Long ago, visitors came down from the stars, and took humans (and possibly other Earth species) away to other worlds. Now that we have the ability to travel between those stars, we keep running into our long-lost cousins.
One variation is that that's how we got to Earth, and the origin planet of humanity is somewhere else. This has become less common, however, as evidence that we're biologically related to other Earth species has become pretty hard to talk your way around.
This trope is often combined with Ancient Astronauts and/or Advanced Ancient Humans. Compare and contrast Transhuman Aliens, where the descendants of the Transplanted Earthlings aren't human anymore, and Ultraterrestrials, where they never were. Compare Lost Colony, where the humans moved themselves. Humanity Came From Space is another possible explanation for humans on other planets.
- Last Exile: Though kind of a subversion, since humans transplanted themselves and two of the three nations became Fantasy Counterpart Culture Lost Colonies at the mercy of the more advanced, Crystal Spires and Togas Deadly Decadent Court faction.
- This seems to be the true origin of the Gradosians in Blue Comet SPT Layzner. The ancestral race of Grados brought over samples from Earth in the distant past in order to use as slaves, the actual gradosians eventually died out and the human descendants took over their civilization and cultural identity.
- Rinne no Lagrange's aliens are all humans who left Earth after a great disaster 20,000 years ago. Madoka expresses a bit of disappointment at finding that out, noting it's like they are just coming home.
- The Post-Crisis DC Universe used this trope to justify the Human Alien Planets of Hats most of the Legion of Super-Heroes came from: after the Invasion! Crisis Crossover,
Mon-ElValor seeded several worlds with humans who had gained powers from alien experimentation.
- According to an offhand comment by Geromi in Crux, this is why nearly all the worlds in CrossGen's Shared Universe have humans of some kind. Even the high fantasy, low fantasy, feudal Asian-ish, and Victorian worlds, as well as the more science-fiction worlds. Ironically, "true" humans on Earth are all but extinct. Because they artificially Transcended this universe and became the Negation.
- The Atlantines in Dan Dare are descendants of slaves kidnapped by the Treens and taken to Venus thousands of years ago. They've been there long enough to evolve blue skin and forehead lumps.
- Future War featured a race of alien cyborgs who had visited Earth at some point in the past and kidnapped both humans and dinosaurs — the humans they used as slave labor and the dinosaurs they used as "trackers".
- Stargate made it quite clear that the people of Abydos were transplanted ancient Egyptians. See the entry for the Stargate-verse under Television for more detail.
- In C. J. Cherryh's Morgaine Cycle the precursors put humans on different planets with various different starting conditions as experiments in the development of human society/culture, and then used their Cool Gates to travel into the future to see the results. However, one of the precursors used the gates to travel back in time and caused a Temporal Paradox, with the resulting Time Crash wiping out the precursors' galaxy-spanning civilization. The main characters use the precursors' Portal Network to travel from planet to planet, encountering feudal and tribal Transplanted Humans along the way.
- Novels of the Jaran by Kate Elliot had a planet full of humans that, millennia ago, an alien removed from Earth and genetically modified before placing them on the planet. His reasons for doing so were never explored, but that may be because the series is currently unfinished.
- In Jack Vance's Planet of Adventure series, the earthman protagonist encounters transplanted humans living side-by-side with (and frequently dominated by) several species of sapient bona fide aliens on the titular planet.
- In David Weber's Empire from the Ashes trilogy, humans on Earth are transplants descended from the stranded crew of an interstellar warship which has disguised itself as the Moon. Humans were originally native to another planet, Mycos (as is all the other life on Earth — explaining why it is biologically related to humanity). Note the Humans from the ship were descended from humans on Birhat, which survived the last cycle of destruction which claimed Mycos at the end of the Third Imperium. It's not fully known if the First and Second Imperiums were human.
- In Larry Niven's Known Space universe all the primates on Earth, including humans, are descended from a race called the Pak that were stranded on Earth a few million years ago. The reason humans are related to other life on Earth is that the Pak terraformed earth and wiped out most of the native ecosystem doing so. Similar colonization attempts resulted in the Morlocks of Wunderland (semi-sapient, cave-dwelling predatory hominids) and the various hominid species of the Ringworld. Furthermore, nearly all carbon-based life in the galaxy is descended from food yeast seeded on developing worlds two billion years ago by the first few alien races.
- The Narnia series has a magical version of this to explain why there are humans in Narnia. They're all descended from a London cab driver and his wife, and/or Mediterranean brigands and their islander "wives", who came later, and/or from various similar transplants that aren't explicitly mentioned in the books but may have happened.
- Everworld is another fantasy version. The various mythological gods all decided that they were sick of our world and created a new one, moving there along with all the other magical beings. But of course, the gods aren't going without some worshipers, which is why Vikings, ancient Greeks, pyramid-building Egyptians and Druids all live in a weird, anachronistic hodgepodge. In contrast, the beings actually native to other worlds, like the Coo-Hatch and the Hetwans, look nothing like humans.
- In Sergey Volnov's Army of the Sun trilogy, this is the main theory (although there is little actual evidence) behind the similarity between humans and three human-like races. Each one looks like a "sub-race" of Earth: Caucasians, Africans, and Asians. It is also mentioned that an ancient wall carving on the "Asian" race's homeworld is the name of a legendary figure in their culture, whose name sounds a lot like "Genghis Khan." This is all mentioned as a side-note, however, and is unimportant to the main storyline.
- In William Shatner's Quest For Tomorrow series, this is revealed to be the fate of the Neanderthals. A ship belonging to a Lizard Folk race found Earth a long time ago and found two sentient species on the planet. The homo sapiens were dismissed as unimportant, while the Neanderthals turned out to be telepathic. Desiring to learn the secret of telepathy, this particular faction transplants a good number of Neanderthals to a remote planet and then wipes out the rest with a virus, engineered specifically to kill them. After a series of failed experiments, the lizards decide to kill off all their subjects as well. They release the virus and leave. This time, however, some of the Neanderthals survive and build a civilization of their own, albeit much slower due to the lack of writing (telepaths don't need to write). Decades before the series initial timeline, the Neanderthals have only reached Industrial Revolution, while humans are already a star-faring race. They then Ascend to a Higher Plane of Existence by turning their star into a black hole.
- The Algebraist, by Iain M. Banks, has "aHumans" (the humans who were taken to join galactic civilisation in about 4000 BC) and "rHumans" (tho ones who made it out themselves seven thousand years later). It turns out that this was a common tactic of several galactic civilizations; by ensuring that the transplanted population was more advanced (and usually more numerous) than the originating population, the original population would have swiftly integrate and conform into the community when it made first contact. The Culmina use it as a form of controlling lesser races. Slightly averted, though; these two groups make up only a small fraction of sentient beings even among the 'Quick' species (of which humanity is a member).
- The Skolian Saga, by Catherine Asaro, posits a small group of Mayans who were kidnapped by an unknown species and transplanted to the planet Raylicon. The kidnappers left their starships behind. The Raylicans experiemented with the discarded technology, created an interstellar empire, fell, reachieved starflight, and then encountered humans from earth just as they invented stardrive theory from scratch.
- S.M. Stirling's novels The Sky People and In The Courts of the Crimson Kings update the Burroughs depiction of Mars and Venus by being set in an alternate timeline in which aliens terraformed Mars and Venus millions of years ago and have since periodically transplanted species from Earth to the other planets.
- A What Could Have Been example: in Star Wars Legends, a novel called Alien Exodus was planned, which established the Star Wars humans as transplanted through space and time from Earth. It was never finished and never made canonical, though the theory that humans were "seeded" through the galaxy by Abusive Precursors cropped up in several places, including Knights of the Old Republic.
- Francis Carsac's Les Robinsons du Cosmos (The Robinsons of the Cosmos) involve an unexplained cosmic event (later theorized to be a "collision of universes") resulting in a chunk of the French countryside (a village, an observatory, a rocket factory, and a Swiss millionaire's castle) being transplanted to another world. The planet (which they call Tellus, Latin for "earth") is Earth-like but features some hostile life-forms that force humans to find a new place to settle. They meet an indigenous race of centaurs called Ssvis, who agree to let humans settle in their territory. The Frenchmen build a new settlement called Cobalt City and help the Ssvis fight their ancient enemies the Slvips (black centaurs). Also, after spotting a strange airplane, the Frenchmen discover that they weren't the only ones transported to this world. A chunk of the US (as well as Argentina and Norway) was also transplanted onto a sinking island. The residents of Cobalt City help rescue the sinking Americans, Argentinians, and Norwegians and let them settle nearby. As a result, the French end up nearly fighting the new American nation. In the end, all friendly nations form the Union of Tellus Republics with Cobalt City as the capital and spend the next several decades exploring the planet. Since the planet is implied to be in a different universe, it's highly unlikely that it will ever be rediscovered.
- The Martians in Spin are all descended from humans who were sent to the planet in hopes that the lack of Earth's time-dilation effect would cause their civilization to outpace Earth's, thus giving them some better idea about the nature of the Hypotheticals.
- The V'Dan Empire from Theirs Not to Reason Why is descended from these. They have been alternate enemies and allies of the Terran United Planets.
- The titular Space Elves of Alistair Young's Eldraeverse are descended from pleistocene protohumans brought to an artificial planet and modified extensively by the Precursors. Unlike most examples the eldrae haven't made contact with their distant relations though, in large part because they live tens of thousands of light-years away and lack FTL other than a Portal Network that they're in the process of constructing.
- An interdimensional version in Destroyermen, where a Negative Sea Wedgie transports a pair of American destroyers from a World War II battlefield to a parallel world, where humans never evolved. Instead, they get stuck in the middle of an ancient war between a race of Lizard Folk called the Grik and Cat Folk called Lemurians. It isn't long before they find out that they're not the only humans to find themselves in this world (there are the Imperial Japanese, who are helping the Grik before splitting off on their own at Zanzibar, the Empire of New Britain Isles at Hawaii, the Holy Dominion in Central and South America, the League of Tripoli in the Mediterranean, the Republic of Real People in Southern Africa, the New United States near the Mexican Gulf, and a bunch of human tribes all over the place). They also learn that our world isn't the only one, from where people have ended up in the Grik/Lemurian world. Norably, the League of Tripoli comes from a world, where fascist France, Spain, Italy, and Germany are at war with the US, the UK, and the Russian Empire.
- Similar to the above, The Lost Regiment focuses on a group of Union soldiers being transported by a Tunnel of Light to another planet just after the Battle of Gettysburg. There, they find various cultures transplanted from Earth at different times, including Medieval Russians, Ancient Romans, Carthaginians, Ancient Chinese, etc. All of them are stuck in Medieval Stasis, enforced by this world's true masters, a race of 9-foot-tall Human Aliens, who ride around the planet as Hordes at different latitudes and collect tribute from their human subjects in the form of supplies and "cattle". It doesn't take long for the Americans to come into conflict with the Tugars, one of the alien hordes. Fortunately, the nearby human peoples are sick and tired of having to sacrifice some of their own to the Tugars every generation and would rather go down swinging. The Americans end up helping the locals industrialize and train in modern (by Civil War standards) combat.
- In Ian Douglas's Semper Mars, an expedition at Cydonia, Mars, discovers ruins half a million years old. An American archaeologist then discovers skeletons that appear to indicate that whoever had built the ruins also abducted Homo erectus from Earth and genetically modified them, possibly using them as labor to build the Face. An unexplained disaster then caused the deaths of both the Builders and the transplanted hominids.
- The humans of Codex Alera are descended from a Lost Roman Legion and its train of camp followers, who were transported to Carna by a naturally-occurring wormhole well over a thousand years ago. The other sapient races of Carna are similar "refugees", along with a lot of its fauna.
- Lake Of The Sun by Wynne N. Whiteford imagines that the Martians living in caverns deep underneath Mars (where there is sufficient air pressure to breathe) are actually humans who came from Earth in some long-forgotten past time (one strain of Martians have adapted to the dim light by developing a single, giant eye but are otherwise human. They see in 3D due to having two focus points in their single eye)
- Wild Cards: It is a matter of debate as to whether the Takisians were taken from Earth by the Network, or if Earth is a lost Takisian colony. Either way, they are biologically identical to humans, or were prior to the Eugenics program which developed the psychic powers and longevity of the Mind Lords.
- Midworld is home to a race of humans that descended from a failed colony but have been living in the world-wide jungle long enough that they've evolved to be shorter than average humans, have green hair for improved camouflage, and have long prehensile toes for gripping branches. They've also evolved a psychic plant-empathy ability they call emfolling and have a symbiotic link with a six-legged bear-like species called furcots. In fact, the entire planet is sentient and chose to adopt the humans into it by giving them furcots, which are actually self-aware, mobile plants. Each human has a single furcot bonded to it, and when either one dies, the other quickly follows.
- Played two ways in The Giants Series. Humans were taken to Minerva millions of years ago, and one of the two rival groups was returned to Earth when Minerva was destroyed. The other group of humans was taken many light-years away and became the Jevlenese, who retained a hatred of their rivals even as the rivals forgot about them.
- Stargate SG-1 is probably the best-known modern example; the vast majority of the Adventure Planets the SG team goes to were colonized with human slaves by the Goa'uld.
- Likewise, Stargate Atlantis populates its galaxy with human societies planted by the more benevolent Ancients. People in the Pegasus galaxy are typically aware of how to use the stargate, so some colonies may have settled on their own.
- There's also the Novus civilization in Stargate Universe, resulting from accidental time travel of the crew of the Destiny 2000 years ago. The alternate (or original) crew encounters their descendants and gives them a ride back to their dying homeworld and then to their new world.
- In Star Trek:
- In Star Trek: The Original Series, the Forgot the Call episode "The Paradise Syndrome" featured a group of Native Americans transplanted to another star system by Precursors as a sort of cultural preserve.
- And Gary Seven's ancestors were taken from Earth to live on another planet, raising the perfect infiltration agents.
- In Star Trek: Enterprise:
- The episode "Terra Nova" reveals that the race with whom Archer and his crew are making first contact are the descendants of an early Earth expedition that lost contact with the home planet.
- And yet another has them finding an Old West-style planet which was populated by abducted humans previously used as slave labor by the aliens who now work as their slaves.
- The Star Trek: Voyager episode "The 37's" has the crew find a planet populated by descendants of humans abducted by aliens in the 1930s as slaves but rebelled against the abductors. Some of the abductees (known to the locals as the 37's) are still in stasis (including Amelia Earhart). Why someone would go to another quadrant to get slaves, given that the galaxy is teeming with intelligent (and humanoid) life, is another question.
- And now Star Trek: Discovery joins the lineup with "New Eden", where a mysterious entity has transported a couple hundred soldiers and civilians taking cover in a church during World War III over 51,000 light years to a habitable world in the Beta Quadrant.
- Farscape this is where Sebaceans, and probably Interions, come from.
- Battlestar Galactica (2003) and Battlestar Galactica (1978) both had this: "There are those who believe that life here began out there." Kind of. In both versions, it was humans leaving Kobol of their own accord to settle the Thirteen Colonies of Kobol. This has been offered by fans as an alternative explanation to identical evolution of humans on Kobol and Earth 2 in the re-imagined continuity, however.
- In Babylon 5, First Contact with the Centauri led to the Centauri claiming that Earth was a long-forgotten colony world of theirs (hence explaining why humans and centauri look so similar). This claim lasted for as long as it took for the humans to get a Centauri DNA sample, which proved the claim was utter hogwash. The Centauri blamed a 'clerical error'.
- In an episode of Sliders an Alternate!Quinn's first test of the sliding machine (on a much larger scale) resulted in that Earth's entire population being transported to another world. As such, that other world now has double the population, although many duplicates try to stick together. Luckily, Prime!Quinn helps send them all back.
- In The Hitch Hikers Guide To The Galaxy, the humans currently on earth were descended from telephone sanitary workers and hairdressers, set to crash into the Earth by the other people on their planet, who were later wiped out by a disease that occured due to contaminated telephones.
- In Dragon Ball After The End, humans have somehow ended up across the galaxy. No one seems to be quite sure how, though.
- In the Traveller RPG and its offshoots the Ancients brought humans and other species to thousands of planets and also created the Vargr by uplifting wolves. The end result being that Terrans went out to the final frontier and discovered they were already there. In fact, one of those transplanted races, the Vilani, had established an interstellar empire thousands of years earlier.
- Forgotten Realms: Done in a more restricted fashion. Humans are native to Abeir-Toril (that is why they count as a Creator Race, and elves don't)... but they are also native to other worlds, and certain cultures are descended from such non-Toril humans (the Mulan, for example, are the descendants of slaves taken from another world that by Word of God was Earth).
- Banestorm: The premise of the game is that the main setting, Yrth, was originally home only to elves, dwarves, gnomes, orcs, and ogres. A faction of elves attempted to rid themselves of the orcs by means of a grand spell, which backfired spectacularly and caused a magical catastrophe — the titular Banestorm — that transported enormous numbers of humans to Yrth from medieval Earth, establishing humanity as a significant presence in the world. This also applies to several other species that the Banestorm brought to Yrth besides the humans, including goblins, hobgoblins, kobolds and reptile men from a desert world called Gabrook, merfolk and shark men from the ocean planet Olokun, and centaurs, giants, halflings and minotaurs from the verdant world of Loren'dil.
- In Warhammer 40,000 they're left over from humanity's efforts at colonizing the galaxy in the distant past. It doesn't hurt that the Imperial bureaucracy is vast and bloated enough to misplace entire sectors for centuries at a stretch...
- While there aren't any actual humans in Spore (except maybe Steve) you can find planets inhabited by tribes or civilizations of your own species and abduct specimens of other species and drop them off on planets.
- The reason why humans, orcs, goblins, elves, dwarves etc can be found on so many worlds in the old Might and Magic verse is that the Ancients (who may or may not be humans/transhumans from Earth) put them there (you can even visit part of the ship that brought your ancestors to Enroth in Might & Magic VI).
- Halo: Some prerelease Halo: Combat Evolved fluff mentioned that during the United Nations' colonization of stars near Sol, they occasionally discovered societies of primitive humans on worlds they knew for a fact no ships had been to; this was quickly made non-canon. However, actual canon media later revisited the theme by giving us Transplanted Human Architecture in Halo: Evolutions and Halo Legends, with Halo: Cryptum and Halo 4 revealing that it's a result of Advanced Ancient Humans: Humanity had a prehistoric spacefaring empire that seemingly beat back the Flood, then tangled with the Forerunners and had their asses handed to them.
- Implied to be the case with the Syreen in Star Control. Or rather, humans originated on Syra, were transplanted by the Arilou to Earth, and were modified to their current state.
- Master of Orion:
- In Master of Orion 3 you can discover planets already populated by splinter colonies of any species in the game, and also a few from the previous games that are not playable in this one. These are explained as the remnants of the empires established in the previous games, having been so small and technologically backwards they were missed when the Antarans conquered everyone and confined each species to a single planet.
- Master of Orion: Conquer the Stars, the Terrans are humans, taken from Earth long ago by the Antarans to fight the Orions, but ended up abandoning them on a dying world in the Alpha Ceti system. Through hardship, perseverance, and draconian policies, the Terrans survived and clawed their way back to the stars, determined to dominate all other races, including their Earth cousins.
- The Anuban race in Unreal Tournament 2004 is a result of this, being humans taken from the ancient Egyptian empire and transplanted to other worlds as part of an experiment. They end up not only surviving but thriving well into the 23rd century.
- In Among the Chosen a race of aliens called "the Overseers" abducted a bunch of humans some time in the stone age as cheap labor. Thousands of years later some of those humans developed resistance to their mind control and built a device to destroy all the Overseers, it worked. The universe is now filled with metahumans but earth is in a No Warping Zone so most of them don't even know where it is.
- In the Global Guardians PBEM Universe, the alien Daribi invaded the earth four times (in 1898, 1938, 1953, and 2005). Each time they were beaten back. During the 1953 invasion, mankind finally captured several of the invaders, only to find out that they were the descendants of Neanderthals who had been transplanted to another planet 75,000 years earlier. They were rescued from extinction on Earth by Sufficiently Advanced Aliens and taken to a world that wasn't actively killing them off.
- Unicorn Jelly: The main explanation for humanity's appearance in a twisted universe: 4th-dimensional holes in space and time (a natural occurrence due to the multiverse's instability) cause random pockets of reality to transport instantly from one universe to another. Chou explains that it's like rain: when rain falls, it's round because of the properties of surface tension, and makes a circular shape when it hits a flat surface; the holes in time and space are similar, teleporting orbs of people into a new reality. The odds of this happening are astronomical, but in the Unicorn Jelly universe it happens. It's unknown how many have died compared to how many survived, but there are enough to start a utopian civilization. This later happens to a different alien species, complete with one person panicking (much like the old lady from the first batch of transplantees).
- The Cyantian Chronicles takes place around the time period when Cyantia culture re-integrates with Earth. Most of the humans from Cyantia are descendants of alien abductees who were enlisted to help a precursor race with a biological problem, and chose to stay away from roman-age human civilization.
- Grrl Power: Due to centuries of aliens abducting small numbers of pre-industrial humans, there are a few million humans living among the wider galactic community. Cora mentions that most of the abductions were probably voluntary, though of course she can't be sure.
Cora: How many people in just this crowd would like to live and work on my ship for a year, then return to Earth to write the best-selling book of all time?
[most hands go up]
Cora: That's what I thought.
- Mewmans in Star vs. the Forces of Evil are discovered in the fourth season to actually be descendants of humans that entered portals into the Realm of Magic, lost their memories, and came out in the dimension of Mewni.
- Combined with People Zoo in Season 4 of Steven Universe; thousands of years ago, Pink Diamond's reign of terror included the abduction of numerous human specimens for her personal amusement or so we're led to believe. In actuality, Pink wanted to save humanity, but Blue Diamond interpreted this as wanting to ensure that the species would survive in any form. The latter was the one who oversaw the Zoo's construction and populating, with Pink never having an opportunity after her rebellion to go and save them. Their descendants have never even been outside their enclosure, let alone been to Earth. By Steven Universe: Future, the humans are given free reign of the ship the enclosure is based in, taking it wherever in the universe they wish (including, briefly, Earth).