Precursor Killers

These people are the reason why the precursors aren't around anymore. Either it is because their technology is so much more advanced than the precursors, or they were just so numerous that the precursors couldn't keep them at bay forever. Expect some sort of Lost Superweapon to be found that the precursors weren't able to finish in time to stop the Precursor Killers.

Often this is a Sealed Evil in a Can that was somehow stopped with the last actions of the precursors. Compare Abusive Precursors and Turned Against Their Masters.


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     Fan Works  

  • In With Strings Attached, the four are told that the invading Tayhil wiped out most Baravadans hundreds of years ago, an event that gave rise to the current skahs/tirin anarchistic civilization.
    • In a twist on the theme, the last known Tayhil were killed only about ten years ago, and the skahs want them back because they're going crazy with boredom now that they have nothing to fight.


  • Transformers: Revenge of the Fallen has The Fallen as one of the first Transformers, the Primes. He killed his brothers in a mad quest for power, but they managed to hide the artifact he was looking for and seal The Fallen away for a time as they all died. As it turned out one Prime escaped his view, Optimus.


  • The entire tragic backstory of the elves in the Deverry series is originally based on a bunch of dimensionally travelling gauls entering a different world and setting off a chain of displacements the end results which brought down the elven civilization.
  • In the Priscilla Hutchins series of Jack McDevitt's novels, every major nonhuman society has disappeared but for a smattering of artifacts left around the galaxy. It turns out that regular waves of comet-like "Omega Clouds" from the galactic core spread out to find and impact with any collections of large, regular, non-naturally-occurring shapes they stumble across — in other words, cities — thereby ending any civilization they encounter.
    • Two characters separately reach the same conclusion about the Omega Clouds' possible purpose, once it's discovered the clouds contain a device that can detonate them in a supernova-esque explosion. They're art. And the galaxy is the canvas for a series of coordinate explosions that will all be visible simultaneously from someone looking down on the Milky Way due to the speed of light. Attacking alien civilizations is a bug, not a feature.
  • In Frederik Pohl's Heechee Saga series, the Heechee had hidden themselves away within Black Holes to avoid the attention of the Kugel (better known as "The Foe" or "The Assassins"), a race of energy beings that regularly wiped out emerging species. They eventually emerge because humanity is on the verge of getting the Assassins' attention.
  • The Inhibitors of Revelation Space were responsible for a lot of dead aliens.
  • It's sort of a toss-up who you'd call the precursor and the precursor killer in Larry Niven's "Known Space" series. The Slavers (aka the Thrint) were a species of beings capable of psychically forcing any other life form to do exactly what they wanted. They weren't total idiots, but neither were they terribly clever, since once they made contact with other species, they had those other species do the thinking for them. The tnunctipun were the master technologists, but most of the artifacts from the Thrint era of the galaxy belonged to the Thrint rather than their tnunctipun slaves. When the inevitable war broke out, the Slavers' final act was to use a psychic amplifier to project the command "DIE!" to everything in the galaxy, killing everything sentient. So even though the Slavers are often billed as the precursors, they are themselves technically the ones who pulled the trigger.
  • The eponymous Berserkers obliterated both sides of the war they were created to end and continued to scour the galaxy of life.
  • The History of the Galaxy has two examples, although they're not 100% true to this trope, since the actual Precursor races are still around, while their killers aren't (yet). The Forerunners are a race of non-sentient Planet Eaters made up of proto-matter (in fact, they're biological machines created by an Energy Being whose "programming" got messed up by a nova) who are responsible for the complete destruction of the Delphons (the only Precursor race to completely die out) 3 million years ago, forcing the Insects and the Logrians to flee their space (inadvertently causing their enslavement by the Harammins). The much more ancient Evolgs and Emulotti were attacked by an expansionist race called the Shvergs billions of years ago. The Evolgs, being Energy Beings, helped the Human Alien Emulotti Ascend to a Higher Plane of Existence, while their worlds were bombarded from orbit. The latest novels (going by the in-universe chronology) have the Evolgs, the restored Emulotti, the freed Logrians, and some of the Insects joining the human Confederacy of Suns as equal members.

     Live Action TV  

  • The Ori of Stargate SG-1 were revealed to have actually been the reason the Ancients traveled to the Milky Way Galaxy in the first place and planted he seeds of our own evolution. The Ancients were then driven out of our galaxy by a seriously nasty plague eons later, before ultimately succumbing to the Wraith in the Pegasus Galaxy.
  • It seems that most ancient empires in Star Trek were destroyed by an unidentified allegiance of La Résistance. The ancient Iconian empire in Star Trek: The Next Generation was destroyed this way. In a reversal in Star Trek: Voyager, the ancient empire of the Vaadwaur were tyrants and they sealed themselves when their enemies attacked.
    • More recently, the Builders of the episode Prototype were wiped out by their own obsessive robot creations.
  • In the backstory of the new Doctor Who, the Time Lords were all killed off by the Doctor himself, ending their war with the Daleks in mutual destruction: by that point, not only was the War causing an insane amount of damage, but the Time Lords had sunk so low that a "victory" for either side would spell bad news for the rest of the universe. The Daleks and the Master survived.
    • He has since had to seal the deal on all three threats, although the Daleks keep popping up again due to Joker Immunity, and the Master has a long history of the same...


  • Zeus and the other Gods of Greek Mythology waged war against the Titans and won, although they didn't kill them (You see two every time you look up at the sky)
  • Several gods in Near-Eastern religions (and one God in particular) acted as this with a Great Flood, destroying the world that came before and allowing only one family of humans to survive.
  • The Maya believed that their Gods created three worlds before this one, but were unsatisfied with the creatures therein and wiped the slate clean.

     Tabletop RPG  

  • In Warhammer 40,000, the Necrons (a race of undying skeletal androids) are the reason the Old Ones aren't around anymore, and the only reason the Necrons didn't end up ruling the galaxy was an outbreak of Warp entities.
  • The job description of the Exalted. There are some surviving Primordials, but that's because they surrendered when they realised how badly dead Primordials broke reality itself, creating an entire world as a shadowy and dead mirror of Creation and damaging the formerly foolproof reincarnation system.
  • In the Alternity Star*Drive setting, the Stoneburners and Glassmakers were a faction of, respectively evil and good, precursors. The Stoneburners wiped out the Glassmakers in a massive war, but were themselves mostly killed off by the war. At which point, the I'krl, a servant race of the Stoneburners, took them out and became the new Big Bad of the setting.

     Video Games  

  • The Reapers of Mass Effect and their master, the Catalyst made this their profession. They were Precursors to all the other Precursor races, for the sole purpose of causing the genocide of them once they were advanced enough. Since they return during the games and can be killed, Shepard qualifies as a Precursor Killer him/herself.
    • The Leviathan DLC reveals the original Precursors, the Leviathans, who created the Catalyst in the first place and had most of their species converted into the first Reaper as the price.
  • The Brethren Moons of Dead Space 3 are implied to be the reason why space is dead.
  • The Dark Precursors of Jak and Daxter.
  • The player character gets to meet the wizard who nearly destroyed (accidentally) the Netherese Empire in Neverwinter Nights: Shadows of Undrentide. The guy who destroyed the rival Illefarn Empire is the main adversary in Neverwinter Nights II.
  • The Flood of Halo is a race of parasitic alien spores that latch onto any sentient life with sufficient biomass, becoming more intelligent as they grew. The Forerunners were forced to use the Halos, a series of doomsday weapons to wipe the galaxy clean of anything the Flood could infect, including themselves.
    • It turns out that the Forerunner wiped out their own Precursors as well. And it turns out that The Flood is what results when decayed Pecursor remains are applied to sentient life.
  • The Orz in Star Control II: The Ur-Quan Masters seem like fairly harmless Cloudcuckoolanders but are actually part of an Eldritch Abomination.
    • Star Control also has the Sentient Milieu being brought down by the Dnyarri, then the Dnyarri being brought down by their Ur-Quan slaves (and then one branch of the Ur-Quan exterminated at least some of the surviving Milieu species). The reason for the actual, Capital-P Precursors in the universe disappearing remains unknown, despite what some people claim happened in Star Control III.
      • For extra twist points, the Sentient Milieu's enslavement began when an Ur-Quan explorer stumbled upon the Dnyarri's homeworld.
  • The Xel-Naga from StarCraft created races as a means to perpetuate themselves, and created the mentally advanced Protoss, and biologically adaptive Hive Minded Zerg, two species that would eventually join to become the new Xel'Naga. Except... Some Jerkass Eldritch Abomination known as the Fallen One threw a monkey wrench in their plans, by subtly altering the Zerg into genocidal killing machines. The Zerg then promptly became Precursor Killers.
  • The Shivans wiped out the Ancients in the VideoGame/FreeSpace backstory, and it's strongly implied that they've done the same to any other civilisation that spread too far throughout the galaxy and/or through Subspace.
  • The Space Pirates seem to be to blame for wiping out most of the remaining Chozo in Metroid. What the Space Pirates didn't get, phazon did.
    • The Chozo are implied to still be out there somewhere, though. With phazon gone, most were presumably able to return to a higher plane of existence.
    • Gorea wiped out the Alimbics of Metroid Prime: Hunters.
  • In the Might and Magic series, it's revealed that the alien Kreegan (which the galaxy's less advanced races mistake for demons) were the ancient enemies of the Precursors. Since the Kreegan are still around, and the Precursors are not, it seems pretty clear what happened (although the good ending of M&M VII seems to suggest that some surviving Precursors moved to another galaxy or something).
    • According to M&M VIII, the Precursors are still around, fighting the Kreegan on other fronts. There are still elements of this trope, though- it was the Kreegans' invasion and sheer numbers that caused the collapse of the old system and the isolation of numerous systems from the Precursors.
  • Assassin's Creed has an antagonist mentioning his belief that the "artifacts" are left over from "those who came before," but Assassins Creed II's ending reveals that primitive humanity's sheer numbers were enough to overwhelm the precursor race. However, it's strongly implied that the playable characters' bloodline is genetically descended from a human-Precursor hybrid, and the Facebook game Project Legacy briefly implies that Giovanni Borgia is part of a hybrid line possibly going as far back as Marcus Junius Brutus the Younger. Yeah, that one.
    • It turns out that a solar flare was the true Precursor Killer. The surviving precursors were too few to repopulate their race, but they worked together with their former slaves/enemies to rebuild the world and took steps to ensure that it would survive the next inevitable solar flare. The existence of hybrids and humanity remembering the precursors as deities show that the precursors and humanity made peace with each other before the former died out.
  • In Blue Dragon, Nene's "pet" Deathroy aka Destroy was the biomechanical living weapon that wiped out the Ancients' civilization.
  • The Juno to humanity in Solatorobo. In an interesting twist, they actually only made the suggestion and provided the kill program. The humans are the ones who made the final suicide call, seeing it as the only way to end their wars and give the planet a chance to recover without them.