Also known as "ancients." They are a standard fixture of much science fiction and fantasy: an ancient race whose culture and knowledge rose to its pinnacle in ages long past but which is now extinct or Ascended to a Higher Plane of Existence. In science fiction settings, they are usually considered the first race to have gained sentience in the universe or galaxy, giving them a noticeable leg up on everybody else; in fantasy settings, they will usually be the original, pinnacle sentient species created by the gods/God. At their height, they are usually rumored to have been capable of doing (and have done) just about anything, up to and including creating intelligent species and reworking entire worlds with a snap of a finger, and almost any strange and persistent mystery in the story's 'verse is usually laid at their feet. They may have been sufficiently advanced, or just much better than everyone else with technology/magic, but either way they left their mark, a mark that remains to this day.
Then they vanished into myth, leaving behind nothing but tantalizing ruins and rare, sometimes incomprehensible artifacts and dangerous weapons. Just why, no one knows. Perhaps they Ascended To A Higher Plane Of Existence, or were wiped out by a disaster or war, or maybe they just relocated en masse to somewhere else where they haven't been found yet.
Whatever the reason, they set the stage for the modern world, left behind a few MacGuffins and surprises for the heroes and villains to find, and then got conveniently out of the way. And then there are the times where they themselves are the reason everything's gone to hell, and they intend to keep it that way. If the Precursors implemented a plan, whether they still exist or not, that still influences outcomes then they are also Powers That Be.
Sometimes the Precursors can be rediscovered; usually nobody — especially not the Precursors themselves — is happy with that. This also applies to the audience: the romance of Precursors can be easily shattered by giving too much away.
Bonus points if Earth Humans are Precursors and their incredibly human descendants try to rediscover their heritage — or, conversely, if Earth Humans are the only descendants. If Humans are the Precursors, that's Advanced Ancient Humans. If everyone's scared of them, that's Humans Are Cthulhu. If they pick on their descendants, that's Abusive Precursors; if they couldn't care less about anyone else, it's Neglectful Precursors; if they help their descendants, it's Benevolent Precursors. If there's one or more race that played Precursors to the Precursors, then they're Recursive Precursors. Any and all of these are susceptible to Awakening the Sleeping Giant. If they gave their tech or it's being used by another race, it's Low Culture, High Tech. Very often, their most powerful technology will appear deceptively primitive and/or ceremonial.
Very commonly used to justifyRubber-Forehead Aliens: everyone was made from a common template by the Precursors, so they look pretty similar (although it also flatly contradicts all current data on the evolution of our species, implying a creationist/Intelligent Design origin of humans instead).
Not to be confused with the space flight sim, The Precursors.
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Anime and Manga
In Heroic Age, the precursors (known as the "Golden Tribe") was the source of many wonders; giving birth to stars, discovering the Star Way which connects all stars, as well uplifting several races. In time they eventually undertook a journey out of their home galaxy and into a new one. The story is about how the lesser race cope with the "Golden Tribe's" absence.
In the Houshin Engi manga, five aliens, The First People, came to Earth millions of years ago after their home planet self-destructed. All but one merged with the earth and its life forms to spread their blood, leaving behind the first seven paopei (magical weapons used in the series) from which all others would be copied.
The Macross series has the Protoculture, who are apparently responsible for everything that happens in the universe: humans and Zentradi were both created and seeded by them, and the Birdman was made by them in an attempt to mimic the Vajra. Moreover, they "created" (it's a bit more complex than that) the Protodeviln, who pushed them to the brink of extinction before being defeated.
About the only thing the Protoculture didn't have a hand in creating are the Vajra, and that's because the Vajra are even older. The Protoculture based some of their most advanced technology (such as Space Folding) after the Vajra's biological systems. The Vajra themselves seem to primarily take a "live and let live" attitude towards other intelligent species; the fact that they don't have a clear means of communication probably has a lot to do with this.
In Neon Genesis Evangelion, the First Ancestral Race (FAR) dropped Black and White Eggs (Adams and Liliths) on several planets. No planet was supposed to get more than one Egg, but because we got two, we got the inter-egg wars that compose the series proper (Lilith's children vs. Adam's children). The First Ancestral Race were never mentioned in the show itself, but is referred to in the early scripts and gets a bit more fleshed out in the Neon Genesis Evangelion 2PlayStation 2 game that served as supplemental material.
A precursor race is vaguely alluded to in episode 21, where Gendo points out to Fuyutsuki that "someone, who was not us" left behind the geofronts found under Antarctica and Japan.
What allows them to escape being considered neglectful is that they sent a contingency against "inter-egg wars" - the Spear of Longinus. Both Eggs had a Spear but Lilith's was lost on impact; since Lilith was first to find Earth, upon Adam's landing, his Spear activated and sealed him; so, technically, everything worked just as expected. It's not their fault the Lilim decided to yank Adam's Spear.
The reason they aren't around anymore? They sacrificed themselves to provide the souls needed to create new life.
In Outlaw Star, an ancient race is revealed to be responsible for the Galactic Leyline, yet another of the many Sequel Hooks in the last episode.
Vision of Escaflowne — The people of Atlantis created fate-altering technology and the "zone of absolute fortune". They were responsible for the creation of the world of Gaea. In the end they were destroyed by the "zone", so it did not quite live up to its name.
In the Marvel Universe, the race of giant Celestials have influenced many planets, including Earth. They wear strange suits of armor, giving the impression that they are mechanical, but that's not the case. They also test races and civilisations according to their standards to see who are worthy. In addition, there are also the Elders of the Universe, a loose associations of beings who all are The Last Of Their Kind, and who hail from the first intelligent races to develop in the universe. They are less active, though, since they are all obsessed with one narrow hobby which apparently is the only thing that keeps them from dying of sheer boredom. The Grandmaster may be interested in the gaming and gambling habits of various lesser races, for instance, but couldn't care less about any aspects of their culture that has nothing to do with his obsession with games.
There is also the race know as the Watchers, who started to do something similar, but got cold feet when early interference with a much more primitive race led to horrible wars. They have sworn to not interfere with their nigh godlike powers, only record what happens. (The Watcher appointed to Earth is a juvenile delinquent who breaks this rule regularly, but surreptitiously, so as to not get in trouble with his kind.)
In the DC Universe, the Malthusians were one of the earliest sentient races in the universe. They went on to become the Guardians of the Universe. And the Controllers, and the Zamarons, and Krona. They pretty much run the gamut of precursor subtropes.
There's also the Old Gods, precursors of Jack Kirby's Fourth World beings. They are actually older than the DC Universe, and are said to have caused the destruction of the one before.
The Merk in Nexus certainly qualify, as they are or were a race of extremely psychically gifted and technologically advanced alien race who left the galaxy and, apparently, their bodies, behind. One of them remained behind, however.
The High Ones of Elfquest surely qualify (even though they have known descendents), because none of the protagonist elves know much about them, and their powers and origins are a great mystery when the series begins.
In Gold Digger, finding the various precursor civilizations is pretty much Gina's job. Of course, she usually ends up encountering the stuff left behind, and occasionally bringing it home.
The Gray of Star Trek: Hidden Frontier are set up to be precursors of some kind, but it turns out they're actually artificial life forms built by actual precursors, of whom Siroc, the Big Bad, is the last one left.
In Shepard's R&R, when Commander Shepard asks Princess Celestia about the fantastical abilities of the Equestrians, Celestia smiles and cryptically states that "their Mother shaped them that way." When Shepard learns the fact that Equestrian DNA is shows almost-impossible levels of genetic engineering, Shepard concludes that this "Mother" must have been one.
Mega Man Recut has the Vannu'bi, an ancient civilization that existed on a small remote island and were apparently destroyed by a volcanic eruption. They may have been Abusive Precursors, since they're architecture describes them as constantly warring with other civilizations and making deals with an Eldritch Abomination.
In Alien vs. Predator, the Predators are retconned to being responsible for teaching humans how to build, farm and write, all so they could have people to sacrifice as part of their barbaric rites of passage.
Contact. The alien says that the Portal Network used by the protagonist was not built by them, but by a long-disappeared race.
The Mondoshawans in The Fifth Element based on their representation apply to this trope aswell, at least to a certain degree.
Alien has the barely-featured Space Jockey's species, which the Expanded Universe claims is responsible for the creation of both humanity and the Xenomorphs. Prometheus clears this up a bit: the "Engineers", as they are called, apparently seeded life on Earth in prehistoric times. Whether this was done by just one Engineer or a collective is not clarified; the characters think it was all of them. They also intervened in some ancient cultures, leaving clues in bas-relief and cave-painting form, pointing to a planet in a certain star system, about 34-LY from Earth. The movie makes it clear that about 2000 years ago, they changed their mind about us for some reason and decided to exterminate humanity; the planet in question was one of their outposts, from where ships carrying biological weapons (much like the Xenomorphs) were to be sent to cleanse the Earth of life. The only thing that saved us was the fact that the monsters escaped captivity and killed the Engineers at the outpost. All except one...
The implication is there that they did indeed create the Xenomorphs as the perfect biological nuke.
The Krell of Forbidden Planet, who created the huge machine beneath the planet's surface. They were all killed in a single night by the Id monsters they'd unknowingly let loose with the machine's completion.
A.I.: Artificial Intelligence has a twist on this in its final act, in that humans have become extinct and are now viewed as an ancient and wise precursor race by the robots who have inherited the planet.
Andy McDermott's action-adventure novels. The first is called The Hunt for Atlantis and is centered around, oddly enough, a hunt for Atlantis. As the series goes on, other mythical items are 'explained' as advanced technology stemming from the Atlanteans. As the series goes on even further, the characters stumble across the Garden of Eden, which is the final resting place of a pre-human civilisation which was driven to extinction by their human slaves, who stole certain technologies and fled. The Atlanteans are then revealed to have been the result of cross-breeding between those pre-humans and the humans, causing the reader to re-evaluate the "it came from Atlantis" explanation.
Also the demons of the Xanth novels, including of course Xanth himself.
There was a (unfortunately) short-lived collection of short stories, edited/inspired by Isaac Asimov called Asimov's Universe, which was notable for featuring space-faring humans alongside five other non-humanoid races. (One was something like sentient bacon.) A recurring background theme/sub-plot were the ruins and remnants left behind of an earlier, seventh space-faring species that had since vanished.
The Martians in the Takeshi Kovacs books. Note: not actually from Mars; it just happened to be the first planet on which humans found their stuff.
In David Brin's Uplift universe, every intelligent race in the galaxy was Uplifted (engineered to sentience and given access to the Great Library) by a previous one, save the first. The Progenitors (self-evolved, now extinct) are considered the next thing to gods. A race's clout in the galactic hierarchy is in part determined by how close they are to having been created directly by the Progenitors. Then along come the Humans, who have discovered hyperdrive and reached the stars alone, with no patron race and a complete fossil record that indicates they evolved naturally. It's practically heretical! It doesn't help matters (from the galactic standpoint) that humans have already Uplifted chimps and dolphins, too.
In the second novel set in the Uplift Universe, Startide Rising,the first dolphin-captained Earth ship discovers what is assumed to be a fleet of the fabled Progenitors, and must try to return to Earth while being hounded by bickering alien battle fleets after the transmission of their findings is intercepted; the most active (and warlike) of the alien races/alliances are not happy that the wolfling Humans might have the key to the fate of the Progenitors (which could prove most or all of their belief systems wrong. The idea that humans may be the descendants or direct product of the Progenitors is also examined.
Alan Dean Foster's Humanx Commonwealth series has humanity and its allies expanding into a significantly used universe, with a wide variety of species at various stages of development from primitive to superadvanced to completely extinct. Several of these, most notably the Xunca, the Tar-Aiym, and the Hur'rikku, had a profound impact on the earlier history of the galaxy and left numerous artifactslying around after they variously departed. The Xunca are actually still around, but they packed up and moved to a different galaxy to avoid an encroaching Eldritch Abomination that the modern day protagonists now have to deal with.
The Cthulhu Mythos, by H.P. Lovecraft and others, features the Elder Things, who colonized the Earth two billion years ago and sowed the seeds of all advanced life on the planet. Among the many monstrous elder races of the Mythos, the Elder Things are portrayed as less alien and less inimical than most. They feature most prominently in Lovecraft's At the Mountains of Madness and are sometimes called the "Old Ones" (but that term is notoriously ambiguous in the Cthulhu Mythos). In The Whisperer in Darkness, the Mi-Go are hinted at being even older, possibly coming from outside the known universe.
In Larry Niven and Jerry Pournelle's novel Footfall, the aliens who invade Earth are actually at a caveman level of social development; the Forerunners left carved blocks on their planet which detail everything from simple metallurgy through advanced laser weapons and Bussard ramscoops. As a result, there are many technological paths they never even thought of.
In Larry Niven's Known Space universe, there are two sets of precursors. First there were the Thrintun (AKA "Slavers"), who seeded the galaxy with the ingredients of life so it would grow and evolve into unique delicacies for them to eat (being hypnotic slavers, they were defeated by the Tnuctipun in the inevitable Turned Against Their Masters, and they took all sentient life with them. Talk about bad parenting). Then there were the Pak, a race of more recent aliens with three life stages (child, breeder, Protector) only sentient in the third stage, and programmed to be homicidal to anything that could conceivably threaten their descendants (mutations were not recognized). Earth was a Lost Colony of them who couldn't advance to Protector stage when their supply of tree-of-life root ran out due to a lack of thallium in Earth's soil. They left behind lost colonies and random apelike animals all over, including the Ringworld, which they had built and abandoned.
Andre Norton worked with this trope in both her science fiction and fantasy novels. She wrote a lot of space opera novels featuring relics of various lost civilizations, collectively called "Forerunners". She was one of the early developers of the abandoned-gateway-between-worlds idea that the Stargate films and TV series are based on; one of her Forerunner cultures left behind such a network, which younger species, including humans, have started to explore.
In her Witch World fantasy novels, humans migrated to High Hallack centuries ago only to find that the Old Ones had been there before them; these Neglectful Precursors left behind quite a few ruins and dangerous artifacts.
Frederik Pohl's Heechee Saga set many of the standards for this trope. Humanity has stumbled on an space station abandoned by the local Precursors, the Heechee, and try to use the Faster-Than-Light Travel spacecraft left behind to search for alien artifacts to reverse-engineer. The destinations are pre-programmed and can only be accessed randomly, making exploration a dangerous crapshoot. Some of the survivors return rich; many return dead, if they return at all.
In the Carl Sagan novel Contact and the movie based on it, an unknown ancient race of aliens built the "cosmic subway system" of wormhole transportation used to bring a single human to meet the successor aliens who inherited the system.
In Charles Sheffield's Heritage Universe novels, the Builders left behind artifacts the size of planets — e.g. Cocoon, the first such artifact discovered by humans, was so named because that's what it looks like if you're far enough away from the planet it surrounds. A whole discipline of Adventurer Archaeologists exists to study Builder artifacts.
In the Strugatsky Brothers' Noon Universe series, the Wanderers may or may not be still active, but they fit this trope closely enough because the humans only ever find the traces of their continued and enigmatic work. They seem to be "progressing" the other civilisations, but their activities often enough utterly screw over local civilisations, though it might be for their ultimate good in some way anyway.
Iain M. Banks's Culture novels are practically littered with Precursors, numerous advanced civilizations that existed in aeons past until they variously died off, Sublimed, or just plain mysteriously disappeared. These Precursors are the Sufficiently Advanced AliensofSufficiently Advanced Aliens, since most of Banks' protagonists themselves belong to a civilization that can casually travel across the galaxy, build gigantic habitats in space, and use the fabric of the Universe itself as a weapon — and they are occasionally awed by the Precursors.
Every known non-human race in Andrey Livadny's The History of the Galaxy series can be considered a precursor, as four of them are at least 3 millions of years old, while several others are billions of years old. Humanity is the youngest known race, even though their technology level means they are strong enough to kick everyone else's backsides should the need arise. It helps that most of those races have long ago passed the peak of the civilization. In fact, two of them spent several million years as slaves, degrading their technology to the point where they forgot about their former greatness.
Ironically, the race that is actually known as the Precursors (or Forerunners, as there is no official translation to English) are non-sentient proto-lifeforms which have been created by an energy being (supposedly, the first being to ever gain sentience in the universe) to serve as seeds for its copies. The Precursors contained within themselves the first ever DNA molecule. The unintended side effect of this was the creation of all known organic life in the galaxy.
Sergey Lukyanenko's A Lord from Planet Earth series features the Seeders, mysterious ancient beings who have left highly-advanced artifacts, some of which are Black Boxes, while others are understood and adapted fairly well. They have also left mysterious spherical temples on every inhabited world (except Earth). It is eventually revealed that the Seeders are humans from the future, who have seeded their past with humanoid races and advanced technology to create an army to fight an extragalactic enemy (Earth was left undisturbed to avoid messing with history).
"The nameless, forgotten ones. Who knows? They have gone back into the still waters of the lakes, the quiet hearts of the hills, the gulfs beyond the stars. Gods are no more stable than men."
The Arisians feature predominantly in the Lensman series. As well being the ancestors of all species (save one), they devise a multi-eon spanning plan leading to the birth of the Children of the Lens. These five psychic superpeople will not only be able to help vanquish the enemy (a race of malevolent being hailing from another space-time continuum), but will grow in power to become greater then the Arisians themselves.
Subverted in many of the books and stories by Ursula K Leguin. The "Hain" are precursors who created humanoid life forms on many worlds (including earth), but they are still around and still a dominant species in interstellar society.
Steve Perry's Matador Series had the Zonn, a race that died out thousands of years before humanity achieved FTL. They didn't leave behind much other than interesting ruins on a number of worlds.
The Star Wars Expanded Universe has several features that are attributed to Precursor-like races. The two most prominent are the Rakata and the Celestials. The Rakata created the first modern hyperdrives, built a vast empire (though it had relatively few planets since their dark side-powered hyperdrives could only travel to worlds with a large Force presence) and created a massive orbital factory called the Star Forge which could build enough materiel to supply their entire empire. The Celestials lived much further in the past, circa 200,000-50,000 BBY. They created Centerpoint Station (a giant repulsor beam that created the Corellian system and is so advanced that a 25,000-year-old Galactic civilization cannot replicate or even understand how it works!) as well as the Hyperspace Triangle that bisects the galaxy (which makes galactic civilization possible), the Maw Cluster of black holes, the hyperspace anomaly that seals off the Unkown Regions and much more.
According to cut content from the 2012 Star Wars Essential Guide to Warfare the Rakatans wiped out the Celestials. Little is known about their biology but it has been confirmed that they were shapeshifters. and they're related to the Ones...somehow.
The Psalms of Isaak has three levels of this, each filling a different precursor niche. Earliest were the Younger Gods, who were so far in the past little of their works remain, but generally come off as Benevolent Precursors. They were followed by the Weeping Czars, Neglectful Precursors who are mainly remembered for bringing the third group down on the world. That would be the Wizard Kings, very much Abusive Precursors, though they still have worshippers in the present day of the series. The last Wizard King, Xhum Y'Zir, used a spell called the Seven Cacaphonic Deaths to devastate most of the world to avenge his dead sons, giving rise to the contemporary civilizations. The Younger Gods themselves were descended from the Elder Gods, who are hardly ever mentioned and so far into the past that they're little more than a mythical footnote, but are implied to be modern humans, or maybe our direct descendants (though Earth All Along is averted- the books are set in what is eventually revealed to be a Lost Colony, not Earth).
In Robert A. Heinlein's Between Planets we have the First Empire which originated on the Fifth Planet and which became the asteroid belt. Its ruins could be found on Mars and Venus and beneath the oceans of Earth. Don Harvey's parents were doing archaeological work in ruins on Mars while Don was at Boarding School on Earth. While its technology was not immediately viable, records left behind contained hints to a new physics that through difficult research led to 20 g spaceships and artificial gravity. The story gave the example of reading a treatise on modern electronics being written in Sanskrit poetry being lucid in comparison.
The Dolbrians In SA Swann's Terran Confederacy universe terraformed an unknown but large number of worlds, several of which still have star maps and/or megalithic artifacts on them. The Face on Mars is one such artifact. They vanished from the galaxy millions of years ago, for unknown reasons.
The "First Ones", who have all mostly emigrated "beyond the rim of the galaxy," although some remain lurking about in known space. Lorien, the "First One," is literally the first sentient being in the galaxy.
the Vorlons and the Shadows, which drive the main plots of the entire series, have meddled extensively in the affairs of younger races.
In an homage to Forbidden Planet, Epsilon 3 (the planet which Babylon 5 orbits) houses many super-advanced artifacts of a long-dead alien race.
the humans and the Minbari, who will become precursors to the future races, as shown at the end of Season 4.
Doctor Who sometimes paints the Time Lords like this. At the dawn of their civilisation, they sent a star supernova, and caged the resulting black hole to fuel their time travel. They fought several wars against other primordial races (notably the Great Vampires), driving them to virtual extinction. They were even worshipped as gods on at least one planet, until their technological gifts backfired, and they instituted a policy of non-interference. The Expanded Universe attributes the widespread presence of Human Aliens in the setting to them (offering multiple versions of the reasons why).
The unseen race (otherwise known as the Disciples of the Light) who caged the Beast also qualify. Bonus points for having done this before the beginning of time. Extra bonus points for the Doctor pointing out that this is both stupid and impossible. But that doesn't stop it from still being true.
The Eidolons from Farscape, who once controlled an entire galaxy through their power to induce "rationality and tranquility" in others before their near-extinction several millennia ago. For good measure, they are actually responsible for the creation of the Peacekeepers and the Sebacean race as a whole, having abducted primitive humans from Earth and altered them to act as bodyguards.
Subverted in the case of Farscape's Ancients, who, despite the name and their status as a Dying Race, aren't precursors at all. In fact, in spite of their impressive technology, they've actually gone out of the way to make sure that nobody knows about them unless absolutely necessary: this is because they were sent from another dimension to monitor the development of wormhole technology.
Red Dwarf postulates that all life originated on Earth; after three million years, there are many variations on sentient life — creatures descended from genetic experiments, animals that evolved into sentient humanoids, self-sustaining races of androids, "pan-dimensional liquid beasts," etc. etc. etc.
The Stargate Verse has no less than five different precursor races. The gate network itself was created by one such race, named (creatively) the Ancients, though they later are discovered to have called themselves the Anquietas (formerly the Alterans, later the Lanteans after the planet on which Atlantis resided). They eventually ascended and adopted a strict non-interference policy on the lower planes. The other side of that coin is the Ori, also ascended beings but with a very different policy; they are eventually revealed to have driven the Ancients from their home galaxy to the Milky Way. Also in the precursors category are the Asgard, Goa'uld, and Wraith. The Goa'uld use humans as hosts, and the Wraith farm humans as food, while the Asgard placed several worlds in the Milky Way under military protection from the Goa'uld.
Andromeda's lead character Dylan Hunt was a (half-Heavy Worlder-half-) member of a highly developed culture which was at the heart of the old Commonwealth. In later seasons, the series begins to pursue those "lost people" because of their amazing advancements which have since been lost, only to learn they intentionally closed themselves off from the outside barbarism.
They're actually Walter and Peter (mostly Walter) in a Stable Timeloop sending the artifacts to the different universes.
In Battlestar Galactica (Classic), the Cylons were originally a race of lizard people. They built robots to act as their servants, but the robots rebelled and wiped the lizard people out. Eventually, these robots ran into humanity. Humans have already been at war with these robots for a thousand yahrens when the series opens.
In the The Sword song, "Fire Lances of the Ancient Hyperzephyrians", the Precursors are humans from roughly the current era. After a presumably nuclear war screws up the planet, the survivors idiotically decide that they need to find and launch more of our missiles.
The Jimi Hendrix song "Up From the Skies" has an alien revisiting Earth after a long hiatus: "I have lived here before/ in days of ice/ and of course this is why I'm so concerned/ and I come back to find/ the stars misplaced/ and the smell of a world/ that's burning." Maybe a precursor,maybe not, but he'd been here a long, long time ago.
According to Loony Labyrinth, the ancient Minos were masters of time travel, genetic engineering, and other amazing feats.
In the Forgotten Realms campaign setting for Dungeons & Dragons, a saurian race ruled the world in the days when the world was warm. They are not entirely gone, though...
The reptilian creator race, the sarrukh, was only one of several races that dominated the pre-human Realms. Others included the dragons, the amphibian batrachians, the birdlike aeree, and the fey.
The Creator Race term is almost this trope. The exact listing is sometimes discussed, but the rule seem to be 'Precursor, and native to Abeir-Toril'. This means humans are a Creator Race (because at least some of them developed on Toril, and built mighty civilizations now gone), but elves aren't (they built mighty civilizations now gone before the humans did, but they immigrated from elsewhere first).
The rhulisti, or ancient halflings, were the first civilized race in the Dark Sun campaign setting; all other humanoid races are descended from them (including humans and giants), while those who retained their original form are now mostly cannibalistic savages.
Subverted in the Ravenloft setting: while many societies have legends about Precursors, it's all false history imposed upon the memories of natives, as their world's only a little more than four centuries old.
GURPS Space, includes Precursors as a potential element a Game Master might want to weave into his game world.
The Mnoren of The Fantasy Trip. Actually, the Mnoren are probably precursors of Precursors for the above two examples, given that TFT was published first and involved a lot of the same people.
The Old Ones in Warhammer (both fantasy and 40k) created most sentient races. In Fantasy they just left, never to return, but in 40k their backstory is given out in more detail. Apparently they had a massive, galaxy-shaking war with another old race, the Necrontyr (which later became the robotic Necrons), and created many races to help them fight. They (as well as most life in the galaxy) were nearly wiped out in the aftermath of the war, when the psychic disturbance caused by the massive amount of warp-fueled power used by them and the races they created caused the reality to tear apart and horrible creatures to spill through.
These may or may not be the same race, and the two collapses may be parts of the same event. The 7th edition Warhammer core book and Lizardman book hint heavily at this, and the 40k Necron book suggests using Lizardman models to represent the last refuges of the Old Ones.
The Warhammer world (un)officially used to be an isolated world in the Eye of Terror of 40k, but had been drifting from that idea for a while before Word of God revealed them to be separate but parallel 'verses (similar to the split between Warhammer Fantasy and Blood Bowl), sometime around '98. Of course, the references noted above are not the only hints: the Amazons of Warhammer have weapons left over from the Old Ones which bear a startling resemblance to wargear from 40k, not to mention Chaos champions with chainswords, and the second half of each volume of the in-universe Liber Chaotica
Iron Crown Enterprise's Spacemaster has the Sianetic Harbingers, a long dead (?) race of beings that seeded the Galaxy with humanoid life. They were powerful telepaths and had a level of technology that dwarfs modern Terran equipment. Their artifacts and ruins are both desired and feared.
Privateers campaign setting. The Architects seeded life on many planets 4 billion years ago and guided the evolution of the seven major races until quite recently, then disappeared. Very little is known about them in-universe.
The history of The Realm from the game TheSplinter stretches back 100,000,000,000 years and includes potentially thousands of precursor species/civilizations. This results in a tremendous range of (some very bizarre) Schizo Tech that can be scavenged by players.
BIONICLE toyed with this idea a lot, but eventually subverted it with the Great Beings: hailed in the story's early years as powerful, mythological figures responsible for creating the Matoran Universe and its creatures, but then moved to other projects, and chaos ensued. Later it was revealed that these Beings were a highly eccentric group of scientist governors, and can only be seen as the precursors to the Matoran Universe's inhabitants — whom they themselves viewed as expandable machines. Otherwise, they were just one of Spherus Magna's (the planet which they once ruled over) several species. They are also still around someplace, but are hiding, as the inhabitants of their world hated their guts.
The Remnant system in Achron (where the game largely takes place) has ancient alien ruins scattered throughout. The technology found in these ruins has become them basis of humankinds most advanced tech, most notably teleportation. The system is then invaded by aliens that use the exact same tech as those found in the ruins. And that technology includes Time Travel. Hmmm...
Assassin's Creed: The premise of the series' Meta Plot is that an advanced Crystal Spires and Togas civilization preceded our own, but was devastated by an apocalyptic event 75,000 years ago. This civilization was ruled by The Ones Who Came Before, a long-lived, hyperintelligent species that regarded humans as inferiors at best and slaves at worst, enforcing their rule with Mind Control technology. After the End, dying of underpopulation, they seeded the world with artifacts programmed to Fling a Light into the Future so that humans in the 21st century could save themselves from a recurrence of the same catastrophe. They also created Half-Human Hybrids in an attempt to pass on their "sixth sense" of "knowledge", which was only partially successful, but resulted in a line of humans who were able to interact with their artifacts and use their powers. Our concepts of gods, in this world, are distorted remembrances of The Ones Who Came Before.
In EVE Online,we are the precursors. We used the EVE wormhole to travel to the Galaxy of New Eden, but when the wormhole collapsed, so to did civilization in New Eden, and as new civilizations formed, their origins faded into myth and legend.
The Apocrypha expansion has given us a glimpse of some of the old technology which the precursor humans left behind: the sleepers. Ancient drone ships guarding long forgotten structures packed with technology that makes the most advanced player ships and weaponry look like we're using BB guns to fight enemies with nukes. The technology that has been scavenged so far has allowed the playerbase to build relatively small cruisers with the firepower and defenses equal to and even beyond battleships. It will be a terrifying day when we can finally build new kinds of battleships with sleeper tech.
The Zilart of Final Fantasy XI. A few of them still remain but most of them are relatively insane and/or genocidal. Only two Zilart favor the current civilizations at all, and one of them Ascended to a Higher Plane of Existence.
The "Ancients" from FreeSpace fit this trope, although for once we actually get a detailed history of their annihilation at the hands of the Shivans. (They recorded this so that later races would be warned not to piss the Shivans off... or, having failed that, would have some insight into the Shivans' weaknesses). The Shivans themselves qualify as Precursors in some respects: while not extinct, their technology is far more advanced than humans' and they've been that advanced for at least 8,000 years. There are Epileptic Trees both in-game and out about the origins of the Shivans (whether they were created as weapons by an even older race), and exactly how long they've been at their xenocidal mission (one character muses that there might be multiple Precursors extending far back in time, each annihilated by the Shivans when they grew too powerful and the later ones founding empires on the ruins of those that came before). None of this has been confirmed nor denied by the authors.
Bungie is fond of this. In most likely the earliest first-person shooter example of this trope, the Jjaro from Marathon were an advanced species that created the S'pht and left a host of technological artifacts on many worlds. They are considered by many to be mythical beings, but since All Myths Are True, Durandal does everything that he does in Marathon 2 to find them. In Marathon Infinity, their technology might be what's for responsible sending the player through different points in time and space to find a way to stop an Eldritch Abomination (which they had previously sealed) from destroying the entire universe.
In the Halo universe, the Forerunners are very much a precursor race, who believed that they held the "Mantle of Responsibility" for all life in the galaxy. All that's left of them are artifacts such as the titular "Halo" rings. They purposely destroyed themselves activating the rings as a last resort to prevent a traveling parasite called "The Flood" from consuming all life in the galaxy, but not before leaving measures for the reseeding of life afterwards. Oddly, humans seem to have a unique connection to them — much of Forerunner technology, including the Halos, can only be utilized by humans, and the major Forerunner installation on Earth is located in East Africa, right next to the area where modern humans are believed to have first evolved. This makes more sense when you realize forerunners were contemporaries of Original Man and are responsible for modern human's existence.
In fact, the Halo 3 terminals reveals that this connection was because the high-ranking Forerunner known as "The Librarian" felt that humans would the rightful "reclaimers" of the Forerunners' legacy. Later, The Forerunner Saga books add a twist to this by revealing that most Forerunners felt otherwise, due to a long and bloody war they fought with prehistoric humanity's own highly advanced interstellar empire, which was invading Forerunner space in order to flee the Flood and cleanse infected planets; it ended with the victorious Forerunners completely dismantling all traces of human technology they could find, devolving the survivors to a primitive state, and shoving them back to their homeworld of Earth.
In Halo 4, we find out that at least one Forerunner still survives; "The Ur-Didact", the former supreme commander of the Forerunner military, who also happens to be the Big Bad. The game also provide evidence, namely a speech given by the Ur-Didact in The Stinger, that there are many more Forerunners living outside of the galaxy, which was confirmed by the audio epilogue to Halo: Silentium.
The Forerunners believed that they inherited the Mantle from a long-gone race of even more advanced beings they called "The Precursors", who are revealed in the Forerunner Saga to have played a major role in the creation of both the Forerunners and humanity, among many other species. They ended up being almost completely annihilated when they tried to wipe out the Forerunners for being unworthy of the Mantle. Most of the survivors turned themselves into powder with the plan of eventually re-constituting their original forms, but they all Came Back Wrong and became the Flood. They then apparently decided to eliminate the Forerunners, "unite" all life in the galaxy, and test whether humanity was worthy of the Mantle... or maybe they just wanted their creations to suffer for all eternity. Either way, their technology (which seems to have been made of thought) was completely destroyed when the Halos were fired. The prisoner of Charum Hakkor, a scorpion-like creature with 4 arms and an impossibly ugly face, was a Precursor-turned-Flood-Gravemind, while the Forerunner Domain, a galaxy-wide information network, was apparently also a Precursor.
In the Neverwinter Nights community module series The Bastard Of Kosigan, the precursor race were early humans who lived on Atlantis, but after the natural disaster that resulted in its sinking split into the 'control' faction and the 'free will' faction. The 'control' faction, led by Gabriel, eventually won the ensuing war with the 'free will' faction, led by Elisa Than (read Satan, though she wasn't actually that bad). Their war was primarily fought by using their advanced technology to mimic deities and create religions among lesser humans, so the 'control' faction are the 'angels' of modern Catholicism (the game is set in approximately 1300, but with magic and monsters and such (the King of France has standing pacts with several red dragons)) while the 'freedom' faction became the 'demons'. Ironically, Jesus was actually manipulated by the 'demons' (and you even get to meet the 'demon' commonly known as St. John), and the 'angels' created the Catholic church to subvert his message.
Homeworld 2 featured the aptly-named Progenitors, who left behind various relics including several Wave Motion Guns which the player and the enemy fight for control of. One of the Wave Motion Gun ships gave its name to a deity that the current races have been worshiping for some time.
In Iji, the Komato are the ancestors of the Tasen, and, although it's not clear how close they are to humans, first evolved on Earth, leaving without a trace some time before the halocene period.
The Jak and Daxter franchise has an ancient race called "The Precursors". They leave deep-voiced oracular statues and various giant robots scattered about, and depict themselves as glowing Energy Beings, but that's just a Wizard of Oz act; they're really ottsels, otter-weasel things like Jak's sidekick Daxter. In fact, he becomes one because all eco contains their essence.
In The Legend of Zelda: Twilight Princess, the Oocca are suggested to be the Precursors of the Hylians — as one Adventurer Archaeologist tells us, the goddesses may have made the Oocca first, then the Oocca made the Hylians before retreating to the City in the Sky. Some fan-speculation surrounds these creatures, probably not the least because of their appearance: primitive harpies with ugly breasts and blue nipples! Many think that they originally looked a lot different than they do when Twilight Princess takes place, because it's very unlikely that the weird harpies we see are physically able to have made some of the stuff they're credited with making, such as the City in the Sky, the Dominion Rod, and the Sky Cannon.
And taken even further in The Legend of Zelda: Skyward Sword, where a race of Ancient Robots can be found in the Lanayru Desert. They are all old and worn away. Once you strike a nearby Timeshift Crystal however, it is revealed they are part of a civilization that takes place 100 years before the present. Their joints, and almost every single device within the premises is powered by electricity. This could justify where all of the Schizo Tech in the Zelda series originates from.
It has been said that this fact about the Oocca is a mistranslation, and that in the Japanese original they are said to have created Hyrule (the country), not the Hylians.
The Protheans in Mass Effect, at least until Dr. Liara T'Soni joins your party and suggests that they probably weren't the actual precursors. Turns out she's right, as the real precursors are the Reapers, which are robotic Eldritch Abominations that are out for everyone's blood. Though the Protheans must have been interested in early humanity, since as the big silver unexplained ball explains; the Prothean research station on Mars would routinely abduct and mess with early humans.Mass Effect 2 eventually reveals that the Collectors are genetically and cybernetically-modified Protheans. In Mass Effect 3, there is one Prothean still alive, named Javik, in suspended animation.
It's also revealed that the Protheans themselves had their own Precursor race to learn from. And so on, and so forth. Each cycle leaves something behind for the next one to find. The ultimate artifact appears to be the Crucible, whose construction started millions of years ago and was continued each cycle by a new race culminating in humanity (possibly) finishing the Crucible and using it to wipe out the Reapers.
The "Leviathan" DLC provided something new: the Leviathans (true name unknown) are the first species, the original intelligent life that preceded the Reapers. The Reapers were made in their image, and they have mental domination abilities that the Reapers used to create their indoctrination ability. They were the ones responsible for creating the Catalyst, and therefore are indirectly responsible for the Reapers. Their kind was harvested and used to create Harbinger, the first Reaper. A few of them are still alive, deep under the ocean on an aquatic world, where they have been hiding from the Reapers ever since the cycles began. Shepard can find them and convince them to give their aid in the current war against the Reapers.
In the Refusal ending, the contemporary major races fill this role - Shepard and everyone s/he cares about get killed or worse, but the records you leave behind prove vital in a future cycle, allowing them to defeat the Reapers.
In Metroid, although they raised Samus to adulthood and had extensive contact with faraway races like the Luminoth, Elysia, and even the Federation, the Chozo have vanished from all known space. Their entire legacy consists of decayed ruins, cryptic messages for Samus, and the odd upgrade module for her Power Suit. And, of course, the Metroids themselves.
In a less significant role, the Alimbic race fits this trope rather blatantly in Metroid Prime Hunters. They go extinct long before the events of the game containing the Eldritch Abomination Gorea in the appropriately named Oubliette. They are said to have created incredibly advanced technologies, including an "ultimate weapon."
The Ancients from the Might and Magic universe (at least when it was in the hands of New World Computing) were creating various worlds out of the four elements and seeding them with life as part of a great experiment. Their true agenda is never entirely revealed but there are hints that they had a specific outcome in mind for most of their worlds, before the Creators and the Kreegan interfered.
Between VI, VII and VIII, it was established that whatever their original agenda was, their current goal is 'Stop the Kreegans'. The settings of the games (and the novels) just happen to be in the galactic arm that was cut off from the Gateweb, and the Ancients are a bit too busy with the Kreegan to bother restoring it (especially as the cause of the breach was Kreegan infiltration of the gate network).
The Myst series of games gradually reveals that the long-lost civilization of D'ni was actually located on Earth; its founders originally came from an alternate universe, but they founded a city Beneath the Earth. However, the D'ni are not the ancestors of humans; the existence of a nearly identical race on the surface appears to be pure coincidence (although the Earth was specifically chosen because it was known to be hospitable to our kind of life).
Pac Man World 3 features the Ancients (possibly members or ancestors of Pac-Man's spherical race), about whose lives little is known, although their deaths comprise a well-known story 'of greed, of tampering with unknown forces, and of running and screaming and dying', to quote an in-game archaeologist. As it turns out, the Ancients were wiped out when they tried to siphon energy from the Spectral Realm (the Pac-Man universe's afterlife), which is exactly what the game's villain is trying to do in the present.
Appropriately for a series where ancient ruins are one of the most populous level types, the Sonic the Hedgehog series is jam-packed with different precursors, whose ancient weapons/relics/monsters set the stage for the world-threatening terror of the game. Interestingly enough, although absolutely all of them are shown to have possessed and utilized the series' recurring MacGuffins, none of them claim responsibility for creating any of the Emeralds. In Chronicles a race referred to as The Precursors.
In the Star Control games, there is a race explicitly called "The Precursors" which vanished but left behind many artifacts and installations across the galaxy. The wondrous second one is notable for containing artifacts and mysteries which are notexplained away with the Precursors. The third one attributes everything to them to the point of retconning previous reveals. The Precursors are heavily hinted to having created at least two of the major alien races in the game, namely the Mmrnmhrm, a race of robots supposedly built to terraform worlds in order to increase the potential for life, sentient life in particular, and the Mycon, genetically engineered fungus who were apparently designed to (or malfunctioned into a state where they) do the opposite: return lush planets to a molten and unstable state. The third game posits that they also left a race of robotic caretakers to make sure things stay orderly while they're gone, although yeah, fans really really don't much care.
In StarCraft the Xel'Naga, who created the Protoss and Zerg, take this role, although the reason for their disappearance is less mysterious than most, or so it seems at first. In the sequel and its associated books it is hinted that they aren't really gone, and they might well make a return before the end of Starcraft 2. Oh, and there's an Eldritch Abomination out there that hates their guts, wants to Kill 'em All and destroy the Universe.
It's worth noting that these beings are actually surrounded in a lot of myth. The Protoss, for instance, seem to think they were judged unfit by the Xel'Naga and were abandoned. In truth, the Xel'Naga were simply done with them, and moved on to create another species. Also, it seems that engineering life is part of their reproductive cycle, where two of their creations unite to give birth to a new Xel'Naga iteration. In addition to this, it's unclear if these guys were just Sufficiently Advanced Aliens or bona-fide Physical Gods. Multiple references are made to their "forging the stars" and managing "the cycles of the Cosmos".
The Star Ocean series plays with this trope. The games are filled with Out of Place Artifacts, mystical technologies such as the time gate on the apparently sentient planet Styx, and near the middle of the third game, there's even a precursor-like group of beings called the Executioners who rain havoc upon ALL the races of the galaxy. It turns out that the universe is actually a video game called the Eternal Sphere, and all the Precursor like artifacts, including the Executioners, were planted by the programmer.
They're basically debugging tools and easter eggs, Styx basically works like the mother of all hearthstones.
Still worse, the pre-release information for the sequel suggests strongly that the Liir didn't finish the job.
No. No they didn't.
The Thief series has the long-gone civilization from the ancient ruined city of Karath Din (a.k.a. "The Lost City"), which is known only under the colloquial moniker "The Precursors". The environments of their ruins and various readables imply that at least part of The City's society and technology has very early roots in the survivors of this bygone civilization. Most of the details on the reasons behind the Precursors' demise are deliberately left open to speculation, given the series' elliptical approach to revealing the history and inner workings of its setting. One of the more notable facts revealed is that the Precursors had much more sophisticated technology than does the present-day civilization, in a way. To quote the Keeper faction's opinion on the Precursors :
When we looked at the relics of the Precursors, we saw the height civilization can attain.
When we looked at their ruins, we marked the danger of that height.
— from the Keeper Annals
Warcraft lore features the Titans, who ordered all the worlds in the universe and seeded them with life, then left to go pursue their unimaginable goals, leaving all kinds of stuff behind. One of them, Sargeras, is also the Big Bad of the mythology. There are strong hints throughout the lore that they may be coming back some day (possibly in a future expansion).
Averted somewhat since the Titans still hang out and occasionally interact with mortals. Borders on a case of Redundant Researcher since there are multiple groups (mostly Dwarves) studying Titan relics and artifacts in an attempt to figure out their history, meanwhile players in Northrend interact with actual living Titans on a fairly regular basis.
Chris Metzen has said during an interview "Will we see actual titans one day?", implying that what we see in Northrend and Uldaman aren't actually titans. He said that what we have seen are just constructs built by them.
Also fitting this, yet to a less extent, are the ancient Night Elves: They were ruling the whole supercontinent, fought off any competing race and had access to unlimited magic - until they attracted the Burning Legion, which resulted in the Sundering, destroying most of their race, a huge part of the continent, and pretty much all of their magic-based civilization. Their ruins are still everywhere to be found and, of course, contain most powerful artifacts.
Even before the Night Elves were the trolls who, while being less advanced than most other races, built gigantic cities and temples that were abandoned after the Night Elf takeover. Modern trolls live in these ruins today, worshipping their ancientry, but unable to achieve their greatness - the ancient trolls are their own race's Precursors.
Of course, it's worth noting that a large number of the ancient night elves are still around and active today, including their leaders Tyrande and Malfurion. The race only lost their immortality within the last decade.
In the anime series Twilight Venom it was revealed that the precursors were from Earth, but left due to the annoyance of Random Encounters.
The Steltek, from Wing Commander Privateer. Arguably they were Precursors of the neglectful variety, though they did make an effort to clean up after themselves once made aware of the problem.
The as-of-yet unnamed race from Sins of a Solar Empire who built the Phase Jump Inhibitors and, presumably, the other obtainable artifacts.
The Ancients from Panzer Dragoon qualify, having made many, many technological breakthroughs, most notably the many, many Towers, the drones to control them, the dragons to protect them, the monsters the Towers create to sustain the environment (or so Craymen claims), and Sestren to tie it all together. And then they conveniently vanished, leaving virtually nobody who understands any of the crap they left lying around, just that it's powerful and needs to be reclaimed. Of course, the Towers keeping the environment in its status quo means removing any factor that could be a detriment. Including humans, should they overpopulate. Thus, the Ancients are kind of the reason the series takes place in a Crapsack World. It's never really stated what the true nature of all of the above is, really, just that it's bad and you have to stop it (which you ultimately do in Saga, leaving it on a somewhat triumphant note - and then in Orta, it's implied that the consequences to the environment afterwards were hardly worth the effort).
Star Trek Online - It's quite likely the Iconians are being built up as the precursor race; the scant few times they are seen, they disable your ship completely to demonstrate their godlike power, and later they obliterate Borg cubes effortlessly. Demons of air and darkness, indeed.
At the end of the Deferi/Breen story arc, the Ancient Humanoids/Preservers are revived and decide to once again explore the galaxy and meet their descendants, making it one of the few cases where the Precursors come back.
In The Elder Scrolls, there are both the Dwemer in Morrowind, and the Ayleids in Oblivion, as well as many others in lore. The Dwemer were technically advanced (enchanted steampunk-style tech) whose reasons for disappearance can be put succinctly as being a race of atheists in a universe where godlike beings are very much real (that and they had a penchant for futzing around with the inner workings of Existence). The Ayleids were wiped out in a much more mundane way: a combination of societal hubris, heavy political infighting, a belligerent neighboring nation to the north, and a slave revolt supported by said belligerent northward neighbors (which possibly had divine backing as well).
The Dunmer, a.k.a. dark elves, were formerly the Chimer, enemies of the Dwemer. They were transformed either as a curse from the Daedric Prince Azura for the Tribunal's betrayal and murder of their leader Nerevar, or as a result of his generals' use of the heart of a dead god to become physical gods.note The lore is intentionally conflicted on this point, so we'll likely never know the real reason. The only remaining images of Chimer are the aforementioned Tribunal of Morrowind, who appear as Chimer (well, two of them).
The Snow Elves, who originally ruled Skyrim. After the arrival of the Nords, they were driven deep underground and sought refuge with the Dwemer, only to be betrayed and enslaved, leading to their devolution in the mindless and feral Falmer. The Dawnguard DLC for Skyrim reveals that some of the Snow Elves survived this and took refuge in hidden sanctuaries, only to be later massacred by their feral cousins, leaving only one survivor.
Valkyria Chronicles has the Valkyrur, a now extinct (mostly) race who learned to weaponize Ragnite and who possessed weapons with seemingly magical abilities that can't be replicated by modern science. Although not the first humans, all non-Darcsen inhabitants of Europa are descended from them and they are credited with starting the proto-civilization from which all others on the continent grew. Many people even worship them as gods. It turns out they were kind of dicks.
Luminous Arc 2 has the Navillian race, who had advanced knowledge in magic and were the ancestors of humans and witches/wizards. 4,000 years ago, a catastrophe ended their civilization and it is believed that the modern world rose from their demise.
In the space stage of Spore, you can purchase "Monoliths" which, when placed upon a planet with life at any stage of development, will cause that planet to develop quickly to the space stage, and gives you a relationship bonus with the resulting empire. Of course, after that you're free to do whatever you like to the poor guys, including conquering their cities by force and enslaving them to extract the planet's resources for your own empire's benefit.
Your planet can be visited by spaceships earlier in your own development, although they rarely do more than abduct a member of your pack or a livestock animal.
The Grox empire, which is violently opposed to your existence by default. They occupy 2400 systems around the centre of the galaxy, guarding the Galactic Core itself, which contains a robotic member of an unknown race (possibly from Earth). His name is Steve, and he gives you the most powerful terraforming tool in the game, although it is limited to 42 uses.
The Orions and Antarans in the Master of Orion series fought a hugely destructive war which led to the Antarans becoming Sealed Evil in a Can, and the Orion homeworld abandoned and protected by the enormous Guardian of Orion. Also, some planets have Artifacts property — contain ruins of ancient civilizations, which boosts local scientists' performance; races with "Artifacts World" have one of these as the homeworld.
The Eridians fill this role in Borderlands. They had created an incredibly advanced civilization on the wasteland planet Pandora, but it all mysteriously vanished millenia before the game's events. Remnants of their civilization are all over the place, and simple artifacts of their technology hold immense power. But by far the most legendary aspect of their legacy is The Vault, a container for...something, no one really knows what, that is the most sought after power on Pandora. The Vault is revealed to be the Tailor-Made Prison for The Destroyer, an Eldritch Abomination which nearly wiped out the Eridians. They sacrificed everything to contain The Destroyer within The Vault, leaving "Guardians" to ensure that no idiot would open the vault and cause the apocalypse. Itdoesn'twork...
It's noted that the various corporations' interest in Pandora is due to alien relics being found on a different planet nearby, so either the Eridians were space-faring, or there is more than one Precursor civilization.
According to Journey's confluences, the White Robes are implied to be this to the Red Robes.
The world of Mega Man Legends features robot-human creatures similar to the Reploids of earlier series. Too bad they're (mostly) under the Kill 'em All directive of the vast computer system that controls them.
In Galactic Civilizations II, the unimaginatively named Precursors and their enemies the Dread Lords (who have become Sealed Evil in a Can). The campaign in the original revolves around you fighting the latter, and if the player is unlucky enough to encounter them in a standard game...
According to the game, the "Precursors" mentioned above are called the Arnor, and were the antipode of the Dread Lords.
There are also the mysterious Mythrilar, a group of five immortal beings that were precursors to the Arnor and Dread Lords (indeed, they created the Arnor and Dread Lords). What happened to them is unknown, although it is known that one of them, Draginol, was a time-travelling ascended human.
Vega StrikeBack Story has the Ancients, "Those Who Have Only Names" (species Ancients' records mentioned) and later "Alphan and Betan". They left lots of ruins, their "lab monkeys" who now rob blind everyone else for access to the best of said ruins, and... the nano-plague that breaks nanomachines, but ignores most lifeforms and non-construction nano scale devices.
The Remnants of Star Ruler, leftovers of a now-fallen space empire. At the start, their small ship fleets are better than anything you'll have, and even if you can blow through those, they have even better (and bigger) ones. Fortunately, Remnants are content to guard systems without acting aggressively. The Galactic Armorymod makes the Remnants much more aggressive, making them send out routine missions to cull the lesser races, using even more powerful ships than in the base game, and the Remnant will keep pace with the player, causing them to eventually start sending planet-sized ships to cull systems.
Ultimately subverted in Galaxy Angel at no surprise to the viewer but the Precursors who created all the lost technology used in the games come from Eden, another name for Earth. Which makes us the Precursors and the people in the game merely our descendents.
The Kingdom of Zeal in Chrono Trigger which in 12,000 BC (during the Ice Age) built floating cities in the sky and an "Ocean Palace" under the sea. Their civilization was powered originally by the Sun Stone (which harnessed solar energy) and then by the more abundant (but of course, more dangerous) Mammon Machine which extracted energy from Lavos the Big Badfrom outer space.
In four of the six mission strings, humanity ascends and becomes precursors in turn to an unnamed alien race.
There are the Solon in Haegemonia: Legions of Iron. You only really find their starbases protected by advanced defenses, which can blow up any ship you have. Presumably, they're meant to hold off their ancient enemies. Once you manage to get past the defenses, though, you get some nifty technology, which helps in your own war against a powerful enemy who turns out to be working for those who have wiped out the Solon. Despite the name, the Expansion PackThe Solon Heritage doesn't explain anything, since it lacks a campaign mode.
In Ascendancy Xenoarchiological Ruins pop up all the time, sometimes giving access to a technology far up the Tech Tree, though these are not always useful without adequate advancements in production capability and/or power sources.
Disturbingly subverted in the first Star Flight. "The Ancients" were thought to be a race that left behind several artifacts and ruins. However, it's later revealed that they are unlike any other form of life, in that they are in fact sapient crystals. Modern civilization has been using these crystals as the fuel Endurium, and in self-defense "The Ancients" began causing stars to flare, setting the game's events in motion.
In the Furry WebcomicJack, the furries that currently live on Earth are the descendants of furries created in a lab by humans, making humans the Precursors. They were wiped out in a war started by the first furry, Jack. The furry version of the United States government knows about furrykind's origins, and is (probably wisely) keeping it a secret.
In Unity, the creatures living in the ship are all distant descendants of Earth life. Humans built the ship, but disappeared long ago.
Homestuck: Turns out that universes are created by sessions of Sburb. And the trolls created ours.
The Cyantian Chronicles have at least two species, the Rumuah who created the Cyantians as servants and heirs, than died out from a genetic disease. And the "Squids" who came along centuries later and enslaved the Cyantians, until Alpha Akaelae led a successful rebellion and wiped them out.
Open Blue has the Iormunean Imperium, a once glorious empire that prospered thanks to their goddess. When a new religion started encroaching on the fringes of the empire and the local Church Militant did nothing to stop its growth, aforementioned goddess turned her back on them while they were in the middle of a war with invading barbarian hordes. Suffice to say, it led to their destruction, and their blessed weapons and artifacts being scattered across the world for the present nations to search for.
In Orion's Arm abandoned ruins with highly advanced technology are considerably more common than living aliens with technology even close to the level of Terragen civilization. Many find this somewhat disturbing.
Not that there's any evidence any of them made it to Old Earth mind you.
In Gargoyles, the First Race, while never directly referred to in the show, has been revealed by Greg Weisman to have preceded the Three Races.
In Shadow Raiders, a mysterious race created world engines (if not the planets themselves). This allowed the natives to not get consumed by the Beast Planet. One has to wonder who they were and why they did it.
Real Life and Mythology
Older Than Feudalism: Atlantis was first recorded by Plato, and may be an allegory he dreamed up to serve his conception of a utopian society by providing it with an enemy. Another possiblity is that the legend of Atlantis grew out of stories about the civilization on bronze age Crete, long before classical Ancient Greece. Another candidate is Santorini, a small group of islands off the coast of Crete with the ruins of a city buried in volcanic ash. About 3,600 years ago it was one big island before a huge eruption blew it to bits.
Theories on the origins of Atlantis are far ranging and include everything from islands in the Mediterranean to the continents of North and South America. Proponents of the latter theories, however, are not taken seriously because no such civilisation could have existed and left zero trace or record of its existence whatever.
Medieval and Renaissance Europeans often thought of the Roman Empire this way. Adventurer Archaeologists in Central Asia often thought of the various Silk Road Civilizations this way, too. Similarly, the early Iron Age civilizations of Greece, Anatolia and Mesoptamia which emerged after the Bronze Age collapse and subsequent "Dark Ages" viewed their predecessors as such, most notably the awe in which the Hellenic Greeks held the Mycenaeans.
One serious solution proposed for the Fermi Paradoxnote in brief: The universe is at the very least not hostile to life, and it's big enough and old enough that we humans shouldn't be alone, so why haven't we encountered any other intelligent species in some way? is that we humans are the Precursors — we are the first intelligent race. Or at the very least, our elders are too recently emerged to have expanded universe-wide yet. If this is true, uncounted billions of civilisations are depending on us not nuking ourselves or sinking to pre-industrial levels via climate change and resource exhaustion. No pressure.
Well if we're going to continue chances are we'll have to keep using, you know, resources. When we run out of the ones we have now we'll simply find something to replace them with e.g. power from tokamaks and petrochemicals from artificially selected bacteria after oil runs out just as we went from creating light from whale oil, then kerosene, then filament lamps and probably very soon LEDs. If anything pushes us back into the Dark Ages it will almost certainly be an ideology. And that will be a problem for humanity long after oil has run out. So even less pressure.
Not necessarily. Orson Scott Card makes a good point in Pastwatch: The Redemption of Christopher Columbus that, if your civilization uses up all the easily-available resources and then manages to destroy itself, then any humans who survive will be unable to get past Stone Age and will never become a global civilization again.
The mysterious Indus civilization (Bronze Age) reached levels of technology, health and urbanism not reached again until the Middle Ages (in India) or later.
Believed by some to be the source of the story of Atlantis, Santorini was an island city-state near Greece. They were very advanced compared to their neighbors, even possessing indoor plumbing, but were destroyed in a volcanic eruption. Many of their developments not seen again for centuries. Alternately, Ancient Phoenician-influenced Sardinia could count. They had iron weapons, conquered Italy and southern France, and had huge stone fortresses long before the middle ages. The end of the Sardinian civilization also coincides with an eruption of Vesuvius, plus the geography and political state of the island could match the description.