Depopulation Bomb

Chemical bomb, chemical bomb
Eyes melt, skin explodes, everybody's dead
It won't be long, it won't be long
People gonna run around losing their heads
A river of blood, who's gonna live?
The earth is tired of humankind
And I think this world
Is gonna wash up in Hell

— The Aquabats!, "Chemical Bomb"

A plot device, such as a weapon (usually biological, chemical or nuclear) or a natural agent (like a plague/virus), which drastically reduces the human population in size while leaving a few charismatic survivors. Sometimes Only Fatal to Adults.

In order for a Cozy Catastrophe to remain cozy and small scale, it helps if said cozy catastrophe takes place After the End. It helps to justify the existence of a nearly deserted but intact urban wasteland that, even if civilization DID collapse in the real world for any reason other than a Depopulation Bomb, would probably still be teeming with people only a few months after the fact. Sometimes major characters have a fortunate random immunity to the widespread plague or chemical/bio-weapon. The use of a biological or chemical weapon may be due to the Nuclear Weapons Taboo.

This is popular for several reasons, largely because it justifies other tropes:

1. It's more budget friendly to pull off a depopulated future with a single band of familiar survivors and a bunch of faceless enemy mooks than it is to portray a vastly overpopulated future on the other end of the Malthusian Disaster Spectrum. Alternatively, a Depopulation Bomb that doesn't wipe out some 90% of humanity may still justify a Crapsack World.
2. Similarly, a depopulation bomb justifies how a Scavenger World, where there's more useful stuff lying around than people who need it, may exist for any reasonable period of time.
3. If the Depopulation Bomb is Only Fatal to Adults, then this trope justifies Parental Abandonment (e.g., Jeremiah, The Tribe, His Dark Materials). It also justifies storylines in which children and teens have to take on the responsibilities of adults, or form extended families of their own.
4. Alternatively, if the Depopulation Bomb only affects one sex, then you have a case of Gender Rarity Value (and a justified Lady Land or No Woman's Land).
5. An underpopulated world in which the Depopulation Bomb only affects humans (or only primates, only mammals, etc...) justifies a return to hunter-gatherer or other primitive lifestyles that can only support relatively small (non-industrial-level) populations, thus solving the issue of how the characters feed themselves. May be part of an anvilicious Gaia's Vengeance.
6. Random genetic immunity to the virus-form of the Depopulation Bomb can be a plot device in itself, as an allegory for historical and/or contemporary themes (like racism and segregation) or as the social obstacle for a pair of Star-Crossed Lovers.

Australia, due to its relatively high industrialization, isolated geography, and population of English-speaking Caucasians, is very likely to be the one nation that survives the cataclysm mostly intact, and become a new global superpower, at least in western media. Japan's proximity to the Asian mainland makes its survival dicier, but Japanese authors have this thing about their nation's invincibility, so look for it to be the fortunate land of survivors in anime and other homegrown media.

In films in this thread, expect outside shots to have lots of Low Angle Empty World Shots, night scenes (less people around) and early morning (Sunday morning, when most people sleep in) scenes. Expect the actors to have to rerecord their dialogue to take out the busy highway sounds in the background. These are all tricks film makers use to make a world look like it's been hit by a Depopulation Bomb, and movies achieve widely varying results with them.

It may be worth noting that while the Neutron Bomb provides inspiration for many such weapons, a neutron bomb is not a straightforward "It only kills people" bomb. It is a thermonuclear weapon, so this is mostly a simplistic comparison to other bombs with more straightforward purposes. That is, if you actually care about things like scientific accuracy.

Compare the much longer-term Sterility Plague.

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Examples:

Anime & Manga

• In Arachnid, Japan was secretly ruled by a psychic ageless person who sought to regulate the world's population for not quite explained reasons. The atomic bombings on Hiroshima and Nagasaki upon losing WWII were arranged on purpose to this end. During the story, one of the antagonists attempts to start a zombie outbreak spread by sex with her as the ruler. The heroine kills her, but the zombies don't recover, and the Organization of assassins gladly let them out into the city in hopes that half of Japan's population gets raped and then dies of starvation. By Blattodea, the country looks like a post-apocalyptic scenario.
• In Cowboy Bebop, the Astral Gate accident in 2021 destroyed a large chunk of the moon and sent the debris raining down on Earth, devastating the surface of the planet, killing billions, and forcing most of the survivors to evacuate. Fifty years later, the human population across the entire solar system is down to only 1.5 billion.
• In Death Note, the Kira killings. More specifically, the ones after Light started having Mikami act as his proxy. Mikami went more than a little crazy with his newfound power (which included the Shinigami Eyes)... and even criminalized such horrible things as being lazy. Between that and all the Kira-related incidents up to that point, there were likely several millions, or even billions of people killed off worldwide. When Mikami killed himself and Light's name was written down by Ryuk, and all the Kiras (and most of the Kira Cult devotees) were gone, and the world was going (more-or-less) back to normal save for a few small remnants of the Kira Cult, it's likely that many countries were facing this issue.
• Digimon: The X-Virus, which Yggdrasil cooked up because it found the Digital World was getting stuffed to capacity. Initially, it seemed to work, but then it turned out Digimon started developing an antibody, meaning not as many Digimon were dying. And then the antibody turned out to act as a power boost.
• In Dragon Ball Z, Super Buu's Human Extinction Attack, which only leaves a handful of survivors on the surface of the Earth, mainly those skilled and/or lucky enough to dodge it.
• In Dr. STONE, some mysterious event turns all of humanity to stone (except six astronauts on the ISS). Subverted in that the petrification is reversible, and the means to do so is one of the first things the protagonist discovers.
• Green Box: The Green Box can in minutes shred every human in any country.
• In Heat Guy J, after humanity appropriated the technology^note Possibly nuclear energy, though this is not stated. of the resident Superior Species and used it as a weapon of war, only a few small, isolated populations of humans remained. They became seven isolationist city-states, perhaps with a few surrounding villages or suburbs.
• In High School D×D, it's not the blissfully ignorant humans who are dealing with population problems, it's everyone else. Previously, Angels were created by God, and enough of them were led astray for the Fallen Angels to keep their numbers up; Devils reproduced sexually, their low fertility offset by long lifespans. After the Great Offscreen War, God Is Dead, and with him any new Angels, and those that are left are far too devout to ever fall, leaving both those factions considering each individual more precious than ever. Meanwhile, Devils experienced such a severe depopulation that extinction was an inevitability and created the Evil Piece system in response in order to stabilize their population with reincarnated humans. Later in the series, Angels and Fallen Angels have both borrowed the reincarnation techniques in their own ways, just in time for the vital element of it to get stolen.
• Mobile Suit Gundam: "Initial fighting lasted over one month and saw both sides lose half their respective populations. People are horrified by the indescribable atrocities that have been committed in the name of independence..." This occurred as the result of a Colony Drop (which actually wiped out Sydney, Australia, while causing widespread destruction everywhere else), the poison gassing of numerous colonies, on top of the actual battles. Most of this genocide took place over the course of a week or so. It led directly to both sides signing a treaty prohibiting the use of "NBC" weapons ("Nuclear, Biological, Chemical") in warfare.
• Neon Genesis Evangelion:
  • Second Impact. Tidal waves and flooding wiped out the coastal regions while the surviving land was ravaged by shifts in the global climate and resulting famines. It's also been indicated that in addition to lower population and vastly reduced lifespans, the birth rate has dropped dramatically.
  • Depending on your definition, Third Impact, too. Fans just can't seem to agree just how depopulating the latter's effect was. Instrumentality depopulates as definitely as old-fashioned explosions, but unlike a bomb victim, those caught in it can return to life if they want... it's just that wanting to isn't easy.
• Rave Master has the Overdrive, which wiped out 1/10th of the world.
• In Sailor Moon, Sailor Galaxia releases an attack that causes black lighting to rain down all over earth removing the starseeds of the people of Earth. It either kills them or turns them all into Phage. Only the Sailor Senshi are left unaffected.
• World's End Harem: The MK Virus killed half the human population within five years. The male half, specifically, leaving just a few survivors who'd gone into cold sleep and just happened to be immune to it. It's later revealed to have been created artificially by a group of Straw Feminists who wanted to turn Earth into a Lady Land.

Comic Books

• Buck Godot: Zap Gun for Hire: A major plot point in Buck Godot: The Gallimaufry is the discovery of an engineered virus that doesn't kill outright, but instead completely eliminates the human sex drive.
• In Crossed, it is said that out of a population of 6 billion, only 200 million of humans survived C-Day, the mass infestation event that unleashed the Crossed virus into the world.
• In The Dark Knight Strikes Again, Lex Luthor and Brainiac placed an entire network of these in orbit around Earth that lets them hold the entire world hostage which they use to force Superman, Wonder Woman, and Captain Marvel to work for them. Near the end, Luthor plans to unleash all of them at once to reduce humanity to a "manageable" population of a billion. He's foiled when Green Lantern makes them all vanish.
• The Killitron in Meanwhile kills every single human being not standing inside it when it's activated. It already went off once, and depending on the reader's choices, it may go off again.
• Watchmen ends with Ozymandias killing millions of people in New York City. The movie makes it even worse, as it's just one of several cities destroyed.
• The whatever that killed off all the men in Y: The Last Man.

Fan Works

• In A Complete Waste of Time, the MMORPG META has a policy of determining the players meant to play the game by compiling a list of everyone the server player knows. If anyone on that list does not install the game within one day after the server starts, they inexplicably die. On the planet Seconia (pop. 12.5 million), the ithicans are all connected with each other through some natural network, and thus everyone would know each other on an unconscious level. Unfortunately, only eight copies of the game were made on that planet, and only the owners of those eight copies survived the ensuing near-extinction of the species.
• In Halloween Unspectacular 9, it's revealed that the virus causing the Zombie Apocalypse in the story "The Plague" was one of these created to empty Earth for an Alien Invasion.
• It's a Kid's World has an Only Fatal to Adults variant. An event called The Big Vanish suddenly wipes out the entire world populace over 15 years of age in a single instant, leaving only children behind. This paves the way for a story about the kids having to fight for power, resources, and survival in a new and hostile unorderly world.
• In Pokémon Reset Bloodlines, it's mentioned that centuries ago there was a plague equivalent to the real world's Black Death, that afflicted Kalos and the other European equivalent regions of the Pokémon world, killing about half the population. The narrative hints it had something to do with the Ultra Space.

Films — Live-Action

• In 12 Monkeys, a man-made virus is released that is so deadly that it kills 5 billion people and, 30 years later, the survivors still have to live underground and can only go outside in environmental suits.
• 20 Years After: A nuclear war and plague wiped out most of humanity.
• 28 Days Later and 28 Weeks Later have a spectacularly contagious Rage virus, plus intense aggression by Infected against non-infected. Britain is drastically depopulated by the end of Days, and Weeks has the virus spreading in Europe, thus probably worldwide, setting up the Inferred Holocaust.
• In Autómata, natural occurring solar flare activity has skyrocketed to the point that planet Earth is now mostly desert and radiation is slowly poisoning organic life.
• In Avengers: Infinity War, Thanos successfully obtains all six of the Infinity Stones and wipes out half the population of the entire universe. Avengers: Endgame shows both the fallout of this, and eventually restores all the snapped-out life.
• Five involves five survivors, one woman and four men, of an atomic bomb disaster that appears to have wiped out the rest of the human race while leaving all infrastructure intact.
• Grimsby: Terrorists plan to release a deadly virus (called RD9 or World Cure) to "delete the garbage, the imbeciles, who lie around drunk, reproduce like rabbits, and expect others to pay". The name RD9 can be translated to "ReDuce by 90%", as announced by The Georgia Guide Stones.
• Juan in a Million: Juan is left alone in an empty Santiago, Chile.
• In L: change the WorLd, Blue Ship, a bio-terrorist group, creates an incredibly deadly virus to depopulate the earth. They stave off releasing it until they create an antidote so that they can survive it, naturally.
• Moonraker has the villain attempting to use a chemical weapon which would kill all humans on earth (only humans; other animals will be fine), to be repopulated with humans from his space station — with him as their leader, of course.
• The eponymous menace in Night of the Comet literally erases animal (and human) life on Earth, except for a few people who were indoors/underground — and a few who were "partially protected" who became zombies.
• The entire premise of The Quiet Earth, after a scientific experiment goes awry.
• Serenity reveals that the Alliance tested an experimental chemical called Pax on a populated planet, meant to curb their more violent impulses. It succeeded too well, causing them to develop severe amotivational disorder, to the point where just about all of them just lay down and died. The ones who survived had the exact opposite reaction to the Pax, becoming the psychotically violent and cannibalistic Reavers.
• The Polish comedy^note Yes, this trope in a comedy, although a rather dark one Sex Mission introduces us to a bomb which was supposed to temporarily suppress Y chromosome in humans, but instead killed all males and left some deadly radiation on the surface of Earth, forcing women to populate caves, use parthenogenesis to reproduce, utilize chemical food and so on. The male protagonists survived because they already were underground during their Human Popsicle experiment. The bomb effects turn out later to be rather blown up, if you forgive the pun, by history revisionism.
• In Star Trek III: The Search for Spock, the Klingons believe that the Genesis Device was developed by the Federation to wipe out Klingon populations, leaving planets intact for easy conquest.
• The 1974 Made-for-TV Movie Where Have All The People Gone has a Solar Flare Disaster causing this.
• In The World The Flesh And The Devil (adapted from M.P. Shiel's The Purple Cloud; see Literature below), use of a radioactive poison kills most of the earth's population, resulting in a remaining New York population of only three people.
• xXx: A terrorist group plots to send biochemical weapons to large cities all over the world. They use a poison gas called Silent Night, to "kill millions", provoke World War and Civilization Collapse, and to restore global anarchy and "absolute, beautiful freedom".

Literature

• In Across the Universe (Beth Revis), 3/4 of the population of the Generation Ship Godspeed was killed off in an event called the Plague. The population has been slowly rebounding since then, but the limited gene pool has led to problems with inbreeding.
• Animorphs: At the end of The Hork-Bajir Chronicles, Alloran's method of "accepting defeat" by the Yeerks is to engineer a quantum virus which will annihilate the Hork-Bajir population, leaving only a small fraction of the potential number of hosts without directly harming any other organisms. Fridge Logic questions why he couldn't have targeted it at the Yeerks, you know, the enemy he was actually supposed to be fighting thus decimating their population without harming the Hork-Bajir. In fact, Arbat tries to do exactly this much later on Earth, but the Animorphs stop him because the virus could mutate to kill humans as well.
• Changes features a magical ritual to kill every member of a bloodline by targeting its youngest member. Harry uses it to commit genocide against the Red Court.
• In The Day of the Triffids, the only people who can really survive are those who keep their sight, or those who are just plain lucky.
• In Alan Dean Foster's remake of Design For Great Day, the Solarian Combine is said to have used a Depopulation Bomb on the worlds of a particularly belligerent species; the effect of said bomb being to completely stop them from reproducing. One hundred or so years later, there were no more belligerent aliens. This rumor is enough to bring the Solarians' current target species to the negotiating table, although it's later revealed that they've grown far beyond such crude methods in the intervening centuries.
• Digitesque: If a child encounters too many people before they grow old enough, they will become "overwhelmed," meaning they will quickly fall sick and die. This even applies in the womb, so cities are filled with adults and absolutely no children. This was part of the technophage that broke humanity.
• In Galápagos, a nuclear war and The Plague wipe out everyone except a few castaways stranded on the Galapagos Islands.
• In In The Mothers Land by Élisabeth Vonarburg, far in the future, many children don't survive to adulthood, and the survivors are more than 95% female. Different societies in this world cope with the situation in various ways, but this story takes place in Maerlande, where the official religious explanation is that things changed to the current state as divine punishment on men who misused technology and behaved badly. In this society, men have very few rights and are confined to reproductive duty, being traded between cities to keep genetic diversity up.
• In Iron Man: Steel Terror, these are what Ultron plans to use to Kill All Humans; they are called Neutron Bombs, but are in fact this.
• In Line of Delirium, the protagonist recalls how, during the Vague War, the Meklar try to wipe out the human race with a virus specifically tailored to destroy spinach. This is because some joker successfully feeds them false information about human dietary needs, claiming that spinach is vital to humans. They spend countless resources creating the virus and then lose many ships trying to seed human worlds with it. After they eventually realize that humans aren't dropping like flies, the shock is so great that they immediately sue for peace. They could've just as easily tailored the virus to kill humans. Of course, from then on, spinach can only be grown in self-contained greenhouses.
• In Lucifer's Hammer, Earth is depopulated by an asteroid strike. Recovery might take ages since the asteroid started nuclear winter conditions.
• The Magician's Nephew treats a magical incantation by the white witch Jadis as this. After ruling her home planet of Charn as a cruel and capricious tyrant with a 0% Approval Rating and on the eve of defeat by her own subjects, Jadis out of pure spite uttered the deplorable word, resulting in the death of every living thing on the planet except herself.
• In The Maze Runner, the Flare virus was unleashed to cull those competing for scarce resources in a world devastated by solar flares. At first, it killed its victims quickly, but it rapidly mutated and the infected started taking longer to die. Not only that, but the Flare also robbed them of their humanity and turned them into animalistic beings known as Cranks. However, a small percentage of the world's population is immune to the virus; WICKED was set up to study such people in the hope that finding out the reason for their immunity might lead to a cure.
• Old Man's War has a minor Depopulation Bomb in the backstory, as justification for the quarantine of Earth. An alien disease called "The Crimp" caused a third of the planet's male population to go sterile.
• In Oryx and Crake, and its sequel The Year of the Flood, a genetic engineering genius creates a super-virus to wipe out the world's decadent human population, which he plans to replace with a race of genetically engineered new humans. His virus is only mostly successful, leaving (by sheer coincidence) a number of people who he personally knew alive.
• In The Peace War, Earth's population has been reduced to about 10% of its pre-War level, mainly by the release of engineered plagues. Paul Naismith, who's old enough to remember life before the War, reflects near the beginning that the town he's in is large by post-War standards but its entire population could have got lost in the crowd at a good high-school basketball game.
• In Plague Year Series, an artificial nanotech virus is released. It kills any warm-blooded animal with a few hours' exposure. Its only limitation is that it was designed to shut off at low air pressure - it will not operate at altitudes above 10,000 feet. The only survivors are the people who lived on or managed to flee in time to high mountain peaks, most of which are isolated from each other by lower altitude plague zones. There are two sequels, Plague War and Plague Zone.
• In A Planet For The President, in order to put an end to the growing environmental crisis derived from global warming, the United States cabinet decides to infect most of Earth's population with a deadly virus, which the US inhabitants are vaccinated against. Thing is, the President is allergic to eggs, so his vaccine must be produced elsewhere. However, all the vaccines (save for the President's) turn out to be faulty, and the illness also affects the US population: in the end, the President is the last human alive.
• M.P. Shiel's 1901 novel The Purple Cloud has the title phenomenon destroying seemingly all human and animal life on earth save for one man... until he learns otherwise.
• In The Quiet Place, a group of astronauts return to Earth after a botched First Contact mission. Because of Time Dilation, they return to a future Earth that's reverted to the Stone Age and with a smaller population. It turns out that an experimental drug to reverse aging was distributed worldwide. The most major side effect was widespread infertility.
• The main terrorist group in Rainbow Six (and the first game) is plotting to wipe out most of the human race with a Synthetic Plague.
• The Road has some unspecified disaster leading to this.
• In The Shadowspawn, the titular species of superhuman beings, who have been secretly controlling humanity for thousands of years, have decided that the global population is growing too large to control, so needs to be curbed. The only problem for them is that they can't agree on how. The ruling elders want to use a string of EMPs to destroy all modern technology and corral all remaining humans. A progressive movement of younger members, however, want to use a Synthetic Plague to merely kill enough to lower numbers, while they then come in with the antidote, letting them be welcomed as saviors and handed open control on a silver platter.
• The Sixth Extinction, book 10 of the Sigma Force series, has an extremist environmentalist geneticist engineer a universally infectious prion virus that would destroy all higher conscious brain functions of humans, turning the human species back into mindless feral animals. At the same time, he accelerated evolution in other species to make them more deadly and aggressive. The end result would be the "natural" extinction of humans and a return of nature to the planet. Of course, he intended to protect himself and his followers from the infection to build a new less destructive civilization in the aftermath.
• In Kurt Vonnegut's "Slapstick", a highly contagious virus made of miniaturized Chinese Communists kills almost the entire population of Manhattan. Various disasters take care of the rest of the world.
• In The Stand, a "superflu" kills 99.5% of the population. The post-plague population of the United States is estimated at 1.5 million people. The world's population would be 30 million, equal to everyone on Earth dying except in California or the entire nation of Canada.
• Star Trek Novel 'Verse:
  • In the Star Trek: Deep Space Nine Relaunch, the Trill homeworld is targeted by a series of artificial pulses harmless to the vast majority, but deadly to Joined Trills, who form a privileged minority. Many of the Joined are killed, with the average citizen completely unaffected.
  • In one of the Starfleet Corps of Engineers stories, the Miradorn homeworld almost falls victim to a depopulation bomb that was accidentally triggered from the planet's moon. It would have killed 98% of the population (all those Miradorn with psychic links to identical twins) but was halted in time to prevent a significant reduction in numbers.
  • Another novel, The Last Stand, has a long-standing conflict between the Krann and the Lethanta. Long ago, the Lethanta developed space travel and discovered the Krann on another planet in the same system. They subjugated them. Eventually, the Krann rose up and fought back. But a virus began wiping out the Krann. Assuming it was an attack by the Lethanta, the Krann bombed their homeworld, making it uninhabitable. The surviving Lethanta fled in sublight ships constructed out of asteroids. The surviving Krann, with their planet also no longer habitable due to the virus, built a fleet and gave chase. Near the end of the novel, as the Lethanta-Krann war is coming to a head, Dr. Crusher discovers that the virus was natural, not engineered. Thus, the Krann have no reason to try to wipe out the Lethanta. However, the temporary peace is fragile, and one of the Krann leaders points out that the long feud isn't going to end just because a doctor saw something in a microscope.
• The Subtle Knife seems like this at first, as the Spectres in Cittàgazze target adults and leave them as mindless zombies, so that a city is found completely empty except for a few scavenging children. However, there are still a fair number of adults around, but as they're hugely vulnerable and often have to go into hiding, society can barely function.
• TimeRiders: The Kosong-ni Virus melts all organic matter that touches it, leaving human victims as nothing but piles of bones and hair. In the days following it there are only a handful of bunkered survivors left alive.
• In Troy Rising, the Horvath drop a series of viruses (and one parasite) on Earth. The parasite is designed to weed out the stupid, being incredibly easy to treat, but fatal otherwise. Four of the viruses target various defects — colorblindness, increased risk of cancer, etc. The last will kill everyone who isn't blond, thus eliminating 90% of the human population. Thankfully, we manage to stop it in time.
• In The Wild Boy, the Lindauzi caused two waves of viruses, twenty years apart, with AIDS said to be part of it, all so that they could show up with a vaccine and get humanity's remains to like them.
• John Birmingham's Without Warning has a mysterious energy wave vaporize almost everyone in the continental United States, as well as the bulk of the populations of Canada, Mexico, and Cuba. While not a global depopulation bomb, it still thoroughly depopulates North America.
• Z for Zachariah opens After the End came about thanks to both literal Depopulation Bombs as well as nerve gas. The protagonist believes she's the last living human, until her valley is found by another man. It gets worse from there.

Live-Action TV

• Alex Rider (2020): Dr. Greif gives a lecture in which he discusses a mass cull as a solution to overpopulation. Alex questions this, asking who decides who gets killed off, and Dr. Greif laughingly tells him that it's only a thought experiment. This makes Alex pretty sure that a mass cull is part of Dr Greif's long-term plan.
• In the Doctor Who episode "The Sound of Drums", the Master sends the Toclafane from the end of the universe to shred apart tenth of the Earth's population.
• Done with a vengeance in Jericho (2006), in which over a dozen major U.S. cities are bombed with nuclear weapons, leaving only small towns and two major cities standing.
• The Outer Limits (1995):
  • In "Resurrection", humanity was wiped out due to a biological war on July 24, 1997, which was then 18 months in the future. In 2009, two androids named Martin and Alicia recreate a human named Cain from uncontaminated DNA samples.
  • In "Rite of Passage", humanity was wiped out centuries ago through unknown means. The Vorak discovered Earth sometime later and used their genetic expertise to recreate humanity using the samples left behind on skeletons.
  • In "The Human Factor", humanity is almost completely wiped out in the final phase of the war between the Free Alliance and the Coalition of Middle Eastern and Pacific States. On April 23, 2084, the Free Alliance launched an all-out attack on the Eastern Coalition in the hope of finally bringing the long war to an end. However, they underestimated the Coalition's firepower, which was equal to their own, and Earth is rendered uninhabitable.
• Sliders:
  • In one episode, the eponymous characters slide into a world where a Middle Eastern country detonated a bioweapon that specifically targets the Y-chromosome, killing most of the men in the world. This gave rise to a new Cold War, this time between US and Australia, the two countries least touched by the virus. Instead of nukes, each tries to "out-breed" the other. The surviving men are rounded up and placed in breeding centers, where they are forced to impregnate multiple women each day. Also, only the most "fit" women are allowed to take part in the breeding program. Professor Arturo explicitly complains about the failure to discover artificial insemination on that world, noting that he could have revolutionized things for them if they actually treated him as more than an animal only good for breeding and actually listened to him.
  • It's also revealed that the humans of Kromagg Prime used a weapon on their Kromagg enemies that kills any Kromagg female attempting to give birth. The goal is to eventually drive the Kromaggs to extinction, as this prevents positive population growth. The Kromaggs are trying to compensate by interbreeding with humans.
• Spellbinder: A number of parallel worlds have had their population reduced to a fraction of its former number. In the Spellbinder world (the setting of much of season 1), it's heavily implied that no one outside Australia survived the ancient cataclysm caused by Spellbinders attempting to increase their power. The surviving population has reverted back to a Medieval Stasis, with the elite Spellbinders being a Cargo Cult that suppresses all scientific advancement and is barely able to maintain the old tech they're passing off as sorcery. Another world went through a Robot War with a few survivors eking out an existence on the ruins of civilization and fearing all forms of "tech". A third world was struck by a worldwide pandemic in Victorian times, wiping out a large part of the population. A cure was found and had the unexpected side effect of turning everyone into The Ageless but also made everyone sterile. As a result, all progress stopped, and the survivors amuse themselves by building childlike automatons in lieu of actual children.
• Stargate SG-1:
  • The episode "Past and Present" implies that one of these, similar to the Star Trek TOS "Miri" example below, was set off. The team encounters a planet with no children or elderly suffering from amnesia after an incident known as "the Vorlix". Inverted when it turns out that the planet had been using a pesticide which caused sterility (hence the lack of children), and "the Vorlik" was a deliberate test set off by a villain from a previous episode after she learned that this same pesticide had properties which could stop or reverse aging. The test reversed the aging of the entire planet, turning the entirely elderly population into middle-aged adults, but inadvertently causing amnesia in the process.
  • Two episodes ("2010" in season 4, and "2001" in season 5) are about the Aschen, an alien race who conquer worlds by supposedly being nice and friendly and handing out life extending drugs... that sterilize most of the population, letting the Aschen move in and take over after nearly everyone on the target planet has died out. It helps that the Aschen are extremely patient, willing to wait a few centuries to take over a planet, which becomes yet another farming world for them. The Aschen can also do this in a more active way — they possess a bioweapon that can be keyed to a particular genome, which kills off most of the species. In the backstory of "2010", they used it on the Goa'uld, and in "2001", they try to use it on Earth when SG-1 figures out their modus operandi. Fortunately, the SGC closes the iris in time.
• Star Trek: The Original Series:
  • The episode "Miri" features a duplicate Earth where a genetic engineering project got out of hand and killed off everyone over puberty. The children are still around, because the intended effect of the project was agelessness, which partially worked for anyone it didn't kill — the kids still age about a month per century. Miri herself shows the first sign of the disease later in the episode (if the fact that she caught the Kirk bug doesn't tip you off she was going into puberty).
  • "The Mark of Gideon" has Kirk kidnapped by a vastly overpopulated planet who want to use germs in his blood to drop a Depopulation Bomb on themselves. This scheme involves a large amount of Fridge Logic, when one wonders where they found the space to construct a full-scale replica of the interior of the Enterprise.
• The BBC has produced two series, one in the 1970s and one in the 2000s, entitled Survivors, which have most of the world population wiped out by a virus which is strongly implied to be artificial.
• 'The Virus' in The Tribe is a Depopulation Bomb with a bonus Only Fatal to Adults.
• The Twilight Zone (1959):
  • In "Time Enough at Last", Henry Bemis may be the last survivor in the aftermath of the nuclear war.
  • In "The Old Man in the Cave", a nuclear war devastated Earth in 1964, killing millions of people in the process. Major French tells Mr. Goldsmith that there are approximately 500 people alive between Buffalo, New York and Atlanta, Georgia. In the ten years since the war, many people have died as a result of eating food contaminated with Strontium-90 or from the plague.
  • In "Probe 7, Over and Out", Colonel Cook's people are wiped out in a devastating war within less than a day. The entire coast of Cook's country was destroyed in only 12 minutes, after which they responded in kind.
• The Twilight Zone (1985): In "Quarantine", a nuclear holocaust occurred in 2043 when each side fired six missiles at the other. 80% of the world's population were wiped out and all of the major cities were destroyed. By 2347, Earth has a population of only 200,000.
• In the final episode of the miniseries revival of The X-Files, "My Struggle II", The Conspiracy enact their endgame by unleashing the Spartan Virus, which shuts down the immune system of anyone exposed to it who hasn't also had alien DNA inserted into their genome. The Cigarette Smoking Man tries to present this as a case of well-intentioned extremism, stating that humanity was wiping out itself and killing the planet anyway, but this way at least humanity will have a chance to rebuild (naturally, with himself and his allies in charge).

Music

• Porcupine Tree: "A Smart Kid"

A spaceship from another star / They ask me where all the people are
What can I tell them?
I tell them I'm the only one.
There was a war, but I must have won.
Please take me with you.

• Some sort of nuclear bomb (as sung about on the Universal Migrator album) is used at the end of Ayreon's "01011001", given the lines like "Washed away by deadly gamma waves" and "All the world's a blazing funeral pyre." And, well, that everyone on Earth is dead afterward. Presumably, the "gamma waves" line is there simply because of the Rule of Cool.

Tabletop Games

• Exalted:
  • Creation was almost reduced to formless chaos as a result of The Great Contagion, followed by the Balorian Crusade.
  • The Dragon Kings are an even more drastic example. Due to their perfect reincarnation (meaning that every Dragon King regains perfect memories of their previous incarnations after a few decades, tied to their basic mental development), their population was fixed at 150 million. During the Primordial War, enormous numbers were destroyed right down to the soul, reducing them to 30 million. The Wyld incursions caused by the Balorian Crusade whittled this down to a mere 4 million. This means that not only is repopulation impossible, but that many Dragon Kings wind up not reclaiming past life memories (since these will inevitably include vast numbers of people who simply aren't around anymore to a psychology which was never really designed to handle bereavement).
• The Chi Bomb, or C-Bomb from Feng Shui 2, which was created by the Jammers in order to wipe out every Feng Shui site in existence so that humanity and other species could live free of the "tyranny" of chi, instead wiped out every Feng Shui site in the Future juncture — along with ninety-seven percent of the world's population in that juncture, as well as everyone else who was attuned to a feng shui site controlled by the Architects of the Flesh, who were all reduced to cellular powder. The bomb also had the effect of messing with the chi of many of the survivors, turning them into mutants.
• The VITAS (Virally Induced Toxic Allergy Syndrome) pandemic serves as this in Shadowrun. The disease, first appearing in India in 2010, proceeded to spread globally and wipe out approximately a quarter of the world's population over the next few years, most of them in Africa, followed by a second wave in 2022 that killed another 900 million. Proportionally, Madagascar was among the worst hit, losing over 70% of its population. VITAS not only caused several governments to collapse, but also set the stage for the setting's bizarre set-up; though highly contagious, the disease was far more lethal to humans than metahumans, and more easily cured through magical means than mundane treatments. This is why there is such a significant number of metahumans, magic is so widespread and respected, and the world is run by the megacorporations (who used their stockpiles to save their own executives and employees first). It also made the Native American Nations a superpower; as millions of Amerindians were confined to isolated "internment" camps during the initial outbreaks, their populations were spared, and their magical talents made future outbreaks a chore instead of a threat.

Video Games

• In the backstory for Alien Legacy, First Contact with the Centaurians involved them sending an armed probe into the Solar System that vaporized a ship sent to rendezvous with it and then launched missiles containing a deadly plague at Earth. One missile made it through the defenses and killed millions of people. Ignoring the question of how an alien race with no prior contact with humans developed a plague capable of affecting us, it only gets worse from there. By the time the game proper starts, it's heavily implied that Earth has been depopulated by the Centaurians for centuries, if not millennia.
• In Assassin's Creed II, one of Warren Vidic's emails features a news story concerning talks in Africa. In 2006, a disease called L-11 broke out in Africa, killing 96% of the continent's population over a 3-month period. Six years later, the continent is still virtually uninhabited and world powers take discussed once again dividing up the land. This is later revealed to all be a hoax created by Abstergo.
• The major conflict in Call of Duty: Advanced Warfare comes about because Private Military Contractor CEO Jonathan Irons developed a special biological agent that can distinguish between his own Atlas Corporation forces and anyone else caught in its blast radius. He intends to use this to remove obstacles in his quest to undo the world's governments, which he sees as a blight and ineffective, taking out countless citizens in the process.
• The big event that the heroes of Chrono Trigger are trying to prevent is the Day of Lavos, when Lavos emerged and laid waste to the world in 1999 (that world's calendar). The human population in 2300 is about thirty people, not counting any captives in Mother Brain's factory.
• Nukes in Civilization will typically remove 3/4 of the population of a city they're dropped on, and pollute the surrounding region with fallout, making population recovery extremely difficult. Repeated nuking or nuking a sufficiently weak city will result in that city being removed from the game altogether (unless it's a capital city, which are indestructible).
• Command & Conquer:
  • In Command & Conquer 3: Tiberium Wars, Tiberium itself is intended as both this and a device for terraforming by the Scrin. Ironically, they don't care about either effect. They only seed planets with Tiberium for one-time future harvesting (once all planetary mass is converted Tiberium, it won't grow anymore) They only attack humans because they're still alive; normally, Tiberium kills off all non-Tiberium-based life before the detonation of a significant mass of liquid Tiberium, which signals them to arrive. Once they do arrive, they judge that humanity needs to be exterminated anyway, as they're apparently criminally insane — GDI and Nod are still fighting each other during a freaking alien invasion, after all. The Scrin, who themselves are so uncaring about other species as to destroy entire planets for harvesting, call humans "Warlike in the extreme".
  • Command & Conquer: Generals also has the GLA with a variety of bio-chemical weapons and their airburst bomb is in fact a depopulation bomb (it unleashes one of three varieties of a modified Anthrax virus, depending on your upgrades). China gains neutron weapons in ZH which only kill infantry even in vehicles.
• In the penultimate story quest of Fallout 3, President Eden provides you a with a vial of Modified Forced Evolutionary Virus, which will kill all mutated creatures in the Wasteland, including most humans (e.g., those not born in vaults), when inserted into Project Purity. During Broken Steel, if you followed through with the President's orders, there will be people in the clinics dying from the virus, and you yourself die if you consume too much of the FEV-laced water.
• In Galactic Civilizations II, the signature ability of the Absolute Xenophobe Korath Clan is a "Spore ship" that depopulates and permanently toxifies a planet while leaving all its infrastructure intact. Surprisingly Realistic Outcome occurs when the conqueror then has to maintain all that infrastructure without any local workforce or tax base to offset the cost.
• The eponymous Halos in Halo kill all sentient life in the galaxy; specifically, The Forerunner Saga says that they use "bursts of cross-phased supermassive neutrinos" tuned to destroy nervous systems. They do this in order to starve out the Flood, by killing both their potential hosts and any Flood form more advanced than a basic Infection Form. Before they fired the Halos, the Forerunners made sure to evacuate as many species as they could to an extragalactic safe spot; afterwards, they were resettled on their homeworlds, with each species forced to start off as hunter-gatherers again. Each individual Halo does have a limited range though, which is why there's seven of them. It should be noted that this was very much a last-ditch plan; the Forerunners first tried both a conventional war and researching an actual cure, and neither of those worked.
• Iron Helix is named after a biological weapon that can completely eliminate all life on a planet with only a single use.
• In The Last Federation, this was the first stage of Evucks attack on Hydral. If Evucks achieve the space travel and start a war with someone, they can use it again.
• Mass Effect:
  • The krogan were hit by a Depopulation Bomb referred to as the "Genophage", designed by the salarians during the Krogan Rebellions. The krogan evolved on Tuchanka, an extremely lethal planet where only massive fertility and hardy physiology made it possible for them to survive, and once they moved off Tuchanka, their numbers, lifespan, and birthrates were so explosive that in order to satisfy the need for more territory to support their growing numbers, they began aggressively moving in on worlds already colonized by other sapient species. The genophage reduced krogan birthrates to less than one successful live birth per thousand pregnancies.
  • Interestingly, the salarians do not view the genophage as a Depopulation Bomb, but rather as a device to control the krogan birthrate to keep them from overpopulating the galaxy. As Mordin so blunty points out, if the salarians wanted to wipe out the krogan, it would have been a hell of a lot easier just to slap them with a permanent sterility version of the genophage instead of the carefully tailored one that allows for "pre-industrial growth levels" which would enable the krogan to give birth to enough young to keep up a steady population. In Mass Effect 2, it's revealed that the krogan began to adapt to the genophage, prompting the salarians to update it to maintain a stable birthrate.
  • Unfortunately, coming from a Death World where only the strongest and meanest survive means that the krogan are all genetically and culturally inclined towards hyper-aggression, and rather than adapt to their decreased birthrate they kept on killing each other as much as ever, without the super-fertility to compensate. Wrex points out this, and the tendencies of the krogan to scatter and work as thugs for hire rather than pull together to preserve their own culture, as contributing more to the decline of the krogan than the genophage itself. Demonstrating himself as one of the few really progressive krogan, Wrex argued in favor of focusing on breeding and rebuilding but gave up the fight in disgust and disillusionment when his own father tried to kill him over their differing views. In Mass Effect 2, he's revealed to have taken over clan leadership on Tuchanka and is busily dragging the rest of his species kicking and screaming into a more sustainable way of life.
  • Curing the genophage is a critical plot point in Mass Effect 3. Not only does Wrex or Wreav (depending on who survived) want it to recover their population, it is also the only thing that will get a disunified and fractured krogan society together enough to focus on the Reaper threat. And once they're united, the krogan bring together the most powerful ground force in the entire galaxy.
  • The genophage returns in Mass Effect: Andromeda, since the krogan that launched for Andromeda left before the cure may or may not have been administered in 3. Apparently, Clan Nakmor had a mutation that is (very slowly) rendering the genophage ineffective, and they've applied some kind of gene therapy during the 600-year stasis sleep to Andromeda to enhance it. As a result, their birth rates have greatly multiplied (they now have a viability ratio of 1/25). If the trend continues, the Andromeda krogan could be cured of the genophage within a few thousand years.
• In the backstory of NieR, humanity was wiped out by White Chlorination Syndrome, which was the result of Caim, Angelus and the Mother Grotesquerie entering the real world in the E Ending of Drakengard and introducing magical particles to the world. The result is a Zombie Apocalypse that wipes out almost all of humanity, the survivors being converted into Gestalts (what you know of as Shades). The "humans" we see in the game are actually Replicants, Empty Shells meant only as bodies for humanity's restoration, but due to them developing sentience, their respective Gestalts are degenerating into mindless monsters, while the Replicants suffer from a degenerative and always lethal disease known as the Black Scrawl. Thanks to the effort of Nier, that plan's not going anywhere and humanity will be extinct within a generation, as he killed his own Gestalt, the Shadowlord and doomed all remaining Gestalts to lose their minds and die, and all the Replicants (except for Kainé, who is made fully human by Nier and Tyrann's sacrifice) to die to the Black Scrawl.
• The entire goal of the flash game Pandemic and its sequel is to make one of these in the form of The Plague.
• The Stone-Like in Radiant Silvergun, which is designed to keep depopulating the planet until humans learn the error of their ways.
• This is Wesker's plan in Resident Evil 5. The "Uroboros" mutagen will tear through the world's populations (ensuring "COMPLETE GLOBAL SATURATION") and devolve anyone who doesn't meet the genetic criteria Wesker has researched into a slimy mass of tangled, oozing tentacles. More able subjects will "evolve" and become Wesker's chosen race to ascend past humanity.
• The murder of Vigilance by Median's hands in Soul Nomad & the World Eaters turned Haephnes into a very slow version of this trope. Births became decreasingly common and the land slowly became more and more barren as a result of there not being a Master of Death to maintain the flow of souls, and another world/god, Drazil, stealing the souls of the dead for his walking graveyard, and by the time the events of the game comes around the land is little more than a dustbowl inhabited by one of the last generations of sentient life. Gig (Vigilance Reforged into a Minion by Drazil), of course, greatly hastened this process by killing off most of the population and burning most of the land to a crisp, before he was stopped by Median's daughter, Layna, and sealed off within a black sword.
• Stellaris:
  • The Apocalypse DLC introduces Colossi, gigantic planet-killer spaceships that can be armed with a variety of genocidal superweapons. One of these, the Neutron Sweep, annihilates the target world's entire population with a single shot from orbit, leaving its infrastructure intact (albeit damaged and in need of eventual repair project) for your colonists to take over. Needless to say, any deployment of a Colossus is considered a huge war crime by almost anyone in the galaxy even against Always Chaotic Evil empires, so don't expect your reputation to come out of it unscathed.
  • Finishing the Irassian Concordate quest chain unlocks the deadly plague that wiped them out as a unique orbital bombardment stance. It deals low damage to infrastructure but very high damage to armies and pops on the target planet, to the point that an entire world can be depopulated in only a few months of bombardment. Unlike the much more effective Colossus deployment mentioned above, this option trades time and effort for no one in the galactic community giving a shit (except for the empire currently getting virus-bombed into oblivion, naturally).
• Sword of the Stars:
  • It is possible to research and build biological weapons. When launched against a planet, each plague missile kills millions of people. Enough of them can quickly depopulate a world with no ill effect to the environment. Another version of the plague makes the target population more willing to join your empire. However, millions still die.
  • Also, in the Liir backstory, they are conquered by a vicious race known to them only as the Suul'ka. When they finally rebel, the Liir use their advanced knowledge of biology to genetically engineer a "bioweapon" designed to kill only the Suul'ka. The bioweapon actually wipes out all Suul'ka in the sector and, as it was previously thought, all Suul'ka everywhere. The sequel reveals that the Suul'ka are Not Quite Dead, also stating that the bioweapon is known as "The Black" and is currently the leader of their military, the Black Swimmers. The Suul'ka are actually, very old, very large, and very insane Liir Elders, the Black is an artificial Suul'ka who is loyal to the younger Liir and was once the Voice of Muur (the ruler of a Liir planet is known as the Voice, and Muur is their homeworld) that led his people to rebel against the Suul'Ka in the first place.
• Touhou Project: According to some of the compendiums, scientific advances was this trope to The Fair Folk, Youkai, gods and beings that affirmed their existence by Painting the Frost on Windows, hence causing the necessity for Gensoukyou to be founded in the first place. The most notable example that is brough up is the yamabiko, benevolent echo sprits that dwell in valleys and mountains... or dwelled in valleys and mountains... Though it's uncertain how many there are left, aside from Kyouko Kasodani, it's canon that they nearly went extinct when a scientific explanation for what causes echoes was discovered.
• The Ultima franchise features the recurring Armageddon spell, first given to the player character in Ultima VI, that effectively destroys all life on Britannia apart from the caster (apart from Ultima VIII and Ultima IX, where it kills the caster as well) and, if they're lucky, a few select NPCs, such as Lord British. Naturally, the games are usually Unwinnable after casting the spell, so pretty much everyone who ever played these games cast the spell once and only once to see what happens, before reverting to an earlier savegame.
• The Facebook game Wasteland Empires is based on this type of scenario, though what type is not stated.
• The Gen-Select bioweapon in Wing Commander IV: The Price of Freedom releases nanobots that kill everyone who doesn't meet the Black Lance's genetic standards. This weapon killed roughly 90% of the population on the planet it was used on.
• In Xenogears, humanity gets hit with a whole series of these:
  • 500 years before the main story, Grahf unleashed the "terminal interface weapons" of Deus, killing over 95% of the population.
  • Then, in the main game, the heroes' attempt to use nanomachines to remove the Limiters on the general population triggers a failsafe that causes some of them to turn into Wels. Just when the heroes begin making progress in treating some of the people who transformed, the Gazel Ministry activates the Gaetia Key, turning most of the rest of the population into Wels. The Wels are then absorbed by Deus, and either used as spare parts or converted into Seraphs, which begin slaughtering any humans who managed to survive this far. By the end of the game, over 90% of the planet's population is dead.

Visual Novels

• Hatoful Boyfriend: In 2070, a lethal form of bird flu spread around the world, killing over 70% of the human race. The remaining humans then tried to spread a counter-virus to kill off the birds which were spreading the disease, but the virus instead changed the birds into hyperintelligent mutants. Humans and birds waged war for thirty years, eventually resulting in birds becoming the dominant species. By 2188, the human population is less than 140 million, living in the wilderness and not allowed to self-govern. Depending on what ending you get, this can become full-on human extinction.
• Lucifer Alpha from Snatcher results in deaths of 80% of the population in Eastern Europe and Asia.
• Virtue's Last Reward gives us Radical-6, an epidemic virus with a 75% chance of driving the host to suicide. The pandemic broke out 40 years before the events of the novel; coupled with a few nuclear disasters, it killed 6 out of 8 billion people on Earth, leaving it an After the End Scavenger World. Safe shelters, quarantined moon bases and nomadic lifestyles were all key to humanity's survival. The point of its sequel is preventing the virus outbreak in the first place.

Webcomics

• In The Cyantian Chronicles, it's stated All There in the Manual that between Akaelae and Campus Safari a super-rabies/zombie type virus wiped out over 90% of the fox population. Which is why fewer of them are villainous in the latter, their tyrannical government is gone, and the sole remaining member of the royal family is less of a racist psychopath than his (adoptive) father and put a death warrant out on Exotica Genoworks for designing the virus.
• In Genocide Man, the population of the world in 2109 is only 3 billion thanks to repeated Synthetic Plagues. Some of them are caused by the titular people who are supposed to be preserving the human species.
• In Homestuck, even if the four main protagonists succeed in The Game and create a new universe, the human race and most other life on Earth will be destroyed by a hail of meteors known as The Reckoning. Only the four of them would survive to carry on the race — and bear in mind these are two pairs of 13-year-old full siblings being told they'll have to repopulate the planet. The kids Take a Third Option and scratch their session, rebooting The Game into a "void session" that at least preserves the possibility of human survival, so long as they eliminate certain outside threats.
• The dragons in The Inexplicable Adventures of Bob! wiped out most of their population, as well as the dinosaurs, with a weapon called the Iridium Bomb. The survivors eschewed technology for a pastoral existence in Earth's wildernesses.^note The iridium reference is Truth in Television. It was the detection of the rare element iridium at the geologic boundary layer between the Cretaceous and Paleogene Periods that first clued palaeontologists into the possibility that a large asteroid may have struck Earth at that time.
• Sluggy Freelance:
  • In one story arc, humanity in an alternate dimension is almost wiped out by the "ghouls". The only people spared are those onboard one of Earth's many space stations when the ghouls appeared.
  • In another Alternate Universe, Riff accidentally teleports everyone on Earth but himself to different dimensions, replacing them all with butterflies.
• In Stand Still, Stay Silent, the Rash Illness killed and mutated into trolls most of the human race, leaving only few survivors who were lucky or The Immune. When the story starts, the already sparsely populated Iceland is down to about 60% of the population the country had in real life at the time of publication ^noteIceland's real population is growing while the story's is static, so the ratio is dropping as the comic continues. Norway, Denmark, Sweden and Finland, meanwhile, went from populations in the millions to numbers oscillating between 10,000 and 20,000. The level of depopulation is illustrated well on this poster (scroll to the lower half to see a comparison).

Web Original

• SCP Foundation has the case of SCP 1322, another world populated by Human Aliens that they found a portal to. Communications and cultural exchange went great until a viral outbreak killed millions of people on 1322's world. The Foundation offered to help and came up with a vaccine that, due to the alien biology of the other world's inhabitants, worked... and rendered everyone infertile. They hate our world now and have been trying to throw a Depopulation Bomb back at us.

Real Life

• The Toba Catastrophe Theory holds that 70,000 years ago, a supervolcano in Toba erupted and did this to the human species. The population was reduced to as little as 10,000 people, possibly split up between Africa and India. To give some perspective, that means the entire human race could get good seating at Wrigley Field.
• The Galveston Hurricane of 1900 killed about a full third of the city's population, The exact death toll has never been confirmed but it is estimated to range between 6,000 and 12,000, with 8,000 being the most common number cited. It remains the deadliest natural disaster in U.S. history. After the storm, the survivors of Galveston rebuilt the city and added the current seawall, which held up nicely when Hurricane Ike came through 108 years later.
  • On a much smaller scale, a town in Alabama had one-third of its residents killed by a tornado.
• An even more tragic natural disaster example: In 1902, the volcano Mount Pelée erupted on the French Caribbean island of Martinique. It sent a pyroclastic flow down towards the city of Saint-Pierre, killing nearly everyone in the city, about 30,000 all total, including the island's Governor. Famously it was reported that only one man, a prisoner protected by his cell, survived. There has been at least one other documented survivor, and a few more who lived but died later from injuries or ash suffocation. The city was eventually rebuilt and new residents moved in, but its present-day population is only 4,590. And the town itself is indeed a shadow of its pre-eruption days when it was called the "Paris of the Caribbean".
• Mt. Pelée isn't the only example in the Caribbean. Although thankfully, not too many people actually died in it, the eruption of the Soufrière Hills volcano on Montserrat completely devastated the southern half of the island, covering it with ash and forcing the British government to declare that whole area an exclusion zone. Two-thirds of the islanders,7,000 out of a population of 11,000, fled Montserrat. Some have started to return, but it's still a long way to go, especially since residents still have to stick to the northern parts of the island.
• Not volcanic, but the Caribbean also lost Port Royal, a trading boomtown founded by the British in Jamaica, to an earthquake and resulting series of tsunami on June 7, 1692. Two-thirds of the busy port vanished under the waves, and ~2000 people were killed immediately; another 3000 of the initial survivors succumbed to injury or disease soon afterward. This, from a town whose population is estimated at 6500 to 7000.
• The Columbian Interchange was effectively this in relation to many Native American tribes. European (and native) diseases ended up wiping out most of the population in the densely populated cities of Mesoamerica; some cities saw as much as 90% of the local population died. The Noble Savage trope comes almost entirely from this. While it is sometimes incorrectly claimed that 90% of the population of *all* of the Americas died in these epidemics, scientific research has failed to back up these numbers. However, it was locally devastating; both the people of the Aztec Empire and the people of the Inca Empire suffered from smallpox epidemics during their respective wars with the Spanish conquistadors.
  • During the war with the Spanish, the tlatoani (emperor) of the Aztecs, Cuitláhuac, died of smallpox. It didn't help either that when Tenochtitlan was seized, the Spaniards and natives (more than 90% of Cortés's men were allied tribes) dropped corpses on Lake Texcoco to infect the water supply.
• Strategic nuclear weapons were designed to destroy large areas of the enemy's infrastructure, such as cities. During the Cold War the United States, the Soviet Union and their allies were all pointing nukes at their enemies' cities, and over 70% of those countries' populations are urbanized.
• Biological and chemical weapons, unlike nukes, are intentionally designed to devastate civilian populations and, more importantly, disrupt the enemy's supply chain and divert resources including vital medical supplies and personnel from the front lines.
  • It should be noted that biological weapons are the only weapons which are fully banned by international law.
• Cobalt bombs. Cobalt absorbs radiation and transforms into the radioactive Cobalt-60 isotope, which falls over a large area as fallout, potentially rendering a swath of land uninhabitable for some years. However, the world-destroying cobalt superbomb feared in pop culture is a grossly exaggerated fantasy, and the only attempt at building a cobalt bomb ended in failure. It would certainly be a Depopulation Bomb for many miles from the impact site though.
• The Neutron Bomb has its own entry, but basically, the concept is to maximize the amount of radiation damage short term, but avoid "poisoning" the area with long-lived fallout ... in other words, it's nearly the exact opposite of the cobalt bomb. They both do share the trait that blast damage is not the main point.
• The Black Death resulted in the deaths of an estimated 30-60% of the population of Europe, including wiping out entire villages. Over the course of fewer than 10 years, it dropped the global population from an estimated 450 million to 350-375 million. It took Europe 150 years to recover from the social and economic aftermath.
• The armies of Genghis Khan acted as a Depopulation Bomb. His march across Asia left so many villages desolate that forests were able to reclaim massive areas of cultivated land. The regrowth was so large and lasted for so long that it removed an estimated 700 million tons of carbon from the atmosphere, more than any other mass depopulation event in human history. This is equivalent to the amount of carbon released by a year's worth of burning of petroleum.
• Myxomatosis and other diseases have often been employed as a Depopulation Bomb against invasive pest species such as rabbits or rodents. Biopesticides are likewise used as a targeted alternative to insecticides to eradicate agricultural insect pests.
• World War II, being the deadliest war in human history obviously qualifies. Roughly 80 million people died and just to put that in perspective, World War I killed only about a quarter of that number. A few eastern European countries got the worst of it, especially Belarus, which lost a quarter of its population. Worsening things were the genocidal campaigns carried out by Nazi Germany (eleven million people, six million of whom were Jewish) and Imperial Japan (roughly three to fourteen million, many of whom were Chinese, Filipino, Korean and others).
• War of the Triple Alliance, while nowhere near being one of history's deadliest wars, still set the record for most deaths of any country percentage-wise. It wiped out half the population of Paraguay.
• China has had a few of these:
  • Most historical cases of changing dynasties were accompanied by a culling of China's population. The chaos during the fall of the Han dynasty and the rise of the Three Kingdoms was particularly devastating. A census conducted before the wars counted around 56 million people. The next century's census — conducted during the Jin dynasty, which unified the Three Kingdoms — counted 16 million people. In other words, the war reduced the population by 70%.^note Modern estimates have put the population before and after the war at 60 and 35 million, respectively, which would mean the population was reduced by "only" half. It's still damn high, though. The transition from Song to Yuan (Mongol) and Yuan to Ming also slashed the empire's population by half. The fall of the Qing (Manchu) dynasty and ushering of the warlord era was actually an improvement because it wasn't accompanied by a catastrophic depopulation.
  • Not including plagues or epidemics, the worst natural disasters in history by the number of casualties were the 1931 floodings of the Yellow River in China, which resulted in the deaths of at least a million people. The Yellow River is by itself the deadliest area for natural disasters in history, as it's even the location of the second deadliest natural disaster in history, the Yellow River flood of 1887.
• The 1918 Spanish influenza pandemic is estimated to have caused between 17 million and 100 million deaths worldwide.
• The Cambodian genocide carried out by the Khmer Rougue from 1975-1979, killed roughly 2 million out of a population of 8 million, reducing the country's population by a quarter, and saw the entire populations of urban centers sent out into the countryside to work on collective farms, reducing once thriving cities into hollowed out ghost towns.
• The Irish Potato Famine left a lasting legacy of depopulation that the island of Ireland never recovered from. The island's peak population of 8.1 million people during the 1840s has never been reached again; as of the 2010s, it numbers about 6.5 million.
• The Syrian civil war. A 2011 estimate, a year before the war broke out, counted 21 million people in Syria. As of 2017, the country has a population of 17 million. The major reason for this depopulation is not because of deaths (not that it's insignificant; a half million Syrians died during the course of the war), but rather the truly staggering amount of War Refugees who fled the country; 5 million Syrians are currently living in other countries.
• Due to the demographic transition, as a result of family planning and greater access to education, many nations in the developed world, and a few in the developing, are seeing a slow-motion population decline, especially as the cost of education, child care, and housing skyrockets. Some nations, like Japan and China, could see their populations cut in half by the end of the century.
• The Russian Cross, in which Russia has seen negative population growth for roughly three decades following the collapse of the Soviet Union, due to a combination of declining birth rates, economic collapse, and alcoholism. ^note Putin's invasion of Ukraine is partly driven by a Russia desperate to have more people within its borders.
• Another intentional example of this trope comes from the Harrying of the North: After William the Conqueror defeated Harold and became the new king of England, the northern half of the country rose in revolt. William ended the resistance through the use of a scorched-earth campaign, to deny the northern rebels any stronghold to rise from. Entire villages were razed, and their inhabitants put to the sword; livestock slaughtered, and stores of food destroyed. A census recorded two decades after the event states only 25% of the population remained. Or, in the record keepers' own words, hoc est vast (it is wasted).
• Thomas Robert Malthus, writing on An Essay on the Principle of Population, observed that an increase in a nation's food production improved the well-being of the population, but the improvement was temporary because it led to population growth, which was also temporary. In other words, humans had a propensity to utilize abundance for population growth rather than for maintaining a high standard of living, a view that has become known as the "Malthusian trap" or the "Malthusian spectre". Populations had a tendency to grow until the lower class suffered hardship, want, and greater susceptibility to famine and disease, a view that is sometimes referred to as a Malthusian catastrophe. Malthus wrote in opposition to the popular view in 18th-century Europe that saw society as improving and in principle as perfectible.
• Charles Darwin, who studied Malthus, asserted that the human "population, when unchecked, goes on doubling itself every twenty-five years, or increases in a geometrical ratio", a geometric progression so that population soon exceeds food supply until it crashes, in what is known as a Malthusian catastrophe. Darwin was well prepared to compare this to Augustin de Candolle's "warring of the species" of plants and the struggle for existence among wildlife, explaining how numbers of a species kept roughly stable. As species always breed beyond available resources, favourable variations would make organisms better at surviving and passing the variations on to their offspring, while unfavourable variations would be lost. He wrote that the "final cause of all this wedging, must be to sort out proper structure, & adapt it to changes", so that "One may say there is a force like a hundred thousand wedges trying force into every kind of adapted structure into the gaps of in the economy of nature, or rather forming gaps by thrusting out weaker ones." It was Malthus the one that inspired Darwin's now-accepted theory of biological evoution.

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