ''[[GreaterScopeVillain Villain]]'' - but he’s always involved somehow. This actually [[NotHisSled made it rather shocking]] when there was a story (''Literature/ShadowsForSilenceInTheForestsOfHell'') where he ''doesn’t'' appear, or even get mentioned.

[[folder: Live Action TV]]

-->''Martin Summers'': Look at us. Couple of desperate cases. Now you've lost your lifeline...
-->''Alex'': *Mumbling in her sleep* No.
-->''Martin Summers'': ...Your constant. Your Gene Hunt.

** In the old series, there was only one actor who crossed the tenures of more than two Doctors: TheBrigadier. Even TheMaster and Davros changed actors. But Creator/NicholasCourtney was there as Brigadier Alistair Gordon Lethbridge-Stewart from the Second Doctor, to the Seventh, making his final appearance in ''Series/TheSarahJaneAdventures''. Companions changed, and the Doctor regenerated, but the Brigadier stood there throughout it all, always taking TheSlowPath, and always ready to [[CrowningMomentOfAwesome do the best he can.]]
*** And that's what makes it so [[TearJerker heartbreaking]] when you find out he has died by the time of the Eleventh Doctor.
** The Second Doctor story [[Recap/DoctorWhoS5E3TheIceWarriors "The Ice Warriors"]] is set in a future Ice Age, full of snow and glaciers. But the human scientists' base is an old Queen Anne mansion (including the furniture), making it recognizably our future (probably England). There's also a present- or past-style nursery shed.

** In [[Recap/DoctorWhoS31E13TheBigBang "The Big Bang"]], [[spoiler: events are put into place that makes Amy Pond the constant for the entire universe.]]
** The Doctor himself becomes this for [[spoiler:Clara Oswald]], as revealed in [[Recap/DoctorWhoS33E13TheNameOfTheDoctor "The Name of the Doctor"]].
--->Sometimes it's like I've lived a thousand lives in a thousand places. I'm born. I live. I die. And always there's the Doctor.

[[folder: Video Games]]

[[folder: Webcomics]]

[[folder: Web Original]]

[[folder: Western Animation]]

->''If anything goes wrong, TV Tropes will be ''MY'' constant.''

* For Creator/MichaelMoorcock, the constant throughout every conceivable phase of the {{Multiverse}} is the Eternal Champion - originally [[TheElricSaga Elric]], but his incarnation is ''everywhere'', often accompanied by the companio to Champions, the love Interest, and the Eternal Enemy.

* ForCreator/MichaelMoorcock, the constant throughout every conceivable phase of the {{Multiverse}} is the Eternal Champion - originally [[TheElricSaga Elric]], but his incarnation is ''everywhere'', often accompanied by the companio to Champions, the love Interest, and the Eternal Enemy.

* In ''VideoGame/DarkChronicle'', there is almost always an overly obvious Constant: That baby [[{{Pokemon}} Lapras]]-looking thing you saved helped to form the labs! That girl was the sage all along! etc.

* In the Franchise/MarvelUniverse, every reality has a version of [[PhysicalGod Owen Reece, the Molecule Man]]. [[spoiler:This is because [[EldritchAbomination the Beyonders]] deliberately created him as one as part of their deranged experiment [[OmnicidalManiac destroy the multiverse]]. The death of a Molecule Man destroys the reality he's in, so they're planning to trigger the self destruct of ''every'' Molecule Man to cause a chain reaction that obliterates existence.]]