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[[quoteright:350:[[WesternAnimation/KimPossible http://static.tvtropes.org/pmwiki/pub/images/kim_ar_wiki_6744.png]]]]
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->'''Sheriff:''' I want you to be honest with me. ''Absolutely'' and ''completely'' honest. ''Have you been time traveling?!''\\
'''Stiles:''' Hang on, ''what''?\\
'''Sheriff:''' Because if time traveling is real, you know what? I'm ''done''. I'm out. You're going to be driving ''ME'' to Eichen House!\\
'''Scott:''' We found him like that.\\
'''Sheriff:''' ''[already ''500% done'' with the supernatural stuff]'' Where? '''''Swimming in the fountain of youth?!'''''\\
'''Stiles:''' No. We found him buried in a tomb of wolfsbane in an Aztec temple in Mexico underneath a church in the middle of a town that was destroyed by an earthquake.\\
'''Sheriff:''' You told me you were ''camping''!\\
'''Stiles:''' Yeah, we were... In Mexico.\\
'''Scott:''' Derek's been aged backwards. He can't remember anything. We just need to talk to him.
-->-- ''Series/TeenWolf''

%% Quote changed per thread: http://tvtropes.org/pmwiki/posts.php?discussion=1327331003042025100&page=127#3159

Some form of AppliedPhlebotinum results in one or more main characters regressing to an earlier age. It may be the result of a [[PhlebotinumBreakdown freak accident]], a plot on the part of the bad guys to incapacitate our heroes, or done on purpose so the characters can relive their childhood (at least temporarily). Always central to the plot of a BabyMorphEpisode, which is ExactlyWhatItSaysOnTheTin.

For some reason this plot is often used in FanFic, where it's called a De-Aging story. Often combined with RaiseHimRightThisTime.

When it's an actual fountain or similar artifact that exists to restore youth, it's a subtrope of {{Immortality}}. These will of course be sought out by {{Immortality Seeker}}s. A downside to this version of the trope is that the fountain is usually stationary and often in a remote region, forcing the newfound immortal to [[WhoWantsToLiveForever permanently stay close to it]] or at least return regularly, and to keep it a secret from others due to ImmortalityImmorality.

When someone dies in his rejuvenated state, expect him to [[NoImmortalInertia turn back old]] immediately.

When a Fountain of Youth effect doesn't get reversed and the younger actor replaces the older one in the cast for good, it's also an example of TheNthDoctor.

It's common for characters to overdo it in stories involving this trope, often winding up as babies, or possibly even regressing out of existence entirely. This may or may not be permanent, but if the character in question was a bad guy, [[RaiseHimRightThisTime expect it to be permanent]]; well, at least, until they grow back up the old-fashioned way. If the character's clothes don't change with them in this event (and it's shown onscreen), it's likely to cause ShapeshiftingExcludesClothing. If the event is offscreen and thus a surprise to the audience or one or more characters, EmptyPilesOfClothing results. The TropeNamer was the mythical Fountain Of Youth that Ponce de Leon searched most of Florida to try and find.

Contrast with OvernightAgeUp and PlotRelevantAgeUp. Compare ReallySevenHundredYearsOld, where an individual is vastly older than even the maximum natural lifespan for their species, and looks nowhere near as ancient as they actually are; MerlinSickness, where the individual's aging progresses in a backwards fashion (i.e. they grow younger rather than older); and LongevityTreatment, where one's maximum lifespan is increased (which [[AgeWithoutYouth does not necessarily come with youth]]). See also HealingSpring.



* In [[http://www.youtube.com/watch?v=mWZYhVNUUUE: this]] advertisement, a young man continues regressing from what may be a high-schooler, all the way down to pre-schooler.
* In a commercial for Nickelodeon in the late 80s, a scientist is trying out a youth potion to make himself a kid again so he can watch "Kids only weekend". But when he drinks it, he turns into a baby which the announcer says "Sorry babies are too young to watch "Kids only weekend"
* There were a couple commercials for the candy Baby Bottle Pop that featured this trope.
** Whenever kids were eating the candy their heads became that of a baby.
** In one, teens at a dance are bored and eat the candy and anyone who ate one is turned into a cartoon baby.
* In an ad for the [=PS2=], we are shown the aftermath of this. In a nursing home, we see empty halls with discarded clothes with no one in sight. A clock is shown moving backwards and then we see naked babies crawling around.
* In a commercial for Bojangles, an old man shows off his Bojangles box. An old woman isn't impressed and drinks a water fountain to become young again and says "I found the water fountain of youth". We see the man again and he's not impressed. We then see the woman has turned into a girl around 13 and she walks away.
* In a commercial for Johnson and Johnson baby shampoo, we see a woman smiling at the camera and bubbles covering the screen. Every time this happens she becomes younger from adult to pre teen to child and then to baby.
* A long-running series of commercials on American television for Frosted Mini-Wheats cereal had various adults stating to the camera their "serious adult side" approves of the cereal's nutritional value. Then they'd suddenly become children in oversized clothes and continue explaining, in the same voice, the "kid in them" enjoys the frosted sweetness. Sometimes they'd reverse the bit, with a child becoming an adult.
* There was a commercial for some sort of body wash where football players showering after a game using the product transformed (off-camera) into infants.
* [[https://youtu.be/oHNSDMMwsg0 This commercial for the South African drink Steri Stumpie]] suggests that the drink will cause a mother and son to get 10 years younger if they drink it at the same time. Unfortunately, in this case, the son happened to be a bit younger than 10 years...

[[folder:Anime & Manga]]
* Because [[PhlebotinumBreakdown Heaven's computer crashed]], this happened to Urd for about two chapters in the ''Manga/AhMyGoddess'' manga (and one episode of the 2005 animé), with [[OvernightAgeUp the reverse happening]] for youngest sister Skuld. Fortunately, she was able to get an interesting advantage out of it.
* In an episode of ''Manga/AkazukinChacha'', the main trio is tricked by some bad guys into drinking rejuvenation potion, and turn back into babies. Seravy and Dorothy are also reverted to kids. Of course, they all turn back at the end.
* A plot used multiple times in ''Franchise/{{Anpanman}}''. A couple episodes have had Baikinman make a spray that changes anyone (or anything) in contact with it into babies (with objects becoming earlier stages, like a tree becoming a sapling). He does this as ways to make Anpanman weak against him, but it always gets foiled in the end. One theatrical short showed there's an entire lake, one side red, which turns the victim into a baby, the other side blue, which returns them to normal. Another theatrical short had Hiyariko, an aspiring scientist, create a potion to make Baikinman stronger...only to turn him into a baby. When he runs off, she makes what she thinks is an antidote, and sprays it all around the town...only to turn the entire town into babies. Thankfully, this potion was only temporary, and everyone returned to normal eventually on their own.
* This is part of the premise of ''Manga/AsatteNoHoukou'' : when they both happen to meet at the same time in front of a wishing stone, a young woman transforms into a little girl, and vice-versa. It is implied they change back at the end of the series.
* In ''Manga/BlackCat'', [[BigBad Creed]] ([[MadScientist Doctor]] did in the anime instead) accidentally shoots Train with a Lucifer bullet, causing Train to transform back into a child (around 8 years old). It only lasts one episode (or a few chapters).
* ''Manga/BlackLagoon'': a non-{{canon}} {{omake}} has the main cast regress to adolescence and, in [[BloodKnight Balalaika's]] case, beyond. For the record, [[TokenMiniMoe loli-Balalaika]] is the cutest thing ever. The most shocking ones are Yolanda (the old nun), who was a delicious and ''hot'' [[ChristmasCake cake]] at 29 and Balalaika's underling Boris, who was {{Bishounen}} to the max.
* In ''Manga/{{Bleach}}'', [[spoiler: Neliel Tu Oderschvank originally had the appearance of a late teenager/young woman, but after being attacked by her rival Nnoitra and having him crack her Hollow mask, she ended up reverting into a small child.]] Later [[spoiler: Urahara uses his devices to let her return to her original age.]]
* In an episode of ''Anime/BrigadoonMarinAndMelan'', Marine eats some weird chocolate [[MushroomSamba that causes her to start hallucinating]]. Among other things, she imagines herself [[OvernightAgeUp growing into a young adult]], then regressing into a baby.
* In the early chapters of ''Chronos Ruler'', a teacher in her forties wished to one of the Horologues to get her youth back, and by the start of the series looks like a young woman. Too bad for her, she ends up becoming ''too'' young the next day; after she turned into a child, she tried to approach the Horologue in question to ger her time back, only for the Horologue to quickly suck out the ''rest'' of it, regressing her out of existence. This serves as a dire introduction to those demons' true nature.
* Played straight then subverted in the fourth episode of ''Anime/{{Classicaloid}}''. When Schubert starts playing his music, everyone else present shrinks out of their clothes as they regress into babies frolicking to and fro, but it soon turns out that they're actually perfectly normal, and that the music merely caused them to ''act'' like babies.
* Amber from ''Anime/DarkerThanBlack'' has this as her [[PowerAtAPrice remuneration]]; she regresses in age every time that she uses her powers. [[spoiler:In the end, she ends up fading into nothingness altogether due to overuse.]]
* In ''Manga/DeathNote'', Shinigami can steal the lifespans of humans by writing their names in Death Notes, which kills the human. Humans who use the Death Notes don't get the lifespans of their victims but if a Shinigami uses their Death Note to save a human's life, the Shinigami dies and the human gets all of their lifespan.
* Who can ever forget [=APTX-4869=] in ''Manga/DetectiveConan''? It regressed Shinichi Kudo and Shiho Miyano's ''body'' by around ten years, causing two {{Teen Genius}}es to live in first graders' bodies. On the other hand, [=APTX-4869=] [[MillionToOneChance is employed as a poison and is generally successful]].
* One of the first monsters in ''Devil & Devil'' is a huge tentacled... thing, that sucks time out of people. It turned a young woman and two young girls into babies, and a third young girl into a child, but they all turned back to normal when it got its ass handed to it by Sword.
* ''Franchise/{{Doraemon}}'':
** This is one of the Time Cloth's main functions; one of its sides makes everything and everyone who gets wrapped in it younger. Gian ends up briefly turning into a baby because of it in its first appearance. In a later episode of the second anime, Nobita's mom is temporarily turned back into a child around her son's age, taking advantage of it to try and find a secret he's been hiding from her.
** ''Anime/DoraemonNobitaInTheWanNyanSpacetimeOdyssey'' follows the story of Eiji, an anthropomorphic dog who travels across time to find his ex-owner, Nobita, but the unstable time tunnel causes him to warp into another place and ended up being turned back into an infant. This also happens later with Gian and Suneo, but only temporarily.
* ''Franchise/DragonBall'':
** King Piccolo and [[Anime/DragonBallZLordSlug Lord Slug]] used the titular MacGuffin to restore their youth, putting their power at prime. Roshi and his sister Baba actually drank from a Fountain of Youth, which, rather than restore their youth, fixed them at that age, unable to die from old age.
** Goku turning into a child is part of the whole ''concept'' of ''Anime/DragonBallGT''.
** The concept was used again in the 2013 film ''Anime/DragonBallZBattleOfGods'' where the [[GoldfishPoopGang Pilaf Gang]] were transformed into children off screen. This still holds true in ''Anime/DragonBallSuper'', to the point that in a BadFuture shown in ''Super'', Mai has merely grown back into her teens/early twenties instead of her original age.
* In ''Anime/ExpelledFromParadise'', Angela Balzack has spent her whole life since infancy digitized, living in a virtual world with 98% of humanity in the same boat. She's also Third Officer for System Security. When a real world hacker potentially threatens the peace and stability of that virtual world, DEVA, she has to go out into the real world. One problem: her original body is long dead. Fortunately, the machines that run DEVA always save a DNA sample of every infant they digitize, in case of just such an emergency, so that they can clone new bodies, and uses age-accelerating incubation pods. However, Angela want to get the jump on all the other agents being sent into the real world, so she cuts her new bodies incubation period short, leaving her body at age 16 instead of... whatever age she is chronologically(we don't actually know).[[spoiler: She eventually gets trapped in her teenaged body when she rebels against DEVA's cruel and oppressive government. Come on, they deleted ROCK AND ROLL!!!]]
* In ''Manga/FairyTail'', a villain in the Taiyou Village arc named Doriate uses magic that severely weakens people's magical and physical power, and has the added effect of turning them into children. Erza, Natsu and Gray are hit by it, but turned back to normal later. Also, everyone present is regressed briefly in chapter 350 (Including Wendy, who becomes an even younger child).
* ''[[BodyHorror Horrifically]]'' deconstructed in ''Manga/FrankenFran'': The villain from the "Eternal Youth" chapter is an old woman who wishes to regain her youth, but kills many doctors and steals their researches to do so. When comes Fran's turn, it comes back to bite her really hard: [[spoiler:At first, it works and she becomes a young woman again, but because Fran's research was still very experimental, she soon afterwards turns into a pulsating mess of cancer cells.]]
* In ''Manga/FushigiYuugi'', the trope is invoked when [[spoiler: the TimeMaster [[NeverMessWithGranny Subaru]] briefly uses her powers on herself and her husband [[BadassGrandpa Tokaki]] so [[BattleCouple they]] can help Miaka and the Suzaku Seishi.]]
* In ''Gakkou Kaidan'' (a Yousuke Takahashi manga that's [[JustForFun/IThoughtItMeant unrelated to the anime]] ''Anime/GhostStories''), a VillainousHarlequin transforms a young girl into a baby and a young female teacher into a kid. Both turn back to normal when the harlequin gets his ass kicked.
* In the episode "Ultra Hot Kid's Meal" of ''[[Anime/GalaxyAngel Galaxy Angel A]]'', the Angel Brigade mistakes a Lost Technology for a box of uirō and turn into children, toddlers, and in Milfeulle's case, a baby. Because TheMindIsAPlaythingOfTheBody, the girls gave the twins a pretty hard time looking after them.
* The Korean manhwa series ''Horror Collector'' depicts ElizabethBathory as a young adult who frequently reverts back to her teenage self through her regular {{Blood Bath}}s.
* In a chapter of the Japan-exclusive ''VideoGame/HyperdimensionNeptunia'' manga (Part of said chapter can be seen [[http://visibletime.ararchive.com/_Anim-Hyperdimension_Neptunia2_.jpg here]]), this happens to Nepgear, Rom and Ram, and Uni, who regress into babies after eating some pills that Neptune accidentally gave them. Of course, Neptune has a pretty hard time looking after them, until Gust gave her the pills to change the girls back.
* ''Ichinensei ni Nacchattara'' has this as part of its core concept, with main character Iori going from high school to elementary school, and getting [[GenderBender gender-bent]] in the process. However, he retains his original personality, and he's not happy about becoming an elementary school girl. Later on, [[spoiler: almost the entire town regresses into kids. This causes mass hysteria across the city, since the rejuvenation virus was rather contagious, but since Iori held the antibody, everyone was later returned to normal]].
* ''Manga/JoJosBizarreAdventure''
** Alessi in Part 3 does this to opponents with his Stand, Sethan. The longer you stand in his shadow (through which Sethan manifests), the younger you get, including your Stand getting weaker (and that's only if you developed your stand at a young age) and in one instance is able to turn a woman into a fetus. Unfortunately for Alessi, when he tries this on Jotaro, he learns the hard way Jotaro was badass even at age seven.
** It turns even worse out for him in the game when he used it on Joseph. Due to Joseph already being very old, it only regressed him into his late teens. Unfortunately for Alessi, that was the age when Joseph was at his prime and beat the Pillar Men, who were FAR stronger than any Stand users in Part 3. Joseph maintains his youth for a while after beating Alessi, but it eventually wears off and he returns to normal, wishing it could've been permanent.
* In ''Manga/KoiKoi7'', after Yayoi Asuka ([[EyepatchOfPower the one with the eyepatch]]) goes berserk, she's rebooted in one of Otome's spare bodies as a cute young girl named Gantai-chan who doesn't remember much of what happened before.
* This is the premise of the ''Kako Random'' arc of ''LightNovel/KokoroConnect''. The heroes find themselves randomly regressing to preteens or young children between 12:00 and 17:00, both physically and mentally. Interestingly, this also causes them to regain some of the memories they had at those ages. This is the work of Number Two, and once the latter's involvement is revealed, the regressions become even more random; lasting from a couple seconds to almost a full day, and/or going all the way back to infancy.
* In episode 19 of ''[[Theatre/TheBlueBird Maeterlinck's Blue Bird: Tyltyl and Mytyl's Adventurous Journey]]'', the animated adaptation of ''Theatre/TheBlueBird'', the titular children and their pets are transformed into babies by the villain's powers. The spirits have to watch over them while Berylude turns herself into a young and powerful warrior to fight the villain and return them to normal.
* In ''Manga/MagicalGirlLyricalNanohaVivid'', [[spoiler:one of Fabian's devils]] has a spell that de-ages the target and successfully enchants [[spoiler:[[OneManArmy Sieglinde]]]] with it to incapacitate her.
* In an episode of ''[[Anime/PrettySammy Magical Project S]]'', this happens to Sasami as an after-effect of an aging potion. The aging initially works well, but after Sasami returns to her normal age, she turns into a baby overnight.
* In ''Manga/MahouSenseiNegima'', WeaselMascot Chamo produces a jar of magical (and illegal) candy that can produce this effect as a sort of illusion (red candy [[OvernightAgeUp for older]], blue for this) both for fun on the part of the girls and as a StrangelyEffectiveDisguise when they [[ClearMyName become wanted people]]. It's been implied that TheMindIsAPlaythingOfTheBody, resulting in the aged-down characters acting with far lower maturity than usual, though they retain their intelligence. This doesn't work both ways, so their [[TheCutie adult forms behave like giddy teens]].
* Happens briefly in an episode of ''LightNovel/MahouSensou'', where Kurumi's crying ends up turning her into a baby. However, this doesn't last long, as she's back to normal the next scene we see her.
* In episode 3 ''Manga/MamotteLollipop'', Rokka temporarily transforms Nina into a baby out of jealousy.
* ''Manga/{{MAR}}'': Much like the ''Anime/DarkerThanBlack'' example mentioned above, [[spoiler: this is what happens to Loco every time she uses her powers. By the time she's introduced, she looks like a child of around 11 or 12, despite actually being 32 years old. She eventually turns back into a baby after a HeroicSacrifice, and is being taken care of by Chaton and Alan near the end of the series]].
* ''Manga/MarvelousMelmo'': Nine year-old Melmo's magical pills allow her to change her age as she pleases. Depending on the situation, she can change herself into a baby, a nineteen-year old girl, or even [[VoluntaryShapeshifting regress back into a fetus in order to be reborn as an animal]], should she need to.
* This is basically the point of ''Mayonaka Lolita'' : Mishiru Kachiwabara, a very beautiful young girl, is given a strange juice by a male student (Aoi Makimura) she had never seen before. As it turns out, that juice is a rejuvenation potion, which their teacher [[WhatAnIdiot had mistakenly given to Aoi as juice]], and Mishiru regresses into a little girl. Her teacher tells her the only way to get back to normal is to kiss the person she loves, but tough luck, Mishiru doesn't love anybody. Because she can't go back home as a child, Aoi brings her to his house and allows her to stay there. [[spoiler:They eventually do kiss at the end of the first chapter, and Michiru turns back to normal... before turning into a child again.]]
* The Nehellenia story is reused in ''Manga/MermaidMelodyPichiPichiPitch'', but with Michal, the IllGirl and not-quite-villain.
* ''Manga/OnePiece'':
** The supernova Jewelry Bonney's Devil Fruit allows her to change the age of whoever she wants. Guess what she usually does when enemies get in her way?
** From the twelfth movie ''Anime/OnePieceFilmZ'', Ain's Modo Modo no Mi powers allow her to rejuvenate her opponents. Unlike Bonney's powers, however, it works on inanimate objects too, and it can only work backwards, whereas Bonney can also age her opponents. [[spoiler:Nami, Chopper, Robin and Brook all got hit by it, regressing the former two into children, Robin into a teenager, and... not altering Brook's physical appearance at all, [[DemBones since he's a skeleton]].]]
** Nightin from the ''3D2Y'' TV special is an [[{{Gonk}} ugly]] and [[MiniatureSeniorCitizen short]] 80-year old woman, but by using medicine of her own conception, she can rejuvenate herself into a much more beautiful young woman.
* [[spoiler:Jack Vessalius]] has this happen to him in ''Manga/PandoraHearts'' as a result of being rejected by the Abyss. [[spoiler:His soul was shattered to pieces during the fight between Alice, Alyss and the Core of the Abyss. As a result, he kept on de-aging in a cycle: every time he reached the age of twenty-five, he will become younger and younger. Jack's mind has disappeared almost entirely due to a result, leaving only B-rabbit! Oz in place of him, who, according to the manga: "Had lost all of his memories and his powers and fell in a deep slumber." It is unknown at this point if it will happen to Oz since he was in the Abyss for ten years, making him twenty-five, but considering the fact that he himself is a chain, it may or may not happen to him.]]
* ''Franchise/PrettyCure''
** In an episode of ''Anime/SmilePrettyCure'', the main heroines are turned into kids, and need to find a way to turn back.
** The same scenario happens again in ''Anime/MahoGirlsPreCure'', albeit with obviously different protagonists this time.
* ''Manga/RanmaOneHalf'':
** Lukkosai, who tried to use the spring of drowned child to regain his youth, but instead just goes from way too old to way too young (both [[MiniatureSeniorCitizens about the same size]]). He then uses this form to get revenge on Happo while pretending to be his own grandson.
** Another story involved mushrooms that change your age in years to their length in centimeters. Ryoga eats a short one and then makes Ranma eat one. They spend most of the chapter trying to change back by growing mushrooms big enough to return them to their normal ages, while constantly sabotaging each others' mushrooms.
** And yet another story from the manga has Happosai feeling the pangs of old age. He finds out about a potion that will restore his youth, but first he needs the tears of a beast that is both male and female. The next thing you know, tear gas and onions fly liberally around Ranma. When he finally succeeds (by poking a pressure point that makes Ranma [[OcularGushers gush out tears like a firehose]]) he trips, and splashes the tears all over the floor. Kasumi wipes them up with a rag, but since it had been used to clean up soy sauce, the resulting potion regresses Happosai's ''mind'' to that of a baby.
* ''Franchise/SailorMoon''
** [[Anime/SailorMoon The anime]] has several examples. In the end of the third season (''Sailor Moon S''), Hotaru, after sacrificing herself to save the world, is brought back as an infant with no memories of her previous life. In the fourth season (''Sailor Moon [=SuperS=]''), [=PallaPalla=] casts a spell on Usagi and Chibiusa that briefly exchange their ages for one episode - causing havoc as Chibiusa, having fulfilled her dream of becoming a beautiful adult, is now unable to summon Pegasus and Sailor Moon can't defeat the Lemures without him. In the beginning of the fifth season (''Sailor Moon Stars''), Hotaru [[PlotRelevantAgeUp rapidly grows back]] as her memories return, and the previous season's BigBad, Nehellenia, is returned to childhood to allow her to relive her life and avoid the mistakes that turned her into a villain in the first place.
** In the [[Manga/SailorMoon manga]], [=PallaPalla=] swaps Usagi and Chibiusa's in the first chapter of the Dream arc, which is actually done to depower the two of them. They eventually overcome it and transform into their proper bodies using their henshin phrases. Later in the same arc, Zirconia depowers both Sailor Moon and Tuxedo Mask in the same manner, turning them into six year olds and preventing them from accessing their magic. Pegasus reverses it by transporting them to Elysion, which has enough purifying power to break the spell.
* ''Manga/RosarioToVampire'' has an example of this one. [[TokenMiniMoe Yukari and Kokoa]], after realizing that they're not being taken seriously due to their age, use some of Yukari's age-up pills for a [[OvernightAgeUp temporary change]]. When the pills wear off, Kokoa finds herself ''younger'' than before. She finds herself in trouble shortly thereafter, only to be saved by the entire UnwantedHarem (sans Tsukune) turned into children along with her. Much cuteness and butt-kicking ensues.
* Episode 9 of ''Manga/SgtFrog'' features mother Aki Hinata getting turned into a teenager by Kururu's newest invention. In a later episode, the same gun turns Fuyuki into a kindergartner. Even later, Natsumi, Keroro, Giroro, and Kururu also get zapped by this gun. [[spoiler:In one episode, the entire planet gets zapped by this gun, setting time back by about twenty years.]]
* Happened in ''Manga/SketDance'':
** The first time was with Bossun after accidentally drinking Chuu-san's youth potion, mistaking it for a bottle of cola. Himeko [[CutenessProximity absolutely flips over him]].
** The second time was with Himeko and Momoka, several chapters later, at the same time, with the ''same bottle of cola''. Suffice to say, Bossun had a swell time looking after them.
** In the anime, two girls from the student council drink it on purpose, because "life is an adventure". Needless to say, it makes things even harder. In both versions, when the rejuvenated girls drink the antidote, they get ten years older than normal. And of course, by the time the next episode starts, [[UnexplainedRecovery they're back to their normal ages again]].
** Happened for the third time in Chapter 239, with [[TheRival Tsubaki]]. Except this time he reverted both in physical ''and'' mental state. Everyone, including Bossun and Daisy, gushes over [[CutenessProximity how cute he is]].
* In ''Anime/{{Stitch}}'', Babyfier (a creature that can turn people into babies) makes 3 appearances.
** In "Rivals stick Together" Babyfier is unleashed at a school turning most of the students and adults into babies.
** In another episode Babyfier turns the main character and her friends into toddlers.
** In the third episode, Babyfier is now good and turns a couple of the villains into babies.
* ''Manga/TheSevenDeadlySins''
** The setting has a literal fountain of youth that makes the drinker immortal if they drink the entire fountain (which is just a cup). This is how Ban gained his immortality.
** For a straighter example of the trope, [[spoiler:Merlin's magic gets reflected back at her in her fight with Chandler, transforming Merlin into a little girl]].
* Some chapters/episodes of ''Manga/ToLoveRu'' and the ''To-Love-Ru Darkness'' OVA feature a creature named the "skunk of youth", which regresses some of the main characters, among others, into kids.
* ''Manga/TheWorldGodOnlyKnows'':
** In the "Heart of Jupiter" arc, [[spoiler: Keima is sent back to the past via MentalTimeTravel and given a mission to save a cute but emotionless and mysterious young girl from committing suicide. If she gets overtaken by despair, she starts getting younger until she's transformed into a baby, which triggers a ResetButton that sends Keima back to the start of the mission. However, he can stop her from getting younger by kissing her before she turns into a baby]].
** The main manga also had a three-chapter spinoff called ''Magical Star Kanon 100%'', focused on, as the name implies, Kanon Nakagawa. In it, she is turned into a child by a Runaway Spirit and has to hide her identity and find a way to get back to her true age. The OVA version even has Elsie turn back into a child.
* In the Dark Tournament arc of ''Manga/YuYuHakusho'', an enemy uses a special mist meant to de-age its victims past the point of conception. Unfortunately for him, his target was Kurama, and once his human body went into non-existence, his previous incarnation - full-powered demon Yokokurama - manifested and quickly dispatched him.

[[folder:Card Games]]
* ''TabletopGame/MagicTheGathering'':
** Jhoira from one storyline was exposed to timewarped water that dramatically extended her lifespan after a horrible accident at Urza's Academy. By the events of the Time Spiral storyline, she is over 1000 years old but looks like a 19-year-old--an almost literal fountain of youth.
** Magic has had the literal ''card'' [[http://ww2.wizards.com/gatherer/CardDetails.aspx?id=1715 Fountain of Youth]] for the longest time. This is how Jodah, Archmage Eternal of the Academy of the Unseen, came to be ''several'' thousand years old by the time he met Jhoira.
* ''TabletopGame/YuGiOh'': Avance becomes younger when donning one of the Nekroz armor. [[note]]As Nekroz of Unicore, his beard is gone and as Nekroz of Valkyrus, his beard is a goatee.[[/note]] He also does this as Sword Saint of the Nekroz - Sephira Saber.

[[folder:Comic Books]]
* In the first issue of ''Super Hero Squad'' (based off the cartoon of the same name), Dr. Doom plans to use a time machine to go back in time to retrieve the fractal shards. The squadies intervene and the machine malfunctions, turning them all (except for Reptil) into babies (Redwing turns into an egg). Now chaos ensues as the babyfied heroes and villains fight.
* This was a favorite tactic of the extradimensional media mogul Mojo in the Claremont-era ''Comicbook/XMen'' comics. Since time passes slowly in comic book universes, this is usually not an issue, as most characters' backstories aren't tied to a specific event. A notable exception is Magneto, a holocaust survivor canonically born in the 1920s. To get around this, he was reduced to infancy and then [[PlotRelevantAgeUp aged back to adulthood]] sometime in the 80s, putting his age firmly back in the traditional comic book "fucked if I know" category. Magneto has naturally gray hair, and was in good physical condition for a man of his age. [[DependingOnTheArtist Different artists]] either draw him as a physically fit older man or a physically fit young man with gray hair.
* Franchise/TheDCU FifthWeekEvent ''Sins of Youth'' combined Fountain Of Youth and OvernightAgeUp, with a combination of Chaos Magic and an "aging ray" turning all the teenage heroes into adults and all the adult heroes into kids.
* Happens twice from two different sources in ''ComicBook/{{Asterix}} and Obelix All at Sea'': First Obelix gets de-aged as an after effect of drinking the Magic Potion, then our heroes discover the remnant of Atlantis, where everyone is a child (and happy from it) after having drunk from an actual Fountain Of Youth.
* ''Franchise/TheSmurfs'':
** Three of the Smurfs were child-ized when Peyo felt he needed a few child characters. There was no cure for the miniaturization, in a rare case where this trope isn't [[ResetButton reset]]. In fact, they didn't mind their new situation.
** However, there were two episodes in the cartoon show where the Smurfs did find a literal fountain of youth that de-aged Papa Smurf and Grandpa Smurf in different situations, both of whom were later restored to their actual ages.
** And there's "Smurf Van Winkle", where the other Smurfs try to pull a RipVanWinkle on Lazy to make him think he has slept for a few centuries while his fellow Smurfs have aged incredibly. Lazy works on a potion to bring them back to the same physical age he is, but the whole thing was revealed to be a ruse when they were all de-aged into Smurflings.
* ''Franchise/{{Batman}}'':
** ComicBook/RasAlGhul's Lazarus pits. While not ''exactly'' the same thing, the pits are used at one point in ''WesternAnimation/BatmanBeyond'' to restore elderly Bruce Wayne back down to his 40s (as part of a Ra's plot to put his mind into Bruce's body).
** One [[UsefulNotes/TheSilverAgeOfComicBooks Silver Age]] ''Batman'' comic features a mad scientist villain who turns Batman into a toddler. However, he still kept his adult mind, memories, strength, and skills. So pretty much all the villain accomplished was to [[NiceJobFixingItVillain make Batman a smaller target]].
* ''ComicBook/JudgeDredd'':
** Dredd a rare example of a comic book character who ages in real time, had a couple of decades taken off in the 1990s after being exiled from the city and getting his face burnt off.
** Within the comic, there are stookie capsules, which dramatically slow the aging process in humans. Since producing them requires the slaughter of a peaceful and harmless alien species, they are highly illegal.
* In ''ComicBook/TheIncredibleHercules'', Zeus gets reverted back to childhood, both physically and mentally, by drinking from the river Lethe.
* In a "Gnuff" story in the UsefulNotes/{{Furry|Fandom}} series ''Critters'', the main characters are stranded on an island divided by a steep mountain range where one side has water that makes you younger and the other has potatoes that make older. So, if you're living off the land on that island, you need to balance these foodstuffs to maintain your true age. Unfortunately, the one pass through the mountain range gets blocked and the characters on both sides realize that they are in terrible danger of eventually overbalancing on one of the materials and dying or disappearing as a result unless they can each get to the other side. [[note]]This story, done by Danish writer/artist Freddy Milton, has a long and strange background, and has no less than four versions going around with wildly different main characters. It was originally made as a WesternAnimation/DonaldDuck story, but wasn't found worthy for publication, so Milton -- who had the right to the story but not the characters -- redrew it with his own CaptainErsatz characters who were geese instead of ducks. Later still, when drawing comics for the Scandinavian WesternAnimation/WoodyWoodpecker magazine, he redid and expanded the story with Woody and his niece and nephew Knothead and Splinter taking the roles of Donald and the boys. Finally, he redrew the story ''again'' as a "Gnuff" story, and this was the version that was published in ''Critters.'' You can find both the Donald Duck version ("The Big Sneeze") and the Gnuff version ("Gargantua's Cure") of the story in the "English Stuff" section of [[http://www.freddymilton.dk/ Milton's official homepage.[[/note]]
* One ''ComicStrip/{{Popeye}}'' adventure involved a search for the Pool of Youth. While the pool doesn't actually make you physically younger, it extends your lifespan indefinitely, and gives you a younger mentality -- a man claimed to be over 200, but felt he was 6. The Pool was guarded by the Sea Hag's sister, and her army of cavemen.
* Mina Murray and Alan Quartermain search for the Fire of Eternal Life in ''Comicbook/TheLeagueOfExtraordinaryGentlemen New Traveller's Almanac''. They fail to find it, and Alan [[FakingTheDead dies]] on the trip. After an indecently short period of time, Mina hooks up with [[MyGrandsonMyself Alan Quartermain Jr]]. [[SuspiciouslySpecificDenial Really, that's what happened]]. [[BlatantLies It's in the Almanac]].
* In Franchise/TheDCU, the Fountain of Youth is what gave Detective Chimp the ability to speak to other animals and stopped his aging. It's either [[DependingOnTheWriter magical, radioactive or alien nanotechnology.]]
* In the story "A-Corny Story", in issue #28 of ''Tales from the Crypt'', this guy who was fired by his late boss' son for being "too old" sent him a tree from Haiti that was supposed to prevent old age. It started out as this hideously gnarled specimen that kept growing younger, and its new owner started doing the same. On the day the tree finally de-aged into a seed, the guy de-aged into a sperm cell or something and vanished.
* ''ComicBook/SpirouAndFantasio'' had the main characters search for the actual fountain. After the [[spoiler: mission ended in failure with the water losing its power permanently]], Spirou [[BreakingTheFourthWall winks]] and says [[spoiler:[[ComicBookTime Do you really think we need that?]]]]
* Several ''Disney'' comics featured either the fountain itself, or characters getting younger. For an example, in the story "History re-Petes itself", Pete's attempt to turn Mickey into a baby backfires, resulting in Mickey trying to RaiseHimRightThisTime. Over the two weeks Pete grows up rapidly, Mickey and his friends attempt to make him into a good guy, but unfortunately, as you might have guessed from the title, it fails and Pete remains bad.
* The Franco-Belgian comic ''Les Petits Hommes'' features a story named "Miss Persil". It centers around a young girl who has the mind and personality of a five-year old, due to entering a coma at that age and miraculously waking up recently. It obviously causes a lot of problems, especially considering her parents intend to place her in a school in the "big world", but the Doctor finds a way to get around that by making her drink an elixir of youth to rejuvenate her, so that her body will match her mind. It works well, but HilarityEnsues when she actually takes the elixir with her.
* The fountain appears in the MarvelUniverse in both the original Man-Thing series as well as the first She-Hulk series, with a small village of people from the Conquistador days living there. Drinking the water however isn't what leaves one immortal but regularly bathing in it (drinking it will leave one a shriveled, red-skinned immortal). She-Hulk eventually convinces them to destroy the titular fountain as they've also grown apathetic (when several villagers are killed by wild beasts they ignore it) as strong emotions break the immortality causing one to begin to age again since they've given up living by what they've sacrificed for immortality.
* Several 1950s Wesinger-era Franchise/{{Superman}} Family comics stories feature characters temporarily regressed to infancy via various means, usually retaining their adult minds. Superman, Lois Lane, and Jimmy Olsen were among those regressed at one time or another.
* A Golden Age [[ComicBook/{{Shazam}} Captain Marvel Junior]] story had the young hero battling his nemesis Sivana Junior, who'd discovered The Fountain of Youth and was using it to regress wealthy businessmen to children he could bully. Captain Marvel Junior is temporarily regressed as well, but finds the cure and turns the tables on the villain.
* Happens to Giles in the ''Series/BuffyTheVampireSlayer'' spinoff ''Angel and Faith'', the result of a resurrection spell that [[CameBackWrong doesn't go quite according to plan]]. The twist is he still has all his adult memories, but they're now at the mercy of a pubescent, hormone-addled body.
* This becomes a plot point in ''ComicBook/AstroCity''. When the hero Crackerjack starts becoming incapacitated due to his advancing age, he desperately seeks ''something'' to reverse the effects.
* In a ''[[Franchise/ThePinkPanther Pink Panther]]'' comic book story, Pink helps somebody who holds him up at gunpoint find the legendary Fountain of Youth, but the person who drinks from its water ends up as an infant, unable to do anything with the wealth he acquired earlier in the story through the same means. Pink takes it upon himself to name himself the [=man/child's=] official legal guardian, which allows him to have access to the man's fortune.
* An example from ''ComicBook/{{Bunty}}'' was "My School Chum Mum". After trying an anti-ageing potion, Mrs Todd was turned into a schoolgirl and forced to attend school with her daughter, posing as "Cousin Emily".
* The trope shows up in a few stories of the German comic anthology ''Gespenster Geschichten''. Being a horror comic, it always ends badly for the victim:
** In the story "Das Geheimnis der verhexten Kamera" (The Secret of the Haunted Camera), young actor John Steven is tired of only getting to play roles as an extra, and becomes so desperate to make his own movie that he attempts to rob a bank. In trying to escape the police, he ends up in an old, decrepit warehouse studio, where he finds an old director. After Steven vents his rage on him, the director pushes a button on a magic camera, making the young actor regress in age until he disappears offscreen, with the film screen representing his life burning away.
** In "Das Geheimnis des Zaubertrankes" (The Secret of the Magic Potion), Tibetan monks have managed to develop an elixir of youth, but have yet to test it on humans. When a young monk tries to drink it to test it, he gets kicked out before he can swallow a sip. Angered, he plots with an old English explorer to try and steal the potion, but they get cornered; with nowhere left to go, the Englishman drinks the entire elixir, and becomes younger until he vanishes, only leaving his clothes behind.
** In "Wen die Stunde Schlägt" (When the Hour Strikes), an old man named Colin is approached by the Grim Reaper. When he laments that he hasn't even written his will yet, the Reaper accepts to give Colin three minutes so he can write the will, leaving an hourglass by his side that symbolizes how much time he has left. Feeling he has nothing to lose, Colin flips the hourglass over, and upon seeing that the Reaper hasn't come back after the allotted three minutes ''and'' the fact that he's become a young man again, rejoices in the fact that he essentially found eternal life... until he later becomes ''too'' young and turns into a child, unable to reach the hourglass before it is too late. The Reaper comes back just in time to see Colin turn into a baby and vanish, and reclaims his hourglass.
** In the story "Die Uhr des Sensenmannes" (The Clock of the Grim Reaper), a young woman named Samantha is lamenting the fact that her father is dying from an incurable disease, with the Grim Reaper on his way to claim his soul. As he arrives, Samantha manages to steal his hourglass, threatening to destroy it; left with no choice but to relent, the Reaper leaves, and the father makes a miraculous recovery. Samantha keeps the hourglass to use as leverage, but when rats come and topple it, she realizes time is flowing backwards, causing her to get younger by the second before disappearing. The Reaper comes back, reclaims his hourglass and claims the father's soul, ensuring that Samantha can never be born again.
* In ''[[ComicBook/AthenaVoltaire Athena Voltaire and the Isle of the Dead]]'', it's recounted that a Spanish explorer discovered the Fountain of Youth. The effects lasted a while, but had to be refreshed from time to time. Eventually, however, he noticed that the Fountain was showing signs of depletion; rather than risk returning one day to find it gone, he filled up as many barrels as he could. The ship he put them on, however, was sunk — setting up the plot.
* One ''Franchise/{{Star Trek|ExpandedUniverse}}'' comic story published by Creator/GoldKeyComics had aliens who invented a de-aging ray and used it on ''Enterprise'' crewmembers.
* The eighth issue of the ''ComicBook/{{Madballs}}'' comic book published by Star Comics (a subsidiary of Creator/MarvelComics that is now defunct) had Dr. Frankenbeans and his bumbling assistant Snivelitch discover the Fountain of Youth. Frankenbeans attempted to use it to his advantage by tricking the Madballs Horn Head, Wolf Breath, and Touchdown Terror into diving into a pool of the water, causing them to become the Madball Babies. In the end, Frankenbeans found infant Madballs to be even more difficult dealing with, so he had them restored to their normal ages by asking them to dive into the toxic pond where the Madballs were originally created. In retaliation to being reduced to infancy, the age-restored Madballs expose Frankenbeans and Snivelitch to the Fountain of Youth, turning them into children.

[[folder:Comic Strips]]
* In a strip for ''ComicStrip/{{Lio}}'', Liō uses a time machine to go to the beginning. As a result he is sent back to the womb.
* One time in ''ComicStrip/JumpStart''. Marcy and Joe are buying both their infant twins a toy. They comment that because they have twins they have to buy two of everything. They then mention they have four kids, the next panel shows them, their two older kids as babies. The same age as the twins. They then comment they are a family of sextuplets.
* One Creator/CharlesAddams cartoon shows a group of children standing next to a fountain in a jungle, all holding metal cups and dressed as Spanish conquistadors. One of them is saying "So, great. We found the Fountain of Youth. Who's gonna sail the old tub back?"

[[folder:Fan Works]]
* In ''Fanfic/KyonBigDamnHero'', Nagato provides this function for Kyon, Mikuru, and Kanae. Otherwise the [[spoiler: YearInsideHourOutside training]] would make them age by over a year every night.
* In ''Fanfic/WithStringsAttached'', the four awaken to find themselves on another planet and 16 years younger—their 1980 minds in 1964-age bodies. They think they've been genuinely de-aged, but at the end they find out they're in cloned bodies. The Fans wanted to give them fresh new bodies as payment for going through all the hassle on the planet; they were going to age the bodies, give them appropriate scars, etc., after the adventure was over. However, things got out of hand, and a whole lot of magic got dumped on the clone bodies. Because the Earth universe has no magic, this meant that the four had to be transferred back to their original bodies in order to return home.
* The [[ExactlyWhatItSaysOnTheTin Youth Restoration Spell]] from ''Fanfic/MyLittleAlicorn'' reverts any pony it's used on to any prior age for two hours, after which they are ''supposed'' to turn back to normal. Naturally, Luna thought it would be a great idea to use it on Celestia as a prank, not realizing that [[ModeLock it works a little bit differently on Alicorns.]] HilarityEnsues.
* The ''Series/StarTrekTheOriginalSeries'' fics ''FanFic/{{Insontis}}'' and ''Fanfic/InsontisII'' detail this happening to Kirk and Spock, respectively. HilarityEnsues.
* The ''FanFic/FacingTheFutureSeries'' features a story where [[spoiler:Danny and Sam revert to five year olds in homage to a ''Series/StarTrekTheNextGeneration'' episode entitled "Rascals."]]
* Happens to Data in [[http://archiveofourown.org/works/765803 "Small Packages]] by [[http://archiveofourown.org/users/RebeccaOTool/pseuds/RebeccaOTool RebeccaOTool,]] via an unoccupied android body left by his late father. Played for laughs. At first.
** The same author gives us [[http://www.fanfiction.net/s/2543741/1/Changes Changes]], where Egon of ''WesternAnimation/TheRealGhostbusters'' is turned into a child due to an experiment gone awry. The [[spoiler: nightmare]] sequence where he de-ages into nothingness [[AndIMustScream while screaming for help from his uncomprehending teammates]] is chilling.
** Also happens to House and Wilson [[http://archiveofourown.org/works/770714 Monkey's Paw Syndrome]] due to magic. MakesSenseInContext.
* Loki turns the Avengers [[spoiler: and himself accidentally]] into toddlers in [[http://archiveofourown.org/works/767023 this story.]] Unlike most others in this genre, the children retain their memories and powers, leading to more than the usual BadlyBatteredBabysitter plot.
* Loki [[http://archiveofourown.org/works/773579 changes himself into a four year old]] semi-voluntarily, but due to [[PowerNullifier exhaustion]] he can't change back. He [[OlderThanTheyLook retains his memories and personality]], and decides to use his new situation...
* ''FanFic/GettingBackOnYourHooves'': This is what Poison Joke does to Trixie. Interestingly, it also affects her mentally (and since she didn't have a happy childhood...)
* The [[Fanfic/LifeInManehattan Manehattanverse]] story "Fillie's Play" focuses on this, as a magical mishap during one of Twilight's experiments turns her and the rest of the Manehattan 6 back into fillies. [[spoiler: And has the [[PlotRelevantAgeUp opposite]] effect on Orange Sherbet's daughter, Tangerine.]]
* Twilight accidentally turns herself into a filly in ''FanFic/DiariesOfAMadman'', after one of her spells backfires.
* In ''Fanfic/PonyPOVSeries'', when Princess Gaia tries to take over the world and turn it into a utopia, she de-ages the citizens into foals, thinking they would be happier that way. Princess Celestia was horrified and feared that the pregnant mothers' unborn children had been erased. Fortunately, they weren't, and once the mothers were returned to normal, their pregnant bellies returned.
* In the second story of the ''Fanfic/Gensokyo20XX'' series, we have this happen to Reimu, due to the side effects of a hibernation spell Ran cast on her. This also results in a ModeLock, as she stays like that until the final chapter of 20XXV, where it's implied she's full grown.
* In ''Fanfic/TheTwoSidesOfDaringDo'', spells and potions that can alter your age are mentioned, but they do not actually affect your lifespan. For example, if an old pony became young again, he would still eventually die of old age in a few years. [[spoiler:In one of the endings, Daring Do chooses to start life over as a filly. Since she was technically only a few days old, she still had a full lifespan ahead of her.]]
* In ''FanFic/FallingBackwards'' Rainbow Dash receives a serious brain injury that leaves her mentally a child who Twilight is forced to care for. Unfortunately there seems to be no way of curing her, so in as a desperate measure, Celestia uses an age spell to regresses her back into a child, so she at least has a chance of growing back into her old self.
* ''Fanfic/{{Kitsune}}'': Conner Jeremy Fox, a 39+ year old man, age-regressed into a teenager girl.
* ''Fanfic/{{Maat}}'': 70+ year old Doctor Daniel Edward O'Neill transforms into [[GenderBender Dani]], a 20-something female priestess of Ma'at.
* ''[[https://www.fanfiction.net/s/11972895/1/The-God-of-Destruction-comes-to-Remnant The God of Destruction Comes to Remnant]]'': In a way, this happens to Rexy. In ''Film/JurassicWorld'', she was in her twenties, making her elderly by T-Rex standards. Then she is transported to the world of Remnant and transformed into a [[LittleBitBeastly Faunus]] woman, still in her twenties and now a smoking hot StatuesqueStunner.
* [[https://www.zerochan.net/455283 This]] ''Manga/SweetBlueFlowers'' fanart has Fumi, having turned back into her 5-year-old self, being consoled with a (sweet blue) flower by the present-day Akira.

[[folder:Films -- Animation]]
* In ''Disney/{{Tangled}}'', originally it was the magic flower that Mother Gothel used to keep her young. But after the Queen drank the flower and gave birth to Rapunzel, Gothel got her Fountain of Youth from Rapunzel's hair.
* In ''WesternAnimation/YellowSubmarine'', The Beatles and Old Fred regress to childhood and young adulthood respectively after travelling backwards through the Sea of Time. When they end up reversing the change, they end up [[RapidAging reversing it a bit too much]].

[[folder:Films -- Live-Action]]
* The MacGuffin weapon of the BigBad in ''Film/SkyHigh2005'' did exactly this.
* The titular character in ''Film/TheCuriousCaseOfBenjaminButton'' has a similar problem: he ages backwards. He is born as an old man, and dies of old age as an infant.
* ''Film/TheFountain'' involves a [[FramingDevice story within a story]] about a Conquistador's [[TheQuest quest]] for the Tree of Life, which can theoretically grant immortality. Outside the frame, there is a tree which essentially de-ages a cancer-ridden monkey and presumably grants immortality to the main character.
* This is the point of ''Film/SeventeenAgain''.
* Also the plot of the very early made-for-TV Creator/KeanuReeves movie ''Young Again'', from which ''17 Again'' seems to be ''heavily'' drawn. ''17 Again'' is practically an unofficial(?) remake of the film.
* The SequelHook at the end of ''Film/PiratesOfTheCaribbeanAtWorldsEnd'' ends with (the immortality-seeking) Jack unfolding a map to something called the "Agua De Vida". The book that the next movie is based on revolves around the Fountain, so...
* The Fountain in ''Film/PiratesOfTheCaribbeanOnStrangerTides'' is played with. It doesn't make you any younger, but instead adds years to your life. However you need someone to take the years from...
* The MacGuffin in ''Film/TheNuttyProfessorIITheKlumps''. Professor Sherman Klump creates a fountain of youth formula which lasts temporarily.
* In Film/TheThreeStooges short "[[http://threestoogespictures.info/all-gummed-up/ All Gummed Up]]", the boys are druggists who invent a youth serum and give it to their elderly landlord's abused wife. Predictably, she turns into a beautiful young woman. But when the landlord tries it, he turns into a bawling infant.
** In the remake "Bubble Trouble", the landlord turns into a gorilla.
* Beautifully played with in the finale of the [=IMAX=] short ''Film/CirqueDuSoleilJourneyOfMan'': When TheEveryman middle-aged hero accepts the old bowler hat of his youth from a little Vagabond Girl and ducks offscreen so she can put it on him, the voiceover narration explains "Years turned to dust. I was young again." [[spoiler: He rises back into frame as an ''old'' man but it's clear he's as full of life and joy as he's ever been, having regained his youthful spirit, making this an example of this trope and Overnight Age Up all at once!]]
* The pool house in the movie ''Film/{{Cocoon}}'', by way of [[AppliedPhlebotinum Alien Phlebotinum]].
* The planet Baku in ''Film/StarTrekInsurrection''. The fact that it remains unused by the rest of the Federation and is only used by the Baku makes it seem much like a [[HiddenElfVillage Not So Hidden Elf Village]]
* Smurf essence becomes this in ''Film/TheSmurfs'' when Gargamel used it on Odile's mother, which makes Odile want to get her hands on it.
* Early on in the French film ''Film/LesVisiteurs'', a witch forces an old woman to drink one of her potions. This causes her to inflate slightly and rocket through the roof (And judging from the other holes in the roof, she wasn't the first victim), only to fall back in the house a minute later, as a younger woman.
* In ''Film/Wishmaster2EvilNeverDies'', one of the burglars who broke into a museum meets the Djinn, who grants him one wish. The burglar, scared out of his wits, wishes [[ExactWords he were never born]]. The poor guy really should have known better than to ask that of a JackassGenie. The Djinn is all too eager to grant his wish, causing the guy to age backwards until he flat out disappears, [[EmptyPilesOfClothing only leaving his clothes behind]].
* ''Film/HoubaOnTheTrailOfTheMarsupilami'': A special orchid's juice can be distilled into a youth potion. The Marsupilami being apparently linked to those orchids, the BigBad is after it. [[spoiler:He eventually gets his youth back, [[RaiseHimRightThisTime plus interest]].]]
* ''Film/TheLittleRascals'' short ''Shrimps for a Day'' involves a wealthy young couple who find a magic lamp and wish themselves into kids so they can play with the Rascals, who are visiting from an orphanage. Naturally, things go horribly wrong, and they get a first-hand view of how badly the orphanage is really run.
** In the last scene, Spanky wishes the mean headmaster into a little kid his own size, and proceeds to give it to him but good.
* In ''Film/JupiterAscending'', a special fluid restores your youth when you bathe in it. [[spoiler:Unfortunately, it's produced by killing and processing people.]]
* In ''Film/{{Faust}}'', Faust, who is an old man, makes his original DealWithTheDevil for altruistic reasons, to save the people of his town from ThePlague. When the townsfolk figure out the demonic source of Faust's powers and cast him out, he gets a lot less altruistic, demanding youth so he can enjoy sensual pleasures. He gets it, and does.

* In Creator/DianaWynneJones' ''Literature/HouseOfManyWays'', the grown wizard [[Literature/HowlsMovingCastle Howl]] became the DeliberatelyCuteChild Twinkle partly as a disguise and partly (he said) because he felt he deserved a better childhood than the one he'd actually had.
* Creator/TerryPratchett did this in ''Discworld/TheLastContinent'', combined with OvernightAgeUp, when the wizards travel to a place (Fourecks), where, due to morphic instability, Ponder Stibbons becomes an eighty-year-old, and the Dean becomes a thirteen-year-old. And then there's [[IWasQuiteALooker Mrs. Whitlow...]]It wears off within a few minutes.
** And in ''Discworld/{{Eric}}'' Ponce da Quirm is an old man who's spent his entire life searching for the Fountain of Youth. Rincewind doesn't quite have the nerve to ask him whether it would have been better to just have a life in the first place. When they later encounter him in Hell, they learn that he did find it, but there's one thing all the legends forgot to mention about the water of the fountain of youth - boil it first.
* K.H. Metzger's ''Skye Sparkler'' is all about this. A woman in her thirties designs a little-girl superhero character and [[BeCarefulWhatYouWishFor subsequently, permanently becomes her]].
* In ''The Thief Lord'' by Cornelia Funke, there is an example of this trope in the form of [[spoiler: the elderly Conte and Contessa, who use a magical merry-go-round to become children again]].
* In the ''Literature/{{Blackcollar}}'' books by Creator/TimothyZahn, a drug called Idunine can reverse many of the effects of aging. In fact, taking heavy doses of it is once used to disguise several characters, as they now look much younger.
* In Creator/RobertAHeinlein's Future History series, medical rejuvenation therapy works to reverse the aging process through a variety of techniques, from swapping the body's entire blood supply to cloned tissue transplants. In extreme cases, a human at near-death can be completely rebuilt to look and feel [[ReallySevenHundredYearsOld twenty years old]] again, complete with a fresh brain that's had the memories from the old one [[BrainUploading copied into it]]. This plus a program of applied eugenics designed to extend the natural lifespan has resulted in a subrace of near-immortals, of whom Lazarus Long (featured in ''Literature/TimeEnoughForLove'' and ''Literature/TheNumberOfTheBeast'') is by far the oldest.
** ''Literature/GloryRoad'', while set in a different continuity than the Future History series, also features medical rejuvenation, known on Center as "Long Life" treatment.
* In ''[[Literature/GarrettPI Gilded Latten Bones]]'', [[spoiler: the King of Karenta is discovered to be shielding a trio of necromancers who have been keeping him and themselves unnaturally young]]. Unlike most examples, users of this age-reversal effect retain their gray hair, so must wear wigs to suit their youthful bodies.
* The Rapture becomes this for older Christians in the ''Literature/LeftBehind'' book series when they receive their glorified bodies, while for children and teenagers it brings them up to the same age level as the adult believers. At the end of the Millennium, even the longest-lived naturals (who are at that point all believers) are restored to the prime of their youth.
* Willy Wonka invented Wonka-Vite, a invention that makes people younger. It's used in ''Literature/CharlieAndTheGreatGlassElevator'' on Charlie's three still-bedridden grandparents. Unfortunately, they don't listen to his instructions and take too many -- one pill takes 20 years off, and each takes four pills. That renders two of them babies, and since Grandma Georgina was ''seventy-eight'' and thus becomes negative two years old, her spirit winds up in the dreary Minusland. Luckily, Mr. Wonka also created a RapidAging counterpart, Vita-Wonk...
* Due to a quirk in their physiology, the Cheela in ''Literature/DragonsEgg'' can rejuvenate. Under particular conditions, when their body has been battered enough, it will revert to [[PlantAliens the plant the Cheela evolved from]] and heal itself, [[RipVanWinkle taking the best part of a lifetime]][[note]]About half an hour -- the Cheela [[YearInsideHourOutside live on a different time frame]] than us[[/note]] in the process. Then the plant turns back into a Cheela in its prime. In the sequel, ''Starquake'', this very rare and risky process has been harnessed and rejuvenation machines are in use.
* The carousel in ''Literature/SomethingWickedThisWayComes'' can function as either this or as an OvernightAgeUp, depending on whether it runs backwards or forwards. Carnival co-owner Cooger uses it to go incognito as a preteen boy.
* A literal fountain drives the plot of ''Literature/DirgeForPresterJohn''. It's nothing like what the characters expected it to be, but it does the trick.
* In ''Literature/TalesOfKolmar'', lansip leaves and fruit, very difficult to get to and already a potent {{Panacea}}, can be distilled into a liquor which can make the drinker younger. There's a tale about an elderly merchant who was found after drinking an overdose, with the body of someone in his twenties. Berys is much more careful with his supply, taking a little at a time and prudently using [[WeWillNotUseStageMakeUpInTheFuture makeup]] to make himself still look old, and arrives at mid-twenties without dying of it.
* ''Literature/HarryPotterAndTheOrderOfThePhoenix'': During the battle of the Department of Mysteries a Death Eater's head turns into that of a baby when he falls into a magical clock.
* On one of the unknown islands visited by Máel Dúin and his companions in the medieval Irish ''[[Literature/TheVoyageOfMaelDuin Voyage of Máel Dúin]]'', the voyagers observe a giant bird rejuvenating itself by bathing in a magical lake. Diuran the Rhymer tries it too and emerges permanently rejuvenated.
* In ''Literature/MistbornTheOriginalTrilogy'', The Lord Ruler pulls this off by being both an Allomancer and a Feruchemist. To elaborate, Feruchemists can store youth in the metal atium, which causes them to look and feel older than they really are for a time in exchange for allowing them to look and feel younger than they really are for the same amount of time later on. Allomancers can "burn", or Allomantically metabolize, various metals to gain specific superpowers: tin grants SuperSenses, brass allows you to dampen someone's emotions, etc. The Lord Ruler discovered that if you burn Feruchemically charged metal you get back ten times the Feruchemical charge you put in. Effectively, the Lord Ruler had an infinite supply of youth.
** However, the atium he needed to burn needed to be charged with his youth, not someone else's. This is how the trick was kept under wraps for as long as it was - there were no Allomancers who were also Feruchemists besides the Lord Ruler who could stumble upon it. (Vin actually burned an allied Feruchemist's "metalmind," just to see what would happen, and could see but not access the power it gave off)
* In the "[[Creator/CordwainerSmith Instrumentality Of Mankind]]" stories and novels, the source of both the longevity of the citizens of the Instrumentality, and the vast wealth of Norstrilla, is the Santaclara drug (called 'stroon' in its raw form), which comes from their diseased, massively oversized sheep.

[[folder:Live-Action TV]]
* The short-lived American Saturday morning TV series ''Series/Big John Little John'' revolved around an elementary school teacher who, after accidentally sipping from the Fountain of Youth, unexpectedly shifts from adult to child size and back again. Only his wife and teenage son know his secret and his younger self is passed off as a visiting relative while he tries to learn how to control the changes.
* The ''Series/BuffyTheVampireSlayer'' episode "Band Candy", in which all of the adults ingested chocolate bars that had spells inside of them that did not physically de-age the characters, but made them act as they had as teenagers. The episode is filled with hilarious examples of the Scoobies becoming more and more horrified by their parents, teachers, and even the stodgy Giles, as they act in irresponsible and (in the case of Giles) criminal ways.
* ''Series/StarTrekTheNextGeneration'':
** The episode "[[Recap/StarTrekTheNextGenerationS6E7Rascals Rascals]]", in which a transporter malfunction turns Picard, Keiko, Ro and Guinan into children, during which time the ''Enterprise'' is captured by hostile aliens. Despite the fact that they clearly keep their adult minds, they still have to save the day using childlike cleverness rather than their usual methods. As children, they would lack the strength and speed to do many of the physical actions an adult could perform.
** The episode "Too Short a Season" has an old Admiral who must negotiate a hostage situation. He seems to have taken a drink from this Fountain as he keeps getting younger. We find out [[spoiler: he takes an alien drug that does this too well---the strain on his body kills him.]]
* One of the few permanent examples comes from ''Series/KamenRiderDenO'', which did this out of necessity. Hana's actress left unexpectedly in the middle of the series[[note]]The real reason is unknown, but the two popular rumors are that she got fired for diva behavior, or that she was overworked due to her role in the show on top of her modelling career[[/note]], but her character was too important to the story to write out. So the producers replaced the twentysomething actress with an eight-year-old. The official explanation was that this was a side effect of Den-O's efforts pushing the future closer to Hana's home timeline rather than the BadFuture the villains wanted to create.
** After the third movie, the show's star moved on to other projects, and thus this happened to protagonist Ryotaro as well. In this case, however, they simply brought back the actor who played the preteen version of him from the first film. It's given a HandWave when he remarks that this sort of thing happens on occasion when you mess around with time travel, which may also explain why there hasn't been a mad scramble for a cure for either him or Hana. Interestingly, Kid!Ryotaro's actor was a regular on ''Series/KamenRiderGhost'', showing that much like ''Manga/DetectiveConan'', he could have returned to his normal age via TheSlowPath at this point.
* ''Series/MightyMorphinPowerRangers'':
** The ''Alien Rangers'' half-season was an extended plot-arc in which all the regular characters were age-regressed to young children.
** This happened in a season 2 episode. In both cases, it seemed to be a strange mix of this and TimeTravel- all the high-school-age heroes were now in elementary school, but they had the same teachers and principal. All the characters who were originally from out of town were still there as well.
* A mild example happens in ''Series/StargateAtlantis'', when Sheppard's tenuous Wraith ally returned the years he had, um, borrowed, plus a bit. Possibly an attempt to balance out the six months he spent in a time dilation field.
* ''Series/StargateSG1'':
** The Goa'uld Sarcophagi can greatly extend life as well as healing wounds (but at the cost of negative psychological effects). However, this isn't that important to the Goa'uld, as they can just take another human host anyway. Though as Lord Yu demonstrates Goa'uld symbiotes age and go senile on their own, and without the sarcophagus have a lifespan of about two hundred years.
** This appears to be the case when 15-year-old O'Neill shows up in the episode "Fragile Balance." [[spoiler: In actuality, he was an Asgard-designed clone that did not mature properly. The [[CaptureAndReplicate real O'Neill was held captive by the rogue Asgard]] the entire time.]]
* ''Series/TheMightyBoosh'': In the episode, "Fountain of Youth," Howard and Vince visit Naboo's home planet, Xooberon, in search of their own Fountain of Youth, but the Hitcher is looking for it, too. HilarityEnsues.
* ''Series/DoctorWho'':
** "The Time Monster" has Sergeant Benton temporally regressed to babyhood by a time-eating monster. He is eventually returned to adulthood, in front of everybody else, stark naked. HilarityEnsues.
** In "Boom Town," Blon Fel-Fotch Pasameer-Day Slitheen is a member of the Slitheen family of the alien Raxacoricofallapatorian species. In the episode, is it explained that members of the family are raised from infancy to be sociopathic criminals. When Blon is exposed to the Heart of the TARDIS, it turns her into an egg; she will be returned to her planet's nurseries, where she will have a chance for a new life.
*** Similarly, "The Leisure Hive" from Tom Baker's last season ends with the villain Pangol reduced to infancy, and his mother Mena promises that she'll RaiseHimRightThisTime.
** "The Lazarus Experiment" episode is about the titular scientist inventing a device that restores cells to a previous state. Being an old man, he tries it on himself first, becoming young. That is until the horrible side effects of the device are discovered. The [[EvilCounterpart Master]] later uses the technology in reverse to make the Doctor old.
* Happened in ''Series/TheGenieFromDownUnder'', where Penelope, after abusing her long-suffering Genie, Bruce, with over 200 wishes in an hour, [[JackassGenie he intentionally made a wish of hers backfire]], turning her into a baby. Oddly though, due to the nature of the wish, nobody seemed to be surprised by her age regression, as though she was supposed to be an infant.
* At the end of the ''Series/{{Merlin 1998}}'' series, when the titular character is a CoolOldGuy complete with beard, [[spoiler: his last act of magic is to restore the youth of himself and his love, returning them to their younger personas seen years earlier in the story.]]
* In ''Series/{{Sanctuary}}'', all of The Five had unnaturally long lifespans [[spoiler:due to the infusion of pure vampire blood with the exception of Watson who was implied to have long life due to a technological device he created (as a result of his increased intelligence due to the aforementioned vampire blood (Aquifer Of Youth?))]] Except for [[spoiler:Griffin, the [[{{Invisibility}} Invisible Man]]]].
* ''Series/TheTwilightZone1959'':
** In the episode "A Short Drink from a Certain Fountain" has an old man try to regain his youth to keep up with his trophy wife. His scientist brother has found an anti-aging serum, but it's untested... [[spoiler:The serum reduces him to infancy. As his wife is about to walk out, his brother (who now controls the man's estate) stops her, informing her that if she wants to keep one penny of her infant husband's money, she'll have to raise him back to adulthood...]]
** In the episode "Kick the Can", all but one of the residents of an old-age home became kids again by playing the titular game.
* In the children's series ''Series/LazyTown'' it occurs in the episode "Little Sportacus" where Sportacus is de-aged by Robbie Rotten's machine. This episode shows Sportacus being just as active and agile as his adult self and sends the message to kids that it's never too early and children no matter how young are capable of amazing things.
* The protagonists of ''Series/TheLegendOfDickAndDom'' stumble onto the Fountain of Youth (or fall into the Muddy Puddle Of Youth, anyway) and are regressed to childhood just in time to meet a bunch of witches who... ''really like'' [[ToServeMan children]]. [[spoiler: Naturally, the witches end up falling in themselves by the end.]]
* In episode 16 of an old Sentai series called ''Series/KyodaiKenByclosser'', the villains use a weird gun to revert a couple of children (Yeah, children, strangely enough) to infancy, convinced that it will ([[MissingStepsPlan somehow]]) make world domination easier. They also turn them into old people with another gun. A young woman is also regressed into a baby. Obviously, all of them are eventually turned back to normal.
* An episode of ''Series/SirArthurConanDoylesTheLostWorld'' had the gang meet a woman with water from the fountain of youth. [[spoiler: Unfortunately, her supply runs out and she reverts to her true age and dies]]. Professor Challenger drinks a little of the water, and while it doesn't make him look younger, it heals his wounds and makes him temporarily strong, agile, and energetic like a teenager.
* On an episode of ''{{Series/Smallville}}'', an old man takes a spill into the koi pond at his retirement home, which turns out to be lined with GreenRocks that make him physically 50 years younger. Unfortunately, he turns out to be a {{sociopath}} with a long list of scores to settle, one of which is against the Kent family.
* ''Series/OnceUponATime:'' [[spoiler:August has turned back into a young Pinocchio]], probably permanently.
* In ''Series/{{Charmed}}'', one is being guarded by nymphs, but is really more of a HealingSpring. Another one shows up, and this one actually looks like a stone fountain. Irritatingly enough, Piper says "But that's just a myth!" when confronted with the second one, even after having come across the first one, possibly because she and her sisters had promised the nymphs from the first fountain that they would keep its existence a secret.
* In ''Series/TheOuterLimits1995'' episode "The Last Supper", an elderly scientist is tracking an immortal woman in the hopes that her blood will restore his youth. After all, he tried it on his (literal) guinea pig the last time he had her in custody and it's been alive for decades. In his desperation, however, he doesn't think his plan through and just scales up the dosage relative to body mass. He gets his youth, [[KarmicDeath plus interest]].
* In ''Series/TheFlyingCestmir'', Cestmir gains seeds for six magical flowers. One of them causes people to de-age for a certain period of time until the effects wear off. The old professor uses it, but apparently nobody else does.
* In the ''Series/{{Supernatural}}'' episode [[Recap/SupernaturalS10E12AboutABoy About a Boy]], Hansel goes around kidnapping people and rejuvenating them to young teens for Katja the witch to feed on, as actual children are too protected by the law for her to kidnap them without being found. [[spoiler:Dean and a woman named Tina end up falling victim to this, but while Dean managed to turn himself back before finishing the witch off, Tina didn't. However, that didn't bother her; Dean offered trying to find another way to return her to normal, but she opted to stay as a kid and get a second, better chance at life.]]
* In the ''Series/{{Haven}}'' episode "Reunion", the thirty-something Robert Taylor occasionally reverts to a teenager who goes on murderous rampages, then later wakes up as himself with no memory of what he had done. His teen self also has the ability to turn other people back into teenagers via touch.
* ''Series/SecondChance2016'': A 75-year old man is given a "second chance" when he is de-aged to his 35-year old self. [[spoiler:He's not the first person this has happened to either, just the most successful.]]
* ''Series/LegendOfTheSeeker'': Zedd is turned into a young man by [[spoiler:Shota]] in "Wizard", so that he can do her bidding. Doesn't work out as intended, when it all goes to his head. Both Zedd and Shota can make anyone, including themselves, young, which means that they can live forever if they wished. Shota appears to make use of this power, as she's implied to be Zedd's age at least, while Zedd does not. She's shown to be very old when her magic is lost to her in "Reckoning".

* The video for Music/FosterThePeople's "Helena Beat" has the frontman's character get kidnapped by a pack of wild children and strapped to a contraption with an old man at the other end. The machine saps whatever youth the old man had left and transfers it to him, turning him into a child. One wonders if all the other kids in the pack didn't arrive by similar fates.
* The Fountain of Youth is alluded to in "Loving You's a Dirty Job (But Somebody's Gotta Do It)" by Bonnie Tyler.
* Music/DanielAmos: In the short story that accompanies the album ''Music/{{Alarma}}'', one scene involves an entire church congregation reverting to babies before the narrator's eyes. This was meant as a satire of certain real-life {{Man Child}}ren.

[[folder:Mythology and Religion]]
* Myth/NartSagas: eating the special apple from atop the golden tree will cause a person to grow ''younger'' with each passing year instead of older, among other powers.

* The finale of the early Creator/CirqueDuSoleil show ''Theatre/NouvelleExperience'' had the inhabitants of a MagicalLand change [[spoiler: TheEveryman hero]] back into a child.

[[folder:Tabletop Games]]
* Mentioned in [[AllThereInTheManual the backstory]] of ''TabletopGame/{{Heroscape}}'' as one of the side effects of drinking from a Wellspring, the other perks being enhanced strength, magic and prophetic visions.

[[folder:Theme Parks]]
* The Fountain of Youth is featured in ''Ride/IndianaJonesAdventure'' at the Ride/DisneyThemeParks. At the end of the ride, Sallah mentions that they have strollers available for anyone who drank too much from it.

[[folder:Video Games]]
* ''VideoGame/{{Civilization}} V'' features a Fountain of Youth as a World Wonder. All units that move adjacent to it gain the Double Healing promotion for free.
* Gilgamesh from ''[[VisualNovel/FateHollowAtaraxia Fate/hollow ataraxia]]'' did this with a youth potion because, apparently, "this whole mess is stupid, screw you all". All the more hilarious, considering that he's been a tyrant (in the past), not to mention a [[KickTheDog dog-kicking]] KnightTemplar and BigBad who wanted to [[spoiler:unleash a terrible curse on humanity because only those who could survive it were worthy of being ruled over]]; when he reverts, he turns into a cute little boy that everyone loves.
* A fountain of youth is present on Easter Island in the ''VideoGame/SamAndMaxFreelancePolice'' game ''Moai Better Blues'', the reason that the island is populated by babies.
* In ''VideoGame/TheCurseOfMonkeyIsland'', Guybrush is age-regressed to the form of a young child when he is trapped in the [[CircusOfFear Carnival of the Damned]] by Lechuck. This also happens to him at the end of Money Island 2: Lechucks Revenge, but is actually an illusion to trick him rather than physical.
* In ''VideoGame/BrainLord'', in the second magic shop you come across, you find it is run by three old women. If you go in the kitchen and talk to the old women there, she'll offer to let you try a new youth potion. Drink it, and instead of you being youthened, all three of the elderly women change to teenagers.
* The Golden Suit in ''VideoGame/HenryHatsworthInThePuzzlingAdventure'' grants youth to whoever wears it. Henry's in his sixties/seventies, so when he dons it, he is restored to young adulthood. [[spoiler:Cole, unfortunately, is only ten or so - so when he dons it in TheStinger, he's reduced to infancy.]]
* The "Babality" {{finishing move}}s in the ''VideoGame/MortalKombat'' games, in which the victor would somehow turn the loser into an infant.
** Seeing as how this is a franchise known for its violence, programmers wisely fixed it so the winning player lost control of their character the instant their opponent became a baby; the victor would immediately go into their win pose. The idea behind the babalities was to provide a more innocent alternative to the infamous fatalities. Unfortunately, a glitch was later discovered that, when exploited, allowed you to viciously attack the baby.
** Despite being unpopular to most fans of the series, the finishing move made a return in the 2011 game "Mortal Kombat". This time instead of the opponent turning into a baby and sitting while crying, the babified opponent would now do a funny animation relating to them. In fact now, even the bosses can have a babality done on them.
* At the end of ''VideoGame/EmeraldCityConfidential'', [[spoiler:Petra deliberately does this to William to [[SetRightWhatOnceWentWrong save him from life imprisonment and his memories of having been]] a [[TheFairFolk Phanfasm]] [[TheMole spy]]]].
* Borf's weapon in the full-motion video game ''{{VideoGame/Space Ace}}'' turns people into infants. He had already used it on the main character, which turned him into a rather weak teenager, but at certain points in the game the player can temporarily restore Space Ace to his proper age. And of course, he ends up being HoistByHisOwnPetard.
* In the ''VideoGame/KingsQuest'' series, there have been 2 cases of this trope.
** In ''[[VideoGame/KingsQuestIIRomancingTheThrone King's Quest II +: Romancing the Stones]]'' you will stumble upon a youth potion. If you drink it, you will turn into a baby and it will be game over. At the end if you give it to the villain she will become a young woman again (good or bad depends on what you do). Trying to use it on Possum or Valanice yields unique sentences, but no penalty.
** In ''VideoGame/KingsQuestVIIThePrincelessBride'', the female villain is turned into a baby.
* In ''VisualNovel/RadicalDreamers'', this is an important plot point: [[spoiler: Kid is revealed to be Schala from [[VideoGame/ChronoTrigger the previous game]]: After the Ocean Palace incident, she was overcome by grief and guilt over what her actions had caused. The Frozen Flame picked up on those emotions, and responded by transforming her into a baby, erasing her memories, and sending her to the modern era, where Lucca found her and raised her]]. Granted, this game is not canon anymore, but an easter egg from ''VideoGame/ChronoCross'' implies that the events of ''Radical Dreamers'' actually happened in another dimension, and one of the many ending cutscenes in Chrono Trigger DS actually does show [[spoiler: Lucca finding baby Schala/Kid and adopting her]]
* In ''Anime/MaiHime Fuuka Taisen'', Yukariko's Child turns her opponents into young children.
* ''[[VideoGame/MysteryCaseFiles Mystery Case Files: The Malgrave Incident]]'' revolves around magical dust that has the power to rejuvenate people and that was the source of the curing properties of the once lively Malgrave Island's thermal waters. The elderly Winston Malgrave wants it to collect some his dying wife, [[spoiler:although it turns out he wanted the dust for himself, so he could regain his youth]].
* [[VideoGame/TheSims The Sims 2]] had the Elixir of Life Aspiration reward, and the "milk" produced by the cowplant available in the ''University'' expansion after it eats a sim, which is a more potent version (making a sim 5 days younger per dose rather than three). The ''Generations'' expansion for the third game added the "Young Again" reward, which is ExactlyWhatItSaysOnTheTin, and the Age Freeze reward, which is also ExactlyWhatItSaysOnTheTin. And then there's the Fountain of Youth (literally a fountain) that came with the Hidden Springs neighborhood...
* In the ''VideoGame/{{Tekken}} Tag Tournament 2'', Heihachi Mishima has found a way to rejuvenate himself back to his prime thanks to a serum made from Ogre's blood. This was brought about by Creator/DaisukeGori's [[RealLifeWritesThePlot unfortunate suicide]], likely to justify a voice actor change, but didn't stick to the main plot as ''Tekken 7'' show Heihachi old again.
* In ''VideoGame/MagicalDrop 3'', the FinalBoss Wheel of Fortune is sent back to the past and transformed into a baby after she is defeated.
* In ''VideoGame/TomodachiLife'' one of the random rewards you can get from granting Miis their requests is a Kid-O-Matic spray, which turns an adult Mii into a kid. There's also the Age-O-Matic spray, which does [[OvernightAgeUp the opposite]]. Though if you use it on a old wrinkly, grey haired Mii. He/she will still be grey and wrinkly, just shorter.
* In VideoGame/{{Super Robot Wars Z}}3: Tengoku-hen, everybody is weirded out by the fact that Noriko's [[spoiler:"big sis" who Noriko told them was a middle aged woman, appears to almost the same age as Noriko]]. [[spoiler:Kazumi]] giggles at this, and says that that she somehow has the body of [[spoiler:when she first piloted Gunbuster with Noriko]]. [[spoiler:Kazumi]] thinks that [[spoiler:after being pulled into the black hole]], she wished and wished to see Noriko again. And that perhaps that wish overcame time itself, and thus she was reborn. Lelouch goggles at the mysteries of the universe, and even C.C. comments that despite having lived a long time, she's still surprised by all this stuff that keeps happening lately. Noriko calls it a miracle born of [[spoiler:Kazumi's]] feelings.
* In ''Franchise/ChaosRings'' ''III'', [[spoiler:Dorothy the kindly old caretaker and 'retired' adventurer who has been looking after the protagonist and his sister since their parents' deaths]] having the same name and voice actress as a much younger looking character is not a coincidence. Humorously enough, her youthful form looks younger than one of her sons, who looks older than his actual age.
* In the [=PlayStation=] 2 and Nintendo [=GameCube=] versions of ''VideoGame/DonaldDuckGoinQuackers'', Merlock becomes a child after he is defeated.
* In ''VideoGame/BlazBlueChronoPhantasma'', about half the results of Amane Nishiki's [[FinishingMove Astral Heat]] turns [[CampGay his]] opponents into children. The other half of the results turn them merely younger (as in, from adult into adolescent or so). The only exception is Platinum, a youngish MagicalGirl who instead turns into Trinity, her (sort-of) previous self.
* ''VideoGame/TwistedMetal 2'' plays this for laughs with Warthog's ending. Upon winning the tournament, Warthog's 105 year old driver asks Calypso to give him the body of a twenty-year-old. So, Calypso gives him the body of a twenty-year-old. His ''head'' on the other hand...
* ''Franchise/TheLegendOfZelda'':
** Kafei from ''VideoGame/TheLegendOfZeldaMajorasMask'' was turned into a young boy by the Skull Kid not long before he was set to marry Anju. He was going to seek advice from the local Great Fairy about how to reverse this change when Sakon, a thief known to [[DirtyCoward prey mainly on children and old folks]], snatched from him the [[LostWeddingRing Sun's Mask that he planned to use in the wedding ceremony]]. He spends several months hiding from his loved ones in the backroom of the Curiosity Shop, not because of any current shame over his physical condition, but because he felt he needed to find the Sun's Mask first.
** Purah from ''VideoGame/TheLegendOfZeldaBreathOfTheWild''. An elderly Sheikah who is the sister of Zelda's maid Impa, she had developed a magical rejuvenation process with the intent of increasing the number of young, able-bodied soldiers who could fight against the forces of [[BigBad Calamity Ganon]]. She decided to test it out on herself first, only to find herself physically a six-year-old. She has largely isolated herself with her assistant Symin in the Hateno Ancient Tech Lab, too embarrassed by her condition to face Impa or fellow Sheikah scientist Robbie. And while she retains her memories and technical knowledge, she [[TheMindIsAPlaythingOfTheBody has the personality and temperament of a six-year-old]].
* In ''VideoGame/DiscworldII'', the Fountain of Youth appears late into the game, as part of a puzzle where we have to find a way to [[ItMakesSenseInContext prevent Death from dying]]. Subverted in that it's not the water we need, but the sand that lies at the bottom of the basin, so that we can refill Death's hourglass.

[[folder:Web Comics]]
* In ''Webcomic/{{Opplopolis}}'' during Luke Dugans' interview with Shirley Kidd about a mysterious movie she appeared in called ''Marvedyne'' (that word being the series' MacGuffin), the latter [[http://www.opplopolis.com/issues/4/5 suddenly de-ages]] from 60-ish to 20-ish with thus far [[LeftHanging no explanation]], though there was a [[SlippingAMickey conspicuous cup of coffee]] earlier in the scene.
* When Mingmei in ''Webcomic/TheWotch'' discovers that she used to be Dr. Sorgaz, everyone assumes that she would want to be turned back… except the Sorgaz persona himself, who basically takes it as a second chance in life, and instead opts to merge with Mingmei permanently.
** Not to mention 21-year-old Evan's frequent temporary escapes into a 4-year-old ([[GenderBender female]]) body, called "Lily".
** Seriously, what about the entirety of ''Adventures in Babysitting''? Even though Evan turns into an adult female, Anne, Robin (Robyn?), and Jason were turned into children (Okay, they turned into the opposite gender too, but that hardly matters!)
* Emily from ''Webcomic/{{Misfile}}'' suffers from this, though she was only regressed by two years rather than the usually much larger amount. Since she was just about to turn 18 and had received her acceptance letter from Harvard these were a rather vital couple of years though.
* In one strip of ''Webcomic/AxisPowersHetalia'', England de-ages Korea to make him less annoying. In a later April Fool's Day event he does it again to France.
* ''Webcomic/TheDragonDoctors'':
** A team of magical robbers are trying to steal a large drum of rejuvenating fluid in the "Thieves of Life" arc. An acid booby trap cracks open the drum, however, exposing one of the thieves to an overdose of the fluid, immediately transforming her into a baby.
** A {{Backstory}} chapter features a [[http://www.drunkduck.com/The_Dragon_Doctors/index.php?p=773779 lake of youth]] that is responsible for the 'deaths' of several colonists. It's basically a {{Deconstruction}} of the Fountain of Youth: the lake is hidden because everyone who goes near it dies. Nothing grows around it because it causes everything to un-grow, so it's a desolate wasteland. Even contact with the vapors from it can erase years or decades of age from someone, so most people who get close wind up vanishing into EmptyPilesOfClothing (which, incidentally, is the TropeNamer for that). The discovery of that lake was actually what enabled the development of the previously mentioned rejuvenating fluid, after people figured out how to harness its effects.
* Morgan of ''GenderSwapped'' after pestering Sven long enough to bend the rules for the two of them
* In ''Webcomic/ElGoonishShive'', [[MadScientist Dr. Germahn]] invented [[http://egscomics.com/egsnp/?date=2004-09-02 one.]]
* Ponce de Leon and his companion look for one in ''Webcomic/{{Oglaf}}'', but only come across the fountains of [[http://www.oglaf.com/fountain-of-doubt/ Doubt,]] [[strike: [[http://www.oglaf.com/fountain-of-death/ Death]]]] [[http://www.oglaf.com/fountain-of-death/ Water So Good Even Dead People Want It,]] and [[http://www.oglaf.com/fountain-of-girl/1/ Girl (NSFW).]]
* In ''Webcomic/KevinAndKell'', the vulture family has a time machine where they sometimes travel to the past. But in some cases, if used right, it can affect someone's age.
** Dolly, a clone of Corrie, begins to age faster than usual. A new identity is created for her and she gets a job as a cleaning lady for the vultures. While cleaning she accidentally activates the time machine and is turned into a baby where she remains still.
** In other strips the characters are briefly turned into babies for laughs, but these are probably not canon.
* The Kids arc of ''Webcomic/{{Roommates}}'' where the resident [[TheTrickster magical troublemaker]] {{Schmuck Bait}}s ("What does this [[CrystalBall glowing orb]] do?!") the other main cast members into this and we learn that some people changed [[FormerTeenRebel a lot]]... others [[StaticCharacter not so much]]. Thank god the magic only lasted thirteen hours.
* In ''Webcomic/DocRat'', [[http://www.docrat.com.au/default.asp?thisItem=1137 heavy duty anti-ageing cream regresses a bird back to an egg.]]
* ''Webcomic/KarinDou4koma'': Seren and Elza's independent attempts at weight-loss magic actually turn them into children. Seren eventually turns herself back, but Elza prefers her new form.
* In ''Webcomic/{{Jix}}'' one of Lamerix's inventions instantly changes one's age, she loses it in the couch cushions and Lauren is accidentally turned into a child after sitting on it, though she eventually reverses it. Later on, she uses it to turn [[spoiler: Aragara, who had been artificially aged by growth hormones]] back into a kit.
* in ''Webcomic/TrueVillains'', old, wizened sorcerer Bayn Pheonix is transformed into a kid by demon Xaneth Antaris.
* ''Webcomic/MiniMari!'' kicks off when [[VideoGame/{{Touhou}} Marisa Kirisame]] eats a mushroom that reverts her back to the body and mentality of a child.
* In ''Webcomic/DecryptingRita'', after Rita the Hat Lady [[spoiler:re-emerges into her native universe from the depths of the Panopticon]], she ends up in a body much younger than her previous one. She even gains a new hat to match.
* Duncan/The Annihilator from ''Webcomic/TheYoungProtectors'' literally becomes a youth [[spoiler:for his end of the deal desiring youth with Laampros.]]
* A Meta heavy instance happened in ''Webcomic/Level30Psychiatry''. With the assistance of Franchise/CarmenSandiego and her ImpossibleThief skills, Dr Gardevoir removed the popularity of the Gardevoir species from the internet so she could browse in peace. Unaware that she is in a webcomic, this lead to her De-Evolving into a Kirlia.

[[folder:Web Original]]
* ''Literature/WhateleyUniverse'' example: retired U.S. Navy officer Sam Everheart was injured trying to save a HotScientist from bad guys. The 'hive' of nanites infected him and saved him... by turning him into someone a lot younger. He now looks like his deceased 17-year-old daughter.
* Wiki/{{SCP|Foundation}}-[[http://scp-wiki.wikidot.com/scp-006 006.]]
* In the aptly-named "Baby Boom" episode of ''WebAnimation/GothamGirls'', Harley is accidentally regressed into a baby.
* In the ''WesternAnimation/MyLittlePonyFriendshipIsMagic'' abridge series ''WebVideo/FriendshipIsForAdults'' like in canon, Luna is reduced to taking the form of a child, after the Elements cleanse her of evil in the pilot. Unlike canon, she is also left with ''[[LaserGuidedAmnesia amnesia]]'' and instead of being back to her adult form in her next appearance, she seems to be stuck like this and Celestia is left to take care of her now juvenile sister.
* The abridge series ''WebVideo/UltraFastPony'' reveals that ''sexual reproduction itself'' has been rendered obsolete by the ability to just turn adults ponies back into babies if need be. Naturally, after three little fillies learn this, they immediately turn The Mane Six back into children for fun.

[[folder:Western Animation]]
* Occurs in a great many cartoons in general. Often, with the humorous side-effect of the subjects eventually reverting to their true age while wearing a diaper.
* A while ago, UsefulNotes/McDonalds released cartoons on VHS featuring Ronald [=McDonald=] and his friends having adventures. One such cartoon sees them go to an amusement park called Birthday world where him and his friends are turned into toddlers and babies.
* In ''WesternAnimation/AdventureTime'', the ([[ReallySevenHundredYearsOld apparently]]) 18-year-old Princess Bubblegum suffers an accident in which she loses some of her body mass. Being [[ExactlyWhatItSaysOnTheTin a sentient wad of bubblegum in a generally princess-like shape]], she is saved by being reconstructed in the shape of an apparently 13-year-old princess. Since TheMindIsThePlaythingOfTheBody, this also causes her personality to take on the traits of a 13-year-old. The situation is, [[StatusQuoIsGod of course]], temporary. [[note]] the writers originally planned for it to last much longer, as an entire story arc. But changed their minds and scrapped the whole idea, turning her back to normal in her very next appearance. [[/note]]
* The focus of ''WesternAnimation/TheAdventuresOfPussInBoots'' episode "Fountains", where the crew looks for the Fountain of Youth to restore a RetiredBadass to his prime. Although they find it, he is forced to return to his old age to escape, and the fountain can only be used once.
* In an episode of ''WesternAnimation/AdventuresOfSonicTheHedgehog'', Dr. Robotnik plans on defeating Sonic by making him so old, he won't be as fast. As usual Scratch and Grounder mess things up by putting the device into reverse, turning Sonic into a toddler and Tails into a baby. Later Robotnik is too turned into a toddler. At the end Robotnik is turned into an old man.
* ''WesternAnimation/TheAmazingWorldOfGumball'': In the episode "The Rerun", Nicole and Richard are regressed to infancy, causing their children to retroactively never have been born. Gumball himself comes dangerously close to disappearing, but he manages to fix things and turn everything back to normal in the nick of time.
* Happens to Batman (again) in ''WesternAnimation/BatmanTheBraveAndTheBold'' after he is zapped by [[ComicBook/{{Shazam}} Dr. Sivana]] starting as a teenager, then a toddler, and then a baby.
* ''WesternAnimation/{{Ben 10}}'' also features the literal Fountain of Youth (though it's more of a natural pool or spring). Max turns into a 10 year old and is revealed to be similar to Ben at that age. Ben and the aliens turn into toddlers. It wears off.
** ''WesternAnimation/Ben10Omniverse'' has a de-aging ray used against Ben and Rook. Creator/TaraStrong returns to voice young Ben, and li'l Rook is ridiculously adorable... with a tail, which his species is born with but sheds at puberty.
* In one ''WesternAnimation/BettyBoop'' cartoon, the patent medicine she and her pals are peddling turns an old bearded man into a large baby -- and the baby accompanying him into a tiny old bearded man.
* The 2006 revival of ''WesternAnimation/BikerMiceFromMars'' had this happen in the episode "Bringing Up Vinnie", where Vinnie was regressed to infancy because of Dr. Catorkian's age-reversing experiments. Throttle, Modo, and Charley then have to take care of baby Vinnie while looking for a way to restore him to his normal age.
* In the ''WesternAnimation/BumpInTheNight'' episode "Baby Jail," Bumpy accidentally swallows some baby formula while trying to feed a baby and becomes one of them.
* An episode of ''WesternAnimation/CareBears1980s'' features it, with the heroes going on a quest to find it and the villains not far behind. Shreeky eventually does drink from the fountain, but because [[DidntThinkThisThrough she's a little girl to begin with]], she turns into a baby.
* ''WesternAnimation/CodenameKidsNextDoor'' had an episode where the Fountain was revealed to be under the school, kept secret by one "girl" who had been using it for years. The Delightful Children from Down the Lane were naturally opposed to its existence and wanted to destroy it.
* The "Little Muriel" episode of ''WesternAnimation/CourageTheCowardlyDog'' has Muriel being turned into a mischievous little girl by a freak tornado. It then turns out the only way to undo the effect is to throw her into a tornado spinning in the opposite direction of the original one -- which entails flying to the southern hemisphere.
* There have been a few episodes in ''WesternAnimation/DarkwingDuck'' that feature this.
** An elderly villain attempted to actually make one of these so as to regain his youth and become immortal. His plan worked and he was restored to his prime. Unfortunately, in a fight with Darkwing Duck and Herb, they all became babies. In the end the fountain was destroyed and his henchmen were turned into babies as well while Darkwing and Herb turned back.
** In "Disguised the Limit", Darkwing is framed for a crime he did not commit. So a scientist blasts him with a ray gun that will turn him into anything he sees. At one point he turns into his daughter and a baby.
** In one episode, Darkwing becomes super fast but the more he does it, the older he becomes (see overnight age up). In the end he fixes it by running backwards to become younger...at one point a little too much and becomes a kid.
* WesternAnimation/DonaldDuck tries to trick his nephews into believing they've found the fountain in "Don's Fountain of Youth." HilarityEnsues.
* In the ''WesternAnimation/DonkeyKongCountry'' episode, "Ape Foo Young", Cranky makes a potion that will make him 40 years younger, with the help of the vision of his past self. However, the effects of the potion are only temporary. Donkey Kong drinks the potion and de-ages into a baby. Diddy gets Candy to look after him until the effects wear off by telling her he's DK's nephew. At the end of the episode, King K. Rool drinks the potion and de-ages into a baby as well.
* The ''WesternAnimation/DuckDodgers'' episode "Duck Codgers" has Dodgers and the Cadet infected with a disease that speeds up their aging, and visiting the Fountain of Youth on Mars to reverse it. While they only go back to their canonical ages, the disease turns out to have reversed effects on Martians.
* In the ''WesternAnimation/DuckTales1987'' episode "[[Recap/DuckTalesS1E15SweetDuckOfYouth Sweet Duck of Youth]]," Scrooge looks for the literal Fountain of Youth so that he can live longer. It turned out that the fountain only made a person ''look'' younger when reflected in its waters.
* ''WesternAnimation/TheEmperorsNewSchool'' features the actual Fountain of Youth in one episode. Yzma uses it to become a (surprisingly attractive) teenager in order to trick Kuzco. It also features Pacha and Chica becoming teenagers, and ends with Yzma and Kronk becoming (somewhat freaky looking) babies.
* In a cutaway gag on ''WesternAnimation/FamilyGuy'', Ponce de Leon Griffin finds the Fountain of Youth and takes a dip, keeping his head above water. When he emerges, his body is the size of an infant, but his head is still adult-sized; he promptly topples over.
* The ''WesternAnimation/FilmationsGhostbusters'' episode "Back to the Past" had Jake, Eddie, and Tracy de-aged into five-year-olds as part of a scheme to scare them to the point that they wouldn't want to be ghostbusters anymore by the time the spell wore off and they became adults again.
* The final ''WesternAnimation/TheFoxAndTheCrow'' cartoon, "Punchy De Leon" has Fox and Crow as con men who claim to have found the Fountain, hoping to get rewarded by the King of Spain. When the King wants them to bring it for real, they set off to Florida to find it.
* ''WesternAnimation/{{Futurama}}'' did this in "Teenage Mutant Leela's Hurdles", where overexposure to rejuvenating tar resulted in Professor Farnsworth going back to late middle age, and the rest of the Planet Express crew (including the robot Bender) becoming teenagers. An attempt to reverse the process made things worse, which instead just sped up the regressing, and everyone but Leela (who opted out of the cure, in order to relive the childhood she never had) started regressing into early childhood, most of the characters went so far back that they turned into fetuses ([[RuleOfFunny blueprints in Bender's case]]).
** And then the trope is inverted and parodied when they seek to be cured at the ''Fountain Of Aging''.
* In an episode of ''WesternAnimation/{{Hercules}}: The Animated Series'', Pain and Panic try to kill Hercules (again), this time by using water from a spring that reverses aging. They accidentally get water on not only Hercules, but on Icarus, Adonis, Pegasus, and Pain himself. Panic and Cassandra have to watch them since they're all infants until they can find a cure.
* In the Disney Channel cartoon series ''WesternAnimation/{{Jake and the Neverland Pirates}}'' episode "Pirate Sitting Pirates", Captain Hook as usual is being chased by Tic Toc Croc. As a result they both take a tumble knocking themselves as well as Jake and his friends into the pirate pool of youth, which can turn pirates into wee pirates. As a result they are all turned into babies. Now Smee and the other pirates must look for a flower that can turn them back.
* ''WesternAnimation/JackieChanAdventures'':
** The Dog Talisman gives its holder immortality. While it doesn't make the holder look younger, it makes him ''feel'' younger. Thus Uncle becomes incredibly strong and agile like he used to be.
** Characters sometimes get turned into children by spells.
** One episode had the fountain belonging to a hidden tribe of people. They used it to preserve their ages for centuries but the source of the magic was stolen by the unscrupulous man that paid Jackie to find it. When he and his butler drank some water, because the village was of such advanced age, they regressed into babies.
* An episode of ''WesternAnimation/TheJetsons'' "Boy George" has George turn into a kid, though his voice is exactly the same. Another episode [[RapidAging inverts it]] by having Elroy turn into an old man.
* ''WesternAnimation/JohnnyBravo'': In one episode, Johnny drinks a potion that reverts him to infancy- physically, at least- to the delight of his mother... until she gets busy and sends him off to day care with an attractive caretaker, to his delight. In the end, he's restored to his adult body.
* In the ''WesternAnimation/JusticeLeague Unlimited'' episode "Kid Stuff", Morgan Le Fay's son Mordred gets his hands on a powerful amulet and, in a fit of pique after his mother insists he's too young to be responsible for it, banishes all the adults in the world to a pocket dimension. Morgan gets around this by turning some of the Justice Leaguers (Batman, Superman, Wonder Woman, and Green Lantern) into 8-year-old children so they can get the amulet back. Eventually, Mordred is tricked into breaking the spell that keeps him a child, and he vanishes into the pocket dimension as per the rules of his earlier spell. [[spoiler: In the end, it turns out that breaking the spell meant he still had eternal life but without eternal youth, and was now thousands of years old and effectively immobile, basically a vegetable that his still-young mother will care for -- ''Forever.'' [[FateWorseThanDeath Harsh]].]] Of course, one wonders if Morgan can't just cast it again... or just won't.
* ''WesternAnimation/TheKarateKidTheAnimatedSeries'': In "Over the Rainbow" Miyagi, Daniel, and Taki stumble on a hidden community with one fueled by the shrine.
* Two instances in ''WesternAnimation/KimPossible'':
** The first in the MadeForTVMovie "A Sitch in Time", when the [[VillainTeamUp teamed-up bad guys]], having possession of a time-traveling idol, use a device to make themselves toddlers so they can infiltrate the title hero's youth.
** The second is in an episode where Ron is continuously sent through a machine that turns adults into babies. He goes through so many times that when he finally gets back to his own age, he is wearing a diaper.
* Happens in ''WesternAnimation/TheLegendOfKorra'' episode "A New Spiritual Age", when Korra's emotions cause her to age down into a child while in the SpiritWorld.
* One episode of ''WesternAnimation/LiloAndStitchTheSeries'' involved an experiment known as the "Babyfier" that turned its victims into infants.
* In ''WesternAnimation/TheMask'' episode "Little Big Mask", Stanley Ipkiss creates a cream that causes him to get younger by the hour and he as The Mask must find a way to fix it while Peggy tries to keep him focused.
* ''WesternAnimation/MyLittlePonyFriendshipIsMagic'':
** Age spells can only be performed by the highest-level unicorns. Trixie is able to turn Snips into a baby and Snails into an old stallion with her magic boosted by an Alicorn Amulet; Twilight Sparkle, on the other hand, is unable to reverse it. In order to rid Trixie of the corrupting amulet, Twilight fakes it by claiming to have an equally powerful artifact while having Apple Bloom and Sweetie Belle impersonate Applejack and Rarity respectively.
** Twilight pulled it off for real in "The Cutie Mark Chronicles", though, but not intentionally; during her entrance exam to magic school, she was startled and lost control of her magic, turning the not-yet-hatched Spike into an adult dragon.
* ''WesternAnimation/TheNewAdventuresOfSuperman'': In "Merlin's Magical Marbles", Lex Luthor and his henchman use the aforementioned marbles to transform themselves into children to allow them to escape undetected from the scenes of their crimes.
* The ''WesternAnimation/OggyAndTheCockroaches'' episode "Back to the Past" features Oggy, Jack, and Bob accidentally facing the wrath of a witch and turned into elementary school-aged kids, with Olivia and Joey forced to track the witch down to reverse the spell, while Dee Dee and Marky watch over the three. [[spoiler: In the end, the same ends up happening to Joey, Dee Dee, and Marky.]]
* In a relatively rare example of kids getting younger, the ''WesternAnimation/PhineasAndFerb'' episode Agent Doof has the titular characters being turned into babies. Needless to say, Candace ended up a BadlyBatteredBabysitter in record time. And at the end of the episode, even their mother and the Fireside Girls are turned into babies. Candace is obviously exasperated, and [[BreakingTheFourthWall openly hopes it wears off by the next episode]] ([[StatusQuoIsGod which it also obviously does]]).
* ''WesternAnimation/TheProblemSolverz'' episode "Time Twister" features a roller coaster capable of traveling through time, which Alfe takes advantage of by going back in time to eat pizza over and over again, and he becomes younger as a result.
* ''WesternAnimation/QuackPack'' has the episode "Can't Take a Yolk" where Donald really ''is'' regressed to youth-- represented here by an ArtShift to his original character design from the 1934 short "The Wise Little Hen".
* ''WesternAnimation/RockosModernLife'': Rocko, Heifer, and Heifer's Grandfather are on a cruise filled with senior citizens when they cross The Bermuda Triangle, which alters their ages. Giving us a mix of overnight age up and Fountain of Youth, all the elderly revert back to young(er) adulthood, the ship's crew become babies, and Rocko and Heifer become elderly.
* The second to last episode of ''WesternAnimation/{{Rugrats}}'' (a.k.a. "Fountain of Youth") has Tommy, Chuckie, & Kimi think that the fountain of youth exists. They are happy until Angelica tells them that she will be in charge when its powers take effect on the adults & tricks them into thinking that the fountain in the lake has said powers. After several unsuccessful attempts at preventing the adults from going into the lake, they decide to drain the lake...[[spoiler: by pulling on a chain that's attached to a boat, which is far too heavy for them to move by even an inch.]]
* The cartoon version of ''VideoGame/SpaceAce'':
** The Infanto Ray made some appearances; one of them was episode 3, in which the victim was Borf. Another example is episode 6, where the Infanto Ray was just a round circle. However, it made its return in episode 11, in which Borf uses it on the vicims, and one of them was Kimberly, but after Dexter was brainwashed with the brainwashing device, Kimberly turned back into her adult form right after Dexter grabbed Kimberly while in the prison.
** Another ray, the ''Age Ray'' appeared in another episode before episode 11. The Age Ray was meant to be used on Dexter so that Dexter can remain as Ace, but when Borf gets hit by the Age Ray, he does not turn into a baby, but rather into a teenager, and Borf energizes at random times throughout the entire episode like Dexter.
* ''WesternAnimation/SpiderManTheAnimatedSeries'': The [[EvilOldFolks aged crime lord]] Silvermane's long-standing goal was to find a way to restore his youth. Unfortunately, the AppliedPhlebotinum worked a little too well, and he reverted to infancy. A later attempt to fix it ''also'' works too well, restoring him to his original old age instead of to his target age.
** Adrian Toomes, the Vulture, shares the same goal and even uses the same AppliedPhlebotinum as Silvermane. It works out considerably better for him, to the point that he is the ''only'' villain in the entire series who gets everything he wanted in the end. He's also the reason Silvermane's attempt to undo his infancy works too well.
* In the ''WesternAnimation/SpongeBobSquarePants'' episode "Goo Goo Gas", Plankton develops both a super-aging gas (a senior citi-spray if you will) and a de-aging gas (the title Goo Goo Gas). The latter ends up working a bit too well, [[RuleOfFunny turning him into an even smaller protozoa]].
* One ''WesternAnimation/StarTrekTheAnimatedSeries'' episode had the Enterprise get sucked into a parallel universe where entropy was reversed and things aged backwards; they quickly started getting younger and younger, leading to an adorable 7-year-old Spock trying to hold the mission together.
** Luckily, the (non-canon) first captain of the Enterprise, Captain Robert April, was on-board. He de-aged from an elderly man to roughly Kirk's true age.
* WesternAnimation/StarVsTheForcesOfEvil'': In "Conquer", [[spoiler: Miss Heinous/Meteora is changed into a baby thanks to a combination of Star's and Eclipsa's magic, [[RaiseHimRightThisTime giving Eclipsa the opportunity to give her daughter a better, happier life]]]].
* Princess Toadstool got turned into a baby in ''Series/TheSuperMarioBrosSuperShow'' after falling in the Fountain of Youth. To get her back to her real age, the brothers had to [[ReversePolarity make the waterfall in the fountain go up instead of down]] [[InsaneTrollLogic and put her in the fountain]].
** [[HilariousInHindsight That technically makes this episode the first appearance of]] [[VideoGame/MarioAndLuigiPartnersInTime Baby Peach]].
** One episode of the ''Adventures of Super Mario Bros. 3'' spinoff had one where Kooky's builds a time machine to take him and Koopa back in time so they can prevent Mario and Luigi from arriving at the Mushroom Kingdom, with the Marios and Toad following them back to stop them. Unfortunately, it malfunctions thanks to Koopa's impatience, so not only do they all go back in time, but they all get turned into babies too. [[HilariousInHindsight Which means this had our first appearances of Baby Mario and Luigi as well.]] Although this Baby Mario and Luigi ''still have their mustaches''.
* ''WesternAnimation/SuperSunday'': The entire series "Bigfoot and the Muscle Machines" was built around a young journalist, the members of a traveling monster truck show and a ruthless elderly billionaire named Adrian Ravenscroft searching for the Fountain of Youth. When Ravenscroft gets to it first, he turns into a young, 30-something man, vowing to destroy his adversaries. But the good guys destroy the fountain of youth, and it isn't long before Ravenscroft reverts to his elderly self ... fleeing but unknowing running into a swamp infested with hungry alligators.
* Happens a few times in ''WesternAnimation/TheSuperheroSquadShow'' all due to messing around with time manipulation.
** The first time occurred in "Fate of Destiny!", where Thanos uses the Time Stone to de-age all of the occupants of a Skrull Ship and Captain Marvel into babies for his own amusement.
** Happens again when Iron Man's time machine in "Revenge of the Baby-Sat!" backfires and turns Iron Man, Scarlet Witch and Falcon into toddlers, where Wolverine (to his dismay) has to babysit them, while the childish Hulk enjoys it. The [[RapidAging opposite]] happens to Ms. Marvel and Thor when Dr. Doom gets control over time, but H.E.R.B.I.E. then reverses all of the inappropriately aged squaddies back and in the process turns Dr. Doom into a toddler as well.
* Leave it to ''WesternAnimation/{{Superjail}}'' to come up with a twisted, disturbing take on this one. When the Warden is feeling old and decrepit on his birthday, Jared buys him some "ancient Chinese mystery butter" that's supposed to restore someone's youth. It ends up getting put on the birthday cake, though, leading to a bunch of inmates regressing to toddlers. Toddlers who then proceed to violently kill each other.
* In ''WesternAnimation/TeenTitans'' Warp is reduced to infancy after his time suit malfunctions.
* Two episodes of the original ''[[WesternAnimation/TeenageMutantNinjaTurtles1987 Teenage Mutant Ninja Turtles]]'' dealt with this; in "Back to the Egg" it happened to Leonardo and Michaelangelo, and in "Adventures In Turtle Sitting" Leonardo, Raphael, and Donatello turned into children and the slacker of the group Michaelangelo had to look after them.
** Another episode "Leatherhead Terror of the Swamp" when the mixture of the leftover mutagen that affected the Punk Frogs and Leatherhead is concentrated creating the Fountain of Youth. Shredder accidentally fell in the fountain turning him into a baby.
* ''WesternAnimation/TinyToonAdventures'':
** In the episode "Love Disconnection" (and within ''that'', the [[TwoShorts segment]] called "The Amazing Three"), [[ValleyGirl Shirley the Loon]] tries to make the moves on an older male duck at a senior dance by asking him what his [[WesternZodiac astrological sign]] is. Out of his beak comes AntiquatedLinguistics as he belittles her, telling her how childish and unfounded astrology is. However, she has such a hard time understanding him that ''[[HilarityEnsues she reverts into a baby]]''! Prior to that, Shirley said that she would impress the duck with [[{{Irony}} her "keen wit and intellect"]].
--->'''Shirley:''' Like, umm, what's your sign?\\
'''Duck:''' Ah! A devotee of the unseen world. The universe fantastique. Almost amusing in an infantile sort of way, though terribly childish and laughably unfounded.\\
(''Shirley reverts into a baby'')\\
'''Duck:''' I believe {{Creator/Voltaire}} put it best when he likened astrology to astronomy as the mad daughter of a wise mother. Don't you agree?\\
'''Shirley:''' I go like, [[BabyTalk nappy-poo now. Goo googoo gaa gaa gaa]]? (''she crawls away'')\\
'''Duck:''' Quite.
** The episode "Fields of Honey" reveal that laughter keeps toons young. This is shown where upon having people laugh at her cartoons after so many years, an elderly Honey is restored to her prime.
* ''Franchise/{{Transformers}}'':
** In the episode "Forever Is A Long Time Coming" from ''Franchise/TransformersGeneration1'', because of the effects of the Quintessons' time travel device, female captain Marissa Faireborn is zapped by a ray and temporarily transformed into a baby.
** ''WesternAnimation/TransformersRescueBots'': Dr. Morocco stole a mechanical FountainOfYouth that he uses to stay young but he must use it very often due to the effects of the machine which make him age much faster than usual.
* The 8-minute pilot ''WesternAnimation/TwelveForever'' has the Butt Witch create a potion that turns people into babies. The protagonist Reggie is tricked into using it on Tristan, a boy she angered. After Reggie and her friend Shane restore Tristan to his true age, the Butt Witch falls victim to her own concoction and has to be carried away by her henchman.
* In the ''WesternAnimation/WackyRaces2017'' episode "Formula Racing", an accident causes Peter Perfect, Penelope Pitstop, I.Q. Ickley, and the Gruesome Twosome to become babies. Dick Dastardly gets stuck looking after them while Brick Crashman and P.T. Barnstorm search for a way to return the racers to their normal ages.
* In one episode of the third season of ''WesternAnimation/WinxClub'', the Winx had to retrieve water from a magical stream that was capable of turning back time so they could save Faragonda who had been transformed into a tree by Valtor. However, they had to be careful not to touch the water, realizing that doing so could cause them to turn back into children. Near the end of the episode, after Flora earns her Enchantix after saving her younger sister from the Trix, she then throws the Trix into the water, turning them into preteens. Of course, the Trix are back to normal in later episodes, so Valtor must've been able to restore their true ages.
* In the WesternAnimation/WoodyWoodpecker short ''Born to Peck'', [[spoiler: this is added in at the last second by the animator to save the life of an elderly, suicidal Woody.]]
* In an episode of the cartoon ''WesternAnimation/YogisTreasureHunt'' called "Secret Agent Bear", Yogi and his pals spoof James Bond movies. In it they accidently fall into the fountain of youth and the adults become little kids and the kids become babies. Later the villian uses the water to turn world leaders into kids and then is turned one himself at the end.