Javik: Pity we did not teach them to speak better.
So, an untold number of years ago a civilization with incredibly advanced technology arose, then for whatever reason vanished into thin air. But what happens when a younger race comes across their incredibly advanced technology or other signs of their presence? Often, religion.
If the adherents come across the name of one or more of the Precursors they will specifically invoke those names. And construct a pantheon if they discovered more than one.
Finding the ancient race is a frequent goal of these people, woe betide anyone who gets in their way.
It's not uncommon for such peoples to adopt the tech of their "gods".
Bonus points if the Precursors actually did create the species that worships them.
If these Ancient beings turn out to be still around Abusive Precursors tend to use these cults as pawns, if they didn't set them up themselves. Neglectful Precursors are often somewhat annoyed by them if they even bother to take notice. While Benevolent Precursors sometimes set up cults before leaving, then are disgusted by what has become of their followers when they return.
- The Saint Church in the Lyrical Nanoha franchise worships the last Saint King of Ancient Belka, a civilization that warred itself into non-existence about a century ago (it would have lasted longer if said King didn't put it out of its misery).
- In Macross Zero, it's suggested that the natives of Mayan Island in the Pacific worship the Protoculture, now extinct, as divine beings. They were also responsible for the creation of the human race.
- Also, the Protoculture worshipped (or at least admired) and tried to uplift themselves to the level of the Hive-Mind Vajra. They failed. Horribly.
- In Spriggan, the Mexican gods (especially Tezcatlipoca) are worshiped as Aztec gods when they first arrived on Earth as Ancient Astronauts.
- In Jordan 179's My Little Pony: Friendship is Magic world of the The Shadow Wars storyverse, the Cosmic Concept of Fusion fairly obviously created the Ponies, as shown in Alicorn Genesis. Later, she incarnates as physical goddess Epona Amaterasu the Sun Mare and still later as the similarly empowered Princess Celestia. In both cases she winds up worshipped by the Ponies, even though as Celestia she doesn't tell them anything about her role in creating their species. Ironically, by the time she becomes Celestia she prefers very much ''not'' to be worshipped, wanting instead to be treated as a normal Pony — which is difficult because she crafted the Alicorn form for equine hyperdominance.
- Most of the patron-lines in the Uplift universe act like the mythical Progenitors that began the whole uplift tradition were gods. With many interpretations of why they vanished and resulting wars. Some of humanity's worst enemies are those who believe the Progenitors will return to cleanse the galaxy of "impure" species like those uppity wolflings in Earthclan.
- Footfall. The alien Fithp (AKA "Snouts") gained all of their scientific knowledge from artifacts left by the Predecessors, a race that lived on their planet long ago. The Fithp worship the Predecessors as deities, with priests studying the artifacts to gain more information.
- In Grand Central Arena, the Faith worship the Precursors who built the Arena as gods.
- Discussed via thought experiment in Chariots Of The Gods?. von Daniken postulates a world where much of civilization has been destroyed. The older generation tell stories of how it used to be to their children, who write it down. Each story begins with "My father tells me..." After a few generations the context of "My father tells me..." is lost, and new translations/editions of the collected stories of the fathers use "My father says..." and eventually "Our Father says..." promoting the first generation to virtual (if not actual) godhood.
- In The Culture Series, Oct consider themselves the true inheritors of the Veil, a precursor race that left abandoned worlds around the galaxy, in a way that seems religious but it's difficult to tell due to the Oct being incomprehensible. Other races know this to be factually not true and consider the Oct to be somewhat pathetic. There are other races with similar aspirations such as Aultridia, which the Oct absolutely despise.
- In Stargate SG-1 and Stargate Atlantis the Ancients are sometimes considered to be gods. They don't really care that much, however their evil counterparts the Ori demand worship. Not to mention that pretty much every ancient pantheon worshiped on Earth were actually aliens, though most of their species are still extant.
- An individual example of this was Knox on Angel, who worshipped the Old Ones and brought about Illyria's resurrection.
- In the Farscape episode "Jeremiah Crichton" it turns out the indigenous people worshipped the Hynerian Dominar who left them on that planet, and since Rygel's a descendant of their "god" they bow down before him on sight.
- The Lizardmen of Warhammer worship the Old Ones, who created the world and try to carry out their plan for the destruction of Chaos.
- It is all but stated that the Adeptus Mechanicus of Warhammer 40,000 who keep humanity's machines running are in fact worshiping the Void Dragon, a C'tan star god who was imprisoned on Mars long ago.
- In Myriad Song the Remanence reveres the Syndics and eagerly await their return, seeing how they are ruled by descendants of their genetically modified slave overseers.
- Classic Traveller supplement Alien Module 8 Darrians. The ancestors of the Darrians were moved from Earth to their new planet by an Ancient named Onsorik. Not surprisingly they worshipped him as a god and passed down legends about him to their descendants.
- Hollow Earth Expedition. Thousands of years ago the Atlanteans were masters of the Earth. They reached heights of technology so advanced that modern day scientists can't understand them. Before they disappeared, their human followers considered them to be gods and built temples to worship them.
- In Rocket Age the Martians worship the Ancients, their far more advanced ancestors.
- The Covenant of Halo are a coalition of species united in worship of the Forerunners (theoretically). Too bad they also believe that humanity's very existence is an insult to their gods. They also mistakenly believe that the Halos will lead them to where the Forerunners ascended to; they're actually superweapons that can destroy all complex life in the galaxy.
- The Forerunners in turn quasi-worshipped Precursors, who, as it turned out, both had a direct hand in their creation and more than earned the respect they were given in terms of technology and might. Unfortunately, while their motives and psychology are far too alien to truly grasp, from a mortal perspective they were very much Abusive Precursors.
- In Sword of the Stars the Zuul worship their Suul'ka creators and are determined to find them in Lords of Winter they succeed
- In Mass Effect:
- The Hanar believe the Protheans (whom they call the "Enkindlers") uplifted their species millenia ago. As seen in the page quote, Javik, the last Prothean, isn't impressed.
- And the heretic Geth worship the Reapers of course they're still around
- In Mass Effect 3, when the temple of the ancient Asari goddess Athame is seen, Javik claims that she was a Prothean who taught the Asari mathematics, agriculture, and gave them biotic powers through genetic engineering. And the oldest depictions◊ of her do look rather suspicious.
- The Cassians of Wildstar believe that they were chosen by the Eldan to rule the Dominion as a shining example of strength and leadership... for the rest of the pathetic vermin that infest the galaxy.
- Those Who Came Before/The First Civilization from Assassin's Creed were the inspiration for divine worship in many cultures after creating human beings in their image. They were the first Etruscan gods along with inspirations for many other pantheons.
- The Xel'Naga began a series of experiment on the Protoss to speed their development, eventually revealing themselves to their subjects. For a time, the Protoss revered the elder race as gods, but began to grow suspicious of them after time, ultimately resulting in a war that drove the Xel'Naga off the Protoss homeworld.
- The Tal'darim splinter faction continue to worship the Xel'Naga, viewing any interference with their sites as desecration. Specifically, the fallen Xel'Naga Amon.
- In The Conduit and the Conduit 2, it's revealed most of the human race had worshipped the gods, who are actually aliens from another planet. And some of them have ruled ancient empires such as Babylonia and Rome.
- Jak and Daxter: The Precursors are revered as divine god-like beings by many of the inhabitants of Jak and Daxter's universe. This makes The Reveal of them as Ottsels, like Daxter and later, after being "blessed with the gift of evolution", Veger, quite surprising and humorous.
- Shin Megami Tensei IV gives off a negative faith in Precursors; Mikado was founded by literal angels who destroyed the world for being a little rebellious, and then built a nation from children stolen from their parents, so having the masses worship the precursors is the last thing they have in mind. The Precursors are reviled (though some sects of the church secretly harbor a Cargo Cult fetish). This goes well for about 2,500 years, but then someone from the ruins of Tokyo decides "fuck em all to hell" and starts handing out specialized books made during the last days that Tokyo saw the sun, which turn humans into demons by simply reading. Naturally, people start to fear the "unclean ones" for their forbidden magics and demon-worshipping lifestyle. It's just post-renaissance literature. And Tokyo is still alive and kicking.
- Wildstar: the Eldan came to Cassius and created a human-Eldan hybrid named Dominus, who became the Emperor of Cassius and the following Dominion, then the Eldan vanished. Hundreds of years later, the Vigilant Church deified the Eldan and made Dominus and his children saints, while keeping watch for the gods to return.