A human colony on another planet experiences a disaster which destroys its tech-base, and for some reason the rest of humanity never checks up on that colony with which it suddenly lost all contact. Alternatively, a spaceship having nothing to do with colonization experiences an emergency which forces its crew to land on a planet in an uncharted star system, and for some reason they never get rescued.

Either way, not only do their descendants' politics, economics and culture regress to match their pre-Industrial Revolution [[TechnologyLevels technology level]], they also forget that their ancestors ever came from another planet, making the story at first glance [[ScienceFantasy seem to be set in a pure fantasy world]]. Oftentimes whatever remains of the [[LostTechnology old technology]] will be [[SufficientlyAdvanced mistaken for magic]] by the colonists' descendants. Sometimes there is genuine supernatural magic happening, or [[PsychicPowers something that can pass for it]], and all advanced technology has been lost. And sometimes the old technology and genuine magic are used side by side.

And of course, it's always [[EarthAllAlong popular to reveal]] that ''Earth'' was really a lost colony, though [[ScienceMarchesOn genetic evidence]] that humans and other Earth organisms are biologically related, all the way back to the first bacteria, has made this increasingly hard to sustain. Of course the theory of panspermia, that the first bacteria were dropped on Earth from space, still enables a scientifically plausible "Lost Colony" in a far more general sense.

These worlds are a popular venue for {{Planetary Romance}}s.

Compare with AfterTheEnd and SpaceAmish. Contrast TransplantedHumans. Usually comes after SettlingTheFrontier.

'''WARNING''': These examples necessarily contain spoilers.
----
!!Examples

[[foldercontrol]]

[[folder:Anime]]
* ''ScrappedPrincess''.
* Earl in ''{{Mai-Otome}}'', while otherwise fitting this trope, at least remembers that the people and the LostTechnology came from Earth.
* ''{{Trigun}}''.
* It's unclear whether ''{{Simoun}}'' is set on a LostColony populated by genetically altered humans, or whether they're humanoid aliens on their homeworld AfterTheEnd.
* ''LastExile''.
[[/folder]]

[[folder:Fanfic]]
* In ''Fanfic/TheSwarmOfWar'', the first story arc takes place on a planet ruled by the descendants of a crashed warship's crew. It is mentioned a couple of times ttat they have conquered some locals.
[[/folder]]

[[folder:Literature]]
* ''DragonridersOfPern'' is set on a LostColony, with the original colonists having used what remained of their technology to genetically engineer the telepathic, teleporting dragons which guard the world from the bicentennial rain of alien parasites.
** It should be noted here that the rest of humanity DID send a ship to check it out, which found a small group who convinced the crew that everyone else had perished. The captain of the ship then quarantined Pern's system because of the Thread.
*** Also, Pern was intended from the start to be cut off from the rest of Humanity. the Pern colonists wanted to get away from the politics and war suffusing the rest of the Galaxy, and live a [[SpaceAmish simple agrarian life]] with limited technology. Thread turned life on Pern into a struggle for survival, and caused them to lose the little bit of technology they intended to keep. The loss of knowledge of life before Pern was gradual; a book set in the Second Pass (roughly 150 years after the colonists arrived) mentions that computers still exist, but are becoming less practical as power and repairs get harder to come by. A book set in the Fourth Pass shows that the idea of Man coming to Pern from space is a one of two competing hypotheses rather than a plain historical fact, and by the Seventh Pass (when the "main" series takes place, 2500 years after Landing), even said ideas are completely forgotten.
* There are few hints that ''Literature/{{Dragaera}}'' is a LostColony. If true, the colonists had landed at ''least'' 150,000 years before the start of the story, with all trace of the old technology long gone, making the use of the trope nothing more than a bit of flavoring.
* Has happened ''at least twice'', and very likely at least three times, to the planet on which ''Literature/TheSagaOfRecluce'' is set. Something about the planet acts like a magnet towards spaceships which have undergone malfunctioning [[FasterThanLightTravel hyperspace jumps]].
* In Creator/LarryNiven's ''[[Literature/KnownSpace Protector]]'', Earth is actually a LostColony of a species called the Pak, who start life as a larval form (unintelligent hominids) and, in their thirties, are irresistibly drawn to eat a certain tuber which is host to a virus that transforms them into ageless hyper-intelligent killing machines (Protectors of their descendants). The colony failed because the tuber can't incubate the virus in soil deficient in thallium oxide (A later protector finds that the virus will grow in a sweet potato), and the humans developed intelligence on their own. One Pak comes looking for the lost colony, kidnaps a human and turns him into a Protector, who is even smarter than the original variety ([[TranshumanTreachery and acts very different]]). Eventually we learn that the Literature/{{Ringworld}} was built by Pak.
* Niven's ''The Integral Trees'' series has a lost colony without a planet.
* In UrsulaKLeGuin's Hainish sequence, Earth (and probably Gethen, too) were lost colonies of the oldest known inhabited world, Hain. Both may have started off as rather ethically suspect experiments, although the Hainish are very ethical these days. It's subtly implied that all the inhabited worlds may be Hainish in origin.
* Erna in the ''ColdfireTrilogy'' is a colony from Earth, which they do know but are much too far from to take advantage of.
** [[spoiler: In the third book, we learn that it's also a colony of an [[StarfishAliens unnamed alien race]]]].
** Also, the original colony has its ''own'' LostColony, although that was founded in a more low-tech manner (putting lots of people on ocean-going vessels). It turns out that [[spoiler: this colony has been ''actively'' staying lost by killing the expeditions sent to re-establish contact with it.]]
* In ''Literature/KingdomsOfThornAndBone'' by Greg Keyes, a part of the American colony of Virginia appears to be the ancestors of some of the characters.
* {{Darkover}} by MarionZimmerBradley is born from the settlement by a lost ship from Earth.
* Barrayar from the ''Literature/VorkosiganSaga'' by LoisMcMasterBujold was a Lost Colony at a point of its history when the wormhole leading to it suddenly closed. However at the time when the series takes place, it's already been rediscovered through another route for three generations. It does still bear the barbaric mark of that time, however.
** Alpha Colony, one of [[UnitedSpaceofAmerica America's]] first attempts at space colonization by using sublight drives, was forgotten after a world war brought other concerns into play. When the war was over and wormhole technology had been discovered, a path was found to Alpha Colony, where all of the colonists had died out.
* Interestingly, ''Literature/ArtemisFowl: The Lost Colony'' does not contain a traditional lost colony. In fact, the "colony" has forgotten magic in favour of technology, and possesses full knowledge of the outside world [[spoiler: though it is later revealed that the colony's leader made up most of his stories about it so the other inhabitants would be easier to manipulate]].
* Christopher Stasheff's ''Literature/WarlockOfGramarye'' series has Gramarye, a colony founded by the Society for Creative Anachronism. In this case the loss of technology was deliberate.
** Considering that the government of Earth became isolationist around the time Gramarye was settled, it is not surprising that they were not found for a long time. This same isolationist policy cut off all of earths colonies from the technological goods of the homeworld, leading many of them to lose all tech. They were not exactly lost colonies, since earth knew where they were in most cases, but it was practically the same thing. Although there were a few that earth had lost the paperwork for, come to think of it.
** Before he settled down on Gramarye, the protagonist's job was to search out lost colonies and steer them towards democracy; in the ''Wizard'' sequel series, his son takes up the job.
* The setting of MercedesLackey's ''Literature/BardicVoices'' books is implied to be a lost colony for at least one of the non-human species, the technologically advanced Deliambrens, and AfterTheEnd for everyone else.
* Part of the backstory of the ''EaCycle'' is that the planet Ea is a lost colony of the [[{{Magitek}} magitech]]-using "Star People". [[EarthAllAlong Ea later turns out to be Earth in the far future.]]
* ''Literature/TheLastColony'', though it was deliberately lost and recovered.
* Creator/VernorVinge's ''Literature/ZonesOfThought'' novels touch on Lost Colonies a great deal - in ''A Deepness In The Sky'' in particular, due to technological limitations and no FasterThanLightTravel, colonies tend to self-destruct on a regular basis.
* Creator/LSpragueDeCamp's ''The Great Fetish'' is set on the distant planet Kforri (K-40), a world in the Mesozoic stage of evolution colonized by humans generations before, their technology lost as the result of a mutiny before landing (or crashing). The established religions of the roughly Bronze Age-technology, Medieval European-culture nations that have developed all embrace the doctrine of Evolution, which states that mankind arose from lesser native forms, while the emergent scientists have brought forth the heretical concept of Descensionism, maintaining that the lack of creatures similar to humanity indicates their ancestors came from elsewhere. Hilarity ensues when the protagonist (a schoolteacher with Conanesque thews) runs afoul of the church by espousing the latter.
* ''Franchise/TheHitchhikersGuideToTheGalaxy''. Humanity comes from a ship whose inhabitants thought they were to be a colony...their people were just annoyed with them and sent them off to an unknown fate. Things happened.
* In David Brin's ''Literature/{{Uplift}}'' series, it is hotly debated whether humanity (uniquely among living peoples) developed intelligence independently or was created by some folk that abandoned the job incomplete.
* In ''Virgin Planet'' by PoulAnderson, a shipload of women goes off course and, by necessity, founds a parthenogenetic society. Generations later, a male scout lands and is denounced as a monster, partly because he threatens the power of those who control the reproductive technology.
* In ''Spartan Planet'' by A. Bertram Chandler, the lost colony is founded by a raging misogynist. Again, reproduction is artificial. As in ancient Sparta, babies with birth defects are left in the wilderness to die; here, lack of male parts is considered a defect.
* HarryHarrison's novel ''Literature/{{Deathworld}} 2'' is a GivingRadioToTheRomans story set on a Lost Colony.
** There are plenty of examples in TheStainlessSteelRat series. Makes sense, considering it occurs at a time when a collapsed Empire is being reassembled.
* Keithland in ''Literature/TheCycleOfFire'' was founded when a ship was forced down on an uncharted world. All post-medieval technology was deliberately abandoned so their escaped alien prisoners wouldn't try to capture it.
* Happens a lot in ''TheHistoryOfTheGalaxy'' novels. After the discovery of the [[SubspaceOrHyperspace Hypersphere]] anomaly, hundreds of colony ships were sent out to colonize other worlds. Many got lost due to the poorly-understood nature of the anomaly and lack of navigation equipment that works in another dimention. Throughout the series, many lost colonies are being rediscovered, many of which have regressed to barbarism and forgotten their origins. One short story details a demonstration of a new type of SpaceFighter that involves dropping a cluster bomb onto a planet thought to be devoid of life. However, during the demonstration, a sensor on the planetary surface detects the presence of a human child, making the testers realize what a horrible mistake they've made. Luckily, a daring pilot manages to save the colony.
** The [[TheWarOfEarthlyAggression First Galactic War]] started when the corrupt government of the overpopulated Earth decided to look outside the Solar System for habitable worlds to offload extra people. They sent scount ships, which returned with disturbing news. Nearly all nearby star systems already had colonies from ships sent centuries before. Realizing the colonists would object to an influx of unwanted rabble from Earth, Earth's president decides to launch a pre-emptive strike in order to put the upstart colonies in their place. What follows is a 30-year war that Earth eventually loses.
* In Creator/RobertAHeinlein's ''Literature/TimeEnoughForLove'', brief mention is made of the discovery of a Lost Colony... founded by the surviving characters of ''Literature/OrphansOfTheSky''.
* Donald Westlake wrote a series of humorous short stories about the small starship ''Hopeful'', crewed by a RagtagBunchOfMisfits[[note]]They sent along a politician just to be rid of him[[/note]] and given the task of contacting the colonies in '''an entire sector''' -- many of which had become [[PlanetOfHats Planets of Hats]]. From the prologue of the very first story:
-->Nearly 500 years before, a clerical error had erased from the computer's memory more than 1000 colonies, all in Sector [[FunWithAcronyms F.U.B.A.R.]]3.\\
For half a millennium, those colonies, young and struggling when last heard from, had had no contact with the rest of Humanity. The Galactic Patrol Interstellar Ship Hopeful, Captain Gregory Standforth commanding, was at once dispatched to reestablish contact with the Thousand Lost Colonies and return them to the bosom of Mankind.
* Donald Kingsbury's ''Literature/CourtshipRite'' takes place on a lost colony so hostile to human life that over the centuries, times of famine have made [[ImAHumanitarian cannibalism]] socially acceptable to varying degrees.
* The planet He, in Creator/JamesBlish's ''Literature/CitiesInFlight''.
* Margolia from ''Literature/AlexBenedict''. The founder said he was going to travel so far away that not even God would be able to find them; and since no one heard from the colony over the next nine thousand years, he apparently succeeded.
* SMStirling's ''TheLordsOfCreation'' series features Venus and Mars as homes to lost colonies of both ''Homo sapiens'' and Neanderthals [[spoiler: (the two worlds having been terraformed and seeded by SufficientlyAdvancedAliens millions of years before)]].
* [[OrsonScottCard The Worthing Saga]] concerns a Lost Colony, odd due to the fact that the Colony actually (re)discovers the rest of the human race before being found themselves due to their development of Psychic Powers.
* Due to the prevalence of Psychic Powers, some of the {{Dune}} sequels are largely concerned with finding ways to block Psychic Powers, so that colonies CAN be lost. Of course, the colonies later come back and start a war, but...
* Adumar, in the XWingSeries, has elements of this. Their technology collapsed, then was rebuilt, they re-developed spaceflight and were rediscovered by mainstream galactic society before ''Starfighters of Adumar''. They hold to some social customs that the rest of the galaxy finds weird, like still having many drastically different countries.
** The Children in ''Literature/GalaxyOfFear'' are like a very small scale of this. Their parents crashed on Dagobah and died when the oldest of the Children was seven. They were malnourished and poorly educated, having no concept of places beyond the swamp, so came off as some kind of weird tribe which revered a parent's ApocalypticLog.
* In SergeyLukyanenko's ''TheStarsAreColdToys'' duology, [[spoiler:Earth and the Geometers' homeworld]] are revealed to be lost colonies of [[spoiler:humans from the galactic core]]. Ditto for [[spoiler:most of the Conclave races]].
* FracisCarsac's ''Literature/TerreEnFuite'' (''Fleeing Earth'') reveals that, at some point in the future, human civilization will be destroyed by a new Ice Age. After the Ice Age, the Second Civilization (slightly more evolved) will rebuild and make great strides in science and technology. Then they will be conquered by a race called Drums, only to be defeated by a biological weapon released by LaResistance. Their "space magnet" technology allows spaceships to reach 80% of the speed of light in short order, and humanity makes use of it to explore and settle other planets and planetoids in the Solar System. Then hyperdrive is discovered that is an extension of the space magnet technology. Colony ships are sent out, but only one manages to come back, revealing that the technology is horribly flawed. When a ship in hyperspace reaches the midpoint between two stars, it encounters a "gravity barrier" that throws it wildly off-course. The ship that returned found itself outside the galaxy after the first jump and only managed to return on the third try. Some time later, a scientist figures out that the Sun will emit an enormous solar flare that will fry anything in the inner system. The Second Civilization builds enormous space magnets on Earth and Venus in order to move the planets behind Jupiter to ride out the flare and then put them back. However, the Sun will no longer be able to support life after the flare, so the plan is amended to move the planets to another system. After reaching Alpha Centauri (it takes many years on sublight), they find it already inhabited by descendants of one of one the lost ships. They aren't blaming Earth humans for abandoning them but don't want them as neighbors. Many years later, the planets arrive to another system and find yet another LostColony, who are actively fighting them. These colonists claim that Earth lied to their ancestors, deliberately sending them into space knowing about the BlindJump nature of hyperspace. It turns out that [[spoiler:a race of aliens with PsychicPowers employs MoreThanMindControl to keep the human colonists as slaves]]. After defeating ([[spoiler:and freeing]]) them, the planets are put in proper orbits in the Goldilocks Zone.
* In ''Eater-Of-Bone'', set in the ''Literature/GreatShip'' universe, a colony ship was catastrophically damaged and flung off of its trajectory, sending it towards one of the lone stars at the periphery of the Milky Way. The [[HealingFactor nigh-immortal]] TransHuman colonists are forced to settle on a world which is extremely metal-poor (particularly in salts and iron), making [[LostTechnology any kind of machinery precious beyond belief]] and every drop of blood lost a tragedy. One character laments that there's metal in the world, but so far below the ground that it is unreachable to the damaged machinery of the starship. The colonists cooperated with each other for a short time, but the strains of resource shortages fractured them into dozens of small groups, who often fight each other for resources. [[ImAHumanitarian "Eater-of-bone" isn't meaningless]], either, [[HumanResources because even bone and marrow hold the metals required for metabolism]].
* Creator/CJCherryh's ''[[Literature/AllianceUnion 40,000 in Gehenna]]'' universe has Gehenna. A planet secretly colonized by the Union (even to most of the Union government) in Alliance space, so that when the Alliance attempted to colonize 60 years later they'd find an entrenched population of Union citizens. In the ensuing diplomatic fiasco the planet is left to live under medieval conditions for centuries.
* In Elena Senyavskaya's ''Star Wanderer'', the first vision tells of a far-away world called Sevir settled by humans 300 years before the events described. However, shortly after the arrival of the colonists, all transmissions stopped. Sending another expedition was too expensive, and the colonists were written off as lost. However, they survived. Sevir is a bleak, dry world with a poisonous fauna and a green star. The colonists managed to survive and have even thrived. They themselves cut off all contact with Earth in order to save on energy but have always been afraid of someone from Earth arriving to claim their world. As such, they have formed the [[SpaceNavy Silver Squadron]] and puts the Admiral in charge in order to protect them from the "evil Thors" (as they call Earthlings due to the symbol of the Earth Star Fleet being black lightning). For their part, Earth only wants to trade with Sevir and invite it to join the Galactic Union made up of Earth and twelve other settled worlds. Any encounters by the Star Fleet and the Silver Squadron have always ended bloody. Eventually, though, a young Sevir boy crash-lands on an uninhabited planet and is picked up by an Earth ship. He learns that Earthlings are not evil and that they have no intention of conquering Sevir. He realizes that the Admiral has been keeping himself in power through fearmongering. He returns home and is summoned to meet the Admiral. Before the Admiral can order his execution, the boy knocks him out and uses the Admiral's communication override to reveal the truth to his people before the Admiral's guards kill him.
[[/folder]]

[[folder: Live Action TV ]]
* Most planets of the week in ''Series/StargateSG1'' and ''Series/StargateAtlantis'' are like this, populated by humans seeded by either the [[NeglectfulPrecursors Ancients]] or their successors as dominant galactic powers, the [[AbusivePrecursors Goa'uld]] and [[ImAHumanitarian Wraith]].
** Atlantis itself was almost a lost colony during the first season as they were completely cut off from earth.
** In ''Series/StargateUniverse'' some members of the expedition attempted to start one of these. [[spoiler: Unfortunately they all (rather depressingly realistically) died from accidents or exposure.]]
*** And "now" an alternate timeline version of the ''Destiny'' crew founded an entire civilization [[TimeyWimeyBall two thousand years ago]], which advanced to the point where they began using the stargates and slowships to colonize other planets. Unfortunately the colonies were then cut off when a supervolcano destroyed their homeworld and drones attacked their stargates, becoming lost colonies of a lost colony.
* Played with in ''Series/BabylonFive'', where the [[RubberForeheadAliens rather human-looking]] Centauri originally claimed that Earth was a lost colony. When called on it, they excused it as a clerical error. "We thought your world was Beta 9, actually it was beta 12."
** The truth was discovered when Humans got their hands on medical data regarding the Centauri and discovered that despite outward appearances, Centauri physiology is [[BizarreAlienBiology very]] [[ExoticEquipment different]] from Human physiology.
** According to the [[ExpandedUniverse Psi Corps Trilogy]], the humans were [[GenreSavvy pretty skeptical]] of the claim to begin with, but decided not to press the issue while the Centauri were willing to do business with the humans and advance their technology base.
* Used ''in spades'' in ''Series/{{Battlestar Galactica|Reimagined}}''. The Twelve Colonies are lost colonies of Kobol, whose civilization was destroyed by [[spoiler: a civil war between humans and Cylons.]] The Colonists spend much of the series looking for Earth, Kobol's other lost colony, before discovering that [[spoiler:Turns out it's [[ShootTheShaggyDog a nuclear wasteland as the result of another human-Cylon conflict.]]]] Ultimately, [[spoiler: our Earth is revealed to be their lost colony which they settled on 150,000 years ago.]]
* A couple ''Franchise/StarTrek'' episodes featured the re-discovery of a LostColony or two.
** ''Series/StarTrekEnterprise'' had the crew visiting one that was mysteriously lost, at the time Earth didn't have fast enough ships to check up on it and they didn't ask the Vulcans because of, um, reasons. A natural disaster occurred but the colonists assumed it was a revenge attack from Earth after they separated; only the children survived living a primitive life in caves shielded from the radiation. They believe themselves to be aliens, and that humans attacked them all those years ago, so are mistrustful when the Enterprise crew turn up.
* The ''DoctorWho'' arc "The Face of Evil" featured a lost colony of humans who were manipulated over generations by [[AIIsACrapshoot rogue AI Xoannon]] into becoming two enemy tribes; the Sevateem(a corruption of "survey team") and the Tesh("technicians"). Leela, a Sevateem warrior, became the Doctor's companion for a time.
[[/folder]]

[[folder:Music]]
* US Heavy Metal band Music/IcedEarth did a variant this with their Something Wicked arc. In it, humanity, a (very nearly) galaxy-spanning empire, came to Earth in order to conquer it. The natives, being at a clear disadvantage, decided to hide away a small fraction of their populace and initiate "The Clouding," completely wiping the memory of the entire human race, causing them to instantly revert back to the stone age. All of this in order to initiate a plan to wipe them all out 10,000 years later. [[FridgeLogic How a galaxy-wide empire was contained on a single planet, or, alternatively, why the ''rest'' of the galaxy-spanning empire didn't come looking for their friends, is never adequately explained]].
** Well, the Setians did sacrifice 10,000 of their people in order to power the Clouding effect, so its possible that it affected more than just one planet. As for the lost part, galaxy-spanning empires are always losing contact with colonies, hence this trope.
[[/folder]]

[[folder: Tabletop Games ]]
* In the HumongousMecha roleplaying game ''{{Mekton}}'', the default campaign setting is a planet called Algol, which turns out to be a Lost Colony of the interstellar SpaceOpera society presented in the [[{{Sourcebook}} worldbook]] ''Mekton Empire''.
* ''TabletopGame/{{Warhammer 40000}}'' has these in abundance, sometimes simply because [[TheGovernment the massive bureaucracy]] that governs [[TheEmpire the Imperium]] loses records of worlds due to filing errors. In other cases, lost colonies that wound up on [[DeathWorld particularly challenging worlds]] are rediscovered and left in their primitive state because their inhabitants make such good soldiers, with the Imperium only occasionally popping in to recruit a company or two for the [[BadAssNormal Imperial Guard]]. Others, such as [[GrimUpNorth Fenris]], serve as [[SuperSoldier Space Marine]] homeworlds, the recruits only learning of the existence of the wider galaxy after joining the Chapter.
** This was the case pre-imperium as well, after catastrophes such as the RobotWar that ended the Dark Age of Technology, and the massive disturbance of Warp routes in the centuries preceding Slaanesh's birth. The Emperor revealed himself to mankind afterwards to end the Age of Strife, and launched the Great Crusade to unite all human-controlled worlds once again, by force when necessary.
** Moreover, it used to be implied rather heavily that the TabletopGame/{{Warhammer}} setting was an example of a world that had been cut off from Imperium contact, with hints that Sigmar and Bel'hakor were the two missing Primarchs. GW have subsequently moved away from this attitude however, treating the two game settings as being completely independent.
*** Implied? It was all but stated outright in the Liber Chaotica background books. At one point the narrator (a scholar from the Empire) has an out of body experience and briefly meets Magnus.
*** That doesn't necessarily mean the settings exist in the same universe. The Warp exists outside the normal universe, and may be shared by the two settings even if they are not in the same universe.
* ''{{Deadlands}}: Lost Colony'' is, rather unsurprisingly, based on this trope - but with the notable difference that the colony has only been "lost" for a decade or so, because Earth had a slight apocalypse.
* The source of the "barbarians" in FadingSuns.
* In EclipsePhase the [[PortalNetwork Pandora Gates]] occasionally malfunction and cut off a planet for years. In one case the colonists formed a HiveMind in the five years it took to re-establish contact.
* This was used in the [[StarFleetBattles Star Fleet Universe]] as a way to insert a small bastion of humans in a section of space outside the main Federation region by causing a colony planet (with sun and all) to be transported about 30 degrees around the edge of the galaxy. Later joined by a Klingon penal planet (and the task force trying to restore order there).
* The Cynidecians in the DungeonsAndDragons module ''The Lost City''.
[[/folder]]

[[folder: Video Games ]]
* All the Argon sectors in the [[VideoGame/{{X}} X-Universe]] prior to ''X3: Terran Conflict'' are Earth's lost colonies. Earth and the Solar System are reunited to the X-Universe in ''Terran Conflict''.
** The Free State of Aldrin is also a lost Terran colony.
* Karak, the starting point for the player's fleet in ''VideoGame/{{Homeworld}}''. The construction of the Mothership started when archaeologists discovered the remains of the colony's landing site, and with it a hyperdrive module. By this point, the colony had spent a few thousand years re-developing sub-light space travel and a modern society, but they had lost all their history prior to the landing. The distant genesis theory had been heretical, but the remains of the ship proved it. The rather important detail that they missed was that [[spoiler:they were the exiled losers of a galactic war, and using a hyperdrive will mark them for death by [[TheEmpire the all-encompassing Taiidan empire]].]]
** Homeworld is a subversion. The Taiidan knew all about the colony and, even after four thousand years, still monitored it. They just didn't announce their presence.
* ''VideoGame/{{Xenogears}}'': A select few in the world are aware of this; others, not so much. It was an accident to begin with, set ten thousand years prior to the start of the actual story, where mankind's creation crash-landed on the planet and respawned humanity through a fabricated "mother" entity. Furthermore, VideoGame/{{Xenosaga}}, the game's "spiritual" prequel, implies that the planet depicted at the end of the third game is the actual planet that Xenogears takes place on--though if they were to make a formal attempt to validate this (through sequels or otherwise), it would involve a fairly heavy {{retcon}}.
** Other interpretations state that [[spoiler: the planet in both the ending of Xenosaga and beginning of Xenogears is in fact Earth, which was lost to mankind in in 2510 AD. Mind you, in both cases humanity is in the far flung future. Xenosaga as a series ends in 7020 AD. whilst Xenogears starts in 17,230 AD if the math is right.]] Either way, you have a ultra civilization dealing with "just still getting there."
* The entire Koprulu Sector in ''{{Starcraft}}'' is a lost colony. Originally, Earth was dabbling with the concept of interstellar colonization, and already had success within the Solar System. One enterprising scientist built a fleet of colony ships, rounded up thousands of "colonists" (in reality convicted criminals because they were easy to obtain), and promptly shot them toward the nearest habitable planet. However, a freak accident caused the fleet to lose the coordinates of both their destination and Earth. They eventually were forced to stop in the Koprulu Sector. Eventually, the various human factions developed into small spacefaring empires. In the expansion, the United Earth Directorate finally discovers the lost colony and attempts to subjugate it. [[FromBadToWorse It doesn't end well.]]
** Actually, [[{{Retcon}} The UED knew about the colonies]] and was just monitoring them from afar, content to let events take their course. Then they found out about the [[HordeOfAlienLocusts Zerg]] and the [[ScaryDogmaticAliens Protoss]] and decided to step in.
* In ''VideoGame/MasterOfOrion 2'', lucky exploration can net you with these. Finding a Splinter Colony effectively means instant colonization of a random, agriculture-supporting planet in the solar system.
** The [=iOS=] port ''VideoGame/StarbaseOrion'' also has this mechanic.
* ''VideoGame/{{Wild ARMs 3}}''
* A popular theory was that [[GearsOfWar Sera]] was a Lost Colony and that the humans were alien invaders, though ''Gears of War 3'' more or less {{Jossed}} this one.
* In ''VideoGame/{{Ys}} VI'', Port Rimorge was founded by survivors of the Great Vortex who washed up on the islands over the years.
* Large swathes of the Galaxy is, by in-game statements of sapients that would know, this in (old verse) VideoGame/MightAndMagic, although we only get to see three of them (Enroth, Axeoth and the world of the novels) -- the four settings of the first five games were not lost, but ''deliberately'' retarded (they were part of [[SufficientlyAdvancedAliens Ancient experiments]]). Unusually, at least the inhabitants of Enroth do maintain knowledge that they came from another world (in fact, their dating system starts from the year off-world contact was lost), it just never comes up in the [[VideoGame/HeroesOfMightAndMagic Heroes games]].
* The village of Haven in ''VideoGame/DragonAgeOrigins'' is a form of this trope. It was established centuries ago by followers of the prophet Andraste, who created the village just outside of an elaborate temple they built to house her ashes. The village residents were charged with the perpetual guardianship of the ashes. While the rest of Ferelden sprang up around the village and changed with the passing of time, Haven remained in complete isolation - it doesn't even appear on any maps of the country and most people don't know it exists. Although its inhabitants are essentially of the same religion as the rest of Ferelden, they're unaware of the Chantry (Ferelden's church) or certain laws and regulations. Worse, in the last several generations, they've come to the erroneous conclusion that a dragon is the reincarnation of the prophet, and the village has evolved into a murderous AxCrazy cult.
* The Forgotten colonists in ''VideoGame/LostPlanet 3'' were abandoned by [[MegaCorp NEVEC]] and left to fend for their own on [[DeathWorld E.D.N. III]] for 36 years until NEVEC returns to the planet and accidentally rediscovers them.
* ''Franchise/MassEffect'' has a throw-away reference to a human colony being found in Alpha Centauri; the colonists set off before the discovery of the settings [=FTL=] travel and had no ideal of aliens populating the galaxy.
** In ''VideoGame/MassEffect2'' the Hugo Gernsback crashes onto a planet with plants that degrade the human mind. The crew decides that only those able to repair the ship/get a message out are allowed to eat the food they brought with them with the rest forced to eat and become "like children". Shortly afterwards the guys in charge decide this colony life isn't that bad and decide to stay.
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[[folder: Web Original ]]
* In OrionsArm the exodus from [[EarthThatWas Old Earth]] following the nanodisaster resulted in many Lost Colonies, though most were re-contacted when the [[TheFederation First Federation]] was formed or sometime later in the next 10,000 years.
** The Metasoft Version Tree maintains "baseline preserves" that are essentially intentional lost colonies. The original colonists were baseline humans who wanted to leave Sephirotic civilization and paid Metasoft for worlds where they could preserve their culture undisturbed. Though at least one preserve world has rediscovered space travel and rejoined interstellar civilization.
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[[folder: Western Animation ]]
* In ''WesternAnimation/JonnyQuestTheRealAdventures'', an interesting variation appeared in the season one episode "Ice Will Burn". The story deals with a people descended from 17th/18th century Siberian Russians, whose ancestors had to fled their town and got trapped by accident in an inescapable deep gorge/icy cavern. They managed to survive and thrive thanks to the heat produced by a small local volcano (TruthInTelevision if it's supposed to be set somewhere in the Kamchatka peninsula).
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[[folder: Real Life ]]
* The adventurer-archeologist Aurel Stein found a Chinese outpost dating to the end of the Han dynasty that had been cut off by the collapse of the dynasty (as detailed in Romance of the Three Kingdoms). Ancient Bureaucratic red-tape indicated that the outpost continued to function after it had been cut off, still keeping up Imperial forms as if the dynasty still held the throne.
* In 1843, German settlers in Venezuela founded [[http://en.wikipedia.org/wiki/Colonia_Tovar Tovar]]. A few years later the jungle reclaimed the only way to them and everyone assumed they were all dead. Well, until they where rediscovered 1953. They still spoke their German dialect and built their houses like 19th century Germans.
* DNA analysis has recently suggested that not one but four or five African and Indian groups may be (as they claim) Lost Tribes of Israel. Besides the famous Ethiopian and Ugandan Jews who got airlifted by Israel in the 70s, a full-blown tribe in Tanzania recently got themselves tested to prove their claim that the tribe itself were a lost tribe of Hebrews, since the Roman era. (Being cut off, they didn't know any other Jews existed, so they adopted local language and customs.)
* There is a group of people in southern Egypt known as Magyarabs who are supposedly descendants of Hungarians brought there by the Turks in 15th century. They were first encountered in 1930s by Europeans (Ironically, László Almásy, himself a Hungarian--who became famous via the movie ''The English Patient''--and his colleagues).
* On a smaller scale is the Lost Colony in Roanoke, NC. A small English colony was founded on Roanoke island in 1584, but vanished by 1589 under mysterious circumstances. Since the 1930s, its been celebrated in an outdoor drama near the original colony site, and figures heavily in various conspiracy themed RolePlayingGames.
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