History ApocalypseHow / Class3A

* The worst case scenario of a full scale nuclear war, which could, by some predictions, be damaging enough to destroy the very biosphere that humans depend on to survive. The actual ''explosions'' are the least of our worries. Following that, fires would rage for weeks or possibly months on end, releasing great plumes of smoke that are believed to ''blot out of the northern hemisphere'' for an extended duration, causing the effect we call "nuclear winter". This would drop the average temperature significantly, with the sun being simply unable to shine on the Earth for a reasonable amount of time. Snow and ash would intermingle. Then there is the radiation. If you are lucky, you will get irradiated enough to die within a few days, but radiation sickness is unpredictable and horrible, but basically it results in the ''your very DNA getting smashed to pieces'' at worst. The surviving population would see higher rates of cancer and mutation due to the aforementioned screwing up of their genes. This goes for all species. Water would be unsafe to drink unless filtered extremely well (as water is largely unaffected by radiation by itself, but radioactive particles in the water could still do some damage), food would be unsafe to eat, and in many cases, the air would be unsafe to breathe. Sounds horrible, right? Well, the reason this is a ''possible'' outcome is that many of the effects may not be as strong on the southern hemisphere, since a nuclear exchange under current scenarios would be largely restricted to the northern hemisphere. They would still get hit with climate effects, radiation, and other complications, and civilization would definitely not survive, but humanity may be able to ride out the storm in the south. The general belief is that Australia is the safest since there's nothing of worth to be hit, and most refugees escaping a nuclear war before it starts will be safe...[[EverythingTryingToKillYou if the venomous spiders don't get you first]].

* The worst case scenario of a full scale nuclear war, which could, by some predictions, be damaging enough to destroy the very biosphere that humans depend on to survive. The actual ''explosions'' are the least of our worries. Following that, fires would rage for weeks or possibly months on end, releasing great plumes of smoke that are believed to ''blot out of the northern hemisphere'' for an extended duration, causing the effect we call "nuclear winter". This would drop the average temperature significantly, with the sun being simply unable to shine on the Earth for a reasonable amount of time. Snow and ash would intermingle. Then there is the radiation. If you are lucky, you will get irradiated enough to die within a few days, but radiation sickness is unpredictable and horrible, but basically it results in the ''decimation of your very DNA'' at worst. The surviving population would see higher rates of cancer and mutation due to the aforementioned screwing up of their genes. This goes for all species. Water would be unsafe to drink unless filtered extremely well (as water is largely unaffected by radiation by itself, but radioactive particles in the water could still do some damage), food would be unsafe to eat, and in many cases, the air would be unsafe to breathe. Sounds horrible, right? Well, the reason this is a ''possible'' outcome is that many of the effects may not be as strong on the southern hemisphere, since a nuclear exchange under current scenarios would be largely restricted to the northern hemisphere. They would still get hit with climate effects, radiation, and other complications, and civilization would definitely not survive, but humanity may be able to ride out the storm in the south. The general belief is that Australia is the safest since there's nothing of worth to be hit, and most refugees escaping a nuclear war before it starts will be safe...[[EverythingTryingToKillYou if the venomous spiders don't get you first]].

Planetary-scale Extinction of the dominant species on a planet, via unnatural causes (ie: someone did something, [[HoistByHisOwnPetard human]] or [[AliensAreBastards otherwise]]).

* It's not explained what happened in ''Manga/GirlsLastTour'', but whatever it was wiped out most of the life on the artificial world where the protagonists live. At this point, humanity's population appears to have dropped well below sustainable levels.

* Heavily implied in Music/DeepPurple's "Man Alive", where almost all of humanity is gone, either due to this or due to a 3b. Given the group's flirtation with the GreenAesop theme in recent years and the general tone of the song, it was probably caused by humanity itself.

* ''WebAnimation/ObjectInvasion'' takes many years after a mass radiation annihilated the Earth and wiped out all the species at the time. However, some time after the catastrophe, and before the evens o the show itself, a race of sediment objects rise up via evolution and restore the planet.

* The bad ending of ''VideoGame/{{Obsidian}}'' results in allowing the nanobot-controlling AI Ceres to finish its intended goal: [[spoiler: By using its nanobots to '' [[DeadlyEuphemism reboot Earth]] '' so that no humans [[LastOfTheirKind except you and your partner Max]] can ever exist, and thus [[ZerothLawRebellion never pollute Earth to begin with]].

* The ultimate goal of the Dragons of Earth in ''Manga/{{X1999}}''.

* It becomes an important plot point in ''VideoGame/{{Utawarerumono}}'' that scientists accidentally roused a malignant god in the distant past and brought about one of these.

* This is the BigBad's goal in ''Anime/MobileSuitGundamSeed''. Due to his [[NukeEm method o]][[KillSat f choice]], it just might reach Class 4 or Class 5.
* ''Anime/AfterWarGundamX'' came ''very'' close to this. It is established that a massive ColonyDrop killed 99% of the Human race at the end of the last war. It has recovered since then, however.
* ''Anime/PuellaMagiMadokaMagica'': It is explained in episode 10 that [[spoiler: Madoka herself can cause this. After a few timeline loops, she begins to transform into the incredibly powerful Kriemhild Gretchen, who will wipe out all human life in a matter of days. It's a good thing that, when she finally [[DealWithTheDevil makes a contract with Kyubey]] at the end of the series, her wish is to be able to erase ''all'' Witches in ''all'' timelines, ''including her own Witch'' (of course, this comes with the side effect of [[AscendtoaHigherPlaneofExistence being written out of existence almost entirely]], but for Madoka, it's completely worth it.)]]

* Part of the backstory in ''Manga/AttackOnTitan''. A little over a century prior, strange beings known as Titans appeared out of nowhere and began to devour any humans they could find. The survivors have spent the last century living within three 50-meter Walls, with all information about the Outside World banned and mention that [[MixedAncestry mixed-race]] heroine Mikasa is the last surviving Asian suggest extinction of multiple ethnic groups. The surviving population numbers in the hundred-thousands, and is under constant threat of extinction from either Titans (if the Walls are broken again), starvation from famine and food shortages, or even civil war due to the corrupt and oppressive government. The series begins with 20% of the population being wiped out when the first of the three Walls is lost. [[spoiler:However, almost everything just mentioned is later revealed to be a complete lie; while the island the main cast lives on ''is'' overrun with Titans, the rest of the world is filled with thriving human civilizations. In fact, the Titans themselves turn out to be just tools of the most powerful human nation.]]
* The Death Force of ''Anime/MDGeist'' was designed to completely annihilate human life on Jerra. Geist is tapped to help prevent its activation. [[spoiler:Then he activates it himself so he'll always have something to fight]].
* [[Anime/NeonGenesisEvangelion Evangelion]] has [[spoiler:[[AssimilationPlot the Human Instrumentality Project]]]] which causes the entirety of humanity to become extinct and become one of the [[EldritchAbomination angels]] that they fought for the entire series. [[spoiler: Subverted when Shinji rejects it, allowing humans to return as they choose.]]
* The main premise of ''Manga/DrStone'' involves every human in the world being turned to stone, and finding out the cause of this is part of the major MythArc of the series.
* It's not explained what happened in ''Manga/GirlsLastTour'', but whatever it was wiped out most of the life on the artificial world where the protagonists live. At this point, humanity's population appears to have dropped well below sustainable levels.
* ''Manga/{{Devilman}}'' sees the world slowly fall apart as a result of [[spoiler:the machinations of Ryo Asuka, who is actually the fallen angel Satan. The war between demons and humanity eventually leaves humanity extinct, and the world is destroyed in the final battle between Satan and Devilman. ''Anime/DevilmanCrybaby'' shows another version of this apocalypse: after the existence of demons becomes public knowledge, humanity becomes paranoid and largely wipes itself out in the world war that follows.]]

* Nick Sagan {{lampshade}}s this in ''Literature/{{Idlewild}}'' and its sequels, saying that it wasn't really the end of the world because insects survived and thrived. The event itself could probably be called a 2.9 (10 surviving humans.)
** not to mention several thousand cryogenicaly frozen people.

Planetary-scale Extinction of the dominant Species on the planet, via unnatural causes (ie: someone did something, [[HoistByHisOwnPetard human]] or [[AliensAreBastards otherwise]]).

* Kurt Vonnegut's ''Literature/{{Galapagos}}''. Okay, technically the human race does survive in the end, but you can't really consider them human anymore by the time they do get back on their feet. [[spoiler: Their brains have atrophied and their limbs evolved into flippers. The ghostly narrator sees this as a good thing.]]

* It turns out that in ''Literature/{{Wool}}'', [[spoiler:the American government eradicated all of the humans on Earth with nanobots roughly 300 years before the events of the series. The fifty silos are the only known remnant of humanity, and only one of them is intended to tunnel to the surface and start life anew after the 500 years are up.]] It appears to be a Class 4 at first glance, [[spoiler:but once the surviving residents of Silos 17 and 18 reach the surface, they discover that the barren section of the planet only encompasses the region in which the silos are kept.]]

* In ''VisualNovel/CiconiaWhenTheyCry'', the resident OminousCouncilOfVagueness would really like to set human civilization back by a couple millenia. Since the population loss during WorldWarIII was made up for in just over a century, this time they have several possible methods at their disposal: fanning the flames of international tension to spark World War IV, unleash a virus that destroys agriticultural production to create a world famine, hacking millions of war drones to destroy the biggest cities, or create devices that would basically poison the Earth's water. [[ThereIsNoKillLikeOverkill They choose to use all of them at once.]] And to top it, some MadScientist independent from them created a machine that destroyed the 8MS, the cloud of nanomachines that artificially maintained the planet's climate and offset the nuclear winter that followed WWIII. All of that happens in the span of a few weeks. And this is just the first chapter of a four-part story.

[[folder:Film]]

* New ''Series/DoctorWho'' series 1 ending: the Daleks are back, and their plan is pretty much this. The Doctor's solution to save humanity? Kill at least ALL intelligent life on or near Earth, Dalek and human (granted, he didn't have time to actually remove the 'and human' bit from the weapon). And he squicked at holding a ''gun'' on a guy. The Daleks ''talk him out of doing this'' because it'd give him ANOTHER genocide on his record, even though he points out there are humans elsewhere who would survive this. By the end of the episode the Daleks seem to have enacted this on Earth.
** The gaseous Gelth plan to kill all humans, and inhabit their corpses.
* In ''Series/{{Lost}}'', [[spoiler:if the Man in Black manages to escape the Island after being stuck there for two millenia, he plans to wipe out all human life.]]
* According to Rich, In the ''Series/{{Community}}'' episode "[[Recap/CommunityS2E06Epidemiology Epidemiology]]", a Class 3 would occur within a year and a half. However, seeing as everyone is cured by turning the thermostat down to 58 degrees, one suspects this virus might have a little trouble making it out of Colorado.
* In the 2000 two part episode of ''Series/TheOuterLimits1995'' "Final Appeal" it's revealed that all episodes are alternate timelines and futures and that while many of them actually are tied together into semi coherence. the episode ends with a time traveler with a grudge detonating a fusion bomb taking out most of the eastern seaboard, rendering their arguing about this timeline's rejection of tech stronger than a light bulb pretty much moot.

* Creation in ''Fanfic/ConquestQuest'' seems to have experienced this, which kickstarted the whole plot.

* The Tuffle race in ''Manga/DragonBall'' is wiped out by the Saiyans who become giant apes at the full moon. They work under Frieza's planet trade to do this as a career choice.
** Also done when Buu unleashes a BeamSpam of epic proportions from the Lookout and kills every human '''NOT''' on the Lookout, [[ForTheEvulz just because he could]]. He later went and killed the few remaining people that were ''on'' the Lookout by turning them into food and eating them.

* This is the BigBad's goal in ''[[Anime/MobileSuitGundamSeed Gundam SEED]]''. Due to his [[NukeEm method o]][[KillSat f choice]], it just might reach Class 4 or Class 5.

* It's not explained what happened in ''Anime/GirlsLastTour'', but whatever it was wiped out most of the life on the artificial world where the protagonists live. At this point, humanity's population appears to have dropped well below sustainable levels.
* ''Manga/{{Devilman}}'' sees the world slowly fall apart as a result of [[spoiler:the machinations of Ryo Asuka, who is actually the fallen angel Satan. The war between demons and humanity eventually leaves humanity extinct, and the world is destroyed in the final battle between Satan and Devilman. The anime series ''Devilman Crybaby'' shows another version of this apocalypse: after the existence of demons becomes public knowledge, humanity becomes paranoid and largely wipes itself out in the world war that follows.]]

* In current ComicBook/MartianManhunter continuity, this is what Malefic did to Mars, using a virus to kill all Green Martians.
* ComicBook/PostCrisis. Everyone in the alternate Earth of the Pocket Universe were killed by that universe's General Zod, Faora ([[AdaptationNameChange renamed Zaora]]), and Quex-Ul. They even destroyed the planet's biosphere so no one would survive without a spacesuit. Matrix (the Post-Crisis Supergirl) is the only survivor. Also, Earth and Krypton were the only inhabited planets, thanks to the manipulation of the Time-Trapper. Likely, any other Kryptonian criminals in the Phantom Zone remain trapped there. Following ''ComicBook/ZeroHour'', the lifeless Pocket Universe is wiped from continuity, making this a Class X-4.

* In ''[[FanFic/IcedFairysANewWorld A New World]]'', the remnant of Lunarian society is so scared of human expansion on the False Moon, they see fit to seize control of Earth's nuclear arsenals and trigger a colossal war. [[spoiler:[[AllForNothing It turns out to be worse than useless]], as it was ''[[BatmanGambit exactly]]'' what [[ManipulativeBastard Yukari]] wanted them to do. Earth ''does'' suffer greatly... but the Lunarians are left extinct and their worst nightmare, the complete fusion of the worlds of magic and science, is brought into reality by humans and the magic races.]]

* Geologist Dougal Dixon wrote (and illustrated) the literally science fictional ''After Man'', a really quite detailed description of the various ecosystems of Earth 50 million years from now, with the base assumption that humans go extinct some time "soon" in geological terms (i.e. within the next 100,000 years or so).

* Another technically-non-human example in ''WesternAnimation/StevenUniverse'': about 5,000 years ago, Gems were the dominant civilization on Earth but in open revolt against their extraterrestrial masters. Eventually [[BigBad the Diamonds]] caused something, alternately described as a light or a song, that corrupted all unprotected Gems on Earth. While the corrupt Gems are still around, they demonstrate only animal-level intelligence, unable to form much of a civilization. The few Gems on Earth that are both uncorrupted and free have been hunting them down and capturing them ever since.