Sterility Plague

For one reason or another, people can't give birth anymore. This is often but not always due to a plague inflicted upon a species due to a Depopulation Bomb dropped on them by their enemies, hence the name. However, this can just as easily be caused by a natural plague, biological changes in a species which might prevent sex, or a cultural phenomenon causing people to be terrified of heterosexual sex (or at least pregnancy). Most horrifyingly, perhaps your enemies just decided to come along and castrate all your males.

Of course, the most popular agent for this problem by far is genetically engineered disease. If you are considering what type of Depopulation Bomb to use on your enemies, you may consider the Sterility Plague the best option for many reasons. First of all, it is a very covert and completely humanitarian method of mass genocide. It will not kill a single enemy civilian or combatant. It is incurable, except where the forces of pure good are involved (But really, what can't they fix?). Your enemies will live just as long as they would have otherwise, but they will not multiply and will cease to be any threat at all after a generation or two. If your race is particularly long-lived then you might consider waiting for everyone to die to be not such a big deal.

Then again, if you are short lived, this might not seem like much of a solution. Also, it does not do much to kill or disable the enemy besides lowering their morale. In fact, it might just really piss them off. And, if they have artificial means of reproduction, a Sterility Plague may be a really dumb idea.

If your civilization for one reason or another has decided to completely abandon sexual reproduction (possibly in favor of artificial means), expect this to become a major issue soon after the story starts. In fact, unless sexual reproduction can be rediscovered by your race, expect disastrous if not nightmarish consequences. This is probably a little homophobic (especially if you have only abandoned heterosexual sex) and a lot allegorical.

Lastly, you can expect any Knight Errant or civilization-redeeming Messiah figure who comes along to cure the Sterility Plague in the space of a single episode or two-hour feature film. The forces of good make fertility a point of focus, often impregnating virgins, men, and the infertile, so you shouldn't be surprised when they pull double duty by curing a plague and bringing pregnancy to the downtrodden masses.

A sub trope of Depopulation Bomb. Compare Gendercide. Likely to result in a Childless Dystopia.

Anime and Manga

 * Fafner: The Festum did this to Japan, prompting the Alvis project which gave rise to artificial reproduction, and, by the same token, genetically engineered supersoldiers (i.e. our heroes) born to fight the Festum. The plague is cured somehow by the final episode as a Someone to Remember Him By, thereby ensuring the future glory of the mighty Japanese people and their superior way of life.
 * Vandread: The heroes come across a planet in the second season which had this done to them by Earth. Needless to say, they cure it.
 * Macross: The Zentrati have totally abandoned sexual reproduction and segregated their race into male and female tribes. Luckily, humans come along to teach them the ways of love.
 * In Mobile Suit Gundam SEED, Third-generation Coordinators (like Lacus Clyne) suffer from this, due to their modified genes and the human body being unable to handle the changes correctly. During both it and Gundam Seed Destiny, there has been no cure to this infliction and many Coordinators (such as Patrick Zala) refuse to entertain the idea of mating with Naturals.

Comics

 * In one storyline in Captain America (comics), Superia attempted to release a plague that would sterilise the world's female population except for her and her cadre of supervillainesses. As the only fertile women in the world, they would essentially have been able to hold the world to ransom.
 * An EC Comics story (based on a prose short story) has female sterility happen as a result of cosmic radiation--after enough years that even the last born child is a senior citizen, they finally develop a time travel gate with the catch that they can only set it up once, and it will be immobile. And travel to the future renders one amnesiac. So the future people set up their gate/trap in New York City in the 1950s; lots of people there to grab. But everyone who comes through the gate is male!
 * In almost the Exact Words of the Laconic ("No more mutants!"), the Scarlet Witch used her Reality Warping powers to not only depopulate the mutant species, but also to prevent mutant births from happening in the future. Since House of M ended, there have only been six mutant births in total.

Fan Fiction

 * The Stargate fanfic "Bless the Children" by Maureen T sees SG-1 meet a race of aliens with a fertility problem and an unusual solution, the consequences of which drives the plot of the story. It can be found on fanfiction.net.

Film

 * Children of Men - This trope forms the basic premise of the movie.

Literature

 * Due to insufficient research on long term effects, the "cure" for AIDS turns out to be one of these in the first third of the novel The Breeds Of Man by making it impossible for women to have more than one child. The second third is about trying to find a cure for the cure before it's too late, and the last third is about trying to find a way to cure the cure for the cure (since the protagonists just can't stop breaking things).
 * In Gulliver's Travels, the Houyhnhnms decide the best way of wiping out the Yahoos is to castrate them all. They got the inspiration for this from Gulliver's description of how horses are treated in England (male horses were castrated to break their spirits and control the population.)
 * Declining fertility rates due to chemical pollution is a central theme in both the film and book versions of The Handmaid's Tale.
 * The novel Children of Men by P.D.James, as noted with the film adaptation, is an archetype of this trope.
 * In the Belgariad's past, when Gorim of the godless finally got a god to accept him, he asked for his people to follow and cursed those who refused with sterility. In Belgarath The Sorcerer he expresses regret on this and surprise that the curse wasn't lifted.
 * In Bumped, a virus went around causing all adults to be sterile. As a result, adults will pay lots of money to teenagers (and in extreme cases, preteens) to be surrogates.
 * In Prized, the sequel to Birthmarked by Caragh O'Brien, Gaia travels to Sylum, a Matriarchy where 9 out of every 10 babies are male, so females are prized members of society. On top of that, a couple hundred of the men are infertile. It is revealed that
 * Le Dernier Homme is an 1805 science fiction novel written as a prose poem where humanity as a whole is going sterile. It involves the voyage of the last fertile man to meet the last fertile woman only to meet with Adam, who has been charged by God to convince the couple to not reproduced, thereby allowing the world to end and the world be reborn.
 * In The Bible, this happens to both a pharaoh and a minor king named Abimilech, because both had brought Sarah (a married woman) into their harems after her husband grabbed the Idiot Ball out of fear for his own safety. Before either of these men can defile her, God makes them sick and their other wives and concubines sterile, until they figure out that Sarah doesn't belong to them.

Live Action TV

 * Stargate Verse:
 * The Asgard suffer from the fact that they have totally abandoned sexual reproduction in favor of cloning.
 * In the Bad Future portrayed in the SG-1 episode "2010", the Aschen plan to surreptitiously conquer Earth involves one of these, distributed under cover of advanced medical tech. As shown in the later episode "2001", this is their modus operandi.
 * In one episode of Star Trek: The Next Generation there's a group of colonists who had too few people to successfully build a colony, so instead of sex the went the cloning route. Now due to replective fading they can't do that any more, so they steal DNA from people on the Enterprise. The resolution if that they marry their cousins from Oireland In Space.
 * In another episode a world where they're going sterile, and steal the kids from the Enterprise to be their next generation (no pun intended).
 * Earth: Final Conflict: the Companions are sterile; Zo'or is the last one to have been born.
 * In Lost, women who conceive on the island cannot give birth there. Those who try all die. It turns out that the island's electromagnetism sets off an immune response that attacks the fetus, killing both mother and child.
 * The The Outer Limits revival episode "Dark Rain" concerns a future where chemical warfare has left most of humanity sterile. The rare viable pregnancies are sought out by the government and confined to hospitals so the newborns can be seized as wards of the state.

Video Games
"Alyx Vance: Did Dr. Kleiner just tell everyone to... get busy?"
 * Mass Effect: The krogan were hit by the 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 they needed countless colony worlds to handle their expanding population -- including worlds controlled by other sapient species. The genophage reduced krogan birthrates to less than one successful live birth per thousand pregnancies -- which, to put things in perspective, would have ideally given them a growth rate still equivalent to a post-industrial society. It went a bit too far and reduced the krogan to a dying species on a slow decline to extinction and gave most of them (including a party member, Wrex) a Nietzsche Wannabe streak that tends to make them criminals. Their society would easily survive, except they're too fatalistic to try and rebuild.
 * In Mass Effect 2,
 * Also
 * In Half Life 2, the Combine have set up some sort of device which makes humans unable to reproduce. In the expansions this has been deactivated, leading to Dr. Kleiner to suggest that repopulation can begin.


 * The Vampires of the Legacy of Kain series were inflicted this (along with immortality and blood-thirst) by their archenemies, the Hylden, when they banished them. The problem is, the Pillars of Nosgoth, which represent the balance of the world and serve as a seal to imprison the Hylden, chose their guardians among newborn Vampires. When the Vampires ceased to give birth, the Pillars started to choose humans: it did not end well at all.

Real Life

 * This is a common method humans use to eliminate harmful organisms in their environment such as mosquitoes and viruses. Scientists tasked with wiping out a short-lived life form often focus on disabling is means of reproduction. They find ways of infecting, poisoning or destroying stagnant water to stop mosquitoes from breeding, and the only known means of effectively killing viruses is to interfere in their reproductive cycle (i.e. interferon medicines).
 * In Real Life some insecticides work this way, making the insects that ingest it sterile.
 * In Real Life, this is the reason why the pesticide DDT was banned. While harmless to humans, it ended up accumulating throughout the foodweb until it reached ospreys in high concentrations. While it didn't strictly make them sterile, it did cause female ospreys to lay eggs with very weak and brittle shells, and when the ospreys sat to incubate their eggs, they would crush them and destroy their young. This led to them because severely endangered as their population plummeted, but the ban on DDT resolved the problem and their numbers are starting to increase again.