Immortal Procreation Clause

aka: Immortal Infertility

The fertility of a species is inversely proportional to its lifespan. Thus, as a species approaches immortality, their birth rate approaches zero.

In many works of fiction featuring immortality, the immortals in question are sterile or infertile: they cannot have children. Legacy Immortality is both impossible and unnecessary.

In many cases, this is an example of Cursed with Awesome, because, along with some STD Immunity, it means that the teen-looking ancient vampire stud can get it on with the ladies as much as he wants without worrying about consequences of any sort, particularly leaving lovers pregnant with a Dhampyr who will eventually grow up and try to kill him. Or at least demand child support.

Immortals may have methods of making mortals immortal (vampire bite, Applied Phlebotinum, or the like) and they may come to view those that they bring over into immortality as their own children, teaching them the lessons and how to thrive as an immortal. This, however, is not the same as having natural children. It's more like adoption and a new immortal being Happily Adopted is certainly possible.

Sometimes the beings in question are perfectly able to have children, but are not allowed to, by the laws of their society, because allowing immortals to breed will quickly lead to overpopulation. This usage tends to be found in hard Speculative Fiction.

Another common twist is to have immortals that are quite fertile/potent but whose children are completely or near-completely mortal. These examples are also included here because they fit in with the theme that unchecked reproduction combined with immortality is unsustainable. This aversion is probably even more tragic, since the immortal will then be forced to watch their children die as they inevitably outlive them all.

In a strictly biological sense this trope is fairly logical. Without death, an immortal population would constantly grow, eventually crowding themselves out and depleting their resources. As such, childbirth isn't really a necessity for such a species, since the members rarely need replacement. Assuming that the offspring of immortals mature at the same relative rate as humans, the time and resources required to successfully rear children to adulthood increases exponentially, becoming far too expensive to be sustainable on a large scale. This encourages longer lived intelligent species to reproduce rarely, but invest heavily into their few offspring to give them better chances of survival. With these factors and more, the above formula can (very loosely) apply to any given species.

This trope includes extremely Long-Lived characters and species with low birth rates, as they fit on the sliding scale properly. The most common example of this is elves; Tolkienesque elves generally are The Ageless and can have children; their population growth is mitigated by a low birth rate (a typical elf couple can live together for several thousand years and produce only one or two children in all that time), the occasional violent death, and the tendency for older elves to journey across the sea to a mystical land, never to be seen again.

Related to Creative Sterility; this is a focus on sexual reproduction. It can result in a Dying Race if the immortals can still be killed. See also Vampire Procreation Limit, which often contains some overlap with this trope.

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Examples:

Anime and Manga

• The Sanzhiyan Humkara from 3×3 Eyes are immortal until they usually lose their souls to Kaiyanwang's Humanization Ritual and are turned into humans. Apparently, also because of their Immortality Immorality, they do not reproduce often. The sole exception may be Kaiyanwang, who has an harem of wives and concubines so that he will always have a source of children to use in his Humanization rituals.
• The Bounts from Bleach's Bount arc were a group of immortal, soul sucking humans who could summon Bond Creatures, but they were incapable of reproduction. The one Bount that did have the ability to reproduce was killed by her own people as part of some elaborate ritual to summon an army of flying, soul-sucking insects.
• Blood+: Chiropteran queens are able to reproduce, but can only be impregnated by a chevalier created by her sister queen in order to maintain their race's purity.
• In Dance in the Vampire Bund it's discovered that the "True Blooded" vampires can, in addition to turning those they feed on into theoretically weaker ones, reproduce sexually. Problem is that females can give birth once and they apparently reach adulthood very slowly. Bigger problem is that Dukes Ivanovic, Li, and Rozenmann apparently killed off the other 97 dukes and their families then slaughtered the whole Royal House of Tepes save for the young Princess Mina (who is under obligation to produce a True Blooded heir).
• DARLING in the FRANXX: The human race as a whole has become immortal and unaging, but the treatment also caused them to become completely infertile as a side effect. The children seen in the show are created via cloning and genetic manipulation, and these children only exist because a FRANXX can only be piloted by a male and female together who are still capable of reproducing.
• In Death Note, there is a rule stipulating that Shinigami are not to reproduce or have sex with either other Shinigami or with humans. Even if they wanted to do it, they wouldn't be able to, because they lack the necessary "equipment." ^note  and if they had the right stuff, they might not be able to produce viable Half Human Hybrids anyway.
• In Frieren: Beyond Journey's End, elves live for thousands of years but have little-to-no reproductive urges and are typically detached from other races because decades to them are as weeks are to us. As a result, they're now a Dying Race after they were massacred by Maou the Demon King, and even if crossbreeding were possible with other humanoids elves' wildly different perspectives make any attempt at romance doomed to fail.
• Fullmetal Alchemist: Homunculi, creatures created by alchemy, are stated as unable to reproduce sexually (though Father was able to produce seven "children" by separating souls from his Philosopher's Stone into new Stones and using them to create Homunculi). They exist outside of any ecosystem. Van Hohenheim is an exception because he Was Once a Man, though he only ever had two children because there was only ever one woman he wanted to have children with.
• Discussed in Heaven's Design Team, when the designers are tasked with creating an immortal animal. They use a simulation to show Shimoda why in an unaging species, population growth tends towards zero, either because no aging means only the weak offspring are eaten by predators, or because overpopulation leads to starvation from limited resources (and lack of genetic diversity leaves them all vulnerable to the same disease). They do show several examples of functionally immortal animals, like lobsters and jellyfish, both of which are frequently eaten by predators (or Jupiter).
• In the manga that Hellsing was based on, Proto-Alucard explains that he kills off vampires who Turn too many humans because if there were too many vampires, there wouldn't be enough (read: any) humans left to feed on. He bring this up in Chapter 1 of the actual series as well.
• In JoJo's Bizarre Adventure it is mentioned that the longer a species life span is, the less they reproduce. The pillar men were a long lived species outnumbered by the short lived humans, and when the Big Bad Cars becomes the Ultimate Life Form, it is mentioned that he can no longer reproduce and doesn't need to, as he will never die.
  Sex = Useless
  • Despite this, it is shown that vampires are still capable of reproduction as seen with series antagonist DIO's four illegitimate children from Golden Wind and Stone Ocean. Although none of them inherited their father's vampiric abilities, let alone his immortality.
  • Although DIO was just a head controlling his adopted brother Jonathan's body. So technically he was using Jonathan's, er, parts to have his children. So we don't know if he could have had children before being reduced to a head.
• In the Metroid manga it's mentioned that the Chozo are slowly becoming extinct because their lengthened lifespan also made them very infertile.
• Played straight in Mnemosyne until a last minute epilogue subversion: Rin herself bears a child, proving that it is possible.
• Negima! Magister Negi Magi averts Immortality Begins at Twenty, causing this problem for pre-pubescent immortals.
  • The vampire Evangeline has been around for hundreds of years, and presumably never reproduced. Although this may have more to do with the fact that she's evil, uber powerful, and scary, as well as the fact that she gained immortality when she was ten years old and has been stuck that way since.
  • Negi himself, due to his transformation into a demon through Magia Erebea, will stop aging "soon". He might still grow up for a few years, or be stuck with the same fate as Evangeline. Setsuna quickly starts to think about how it will be practically impossible for him to father any children like that. According to the Stealth Sequel series UQ Holder! Negi was indeed incapable of having children. Someone decided to try to "clone" him to ensure his powers would be passed on somehow, and Negi's "grandson" Touta Konoe apparently resulted from that program. The finale of the series shows that Negi gave up his immortality and as a result was able to have children with many of his admirers.
• Princess Resurrection: This is specifically the reason for the Royals killing each other off. Since a fully mature Royal becomes a Phoenix who cannot die, There Can Be Only One to become one.
• Near the end of Soul Eater, it's revealed that while Lord Death is immortal and was able to have a child, that child unlocking his full power will cause the previous incarnation of death to die. Excalibur even points out that they can't just have immortals running all over everywhere, and he's right. Each of them are more Anthropomorphic Personifications than living beings, so the usual rules don't apply.
• The Juraians in Tenchi Muyo! have vast lifespans (one prominent member of the royal family is over 5,000-years-old; she looks 35-40, tops), but their birth rates seem to be quite low. The Juraian emperor, for example, has been married to two women (at the same time) for over 700 years, and only had 3 children between them. His mother-in-law (the above-mentioned 5,000-year-old Juraian) has only one biological daughter; while she's raised several other children, they were all adopted.
• In Toriko, the Heracs are nearly immortal thanks to their extremely powerful Healing Factor. They also have very low birth rates. The Herac species is in decline because they need "AIR" to reach maturity, and the Nitros have been harvesting "AIR" before the Heracs can reach it for a long time. In the present, the only Herac that can reproduce is the Horse King itself. During the course of the AIR arc, a pristine AIR fruit is finally harvested properly at peak ripeness. It has the effect of purifying the entire area, allowing the Horse King to finally birth a healthy foal.

Comic Books

• Most elves of ElfQuest can only breed after a "recognition" (which is the instincts or 'lizard brain' of two elves deciding the two are genetically very compatible, and forcing them to conceive a child). One of the stories set before the Original Quest mentions that the tribe's Healer tried, and was in one case successful, to break that limitation, because there were worries the tribe was too small. And later on Leetah managed to induce Recognition for Nightfall and Redlance.
  • One tribe of elves had no children for millennia, partly because of stagnation (they were hiding from the world in a "fortress" and would not outgrow it). On the flip side, the Wolfriders have wolf blood, which may make them more fertile (they're definitely not immortal anymore especially compared to the other tribes); a past chief, Two-Spear, was born to his father's lifemate, not his Recognized mate.
• After a retcon, The Eternals are completely infertile with each other, since they are Nigh-Invulnerable, simply regenerate when you do hurt them, and are eternally young. Several of them have sired completely normal baseline human offspring with mortal lovers/spouses over the centuries, but this presents other problems. Originally, the Eternals could and did procreate, albeit very rarely and many Eternals were noted as being the children of other Eternals and born long after the Celestials created their race.
• This seems to be an Enforced Trope among the Deep Ones in Providence. Genital mutilation is a big part of the coming of age ritual of male Deep Ones, presumably as a measure to prevent overpopulation. This practice has apparently fallen out of favor by the time the 21st century rolls around... unfortunately.
• Wanted: African supervillain Adam One is an immortal man who can procreate, but his offspring don't inherit his immortality, given that he's shown attending the deathbed of one of his sons.
• In the WildStorm universe, the effectively immortal Kherubim suffer from an abysmally low birth-rate. Subverted in that it seems they can breed with humans more prolifically than they can with their own kind.
• Being a One-Gender Race, the Amazons of Wonder Woman in Gail Simone's run suffer from this, being reincarnated from women who were killed by men, including many mothers. They make "Whittle Babies" out of wood to keep themselves occupied, and until Diana was created by the Gods at Hippolyta's demand there were no children born on the island. A group of Amazons turned evil primarily because they were jealous that Hippolyta was given a daughter while they remained childless.

Fan Works

• Justified by a similar lack of desire in Undocumented Features. Humans who have taken the Detian treatment can have children. It's just that the current crop of Detians haven't had very many. For instance, Gryphon has been alive for over 400 years, but only started having children in the last couple decades.
• In the Marvel Cinematic Universe fandom, this is a frequently-used fanon for Asgardians.
  • Child of the Storm notes this with regard to Asgardians (who are, in turn, more fertile than their technically immortal godly relatives, and significantly more fecund with human men and women - though even then, children aren't common). It also notes that those who take the Elixir of Life, such as Nicholas and Perenelle Flamel, automatically become infertile as a result of the Elixir. The Infinity Formula, on the other hand, subverts this trope, possibly because it's implied to 'merely' make one very Long-Lived.
• In RainbowDoubleDash's Lunaverse, alicorns are incapable of reproduction. There are only two known cases of alicorns producing offspring. The first involved six alicorns in the deep past of the series who gave up their immortality to bring forth the first ponies. The second was the birth of Cadence, daughter of Princess Luna, as the result of a unique confluence of magical forces.
• The Justice Champions from Sailor Moon: Legends of Lightstorm are kind of like this. Their infertility comes from their bodies diverting resources toward more critical systems, such as the mechanisms that generate their powers. This condition can be temporarily reversed by drinking the correct chemical compound.
• Anyone made immortal by Naruto and Xanna in The (Questionable) Burdens of Leadership of a Troll Emperor are also rendered sterile both to prevent straining the empire's resources with a growing immortal population and to make sure they're serious about it. Only one named character, Setsuna, is shown to have become immortal and after all the enemies of the Celestial Empire are defeated, she asks to be made mortal again and to have a child with the God-Emperor.
• An unusual variant comes up in Eroninja. The rejuvenated and now ageless women can have children but doing so will remove their immortality. Also, Naruto can't have children (Kyuubi/Kiyomi's chakra kills his sperm when he orgasms) so the only way for them to have children is by breaking up with him and taking another lover. Kiyomi is willing to also make immediate family of Naruto's lovers immortal but they'll be under the same conditions: being rendered sterile in exchange for eternal youth.
• In Blood Sisters, Trick explicitly explains that succubii are one of the few fae species that are potentially immortal (most fae can only manage a millennium or so), since their chi-eating can sustain them easily and they don’t generally live violent lives. However, to contrast this potential immortality succubi have a low birth rate; Trick had been aware of Bella’s birth but assumed she died as an infant like most second-born succubii.
• The completely sterile/infertile version is played straight in The Melinda Chronicles just like with the immortals in Highlander canon. Melinda notably averts getting angsty over it because she considers the children she's adopted over the centuries like Tails no less her children than biological offspring would be.
• Subverted in Delusions. Celestia and Luna can't reproduce not because they're alicorns, but because they're just infertile—they were born mules and kept their infertility even upon ascension. Cadance and Twilight don't have this issue.
• In Wishing Well, ponies aren't immortal but they are long-lived and they do age slowly. However, due to their longevity, it is difficult for ponies to conceive.
• The Infinite Loops: There's a patch to prevent loopers from having children not native to their loops (i.e. canon), as the children are completely wiped from existence after the loop is over. This patch was made in reaction to Ranma's near descent into insanity after the loss of one such child.
• A Diplomatic Visit: Subverted with the alicorns, as noted in chapter 8 of the sequel Diplomat at Large. Luna explains to Pharynx that because of how long it tends to take them to find a partner, they're fertile for a lifetime once they come of age.
• Earth-27: Several long-lived and near-immortal species have this issue.
  • New Gods from both New Genesis and Apokalypse are immortal but also very infertile due to the genetic tampering of their ancestors, and so far the only known New Gods to have been born recently are the children of Mr. Miracle and Big Barda.
  • Fables are borderline immortal and it's very difficult for them to procreate with each other, although it's significantly easier to do so with non-Fables.
  • Dwarves are very long-lived, as such females only become fertile when they reach their thirties and males take even longer to mature, so The Oldest Profession is seen as an important duty to keep the population and those who indeed procreate are seen with great respect by their peers.
• In the J-WITCH Series, beings like the Demon Sorcerers are Born of Magic and therefore don't typically need to reproduce, so Uncle is initially skeptical that Drago is Shendu's son.

Film

• In Highlander and its various spin offs, the immortals cannot have children. If you believe the second movie, it's because they're actually from another planet. In the later films (but not in the TV series), Immortals are capable of reproducing until they die for the first time. In the third movie Connor has adopted a kid so he could have a son. This is also a plot point in the fourth and fifth movies.
• In In Time people can reproduce freely, but to stay alive past the age of 25 you must work to obtain time, which also functions as currency. The practical effect of this is that only the rich are immortal, while the average lifespan is, if anything, far lower than normal thanks to the poor being worked to death by the system to control the population.
• K-PAX handles this in a unique way. prot claims that while K-Paxians live for thousands of years, overpopulation has never been an issue; their reproduction method is so disgusting and painful that breeding is done as little as possible and many people never go through with it.
• The Man from Earth fathered many children during his looooong life, but since he is forced to leave his families after a few years, nothing is known about their immortality, apart from one, and he is most certainly mortal.
• Perfect Creature: Vampires are long-lived mutants created by a virus instead of undead creatures; they have been able to live for centuries with none have died of natural causes yet. However, they are incapable of reproducing with female humans and are reliant on the virus to create more of their kind, since no female vampire was ever created for them to reproduce naturally. This turns out to be a plot point when the elders reveal that no new vampires were born in the past few decades and they have performed experiments to circumvent this problem. The Big Bad is a vampire scientist that went insane while experimenting and being infected with the virus, making them indirectly responsible for the movie's events. Also, the first female vampire baby is born at the end of the movie, but her existence is concealed from the vampires themselves.
• In the Underworld (2003) films, the immortal father of the vampire and lycan bloodlines seems to have stopped reproducing after his original three sons. At least, there's no indication that any other Corvinus bloodline existed for Lucien's agents to hunt down. Considering that Alexander Corvinus has spent much of his immortal life "cleaning up" after vampires and lycans, keeping the existence of immortals secret, it's also possible he could have had other children in secret. Given how old he is, it could very well be that a good number of people are his descendants and don't know it (it's also made clear that not every descendant carries an inactive form of the immortality virus).
  • Also, the Vampire Elder Viktor seems to have only reproduced once. There doesn't seem to be any reason for it other than the fact that, being immortal, he doesn't really have to worry about a silly thing like an heir.
  • Its shown that vampires are actually capable to reproducing naturally with several being established to be born naturally such as David and Lena. They are even capable of breeding with lycans and producing hybrid children such as Selene (vampire/Immortal hybrid) and Michael (half-Lycan/half-vampire hybrid) giving birth to tri-blooded hybrid Eve.

Folklore, Religion, and Mythology

• Played With in Classical Mythology. The gods have no problems with producing offspring. However, demigods aren't born with immortality. A demigod must be given ambrosia by the gods in order to gain godhood.
• Averted in The Bible.
  • Before The Flood, people could live centuries, and were stated to have children, some of them had lots of them. But that is not immortal, although it is similar in principle. After the resurrection, Jesus states people will not marry anymore, therefore implying having children will be ended too, although they live forever.
  • However, the Old Testament does state that one of God's first words to a newly-created humanity is "Be fertile and increase", as well as that He gave Eve the curse of having "pain in childbirth" after the fall rather than having to have children period to continue the human race, possibly implying that procreation was always a part of God's plan for humanity. Ultimately, either interpretation is valid.
  • In the New Testament, in Jesus' answer to the Sadducees' question of whose wife a woman would be of the seven brothers that married her and left her childless when the resurrection takes place, He implies that all who are resurrected will be celibate and thus will not be able to or even would need to have children, for "they will neither marry nor be given in marriage, but will be like the angels in heaven."
  • Also played with regarding God, who is both eternal and immortal, and exists as a Trinity, which includes a Father and a Son.

Literature

• In the short story "2 B R 0 2 B" by Kurt Vonnegut, medicine has conquered old age and death. The population numbers are kept under tight control to avoid resource overuse. This means you have to convince someone to volunteer to die in order to have children. The main character's wife is giving birth to triplets...
• Sort of the case in the universe of the novels American Gods and Anansi Boys with two notable exceptions. In the former, Wednesday (Odin) tells Shadow that people like him generally "shoot blanks" Shadow is Wednesday's son with a human woman, but rather than being a completely new god or simply human, he is an incarnation of the God Baldr. The book also informs the reader in American Gods that Mr. Nancy (Anansi) has a son, Charlie, who is the protagonist of Anansi Boys and is seemingly completely normal. His brother, Spider, who was split from him, is a god, although the protagonist turns out to have Reality Warper powers. Charlie ends up having children, who seem to be human while Spider appears to be infertile. Possibly on purpose, considering that the mother-in-law lives within spitting distance of them.
• Amtor has the Vepajans, Venusian Human Aliens who consumed an anti-aging serum that extended their lifespan and allowed them to live indefinitely. Half their women are also infertile, and the other half is allowed to breed a limited number of children to avoid overpopulation.
• Averted in Arc of a Scythe, where humanity has effectively cured death with only scythes being allowed to permanently kill people. Despite this, people are still having children that are just as immortal as they are, and it's acknowledged that even with the Thunderhead's rule and the efforts of the Scythedom the planet will reach its capacity soon with no real solution on the horizon. At the very end of the series, a specially engineered nanite plague is unleashed that will wipe out a random 5% of the population every 20 years and adjust to the birth rate, ending the Scythedom and stabilizing Earth.
• Arrivals from the Dark:
  • Paul Richard Corcoran, being a Half-Human Hybrid, and his descendants have unnaturally long lifespans (150-200 years). However, this also means they are highly unlikely to have children until they are well in their 40s or even 50s. This could indicate a slower rate of maturity. However, once able to have children, they usually have at least 2. One is noted to have 3 children of her own and then adopting 3 more (keeping a promise she makes at one point). One of the advantages the humans have over the Faata is their numbers and reproductive ability. Despite centuries of genetic engineering, the Faata still haven't figured out how to grow their race at a rate even approaching that of the humans. It also doesn't help that they deliberately engineer their lower castes to have a lifespan measuring only a few years, further reducing their population growth, despite the fact that they have a whole caste of breeders who are artificially inseminated and whose gestation is accelerated to a matter of weeks.
  • This also applies to the Metamorphs, whose lifespans are measured in millennia. Being a One-Gender Race, they reproduce by having several individuals fertilize one of them, which starts the budding process. It's mentioned by the Exile that his parent may or may not have another child, as births are a very rare occurrence for them.
• Fairies in Artemis Fowl (who are not immortal but very long-lived) can only have one child every twenty years; humanity's faster reproduction is actually the main reason it was able to more-or-less take the world from them.
• Huey Laforet in Baccano! procreated after becoming immortal just to see if this applied. His daughter doesn't inherit his immortality.
• In Poul Anderson's The Boat of Million Years, the immortals are perfectly capable of reproducing. Unfortunately, the children are never immortal, even when both parents are.
• Completely averted in Captain French, or the Quest for Paradise, in which humanity has discovered a cure for aging (called Cellular Regeneration, or CR). This doesn't stop people from having kids in the least, and many colonies have to impose Population Control. In fact, the titular character, being quite possibly the oldest human alive (being born in pre-CR days on Earth), has hundreds of thousands of children, although he explains that he didn't technically father any of them save one (his first daughter with his first wife), as they're all the result of artificial insemination with his sperm donated on many planets. However, this trope is, technically, preserved in that the CR treatment is not passed down to children and must be reapplied to everyone once they reach the age they want to be "frozen" in (most choose early 20s, although some prefer early 30s).
• Both averted and justified in Carpe Jugulum. Vampires are perfectly capable of reproducing, through both the bite and the normal way, but they seldom want to because it means more competition for food. Even worse, the vampire parents usually expect their offspring to remain their loving, obedient children for all eternity. This does not go over well with the kids.
• The Chronicles of Amber:
  • As the books themselves comment on, the immortal lords of multiverse have been around for millennia but are not particularly fertile: the first book is Nine Princes in Amber, not Nine Hundred Thousand Princes in Amber. That said, several bastard or otherwise secret children of the Princes come up in the first series, and the sequel series features more of these children, as well as some secret children of King Oberon.
  • There are also references to several older princes who died "For the good of Amber" after becoming too ambitious or otherwise falling out with their father Oberon, which also helped in keeping the number of princes and princesses to a minimum.
  • This trope is fairly well averted for the Courts of Chaos; they're just as immortal as the Amberites, and while there are fewer of them than you'd expect with their lifespan, there are far more than their counterparts in Amber. It's stated that perhaps hundreds of assassinations and suspicious deaths were required to move Merlin in line for the throne.
• The Color of Distance: Amy Thomson said in an interview that "I believe that societies whose individuals have immensely long lifespans, must either have very few young, resulting in a stagnant, inflexible, rigid culture, or else they must place cultural limits on lifespan in order to have the cultural renewal of a younger generation." She chose the latter, so while both the Tendu and the harsels in her books can theoretically live forever if not killed... they don't. Harsels choose to reproduce and die in the act of giving birth to hundreds of nonsentient harlings, which chew their way out of their mother's flesh. Tendu spawn in huge numbers throughout their lives, but they eat their nonsentient young, or otherwise are not concerned by animals eating them. Most adult Tendu select one nonsentient subadult and cause it to metamorphose into an adult which is then cared for and taught, and choose to die soon after this child/apprentice is fully mature; there are a few individuals who choose not to die, and then they are culturally compelled to leave home forever and metamorphose again, becoming sort of wandering judges/problem solvers. This is portrayed as more frightening than death. It's mentioned that there was a time when they did things differently and the ecology was absolutely swamped with Tendu, and there weren't enough resources for everyone.
• The immortals from The Company Novels, though Mendoza manages to have children later on in the series — very, very weirdly.
• Cruel Illusions: Magicans who take the immortality spell cannot have children, because their bodies are frozen at the age that the spell was cast. Hence, the biological functions required for conception and pregnancy will not occur.
• The Culture generally discourages having more than a few children, but no one stops those who wants dozens. Given that they have unlimited resources it's not really a problem.
• In Cyteen, it is mentioned in passing that rejuvenation drugs have a side effect of making the user sterile. Though saving a sample before beginning treatment is standard procedure and reproductive cloning isn't uncommon.
• In the sci-fi novel The Declaration by Gemma Malloy, immortality has been made possible. Unfortunately, this has resulted in severe overpopulation/resource shortages, forcing all countries to establish the law that no one who "opts-in" is allowed to have children. Any children, or "Surpluses," born to people who opt in are sent to group homes and taught that they are worthless beings that do not deserve to exist.
• Deverry:
  • The Elves of usually live around 500 years, looking young until the last year or two of this, but have very few children during this time. Dallandra discusses the low elven birth rate with Cal and some other elves. It's hypothesized it's not just the length of their lives that restrict their birth rate, it's that part of their diet is meat, and meat-eating animals generally have a comparatively low birth rate. She also compares having children with humans as trading in some of their race's lifespan to have more children.
  • Dwarves are also very long lived. Otho lives at least 400 years. Combined with their legendary stubbornness, it makes it very hard for them to let go of grudges.
• Dora Wilk Series: Inverted. The nigh-immortal angels are insanely fertile, to the point where any sexual encounter, even with contraceptives, is nearly sure to result in woman getting pregnant.
• Downward to the Earth: Invoked. The ceremony of rebirth allows the nildoror and sulidoror to live basically forever by periodically transforming into healthy specimens of the other species, and true death is very rare. As a result, they only reproduce sparingly, and to make up for specific losses in the population.
• Dragaera: The elf-like Dragaerans have an ancient, continent-spanning empire and a two- to three-thousand-year lifespan but avoid overpopulation problems because their biology lets them consciously choose whether they can become pregnant. Justified since their species was genetically engineered by the Jenoine Abusive Precursors.
• The Dresden Files:
  • Averted with wizards and other powerful magic users, who are very long-lived (they can be killed, but left to their own devices and otherwise unmolested, they'll go on for centuries) and can reproduce.
  • All seven Carpenter children are the product of at least a sorcerer-level talent and Maggie Dresden is the unexpected daughter of Harry (a full-blown member/wizard of the White Council).
  • Additionally, Harry's mother was canonically over a century when Harry was born, also had another son a mere five years before Harry. However, the woman in question was known as Margaret LeFay for damn good reason, and the Nevernever has odd effects on time, meaning it's not entirely clear what her actual physical age was. While her father was also a wizard (specifically, Ebenezar McCoy) and would have been at least 150 years old when she was born, it's still not entirely clear how wizardly ageing affects fertility in general.
  • Harry also managed to give psychic-birth to a spirit of intellect "fathered" by the psychic coppy of the (female) Fallen Angel Lasciel, although this isn't exactly a normal situation.
  • However, the descendants of wizards/sorcerors are only occasionally gifted, meaning their lifespan is that of a mortal. Of the seven children born to Charity Carpenter, only Molly has shown any magical skill (although she has enough to be considered a true wizard) - however, per Word of God, that's because the parent in question went cold turkey on magic shortly before the magical child's conception, and kept it up ever since, which is indicated to have an effect. Anastasia Luccio (born sometime in the 1800s) laments the fact that she is now a many times great-ancestor, observing her family from afar for the rare magical talents. Senior Council member Martha Liberty is in a similar situation, although she lives with her family.
  • The truly immortal Sidhe are apparently only able to have children with mortals. The child will be born a changeling, and can choose whether to become fully human or fully Sidhe later in life. Since humans have free will and Sidhe don't, it can be a tough choice. Changelings are effectively immortal till this choice is made. While it is unknown exactly how common changelings are, four born in modern times are seen in Summer Knight, suggesting that the numbers could be relatively high.
  • Played with for the vampires of the White Court, who are functionally succubi/incubi. They breed relatively often for immortals. There are at least five Raith children in the main household, and the patriarch of this family is known to have killed many of his sons. White Court vampires can avoid activation by having their first sexual encounter with someone they love, which essentially kills the demon inside them and renders them mortal. In addition, Thomas implies that the females of the Court don't get pregnant unless they choose to. In Peace Talks, he indicates that it is very unusual for males to impregnate their partners which is why Justine getting pregnant blindsided him and is confirmed in Battle Ground (2020) to have been intentionally caused by the thing possessing her to manipulate Thomas.
• In The Folk of the Air, faeries have an incredibly low birth rate, and most households are happy to have one child ever. The current king having six children/potential heirs is almost considered to be vulgar. Characters also comment that despite the Fantastic Racism faeries have towards humans, having human wives/consorts and half-human children in the family strengthens bloodlines and is why faeries haven't gone extinct.
• Played straight so hard it hurts in Fragment. When the protagonists discover the mandatory sentient species that seems to be a part of any Lost World or Alien planet, they discover that they are immortal because they don't have any babies in a combination of Cliché Storm and Artistic License – Biology.
• Averted in Full Clearing Another World under a Goddess with Zero Believers. Elves have a life expectancy 5 times as long as humans but are just as fertile. One of the main characters is the descendant of a legendary elven hero who married over 50 women and fathered hundreds of children. Even Lucy has over 50 siblings through her elven mother.
• Georgina Kincaid: Ever since Georgiana became a succubus, she's been unable to bear children.
• Humanity's Transhuman descendants in the Great Ship series rarely ever have more than one or two children (in normal circumstances) despite living for an hundreds of thousands of years. Part of the low birth rate seems to be implied by parents having to pay for addition berths on the Great Ship. However, their fertility is unchanged — Dream's mother in Eater-Of-Bone had several children, though all but Dream died from malnutrition due to the Lost Colony's near-total absence of metals and salts vital to their augmented metabolism.
• In Guild Hunter, vampires over 200 years old cannot have children, while angels have a very low birth rate, with sometimes decades between two angelic births on the planet.
• Pure-Blooded Devils in High School D×D are implied to have 10,000 year lifespans, and proportionately low fertility. After the Great Offscreen War caused a severe depopulation, with the 72 former great houses being reduced to three and remnants, this has become a serious problem. As of the start of the series, even high-ranking devils of the remaining noble houses are recruiting from humans they personally reincarnate, just to get their numbers back up and stabilize the population. Things have gotten so desperate for the devils that it's stated point-blank (in the novels, at least) that Fantastic Racism has been marginalized by how dire the situation is, and the proudest pure-blooded houses consider blood purity secondary to just surviving. The few who strictly stick to creating pure-blooded peerages are considered shortsighted and selfish by most of the population. On the other hand, Starter Villain Riser is able to strongarm the entire Gremory house into giving him Rias in an arranged marriage none of them support just by saying it's to preserve the Pure Devil race.^note His exact motivations vary by adaption; in the original Light Novel, he did want the marriage for the purity and pride of the race and being married to drop-dead-gorgeous Rias was just a bonus, in the anime it's the other way around.
• Witches in His Dark Materials live roughly a thousand years. They take human men for lovers and bear children; if the children are girls, they're witches and if boys, human and short-lived. Presumably, they don't have children especially often. One character suggests that a witch dies when her heart is so broken from watching her lovers and sons grow old and die that she can't go on.
• How a Realist Hero Rebuilt the Kingdom: Long-Lived races (mainly elves, dragons, and the two races of Draconic Humanoids descending from the latter) are stated to be less readily fertile than shorter-lived humans and beastmen. Souma considers this in volume 6 when he propositions his second fiancee Aisha, a dark elf, noting in his Internal Monologue that her infertility compared to his Top Wife Liscia would mean there's little risk of Aisha getting pregnant ahead of Liscia and fouling up the order of succession, though Aisha turns him down anyway out of respect for Liscia. It turns out in the next book they needn't have worried, because Liscia has already conceived by this point.
• In Incarnations of Immortality, while serving as an Incarnation, one thing that is stopped is aging and, since reproduction is an aspect of aging (cellular meiosis), they are unable to bear or sire children. When they leave "office", the restriction is lifted. This causes one of the characters to be nearly the same age as her son, physically at least (she had relatives raise him while she was in office).
• Similar to Tolkien elves, the elven race in The Inheritance Cycle can reproduce, but don't really see much reason to as they are immortal. When elven children are born, however, they are treated as something special and wonderful for these very same reasons.
• Inkmistress: Demigods like Asra will live for centuries more than mortals. They're incapable of having children, which pains her greatly, as she would love to be a mother. She gets her wish by another means, adopting a son.
• In Is It Wrong to Try to Pick Up Girls in a Dungeon?, the gods don't have parents or siblings. They have always existed and cannot have children with each other or with mortals.
• There is a cultural mandate against reproduction by immortals in Jitterbug Perfume by Tom Robbins.
• Journey to Chaos: Elves zigzag this trope. The first time a female elf has sex she will become pregnant, no exceptions. After giving birth, she will be barren for a century or two and then be able to conceive again. Thus, the only siblings that can experience growing up as siblings are twins, triplets etc. If their population needs an emergency boost (such as after the Conversion War) then the males in the population can sex-shift into females and carry a child to term.
• According to prot from K-PAX, since the K-PAXian lifespan is over a thousand years, combined with their unappealing mating process (which involves profound pain, nausea and a bad smell), there's no problem with either underpopulation or overpopulation.
• In Mercedes Lackey's Urban Fantasies and Historical Fantasies, the immortal sidhe can reproduce, but it happens extremely infrequently. As a result, children are treasured by both the Unseighlie and Seighlie Sidhe, although only the Seighlie expand this love to human children and try to save them from unpleasant fates. For the elves in The Obsidian Trilogy, children are also very rare and precious.
• Brought up in one of Joanne Bertin's The Last Dragonlord. Dragonlords, the people who shapeshift between dragons and humans, have exceedingly long lifespans; as of the first book, the youngest is really six hundred years old, still looks the same, and is still called "little one." They cannot have children with ordinary humans, and while that does not apply between Dragonlords, they voluntarily do not have children, since when they do reproduce their offspring are very nearly always human. The same Dragonlords who enjoy their human friends and grieve and let go when they age and die have a lot more trouble with it when it's their own children.
• In The Last of the Renshai and its sequel The Renshai Chronicles, it's remarked that the Norse Gods are almost completely infertile, and that many of them had a human parent. In the second trilogy, the life cycle of Elves becomes an important plot point: a new elven child can only be born if one of the currently existing elves dies (freeing their soul for reincarnation), so the Elven population can never grow beyond its current numbers. Furthermore, the elf needs to have died of natural causes — any violent death permanently reduces the maximum elven population. There's a way around that limitation.
• Touched on in The Last Unicorn. The unicorns, which are immortal but can be killed, live solitary lives in separate forests, needing only the knowledge that other unicorns exist for company. As such, they mate very rarely, and the narration mentions that that for this reason, no place is more enchanted than one where a unicorn has been born.
• The Left Behind book Kingdom Come goes beyond this with the "glorifieds", since they won't even have the desire for sexual intercourse (because there is neither marriage in Heaven, nor any desire to sin, and extramarital sex is sinful).
• In The Life & Adventures of Santa Claus, none of the immortals are allowed to reproduce or even seem to have a concept of children, but the idea is so attractive that it prompts Nicele, a nymph, to raise the foundling Santa Claus as her child.
• In Aleksandr Zarevin's Lonely Gods of the Universe, the Human Aliens from the planet Oll arrive to Earth in distant past, escaping from a power-hungry official. They plant some seeds they bring with them to grow food, and the seeds of a salad plant known as ambrosia grow practically overnight. After eating a salad made from ambrosia, they suddenly fall ill and wake up young and immortal. Somehow, an alien plant has acquired entirely new properties on Earth. They make a few locals immortal as well and establish themselves as gods on the island. While the females who become immortal are incapable of conceiving a child, this is absolutely not the case for any immortal male who sleeps with a human woman. That is, in fact, the cause of the many hair colors modern humans have. The original humans all had dark hair, while the Olympians (yes, those Olympians; they also call their island Atlantis after Atl, their home country on Oll) are all redheads. Immortality can only be achieved through consuming a sufficient quantity of ambrosia, which withered and died soon after blooming. The Ollans have managed to dry and preserve some ambrosia leaves. One of them is awakened by a Russian man after centuries in stasis. In return, she gives him a full dose. However, he decides to only take half of it and keep the other half for later. The half only heals his grave wounds and extends his life but doesn't turn him young or stop his aging. Later, he gives the other half to the protagonist's friend, who has lost a leg during the Soviet invasion of Afghanistan. The leg grows back overnight.
• Straightforwardly stated in The Madness Season. The vampires of that book are only fertile when they subsist on a diet of willingly provided human blood. This is explained in-text as an evolutionary mechanism to keep them from reproducing in an environment that isn't willing to support new vampires. The Marra, as well, are subject to this. Energy beings who are not able to die but can also not create new Marra (or, if they can, they have forgotten how).
• Mercy Thompson:
  • The werewolves don't age (and if they were old when they were turned, they'll revert to looking adult, but permanently young and fit). Male werewolves can have children with ordinary women, but they'll be born mortal, and there's a high risk of miscarriage. Female werewolves can get pregnant, but inevitably miscarry when they change, which they must do at full moon. The only exception is Charles, the son of the Marrok, who is the offspring of two werewolves and was born one; his Native American mother used magic to hold off the change, but the effort depleted her strength, and she died in childbirth. It's often a plot point that older werewolves often become unstable because they have outlived too many partners and children — in the Briggs 'verse it's dangerous to try to become a werewolf, as you have to be savaged to the point of death and not many survive the process, so they can't automatically turn their wives and children.
  • Vampires seem not to reproduce in the usual way as they're not so much immortal as undead; they're dead during the day. They remain the same age as when they were turned. However, many of them assume a parental responsibility for new vampires that they have turned, and a vampire seethe acts very much like a big dysfunctional mafia family.
  • Fae, on the other hand, can have children with mortals or with each other, and how "immortal" the children are seems to vary. There are lots of different kinds of fae and not very many of them in total.
• In The Mote in God's Eye, the Moties invert this — if they don't have children, they die young and horribly, while as far as anyone knows a Motie who keeps getting pregnant and giving birth on schedule can live indefinitely. (Because of this enforced fertility, civilization crashes periodically.) Oh, and the most likable group, the ones who learn English and talk to the humans of the series? They're sterile hybrids. They die after 25 years or so.
• In Neogicia, a character suspects this is the reason for which the imperial family doesn't share the Longevity Treatment that is being used on its own members. Also, thanks to that technology being something that started small and got better over time, the emperor is expected to produce a heir at some point just in case. Said emperor is currently more than a thousand year old, looks 35 (his father died around the same age looking like old man) and is still single despite the long line of candidates to be his wife.
• A rare aversion of this trope for Elves is in the manga/light novel series New Life Plus Young Again In Another World. Here Elves are extremely long-lived and just as fertile as humans. The Elven King (who's been around for a few centuries) is noted to have over 150 children, which makes the royal succession a nightmare.
• In Nightrunner, the human wizards live up to 400 years but are also sterile (and most of them are celibate as well, apparently mostly for cultural reasons). This is actually a problem in the setting, as only humans with some degree of aurenfaie blood can have magic powers and the Aurenfaie have been very isolationist for the last few centuries. So the number of wizards is slowly dwindling, and this is becoming a military disadvantage for the main culture in the story. The royal family, who have an Aurenfaie ancestor a few generations back, live about twice as long as pure humans and most of them can reproduce, though. On the other hand, they don't appear to have any magic talents. The Aurenfaie themselves live 300-400 years and are fertile (the family the reader learns most about had at least 4 children before the mother died) but despite occupying a limited territory, they don't appear to have any population problem. This may be because they don't allow a youngster to marry until he or she is well on their way to their 100th birthday, even though they develop a sex drive somewhere around the age of 20.
• The Others in Night Watch (Series) are fully capable of reproduction, but their children have just as much chance of being an Other as a child of two Muggles (i.e., very slim). This is why many Others avoid having children, so that they don't have to watch them grow old and die. The Others aren't, technically, immortal, but even the weakest of them can enjoy several centuries of life. The most powerful ones tend to be thousands of years old and not look it. The vampires and werewolves are the exception, as they're able to "initiate" (i.e., bite) their children to turn them. However, vampires and werewolves are the lowers rungs of the Dark Others and are viewed at with little more than disdain. The Light ones see them as nothing more than beasts, while the higher Dark ones consider them cannon fodder. Additionally, they can only feed on humans with a license granted by the Night Watch. Doing so without one is punishable by death. Additionally, vampires can only have one child after being turned, at which point their reproductive ability disappears. Nothing of the sort is mentioned for werewolves, but then the author can't seem to decide if they're undead or not.
• The Obsidian Chronicles: Although they can live for centuries, dragonhearts are incapable of having children.
• In Paradox, the Eldritch live for over a thousand years, but due to complications with their genetic engineering and inbreeding their fertility rate is dropping. Jahir's mother was noteworthy for bearing two children.
• Vampires and werewolves in The Parasol Protectorate cannot sire/bear children after their transformation. Understandable, since Step One in either transformation is "die". With one exception; a supernatural (vampire or werewolf) and a preternatural such as Alexia can produce a child. But this is so rare that no one can confirm this until well into Alexia's pregnancy.
• In Prospero's Daughter, since the immortality comes from an external source, they are fertile and most have had dozens of children. But the source is not extended to the children or spouses, and so some swore off it.
• In Second Genesis by Donald Moffitt, the newly immortal humans have a cultural norm allowing one child per couple every hundred years.
• The Shadowhunter Chronicles:
  • Vampires are immortal and sterile. All vampires are humans infected with vampiric blood (this is in contrast to werewolves, who can be born in addition to turned).
  • Warlocks are much like vampires in that they will live forever if nobody kills them but are unable to breed. The only exception is Tessa Gray, because her mother is a Shadowhunter, which negates her demonic blood and allows her to procreate, but her children are mortals and therefore always predecease her. Tessa technically can have as many children as she wants, but, for understandable reasons, she has only given birth to three so far.
  • Averted with faeries. They are immortal and can have children as many times as they want. The Unseelie King has lived for thousands of years, has hundreds of children, and is still a young Bishōnen.
• So I'm a Spider, So What?:
  • Elves are extremely long-lived but only have enough population to fill a single Hidden Elf Village. While they occasionally interbreed with humans, the resulting children are always exiled on adulthood. This small population is only stable because a large number of elves are clones of Potimas and humans he abducted and forcibly evolved into elves.
  • Demons have shorter lives than elves but slow birth rates. Their population has begun to decline in recent years as the birth rates had dropped even further due to near-famine conditions and damage from the System. Most souls in the system are on the brink of soul collapse and thus cannot reincarnate, meaning less children are born. Human birth rates are also declining, but they have a larger initial population which masks the effect.
• In Spin, the Martians have a series of drugs that induce their "Fourth Age". It prolongs their life and greatly enhances their abilities, but in order to prevent overpopulation, the drugs also cause sterility.
• In the fourth book of the Spirit Animals series, the heroes stumble across a town which has been drinking from a magic pool. The pool makes you immortal as long as you keep drinking (if you stop drinking, you die within a few years), but also renders you infertile.
• In Strata, the universal currency is a life-extension treatment. One of the main characters, who is several centuries old, wonders what life would have been like had she been a "short-lifer" and thus able to have children.
• In Sunday Without God, when people lost the ability to die due to God abandoning the world, they also lost the ability to give birth. As pointed out in-series, this makes Ai's existence even more perplexing, as she was born three years after God had abandoned the world.
• The Kantri of Tales of Kolmar can live around two thousand years and are considered mature at two hundred fifty. About two hundred of them fled to the Dragon's Isle five thousand years ago and never increased their numbers. One observes with frustration that they should have increased, but the species seems demoralized and getting more so. There are fewer mated pairs and fewer births happening all the time. It's mentioned with great concern that there have been only three births in the past eight hundred years — and the Kantri with their huge claws are helpless in the face of complications of birth. If a human hadn't stepped in and midwifed during Song In The Silence, the first birth in three hundred years would have ended tragically. Also, Kantri only feel the desire to have sex a dozen or so times in their long lives, and the act is difficult and painful, not fun. Mated pairs enjoy 'joining souls', but this gets no one pregnant.
• "Magic-born people" in That Time I Got Reincarnated as a Slime can breed but usually don't because their immortality removes the need to leave descendants.
• This Immortal has the variety where the immortal, in this case Conrad Nomikos, can and does have offspring, but they only marginally benefit from that, living slightly longer than normal but not unsuly so, thus causing him to watch them die. Conrad, however, does not seem particularly fazed by that as that's just how things are.
• In Three of Heart, One of Blood, the Legacies are incapable of breeding, though the systems still work. This is a fact that Doryn uses and exploits. A lot.
• In the Tide Lords tetrology, the immortals cannot interbreed with each other (The union of an immortal egg and an immortal sperm would become immortal at age ~9 months and thus never come to term), but they can and frequently have interbred with mortals (There are four entire species who are descended entirely from the mortal offspring of immortals). Said children are always born mortal, but those children whose heritage makes them more than 50% immortal by genetics (Such as an immortal father and one or more immortal ancestors in the mother's line) can potentially become immortal.
• Completely ignored in Time Enough for Love. Many near-immortals live throughout the galaxy and reproduce like bunny rabbits, even if they're 20 centuries old. Their children may also be effectively immortal, depending on what genes they picked up and whether they have access to a rejuvenation clinic. They solve the overpopulation problem by continually colonizing new planets. Justified as reproduction was the entire point of the Howard Families. They were an experiment in human longevity that worked spectacularly well. It is worth noting that Tellus Secundus, the planet where the story begins, has an unusually high population of near-immortal "Howards" and in consequence has instigated population controls. The planet's chief executive mentions to Lazarus Long that he'll grant an exception to any woman Lazarus feels like having a child with. Lazarus himself is a special case as, being over two thousand years old and born at the start of the Howard experiment, he can claim over 80 percent of the galactic population and over 99 percent of Howards as his descendants to some degree or another.
• Averted in Tinker. The Oni are immortal and breed like mice. Famines are common in the Oni's overpopulated world. The Elves on the other hand are just as fertile as humans but don't feel the need to have as many children since they are immortal. The population of Elfland has dropped by 50% over the last two thousand years due to war, accidental death, and suicide.
• In Tolkien's Legendarium, Elves are immortal and only have children infrequently; overpopulation isn't a problem, especially since most of them are leaving Middle-earth by The Lord of the Rings. In the stories set in the earliest time periods, though, there are frequently several generations of a single-family living and ruling together. There is also the implication that having children can be very spiritually draining for elves, and that they get bored with sex over the centuries. In his notes at one point, Tolkien indicated that elves do not have children after a certain age. (So, menopause?) Also, Fëanor and Nerdanel had the most children that any elven couple ever had, whereas seven children would be, if anything, low for most fertile human couples if they both lived through the women's child-bearing years in most eras.
  • The Cracked article 6 Horrifying Implications of Awesome Fantasy Movie Universes discusses this: "no one in the Elfish kingdom is getting any, anywhere."
  • Also averted with hobbits, who often have large families despite living longer than humans.
  • Played With: Ents live nearly forever, but all their women disappeared during the huge wars of the past, dooming them to eventual extinction.
  • Meanwhile the Valar and Maiar (gods or angels) don't reproduce at all, the exception being Melian, who married an Elf (and is the ancestress of many important characters). They did have families in earlier drafts, however.
• The Tucks from Tuck Everlasting cannot change; they don't age, they don't die. Mrs. Tuck was past childbearing age when she drank from the spring, so it isn't an issue for the elder Tucks. However, the eldest Tuck son got married in the years after they drank from the spring and before they realized its effects; he had children, but his wife eventually thought he'd made a Deal with the Devil and left him.
• The Twilight Saga:
  • Vampires were believed to be infertile, but it turns out that this only applies to the females. Male vampires can impregnate human women (though it will always be fatal to the latter unless they are turned into vampires), and their children inherit both of their parents' traits; they are immortal and strong, but they can subsist on human food and generally resemble their mothers in look (for instance, Renesmee has Bella's brown eyes, rather than Edward's gold ones). Stephenie Meyer has been mum on whether human-vampire hybrids can procreate, though.
  • The vampire procreation rule applies more or less to werewolves (though they only get immortal if they are in their wolf phase). Female werewolves like Leah Clearwater become menopausal after they awaken their powers, while male werewolves can still have children, a fact which is publicly known because of imprinting. It's stated that all current werewolves in the Quileute tribe are descended from three people, all of whom were also werewolves.
• Nathan Brazil, the immortal guardian of the universe in Well World. Since it's not possible for anyone else to be immortal (you have to be programmed into the computer that stabilizes the universe) he considers not being doomed to outlive descendants a mercy.
• The Witcher:
  • The Elves breed much more slowly than humans, because their women ovulate once in a couple of years (or even tens of years). After a hundred or so years, the sex gets boring. It's also mentioned they're only fertile at young age, but as later in the books a girl is bred with an elf over 500, it's probably only the women.
  • Witchers themselves. Thanks to the mutagens that give them their abilities, they live very long lives, but are unable to procreate. Therefore, they have to recruit children from outside, since they can't just breed new witchers.
  • Sorcerers are generally sterile after their training, though there are a few exceptions. Geralt's mother, for example.

Live-Action TV

• In Babylon 5, Lorien mentions that his naturally-immortal species had a very low birthrate, "less than a handful each year". Since their immortality only made them ageless, not indestructible, their population was kept in check by injury or illness.
• The Cylons from Battlestar Galactica (2003) are immortal due to their resurrection technology. They are also near-universally infertile, with only a single half-human child born to the entire race.
  • One notable exception exists, as Saul Tigh impregnated Caprica Six, but did not survive to term. It's all but implied that the only reason it worked at all is that the father wasn't an ordinary Cylon to begin with.
  • Inverted with the all-Cylon Thirteenth Tribe. The ancestors of the Final Five could reproduce, so they abandoned their resurrection technology.
• Buffy the Vampire Slayer/Angel: With one important exception, the immortal vampires in the Buffyverse cannot create natural children. Even in that one exception, the vampire mother could not bring the child to term the normal way, and the child was mortal (albeit with the superhuman strength, agility and senses of a vampire).
• Doctor Who:
  • Time Lords can live for millennia. Though the TV show never mentions it, this trope is fully in play in the Doctor Who Expanded Universe: the whole species has been infertile for hundreds of thousands of years, and reproduces artificially through "Looms".
  • The only reason they are infertile is because the original leader (who was overthrown as a result of a revolution), placed a curse on them that took thousands of years to remove. Odds are that they reproduce like normal humans do, but now have gotten so used to the looms that they have stopped sexually reproducing.
  • There's also a case of Depending on the Writer; sometimes the explanation is that Time Lords aren't a race at all, but rather a modified caste of the long-lived but mortal Gallifreyan people who have families perfectly normally.
• In Forever (2014), Henry doesn't appear to have any children of his own, not for the lack of trying. He adopted Abe as a baby after finding him in Auschwitz after the war. In fact, Abe later finds out that they are, in fact, related, as Abe is descended from Henry's uncle.
• Forever Knight: Vampires cannot have children of their own. This leads a 200-year old vampire lover of Nick to kill herself by committing Suicide by Sunlight because she can't bring anything new to the world.
• Helix: Averted; immortals are capable of having children, including to each other. Julia is the offspring of immortals Hiroshi Hataka and Jane Walker, although her own immortality had to be "activated" first.
• Angels in Lucifer (2016) live forever and can't have children. This is probably the only reason why Lucifer hasn't sired a horde of devilspawn. Turns out there's a loophole; if an angel regards itself as unworthy of being an angel, it becomes human until it regains its self-respect, and while human is capable of having children with another human.
• In New Amsterdam (2008), John Amsterdam has had several children, who, unlike him, are mortal. One of these children, Omar, looks older than John himself, and knows about John's immortality. One episode shows that John keeps records of his descendants, so he can keep track of them and avoid dating female descendants. Both Omar and an elderly female descendant shown in a flashback where John is secretly dating Omar's mother are upset when John tells them that he still hasn't found his soulmate. What John means is the one woman who would cause his "curse" of immortality to end.
• A second season episode of Spellbinder has the protagonists end up in a parallel world where, somewhere around Enlightenment, a deadly plague wiped out a large number of people and threatened to make humans extinct. A cure was found that, miraculously, also made them immortal. Unfortunately, they found out too late that this trope was in full effect. No one subjected to the cure (all survivors) can conceive. Thus, when the protagonists arrive, it's been over 200 years since the plague, and the world still looks like it's in the middle of 18th century with almost no progress having been made, except with animatronics, which are used to make child-like automatons that the immortals can pretend to be children. When a Mad Scientist finds out that the arrivals (a teenage girl and a 20-some man) are fertile, he kidnaps them, intent on using them to repopulate the world or at least provide some new people around.
• Stargate SG-1:
  • The Asgard are not capable of sexual reproduction; they lost the ability due to extensive genetic alteration. To achieve immortality, they upload clone bodies with their memories when their old bodies die. Eventually even this tactic fails.
  • The normal life cycle of Goa'uld includes the spawning of new parasites by extremely rare slug-like queens, with Jaffa specially prepared to incubate the larvae; this almost always happens off-screen.
  • Procreation between two Goa'uld hosts is forbidden. The resulting child is very dangerous; thus the practice is proscribed. Such a child, known as a Harcesis, would be born with all the genetic memories of the Goa'uld. Exactly why this would be a bad thing for the Goa'uld is never spelled out but it's probably to prevent Goa'uld secrets from falling into the hands of enemies like the Tokra or the Asgard.
  • In the episode "2010", the Aschen weaponize this trope. After making contact with Earth, they offer a treatment that cures all diseases and drastically (though not infinitely) extends human lifetimes. After everybody on the planet gets the treatment, SG-1 finds out that it has a component not in the original formula; it causes sterility and will lead to the extinction of 90% of humanity. This is their civilization's way of taking over planets without a fight, just a bit of patience. Fortunately, the main characters are able to cook up some time-travel gimmick to warn their past selves to not allow this to happen.
• Tidelands (Netflix): Tidelanders (half human/half siren hybrids) live for centuries without aging, but aren't able to have children... or so it seems until Violca is impregnated by her lover Colton, a human.
• Captain Jack Harkness, from Torchwood, is another aversion. He's immortal, but can have children. The children, again, are not immortal, thereby preserving the intent of the Clause.
  • Given that he Really Gets Around, he should have lots and lots of children and grandchildren running around if that was the case, not just one family. It makes more sense that the Time Agency routinely sterilised its agents (Would you let people like Jack or John run around in eras without reliable birth control and potentially father their own ancestors?) and that the daughter in season 3 was the result of a 1960s orgy. It's not like Jack is the jealous type who'd refuse to raise the kid as his.
  • The fourth series, Miracle Day, is set to involve a thorough subversion of this trope; humanity mysteriously becomes immortal and one of the immediate problems is an impending overpopulation crisis.
    • Seems a bit fast though: if the average human lifespan on all of earth is say 50 years, than the population would grow with a staggering 2% a year. This trope only a problem in the long term. (Though in its defense, the show mostly shows us overpopulation in hospitals, which would happen far earlier than overpopulation of Earth.)
    • They also quickly state that humans still age normally. Nursing homes would end up being overpopulated fairly quickly too.
    • Abortion also becomes an issue (even more than in Real Life), when it's stated that an aborted fetus would probably still be alive but no longer able to grow outside the uterus.
• The Twilight Zone (1959): The episode "Queen of the Nile" features a movie actress who remains remarkably youthful despite starring in films from the Silent Age (this taking place in the 1960s). She is accompanied by an old woman who acts as a maid. It turns out that the actress is none other than Cleopatra, who regains her youth by draining the life force from other people... and the old woman is her mortal daughter.
• In The Vampire Diaries, vampires cannot procreate. This actually comes up when Elena wonders whether, supposing Katherine was her ancestor, she was part vampire. Damon shoots this down and says that if Katherine had any children, it was before she became a vampire. Although Klaus, the Original Hybrid, can have children thanks to a loophole. In matters of procreation, his werewolf side trumps the vampire side. His daughter Hope is a tribrid (vampire, witch, and werewolf) and it's assumed she has the same loophole. Other vampire and werewolf hybrids don't seem to have this ability though.

Tabletop Games

• Ars Magica has the Longevity Ritual, which can greatly extend a mage's lifespan and weaken the ill effects of aging. The problem is that it does so by concentrating a mage's life force and preventing it from being expended. As such, a mage who uses any variant of the ritual becomes permanently sterile. (There are a handful of exceptions, but they don't work quite as well and their owners tend to be very iffy on lending them out.)
• Dungeons & Dragons:
  • The lifespan of elves has decreased somewhat over the various editions (from a maximum of two thousand years for grey elves in 1st edition to a handful of centuries now); perhaps this is appropriate, considering that they've become more and more common in their game worlds, suggesting higher levels of procreation. Their pregnancies are still long, and they need to wait five years to get pregnant again.^note The Book of Erotic Fantasy has it that elven pregnancies last a full two years, which does a number on the mother's body.
  • 3.5 has the elan, a race of psionically enhanced and modified humans who are functionally immortal. They can no longer procreate with humans due to their modifications (they are classified as aberrations, not humanoids), and the only way to make more elan is by modifying an existing human with a mixture of psionics and an alchemical conversion process.
  • The Ecology of the Unicorn in Dragon Magazine #190 states that unicorns are so long-lived that they seem to be nearly immortal, but remain rare because they almost never breed.
  • This is completely averted with dragons, however, which are some of the longest-lived beings in D&D but breed several times over their lives and tend to produce large clutches on each occasion. The only issue with them is that after a certain point in their lives females stop being fertile, and mortality rate is relatively high amongst younger dragons, so they're not overrunning the world.
  • Most fiends are immortal and completely sterile. They replenish their numbers when needed by torturously transforming evil souls that fall into the Lower Planes into more of themselves. Devils and demons powerful enough to have unique forms and identities can become pregnant (if female) or sire children (if male), but they generally don't, because they don't need heirs and certainly don't need competition. They have looser standards when it comes to Half-Human Hybrids, as any fiend can use a good pawn in the Material Plane, and half-fiends aren't likely to become strong enough to be an unnecessary risk.
• Exalted: The Dragon-Blooded can live for three to four centuries (longer with strong Essence) and are fertile virtually their entire life. However, their children have at most about a fifty percent chance of being Dragon-Blooded, often much less depending on bloodline strength and how long it's been since the last kid. The other kinds of Exaltation, meanwhile, aren't passed down through genetics at all.
• Hack Master: Taken to almost parody extremes with dwarves and gnomes. Dwarven women make up only 25% of the population, gestation takes three years, and a significant percentage of the females are either gay or asexual; as dwarven society has complete emancipation of its women, very few dwarf women actually give birth. As for gnomes, gnomish women are only fertile between the ages of 100 and 130, but gnomes of both genders are about as interested in sex as pandas, so they rarely have kids.
• Pathfinder: Neothelids are technically mortal creatures, but are functionally immortal insofar as most other races are concerned — their lifespans are measured in the tens of millennia — and magic can easily allow them to transcend their own theoretical mortality as well. This is offset by a glacial birth rate, as neothelids are born very, very rarely. This is a significant problem for them, as they have effectively no ability to absorb losses in population and the death of even a single neothelid is a disaster, and as they simply cannot keep up with the rapidly swelling numbers of more short-lived species.
• Spycraft: One of the factions in the ''World on Fire'; setting is the Eternals, which are Exactly What It Says on the Tin. They can have children, but these are very very mundane.
• Warhammer 40,000:
  • The fluff and lore about Space Marines and whether or not they can even sire children, much less raise them, is very vague and ill-defined, but given the massive physiological changes a baseline human goes through to become an Astartes, along with his psychological conditioning and the simple fact of Marines being created specifically as soldiers, it's very unlikely that any would have kids.
  • The Eldar combine a low birth rate with a natural aversion towards any sort of extreme emotion (an Eldar having sex is practically begging to get his soul sucked out by Slaanesh), to the point where their population is likely just below sustainability levels. It's also stated that Eldar pregnancies are long and complicated exactly due to them being such a highly-developed species that can afford little in the way of mistakes, which makes things only worse. This probably has something to do with the fact that they were originally created by the Old Ones to fight the Necrons and reproducing naturally wasn't high on their priority list.
  • Played with by the Dark Eldar. They can indeed reproduce, but the majority of Dark Eldar are vat-grown clones (which serve as mooks in combat or spare bodies in experiments) which are only sub-par (allegedly) in combat skill but otherwise differ little from actual Dark Eldar. Dark Eldar feed on pain and uses this to extend their lifespans. Asdrubael Vect, Archon of the largest Dark Eldar Cabal, is currently the oldest living being in the universe, bar the Chaos Gods and Necrons. Having natural "True-born" children is a privilege reserved for the upper-echelons of Dark Eldar society.
  • The Necrons gained immortality by being transformed into robots, which obviously presents a rather insurmountable obstacle to reproduction. In fact their (active) population is not particularly high, yet can war with other races with little issue because any "killed" Necrons are immediately teleported back to their base and repaired by automated systems.
  • In early editions, the God-Emperor had fathered quite a few children in his 39,000 years. Known as the Sensei, they were also immortals with psychic powers, and were hunted down by the Inquisition either to make more psyk-out weapons or to sacrifice them to jump-start the Emperor.
  • The Orks, by contrast, are an object lesson in the disastrous effects of averting this trope. Orks don't die of old age and are constantly shedding spores to grow more Orks and related organisms. As a result they are the most populous race in the entire galaxy and an ever present threat to humanity and the other races. The only reason they haven't conquered the universe yet is their infamous compulsion to immediately start fighting each other the minute they run out of enemies.
• Warhammer:
  • Invoked by Tzeentch. The ancient race of Dragon Ogres asked the Lord of Change for a boon, to make them immortal. He did, but also rendered them sterile. Most of the still-living Dragon Ogres consider this to be Tzeench's idea of a joke.
  • The Slann, the rulers of the Lizardmen, do not seem to be able to die of old age (the oldest are old enough to remember the Old Ones), but there have been no new spawnings of Slann since the disappearance of the Old Ones some eight thousand years before the present day. None of the Lizardmen species in Warhammer breeds in a sexual manner, their eggs simply come into being in magical spawning pools deep in the Lustrian jungles — each new spawning occurring according to the (now much fragmented) plan of the Old Ones. But the Old Ones didn't plan on needing more than five generations of Slann, and there is nothing the Slann themselves can do to increase their numbers, so they are now a dying race, and the loss of even one is an incalculable blow (See Warhammer: Lizardmen (2013), p. 31).
  • Elves can live for thousands of years, but produce so few children that they are slowly declining and dying out. Warhammer's Dwarfs live for hundreds of years, and seem to breed at far below replacement levels as well. Meanwhile short-lived humans breed at human-normal rates and the rat-like Skaven, the vast majority of whom never live past twenty, breed in huge numbers like the swarms of vermin they are.
  • The Undead, including Vampires, are completely unable to reproduce. Except by raising more corpses with magic.
• The World of Darkness:
  • Old World of Darkness: Most of the various immortal races are like this.
    • Demon: The Fallen: Demons might possess human bodies, but they lack the spark of life to create true progeny.
    • Kindred of the East: only extremely yang-imbalanced kuei-jin can have children (their version of dhampyrs), and that's made increasingly complicated by the fact that a female kuei-jin has to remain yang-imbalanced throughout the pregnancy.
    • Mummy: The Resurrection: The original mummies were sterile too. However, their successors, the ones players control, are fertile and capable of having children — their immortality is the result of the Spell of Life — but these are always mortal humans.
    • Vampire: The Masquerade: Only the weakest 14th or 15th generation vampires can have children, who end up as dhampirs.
  • Not uncommon in the New World of Darkness either:
    • A vampire can only give birth to a dhampir through the use of certain dark rituals and curses.
    • The True Fae of Changeling: The Lost are immortal, all-powerful, and utterly sterile. That is, until you find out that the titular changelings risk becoming True Fae if they hit Wyrd 10 and Clarity 0 — which means their abduction/Mind Rape is the Fae's reproductive cycle.
    • The Dragons of fan gameline Dragon: The Embers made a deal with the Deep Ones for immortality, the price of which was their ability to increase their numbers. Dragons can still have children, but those children will be 100% mortal. The only way for a new Dragon to be created is for a mortal to kill an existing Dragon and devour its Heart.
• World Tree (RPG): Invoked for the Zi Ri. They're biologically immortal, and individuals who don't take stupid risks have every reason to expect to live essentially forever. To avoid overpopulation problems, their creator deity made them such that reproduction is intensely painful for them, in order to make sure that new Zi Ri only come into the world after careful deliberation between prospective parents who have decided that their desire for a child outweighs the effort of enduring "the pain of love". As a result of this, Zi Ri have always been the least numerous of the Prime species.

Theater

• The website for Seth Kuberaky's production of The Rocky Horror Show says that Transylvanians had genetically engineered themselves to be near immortal but had lost the ability to breed. Hence Frank's research on Earth was trying to fix this by studying humans.

Video Games

• A key plot point in Bloodborne, is that The Great Ones are unable to have children of their own, and thus yearn for surrogates among humanity.
• In Creatures games, there are many "immortal" third-party breeds; the majority of them are infertile by default, because immortal creatures capable of breeding would overpopulate the world pretty quick.
  • But the Fast Ager Norns, who tend to evolve spontaneously in many C3/DS wolfing runs, avert this. Maturing within seconds, very fertile, and immortal, they will easily max out your population no matter what population limit you choose. They're the cancer of the norn population.
• In Cultist Simulator, this trope exists as a universal law of the world. However, it doesn't directly prevent the immortal Long from having children – it works by instilling immortal parents with an inescapable compulsion to devour their own children.
• A female dwarf in Divine Divinity mentions that she is pregnant, but she's only in her tenth month, so she's not showing any visible signs yet.
• The elves, in Divinity: Original Sin II, are very long lived and reproduce rarely and slowly. All well and good aside form the whole deathfog incident killing off a huge portion of their population, meaning it's going to take a long time to get back to the numbers they had before they were nearly wiped out, if they even can. This is a major issue that the elven leaders you speak to talk a lot about.
• Averted in Dwarf Fortress, with interesting results. Elves mature and reproduce at the same rate as humans, but have no upper limit to their ages. This results in massive populations; they could take over most worlds during generation by sheer dint of numbers if it weren't for two weaknesses: they are poorly armed (having only wooden weapons and armor) and they are cannibalistic maniacs who start wars over the way other species treat plants, resulting in them warring with all of their neighbors. Battles with thousands of elves fighting (and losing to) less than a hundred dwarves are not uncommon.
• In The Elder Scrolls, the Races of Mer (Elves) are much Longer Lived than their counterparts in the Races of Men. (Exactly how much longer they live is inconsistent throughout the lore, and usually Hand Waved when brought up, but there are plenty of (non-magically enhanced) examples living 200, 300, or even 500 years without it being seen as too unusual.) However, the races of Mer are also implied to have far fewer children as a result, with some sources even indicating that there may be a "cap" on the amount of children a Mer woman can have in her lifetime (with few ever having more than three). Additionally, their chances of having children are higher if they take a non-Mer lover. (For example, the Bretons are a race of Mer/Man hybrids who eventually outbred both of their parent races in the region of High Rock. Due to the Uneven Hybrid nature of inter-species offspring in the ES universe, the Bretons are still far more Man than Mer.) This is stated to have caused a major problem for the Falmer (Snow Elves) back in the 1st Era, since they did not breed as much as the invading Atmorans/Nords did. This caused peace to break down and the result was that the Falmer were driven to extinction or horribly mutated, bar a few hundred individuals that did indeed survive at a remote outpost.
• In the Fallout series, the two types of creature that are biologically immortal, Super Mutants and Ghouls, are both unable to reproduce. The former due to sterility as a side effect of FEV perceiving the 23 chromosomes in sex cells as "damaged" and "repairing" them by filling in the missing chromosomes, and the latter... radiation sterility and, well... rot?
  • Van Buren would have had "born ghouls," children born into ghouldom. To Drs. Sebastian and Clark, the masterminds of the breeding program, the born ghouls represent the future of the ghoul "species."
• The Manaketes of Fire Emblem live for thousands of years, and depending on the setting either are almost all sterile or reproduce at a slower rate.
  • Mystery of the Emblem mentions that the event that caused dragons to assume Manakete form made them unable to give birth.
  • Fire Emblem: The Binding Blade has dragons losing the war with humanity due to their inability to reproduce at humanity's rate, forcing them to rely on Artificial soldiers.
  • Fire Emblem: Awakening averts this with three Manakete characters that can potentially give birth to daughters.
• In Golden Sun: The Lost Age, the ancient lost civilization of Lemuria has a grand total of two children, both of whom comment on how lonely it is being surrounded by ancients. (Lemurians aren't strictly immortal, but they slow down their aging process to live many centuries.)
• Horizon Forbidden West: Played Straight with Far Zenith who never bother to have children once they perfect biological immortality. A few data logs you can find in the prologue state that they were planning on having children (it's why they developed ectogenic chambers that they then traded to Zero Dawn), but when their founder died the new leadership shifted to immortality research.
  • It also contributes to their Society of Immortals calcifying as without the new voices children bring they grow Deathless and Debauched in their personalized Virtual Realites.
• Janos Audron in Legacy of Kain says "Vampires are no longer born" implying that Vampire meant a race, and the curse that caused them bloodthirst and immortality also made them sterile. They tried to preserve their line by passing the curse onto humans.
• Averted in Lost Odyssey: the five immortals can and do have children, but their children, even when both parents are immortal are not themselves immortal, mainly for plot reasons. This prevents any potential overpopulation problems.
• Mass Effect:
  • Initially averted, then invoked, with the krogan. They were a species of walking tanks that gave birth in litters of over a thousand, and are presumed to be The Ageless. However, while their Death World homeworld kept their numbers in check, once they were colonizing more pastoral worlds, their population exploded in a single generation. To stop the Krogan Rebellions, the entire species was infected with a virus that devastates their birth rate (1 out of 1000 is live, the rest are stillborn). Even with the high mortality rate, they'd still be capable of maintaining a population equilibrium if not for the species wide fatalism that followed the genophage (kind of hard to keep your chin up when your contemporaries annihilate a fundamental aspect of your biology and society).
  • The asari, who live for one thousand years, don't seem to have a problem with this trope. They happily breed all they want to. On the other hand, in order to become pregnant, the asari has to be consciously trying to become pregnant. They can have sex all they want and only reproduce when they have a desire to. The asari are a race of Blue Skinned Space Babes, which probably rejiggers their place on the immortality vs. fertility continuum. Most of the time, the asari don't choose to procreate until they pass their 300th birthday and become Matrons, and generally don't have that many children in their whole lifetime; nearly 1000-year old Matriarch Benezia only has one daughter, for example. Aethyta, who's as old, is implied to have had a good number, but her father was a krogan.
• In the Metroid games, this is why there are so few Chozo left. Their species had become Long-Lived as their civilization reached its peak. However, they realized too late that this had reduced their ability to reproduce. The remaining Chozo dedicated themselves helping galactic civilization prosper as a means of leaving behind a legacy while facing inevitable extinction. Given that part of the legacy was their adopted daughter Samus Aran, one can only say they succeeded wildly.
• In-game documents and supplemental materials for the Myst series reveal that the D'ni, whose lifespans could run into a fourth century, reproduced very slowly due to the narrow window (30 hours every 72 days) in which their women could conceive.
• The Trow in Bungie's Myth series were created as a species by the god Nyx at the begining of the world. They have no natural causes of death, are eighteen feet tall, and have bodies that are as tough as stone. For many thousands of years they dominated the world, but entropy and a series of costly wars took its course, and now there are only a few hundred Trow left, if that. The ones that remain tend to keep to themselves, but pray you never have to run into one on the battlefield.
• In the Pokémon games, there are Pokémon which are known as "Legendary Pokémon" which have immense powers and mostly serve as deities in legends. Most of them may be immortal, and with a few exceptions, unable to produce more offspring. In the games themselves they're unable to breed (mostly so you can't produce more of them in-game).
• In RuneScape, the Dragonkin are nearly immortal, living for thousands of years at least, but can still be killed, and can't reproduce. This has lead to them becoming very afraid of death.
  • Justified for the Mahjarrat; creating children costs them massive amounts of their difficult-to-replenish divine Life Energy. This ultimately lead to the extinction of the other two tribes of their race as they were no longer receiving enough Life Energy from The Maker that made them. Also, there's only one (pure) female still alive, and she's rejected all suitors.
  • The vampyres avert this trope with severe consequences — they've overpopulated Morytania and are running out of prey.
  • The elves live so long that one of them loses track of entire centuries, but elf children can be seen prancing around Lletya and Prifddinas, so clearly fertility isn't a problem.
• Played straight and Averted in The Sims 2. Zombies and Servo robots are immortal but cannot have children, while Vampires can reproduce, but any children born will be completely normal.
  • In The Sims 3 Vampires are no longer immortal (though they still live much longer then regular sims), and can have children at the same rate as ordinary Sims at least in theory although only half of their children with an ordinary Sim will be Vampires. Also, the Fairy Sims in the Supernatural expansion have the same lifespan as Vampires, and can likewise reproduce at the same rate as ordinary Sims. Both also age at the same rate as ordinary Sims until they reach adulthood.
• In Sonic Adventure and Sonic Adventure 2's Chao Gardens, Chaos Chao are immortal, but can no longer breed.
• In the StarCraft universe, the Protoss are a very long-lived species; Artanis, at 262 Earth years old, is considered "young", while Matriarch Raszagal was 1,045 at the time of her unnatural death. They are also stated to be "not a prolific people"; even before the events of the first game, the Protoss' population was steadily declining, as they were dying of old age faster than they could bear new children. The Fall of Aiur, with the resulting tremendous fatality count, worsened the situation.
  • In novels for StarCraft, the Xel'Naga were incredibly long-lived but couldn't reproduce. Instead, they turned other races into more of them!
    • Technically, what they tried to do was create 2 races: one to have a "perfect form" and one to have a "perfect spirit". After millennia, the two would eventually join to evolve into the next cycle of the Xel'Naga. Unfortunately, someone threw a monkey wrench in the works. Legacy of the Void sheds more light on the situation. The Xel'Naga don't specifically create or modify any race to become their successors. They simply wait until races with the proper qualifications (the purity of form and essence) find their way to them pass on the mantle of Xel'Naga to them. The term Xel'Naga doesn't describe a species — it describes a duty.
    • It doesn't help that the various Protoss tribes killed each other in droves during the Aeon of Strife, only stopping after Savassan (AKA Khas, "He Who Brings Order") used Khaydarin crystals to mentally unify the race.
• When you end up in ancient Iconia in Star Trek Online the (to all appearances immortal to age) Iconians mention that they do reproduce... very, very slowly. That there were twelve Iconians at the fall of Iconia and twelve Iconians at the beginning of the Iconian War, 200,000 years later, probably has something to do with what they turned themselves into in their quest for vengeance... as well as the loss of the World Heart, their central repository of information on the universe and themselves.
• In Stellaris, both species longevity and reproduction rate can be controlled via traits, letting you play with this trope at your leisure. While it's possible for a species to start with both "Enduring" and "Quick Breeders," you'll have to take at least one negative trait and forego any other positive benefits you could have instead, so most players pick one or the other (or neither) and hope to fix the weaker trait later through genetic engineering.
  • Played straighter, the Necroids species pack introduces the Necrophage origin, which gives a species increased lifespan but also significantly reduces reproduction speed. This encourages using a Necrophage species' other unique trait to convert other species into more of yours to keep your economy from falling behind.
• True Ancestors in Tsukihime are noted in supplementary materials to have been rather on the decline. They did not even have enough children to replace the members they lost, so the birth of Arcueid itself was pretty big news even before people knew how powerful she was. Possibly tied to the fact that they were almost entirely all male.
• Boss Monsters in Undertale do not age past maturity except when they have living children. If their child dies before their parent, the parent ceases aging again.
• World of Warcraft has the Draenei, who live for at least tens of thousands of years (and may be immortal), and very rarely have children.
  • Also, now that Night Elves are no longer immortal (their natural lifespan is still probably pretty long, but not infinite) they're starting to have kids more, as evidenced by some of their quotes.

Visual Novels

• In Aselia's ending for Aselia the Eternal - The Spirit of Eternity Sword both she and Yuuto are Eternals and have a child together. This is apparently completely unheard of and they're a bit nervous about how they're going to explain it.
• Fate Series: Servants are spirits that don't age and can't die unless they run out of Mana or are killed via violence. They cannot have children with each other or with humans under normal circumstances.
  • Fate/Apocrypha: Sieg asks Jeanne directly about this out of curiousity, to which Jeanne replies that this only applies if the Servant isn't incarnated with an actual physical flesh-and-blood body from the Grail, as their existing "bodies" are just magical energy shaped into an approximation of what they were in life. For example, Jeanne as she is possessing the body of Laeticia could in fact get pregnant and give birth, though obviously she has no intention of doing so while in Laeticia's body no matter what her growing feelings for Sieg say.
  • Fate/Grand Order: Queen Medb, the Mother of Soldiers, is a partial exception. Whenever she has sex, she stores the semen within her body. Then, she uses the genetic material to create soldiers from her spilled blood that are biologically her children.
  • Fate/Requiem: This causes a stir when Erice Utsumi is revealed to be the daughter of the Servant Izanami and a human man, with several parties wondering how it is possible.

Webcomics

• The Enchanters in At Arm's Length are fully capable of having children at any time, but social norms tend to prevent this. Also, the biological clock normally doesn't start ticking until a few millennia, eliminating the desire to have children for quite a while. Enchanters who have children while they're still relatively young, or have more then one, are typically frowned upon.
• Dan and Mab's Furry Adventures:
  • Cubi Clans are led by a Tri-winged Succubus or Incubus, who are as close to immortal as one can get with a an ungodly long lifespan and are so powerful very few dare to challenge them. The catch is they cannot have children of their own, and while it is possible to convert non-blood relatives to their clan there must be at least one fertile member of the clan alive who has had a child with the prospective member. The character Fa'lina shows how this can be bad, being a clan leader and being the last surviving member of said clan.
  • In addition to Cubi, no new members of the Fae race may be born until living members willingly and deliberately die. They can have children with anything, but, well... The problem is that the fae race has only so many souls to go around, and nothing can be done to increase that number. That's why a fae has to die before a new one can be born — the dying fae's soul is reincarnated in the newborn fae.
  • Destania's clan leader Cyra is in a similar boat as Fa'lina. Destania is her last surviving "child" and she can't even speak with her anymore since Destania has given up dreaming — and Cyra mostly communicates in dreams. So she's absolutely thrilled when she gets the chance to speak with her "grandson" Dan.
  • Most of the other Long-Lived races such as Demons don't seem to have this problem. Overpopulation isn't an issue since Furrae is dangerous enough that most people, Beings and Creatures alike, do not live to die of old age anyway. The Angels' birthrate has been waning in recent years for some reason, and they are very worried about becoming a Dying Race.
• Drowtales:
  • Played straight with Light Elves and Drowwusu, who have low death and birth rates.
  • Played with in Dark Elves and Drow, in that they are The Ageless^note Something Word of God has said is technically not true in that they have a finite lifespan of somewhere over 1000, but almost none of them survive long enough to reach this but some, including Ash'waren and Zala'ess, are known for their extremely large families, but they tend to be the outliers on the far end of the scale. Meanwhile Diva'ratrika Val'Sharen is over a thousand and has only had five (surviving) daughters and one son, which the suggestion that politics has played a role in this. Meanwhile, during a 15 year timeskip, Mel'arnach has three children, which suggests fae are able to have multiple kids within a short amount of time with relatively little trouble, and drow in particular elevate motherhood to a sacred level, with one character's losing her ability to have more children playing a critical role in her motivations and actions. The Crapsack World nature of the environment means that despite people having lots of kids the population has stayed relatively stable due to the high chance of death.
• In El Goonish Shive, Immortals are capable of having children, at least to some degree. Most do not seem to do so, though. "Half-Immortals" (called "elves" in the series jargon), the offspring of an Immortal and an ordinary human, are confirmed to be sterile. No word on what happens if two Immortals attempt procreation.
  • It's later confirmed that elves are not, in fact, sterile, though they are less likely to become pregnant or get someone else pregnant than a normal human. The sterility is deliberate misinformation the Immortals pass on to their reset selves, in part so they can avoid attachments to extended families after resetting. Jerry's reset version only knows this at all because Jerry wanted him to be a responsible successor, and Pandora only learned the truth relatively recently herself, with it being confirmed that Susan and Diane are descended from Raven.
• The elves of Errant Story previously had an extremely low fertility rate, which is part of the reason why taking on human lovers was so popular among them; as Sarine put it, elves could "try for centuries to have an elven child with no success, or they could go fuck a human and have the next best thing." In the wake of the Errant Wars, the elven fertility rate seems to have dropped from "low" to "zero," as the last elven child born is now some 1,500 years old.
  
  When Meji finally starts 'talking' with Senilus, one of the things she learns is that the something went wrong when the 'gods' made one of the races; the race would lose the ability to reproduce itself after 427 generations. Since the first two races the 'gods' made weren't able to reproduce, and the last race made by the gods is generally agreed to be the trolls, it is very strongly indicated that the race in question is the elves. But they are still fertile with humans, since errant Meji is only 17, and errants can be very long-lived. The elves originally took advantage of this to increase their population, until one powerful errant mage went mad for some reason and went on a rampage. The elves thought it was an inherent problem with errants and forbade future errant births.
• Averted by Master Voltaire and Queen Albia in Girl Genius, and neither's form of immortality appear to be hereditary. Many of Voltaire's children live in the family chateau, and with Albia we're introduced to seven young women who are revealed to be her daughters, and later to five old women who are also her daughters.
• Canonically, the Nemesites in The Inexplicable Adventures of Bob! don't have much of a libido for precisely this reason, and view romantic love primarily as a purely emotional matter based on personality. Notably, this makes them quite open to the prospect of Interspecies Romance, albeit of a very chaste sort.
• Parodied in Irregular Webcomic!'s "Fantasy" storyline, where it's pointed out that Elven longevity also means that young Elves take centuries to grow past adolescence. As a result, the Elves invented prophylactics before they discovered how to use fire. The comic's commentary even links to this trope page.
• In Jack there are some people who have missed their chance to die for some reason, their biology is frozen at the point where they should have died and they can't reproduce as a result. And it appears that sterile immortality was intentional.
• Kill Six Billion Demons does it a couple of ways. On the extreme end, there are the wholly immortal (of a resurrective variety) angels, whose number is fixed and who are entirely sterile. The majority of Servant species can live forever unless killed, and seem to vary between fairly low fertility, and something that is about normal for humans. Then there are goblins, a species of Servant that was created to fulfil a task that would have a high mortality rate, meaning that they reproduce at an extremely high rate; since they no longer do that job, they greatly outnumber virtually every other race in the multiverse, meaning that their clans are very well represented amongst the businesses and criminal enterprises that run everything.
  • Results vary for the Demiurges ruling over this mess; Jadis is sealed in a stone slab and suicidal, so analog reproduction is out the window. Solomon has thousands, if not millions, of mortal sons who have been general disappointments, while Gog-Agog is a sentient colony of worms so she has a tide of her 'babies' infesting various minions across the multiverse, but all of them can be classified as 'limbs', 'toys', or 'food'. The rest have no descendants or heirs of note.
• The Bradicor of Ghanj-Rho in Schlock Mercenary have, individually, survived millions of years and watched the evolution of intelligent life forms, but are indifferent to the gradual extinction of their species. The heroes end up accidentally flattening their last female during first contact and dooming them to extinction. The Bradicor react more with annoyance than anything else seeing how they were already sterile.
• Unsounded: Senets can be killed, though its remarkably difficult to off some of them, but they cannot die of old age as they do not physically age beyond loops some of them grow through and then start over. They also cannot procreate and no new Senets can be created; those that remain are a leftover from the deathless world that preceeded the one in which humanity evolved in.

Web Original

• In 17776, humanity as a whole suddenly loses both the ability to die and the ability to conceive on April 7th, 2026. Immortality Begins at Twenty is in effect, so those who were already pregnant at the time aren't stuck that way for all eternity and children are able to grow up normally.
• As a demonstration of why this trope is often necessary, the site Grudgematch had a hilarious take on the disastrous consequences of James Bond winning immortality in the grudgematch: massive inbreeding due to James' libido.
• Looming Gaia:
  • When people are granted divinity, they become immortal (able to die, but with Resurrective Immortality), but they also become unable to have natural children. But they can use their divine powers to create soulless monsters which may or may not be sapient.
  • Nymphs aren't really immortal, but they don't age and are harder to kill than normal people. They are also sexless and unable to reproduce.
• The alien race known as the Silent Ones in Orion's Arm use a treatment that completely halts aging but severely stunts the development of their larvae, so they keep small groups of mortals to replace the few immortals that die. However most Terragen (human-derived and/or created) sophonts are effectively immortal and decidedly not infertile, the population being in the quadrillions about 10500 years in the future.
• Word of God (pun intended) has this as being the demographic issue with the angels in The Salvation War — "angelic females simply are not very fertile and the chance of conception is extremely low," so the reason for the war being fought on Earth is to put off or prevent any human incursion into Heaven. Whereas the daemons tended to be killed en masse in generally horrible ways during the Curb-Stomp War, their birth rate will allow them to eventually recover, whereas angels dying off in those numbers might actually cause them to go extinct.
  • Although as of Chapter 83, it seems that the low birth rate of the angels was at least partially due to Yahwehh's obsession with controlling sex and sexuality and now that he's been killed there's been a rash of pregnancies among the angels including Maion.
• Elves in Tales of MU are true immortals in terms of lifespan, and generally quite sexually potent as part of their being better than everybody. They keep their birth rate low by doing things that don't produce children.
• This blog post hilariously suggested that romances like the one in The Twilight Saga prevent vampire from population problem.

Western Animation

• In The Dragon Prince, Rayla mentions that Sky Dragons only lay one egg every thousand years, which is why they're considered so precious.
• In The Fairly OddParents!, fairies are forbidden to have children, mostly because A) they're immortal and don't really need to, B) A newborn fairy's Reality Warper powers are dangerously unstable and C) the last one born was Cosmo. The only reason Poof exists is that no one forbade their godchildren from wishing for them. More accurately, Jorgen keeps forgetting to implement that rule, so it's possible that there may have been more Fairy babies brought into life (explaining Poof's peers in nursery school.) Poof seems to be a big case because of who his parents and godbrother are.
• My Little Pony: Friendship Is Magic:
  • Celestia and Luna seem to follow this trope. Their personal lack of children could just be because they've never had mates, but they have both lived at least a thousand years, possibly much longer, and their only onscreen relatives are a niece and a nephew (and presumably their offscreen relatives). The existence of Age spells only accessible to really powerful unicorns further complicates things, as their immortality may not even be natural. Said niece and nephew aren't even blood relatives. As far as we know, the sisters have no other living relatives.
  • The Journal of the Two Sisters implies that natural alicorns, as opposed to ponies changed via magic, are apparently a very rare and Long-Lived pony race.
  • Dragons are capable of producing offspring, though the rate at which they do is not established and one can assume they follow the rule of longetivity as most dragons do.
• Played with in Steven Universe. The immortal Gems do reproduce, but it's an asexual process that grows them out of the ground and sucks the life force out of a planet. They're Born as an Adult and have no real families, until Rose Quartz hooked up with a human gave birth to the title character. This process however, killed Rose and left her Heart Drive in Steven's body.

Real Life

• Since 1951, it was thought that human oocytes (eggs) were produced by a woman's ovaries before she, herself, was born, and therefore a hypothetical immortal woman's capacity for natural reproduction would expire when her "supply" runs out, even if she never goes through menopause. As we now know this is Jossed given the discovery of egg-producing stem cells (so-called oogonial stem cells) in adult women's ovaries. Regardless of this, menopause still renders our "immortal woman" infertile unless Immortality Begins at Twenty.
  • There are several other workarounds; giving birth to a baby conceived in vitro from a donor egg, or the woman's eggs are preserved in case she doesn't have a baby before menopause. Services exist now that cover both of these options.
• Throughout history people have attempted to discover the secret to eternal life and Aubrey De Grey is probably the most famous example in modern science. He has come up with his own theories and has even gone so far as to speculate that, once technology can stop and reverse aging, people will have to file a form to have children and then wait for other people to die (through natural causes or requested suicide) to be given the go-ahead.
• Thought experiments on population growth rates suggest that extending lifespan needn't necessarily produce an Explosive Breeder, as it's really the age at first reproduction that determines how fast a population grows. Mathematically, having a breeding female live forever will do less to increase birth rates than having her produce a daughter (who'll breed early in turn) slightly sooner.
• Averted with amoebae, and other single celled organisms that reproduce by binary fission. When you split in half (as opposed to budding off a daughter cell), you can consider both resulting amoebae to be an extension of the life of the parent. In short, every single amoeba on the planet is the very first amoeba. They're immortal and reproduce like crazy. Good thing they're fairly low on the food chain, so their hypothetical immortality isn't much of a problem.
• This idea is truth in television in human communities insomuch as the childbirth rate of a country appears to be inversely related to its average lifespan. This is attributed to things like education, not seeing everyone around you die young (which tends to cause survivor lust), and good healthcare that improves lifespans and reduces infant mortality, meaning people don't need to have as many children to guarantee some survive. More developed countries also tend to have less of a primary-industry focus, meaning children are a net drain on assets rather than a source of income. State welfare and wealth in general also means parents aren't as reliant on children to support them in their old age.
• The immortal jellyfish doesn't die; it turns back into a baby and starts over. A total aversion because it also reproduces quickly.^note That tends to happen when you're the ocean's snack food.
• Lobsters seem functionally immortal, remaining fertile and growing with age (the oldest known lobster weighed 44 pounds and was estimated to be 140 years old!). However, they eventually grow so large that molting their exoskeleton is too difficult, and they often get trapped inside it, opening them up to infection and predation.

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