Javik: A 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 usually disgusted by what has become of their followers when they return. Often done with Ancient Astronauts.
- Lyrical Nanoha: The Saint Church 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 long-extinct Protoculture as divine beings. Said Protoculture were responsible for the creation of the human race.
- Macross Frontier indicates that the Protoculture themselves deified to some extent the insectoid Vajra, to the point where a good chunk of Protoculture technology was made in imitation of the Vajra.
- In Spriggan, the Mexican gods (especially Tezcatlipoca) are worshiped as Aztec gods when they first arrived on Earth as Ancient Astronauts.
- The Shadow Wars: 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.
- Chariots Of The Gods?: Discussed via thought experiment. 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.
- The Culture: 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.
- Footfall. The alien Fithp 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.
- Nexus Nine:
- Dogs tend to worship humans as the "First Ones". Rheun is understandably reluctant to tell dogs that they were human in prior lives, and octopi before that.
- The Aviorans worship the builders of the Nexus near their homeworld, or "Sky Nest" as they call it, whom they refer to as "the Unhatched".
- Uplift: Most of the patron-lines 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.
- Angel: Knox worships the Old Ones and brings about Illyria's resurrection.
- Farscape: In "Jeremiah Crichton", the indigenous people worship 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.
- Stargate-verse: In Stargate SG-1 and Stargate Atlantis, the long-ascended Ancients are sometimes considered to be gods. They don't really care that much, but their evil counterparts the Ori demand worship. The majority of deities worshiped on Earth turn out to be Goa'uld or Asgard Ancient Astronauts, but both species are still on the material plane.
- 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.
- 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.
- Pathfinder: The Morlocks worship their Azlanti ancestors as gods, and treat the ruins of the cities as holy places.
- Pugmire: The predominant religion of the dogs is the Church of Man, who believe that Man uplifted dogs to be their faithful companions before they ascended to another plane (what actually happened is left ambiguous) and Good Dogs who follow their tenants will join them in the afterlife. Mainstream cat belief is very similar, but beyond substituting "dog" for "cat" differs in one key detail: they place the humans in the role of the uplifted faithful companions to the cats (faithful up to whatever caused them to disappear, at least). Understandably, there is some religious tension between cats and dogs.
- Traveller: In 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.
- Warhammer: The Lizardmen worship the Old Ones, who created the world and try to carry out their plan for the destruction of Chaos.
- Warhammer 40,000: It's all but stated that the Adeptus Mechanicus' Machine God is in fact worshiping the Void Dragon, a C'tan star god who was imprisoned on Mars long ago.
- Assassin's Creed: Those Who Came Before 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 Conduit: Most human gods are actually aliens from another planet, and some of them ruled ancient empires such as Babylonia and Rome.
- The Covenant is a coalition of species united in worship of the Forerunners (theoretically). 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.
- 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.
- 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. And the Reapers are actually offended... though they're not above putting the heretics to use as goons.
- 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 and agriculture, and gave them biotic powers through genetic engineering. The oldest depictions◊ of her do look rather suspicious.
- At one point in Mass Effect: Andromeda, Ryder hears about a cult on Kadara who worship the Remnant tech. Since the Remnant 'bots tend to attack anyone who come near them, you can guess how that works out for them. Meanwhile, an unseen race is said to also have worshiped the Remnant, but with less directly fatal results, until the kett came along.
- 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.
- The Xel'Naga began a series of experiments 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.
- Sword of the Stars: The Zuul worship their Suul'ka creators and are determined to find them. In Lords of Winter, they succeed.
- Wildstar: The Eldan came to Cassius and created a human-Eldan hybrid named Dominus, who became the Emperor of Cassius and the following Dominion. The Eldan then vanished. Hundreds of years later, the Vigilant Church deifies the Eldan and makes Dominus and his children saints, while keeping watch for the gods to return.