History Main / ImmortalityBeginsAtTwenty

* {{Justified|Trope}} in ''LightNovel/{{Kieli}}''. The [[OurZombiesAreDifferent Undying]] are immortal soldiers [[BodyHorror made out of the corpses of dead ones]]. There weren't a lot of kids fighting in the war (which doesn't mean that they weren't [[HarmfulToMinors dying in it]]), and a fully grown healthy adult is going to make a stronger, stabler, more efficient, soldier than a child. [[CameBackWrong Usually.]]

* In ''Literature/{{Twilight}}'':

* ''LightNovel/CrestOfTheStars'' has the Abh. Barring accident or illness they live to between 200 to 250 years. From birth to 15 they age at more or less the same rate as a normal human. From 15 to 25 years their maturation slows until they're at a point somewhat equivalent to a lander at age 20 at which point they only age very, ''very'' slowly.

* ''LightNovel/KyoKaraMaoh'':
** While not immortal, Mazoku age ''much'' slower than humans. This is tragically {{deconstructed|Trope}} at the end of episode 47.
** Wolfram, who looks like a 15-17 year old {{Bishonen}} physically, is actually 82.
* Although Witches in ''Manga/SoulEater'' live for hundreds of years, the few young witches we've seen (Angela and [[spoiler:Kim]]) are by all indications the same age as they appear to be, implying witches grow to adulthood as fast a humans then grow elderly extremely slowly. ''Manga/SoulEaterNot'' reveals this has a ''small'' degree of ProportionalAging, as [[spoiler:Kim]] turns out to be a few years OlderThanTheyLook. Presumably their aging slows down gradually instead of at an instant.

* [[JustifiedTrope Justified]] In LightNovel/{{Kieli}}. The [[OurZombiesAreDifferent Undying]] are immortal soldiers [[BodyHorror made out of the corpses of dead ones]]. There weren't a lot of kids fighting in the war (which doesn't mean that they weren't [[HarmfulToMinors dying in it]]), and a fully grown healthy adult is going to make a stronger, stabler, more efficient, soldier than a child. [[CameBackWrong Usually.]]

** In the ''Series/StarTrekTheOriginalSeries'' episode "Plato's Children", an alien race that based itself on UsefulNotes/AncientGreece genetically engineered themselves to stop aging at about 30-40 years old. (When Spock informs one of the female aliens that she looks a few years [[OlderThanTheyLook older than the age at which she officially stopped aging]], she's a bit miffed, despite being ''thousands of years'' older.)

* ''[[Series/WonderWoman1975 Wonder Woman]]'': Wonder Woman is thousands of years old, but she looks like she's in her 20s - especially since Creator/LyndaCarter was in her 20s during the show's run. This is even mentioned specifically in "The Return of Wonder Woman":
--> '''Steve Trevor:''' You can't be more than 23 or 24 years old.
--> '''Wonder Woman:''' I will be 2,527 years old on my next birthday.

[[folder:Web Original]]
* Humanity in ''WebOriginal/SeventeenThousandSevenHundredSeventySix''. The entire human race mysteriously stops aging or dying ([[ImmortalInfertility or reproducing]]) in April of 2026, but it's then clarified that children conceived before that date are still born and grow to adulthood, as do those who were still children at the time.
[[/folder]]

** Aes Sedai use an Oath Rod (originally produced as a RestrainingBolt for criminal channelers) as part of their InitiationCeremony. As a side effect, it makes them "ageless" (essentially, wrinkle-free). It also cuts their lifespans in half, which they don't know until they meet wrinkled (though not ancient-looking) channelers who are over 400 years old. It also causes an UncannyValley effect in the eyes, since these apparently continue to age, even if the skin around them doesn't.

* ''Series/AlienNation'': In the episode "Fountain of Youth" the Tectonese (aka Newcomer) George Francisco explains to his human partner Matt Sikes that Newcomer and humans age at about the same rate until their early 20s when the aging process slows down signifigantly for Newcomers. George goes on to explain that he and most Newcomer adults are [[OlderThanTheyLook quite a bit older]] than their appearances suggest.

* In ''Videogame/{{Warframe}}'', the aging process of the transhuman [[PreCursors Orokin]] and their profit-crazed descendants, the Corpus, have been ''dramatically'' slowed down. Darvo is 105 years old, looks 20, and acts and is treated like an unruly teenager. However, the aging seems to stop at the mid 40s rather than 20s; Alad V, Frohd Bek, and Nef Anyo are all several hundred years old and look like 40-something [[FashionVictimVillain fashion victims]]. Teshin was around when the Orokin Empire was at its height a millenia ago and likewise looks like he's in his early 40s. [[spoiler: The Tenno look like teenagers or young adults, yet are nearly as old as Teshin. It's not made clear if it's from their life support systems, their times in cryosleep, or from standard Orokin augmentation.]]

* In Philip Jose Farmer's ''Literature/{{Riverworld}}'', the entire human race through history over the age of 5 is resurrected on an alien planet at the same time. Everyone is at age 20, and those who were chronologically younger than 20 continue to develop until stopping at 20. There's even a term for them "Rivertads".

* Inverted in ''Series/TheMandalorian'', Mando has a bounty to retrieve an unknown target who, he is told, is 50 years old. When he finally finds his quarry, he finds an infant/toddler of Yoda's species, nicknamed (by fans) "Baby Yoda." When he questions this to the Bounty Hunter droid IG-88, 88 reminds him that some species take longer to mature than others.

** This appears to be the case with Vulcans in general as well given their extended life spans. The character of Tuvok on ''Series/StarTrekVoyager'' visibly aged in appearance from the 2270s as a teenager to when he served on the USS ''Excelsior'' in the 2290s. However, his appearance changed little from the 2290s up through the 2380s.

* In ''Fanfic/OperationSoulmate'', those that get vacinnated against adulthood virus stop aging at 10 years old.

** In the ''Series/StarTrekTheNextGeneration'' episode "[[Recap/StarTrekTheNextGenerationS3E9TheVengeanceFactor The Vengeance Factor]]" the Acamarian Yuta of Clan Tralesta was [[TheChosenOne chosen]] to carry out a mission to kill all the members of Clan Lornak no matter how long it took after the Lornak killed almost her entire clan. Among the genetic modifications made to her were ones that slowed her aging signifigantly.

* In the ''Series/StarTrekTheOriginalSeries'' episode "Plato's Children", an alien race that based itself on UsefulNotes/AncientGreece genetically engineered themselves to stop aging at about 30-40 years old. (When Spock informs one of the female aliens that she looks a few years [[OlderThanTheyLook older than the age at which she officially stopped aging]], she's a bit miffed, despite being ''thousands of years'' older.)

* ''Franchise/TouhouProject'', especially in fanon, plays with this trope for all it's worth, thanks to its huge cast who are ReallySevenHundredYearsOld. The Scarlet sisters were born vampires and have a literal case of ImmortalImmaturity. All of the fairies in the series are referred to in ''Perfect Memento'' as having at most the appearance of a 10-year-old child and CantGrowUp. Most of the others, however, are adults who have lived thousands of years, and include some apparent teenagers who are [[CompleteImmortality truly immortal]]. Yukari, especially, (thanks to dressing up and occasionally acting like a younger woman than she appears to be normally) gets jokes from fandom about being the "old maid" (in spite of only being a couple thousand years old, which is fairly normal by Touhou standards) by some corners, and having her boast that she's (eternally) seventeen by others.

--->'''Haley''': I can't really see the downside of --\\

* WesternAnimation/Castlevania2017 has the {{Dhampyr}} Alucard, who aged very quickly through his childhood and who will now presumably keep his young-adult looks for many years to come.

* Zigzagged in ''Manga/{{Bleach}}'': [[OurSpiritsAreDifferent Pluses]] appear to live much longer than humans, but how they mature and age seems to vary arbitrarily. Rukia and Renji are implied to grow from children to young adults in a roughly normal amount of time, but then don't age at all over the next fifty years. The epilogue, which takes place tens years after the series shows [[spoiler:their daughter]] who looks to be about eight or nine years old. On the other hand, Toshiro looks like he's twelve and hasn't age at all for over thirty years.

* Subverted in Creator/IanMcDonald's ''River of Gods'' - one of the many enhancements given to the so-called "Brahman Babies" is a doubled lifespan. They age half as fast physically, but mentally (or at least legally) grow up at a more-or-less normal pace, leading to apparently ten-year-old night-club owners. A short story set in the same universe points out the rather nasty effect this has on marriages.

* PlayedWith in the third book of ''[[Literature/TheIdhunsMemories Memorias de Idhún]]''. [[spoiler: Wina, [[FertilityGod the goddess of life]], [[YouCannotGraspTheTrueForm manifest herself as a zone where all life thrives, grows and reproduces extremely quickly]]. Children become adults [[QuickAging in a matter of minutes]]. However, since the main characters are in their early twenties at this point, and the goddess of life causes growth, but not decay, they are unaffected by this. That doesn't mean they aren't [[LoveIsInTheAir affected]] by the [[ExpressDelivery "reproduces"]] part, though.]]
* Franchise/TolkiensLegendarium:

* Played straight in ''Literature/{{Duumvirate}}'', where it's referred to as "maximum age".

* Literature/{{Dragaera}} definitely uses this. Dragaerans are immature from about ages 1-70, but are still in fighting shape after 1,000 years. They do get old eventually, but the series is remarkably low on infirm, elderly Dragaerans, so it's not clear how long they last as "old people".

* ''Franchise/TouhouProject'', especially in fanon, plays with this trope for all it's worth, thanks to it's LoadsAndLoadsOfCharacters who are ReallySevenHundredYearsOld. The Scarlet sisters were born vampires and have a literal case of ImmortalImmaturity. All of the fairies in the series are referred to in ''Perfect Memento'' as having at most the appearance of a 10-year-old child and CantGrowUp. Most of the others, however, are adults who have lived thousands of years, and include some apparent teenagers who are [[CompleteImmortality truly immortal]]. Yukari, especially, (thanks to dressing up and occasionally acting like a younger woman than she appears to be normally) gets jokes from fandom about being the "old maid" (in spite of only being a couple thousand years old, which is fairly normal by Touhou standards) by some corners, and having her boast that she's (eternally) seventeen by others.

* Genetic elites in ''Webcomic/TheCyantianChronicles'', though their age catches up to them quickly as they reach the end of their lifespan (ranging from 120 years in foxes to nearly a millennium in wolves). Elite wolves don't reach their full height of about 7'6" for several decades, as Darius and his classmates are teenagers or mid-twenties they tend to be pretty short (~6 feet) by their species' standards.

* This is the case with warlocks in ''Literature/TheMortalInstruments''. As [[HalfHumanHybrid half-human/half-demons]], they age more or less normally until they reach adult, and then their aging just stops.

* PlayedWith in the third book of [[Literature/TheIdhunsMemories Memorias de Idhún]]. [[spoiler: Wina, [[FertilityGod the goddess of life]], [[YouCannotGraspTheTrueForm manifest herself as a zone where all life thrives, grows and reproduces extremely quickly]]. Children become adults [[QuickAging in a matter of minutes]]. However, since the main characters are in their early twenties at this point, and the goddess of life causes growth, but not decay, they are unaffected by this. That doesn't mean they aren't [[LoveIsInTheAir affected]] by the [[ExpressDelivery "reproduces"]] part, though.]]

* Franchise/{{Superman}}: The comics have gone back and forth on whether Kryptonians are immortal but no matter how slowly they age in adulthood, they always age normally up to about their mid twenties to early thirties.
* [[ComicBook/ThePantheon Pantheon leader Agamemnon]] from ComicBook/TheIncredibleHulk. Although he likes appearing to people in the holographic form of a very old man with a long white beard, his immortality kicked in when he was 16. His descendants all had their immortality hit as young adults too.