Fountain of Youth



Some form of Applied Phlebotinum results in one or more main characters regressing to an earlier age. It may be the result of a 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).

For some reason this plot is often used in Fanfic, where it's called a De-Aging story.

When someone dies in their rejuvenated state, expect them to turn back old immediately.

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

It's common for characters to overdo it in stories involving this trope, often winding up as children, 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, expect it to be permanent - well, at least, until they grow back up the old-fashioned way.

Contrast with Overnight Age-Up and Plot-Relevant Age-Up. Compare Really Seven Hundred Years Old and Merlin Sickness. See also Healing Spring.

Advertising

 * In 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 take part in the "kids-only weekend", but [[Gone turns into a baby upon drinking it which the announcer says "Sorry, babies are too young to watch "Kids Only Weekend!""
 * At least a couple commercials for the candy "Baby Bottle Pop" feature this, naturally. One turns eaters' heads into baby heads; another has teens at a dance eating the candy and turning into cartoon babies.
 * A PlayStation 2 ad shows a nursing home is fully of empty halls with discarded clothes strewn around, but no one in sight. The camera then pans to a clock moving backwards, followed by clothless babies crawling around.
 * One Bojangles commercial has an old man showing off his Bojangles box. An old woman isn't impressed and drinks from a water fountain to become young again, claiming that she found "the water fountain of youth". The old man isn't impressed himself.
 * A commercial for Johnson and Johnson baby shampoo shows a woman smiling at the camera as bubbles cover the screen, disappearing to reveal a younger version of her and continuing until she becomes a baby.

Anime and Manga

 * Happened twice in Sket Dance:
 * The first time, Bossun accidentally drinks Chuu-san's youth potion, mistaking it for a bottle of cola. Himeko absolutely flips over him.
 * The second time, several chapters later, Himeko and Momoka end up making the same mistake 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're aged ten years older than normal. And of course, by the time the next episode starts, they're back to their normal ages again.
 * Because Heaven's computer crashed, this happened to Urd for about two chapters in the Ah! My Goddess manga (and one episode of the 2005 animé), with the reverse happening for youngest sister Skuld. Fortunately, she was able to get an interesting advantage out of it.
 * Episode 9 of Keroro Gunsou features Hot Mom Aki Hinata getting turned into a teenager by Kururu's newest invention. In a later episode, the same gun turns Fuyuki into a kindergartner; later still, Natsumi, Keroro, Giroro, and Kururu are subjected to its effects.
 * Sailor Moon has several examples.
 * At the end of the third season (Sailor Moon S), after sacrificing herself to save the world, Hotaru is brought back as an infant with no memories of her previous life. In the beginning of the fifth season (Sailor Moon Stars), Hotaru rapidly ages back as her memories return, and the previous season's Big Bad, 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 fourth season (Sailor Moon SuperS), Usagi and Chibiusa briefly exchange ages for one episode.
 * The Nehellenia story is reused in Mermaid Melody Pichi Pichi Pitch, but with Michal, the Ill Girl and not-quite-villain.
 * Ranma ½:
 * Lukkosai, who tried to use the Spring of the Drowned Child to regain his youth, instead just goes from way too old to way too young (both and 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.
 * 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 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.
 * Alessi in Part 3 of JoJo's Bizarre Adventure does this to opponents with his Stand, Sethan. The longer you stand in his shadow (through which Sethan manifests), the younger you get. (A young woman was reverted to a fetus when she had the bad luck of standing in Alessi's shadow for ten seconds. Fortunately, she is saved.) 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 one of the games 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, with him wishing it could've been permanent.
 * In Koi Koi 7, after Yayoi Asuka (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.
 * In the Dark Tournament arc of Yu Yu Hakusho, 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.
 * Rosario + Vampire has an example of this one. 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 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 Unwanted Harem (sans Tsukune), who were turned into children along with her. Much cuteness and butt-kicking ensues.
 * In Dragonball Z, King Piccolo and Lord Slug used the titular MacGuffin to restore their youth and their power. Roshi and his sister Baba actually drank from a Fountain of Youth, which, rather than restore their youth, instead prevented them from aging any further and dying of old age.
 * And of course, Goku turning into a child is part of the whole concept of Dragon Ball GT
 * Who can ever forget APTX-4869 in Detective Conan? It regressed Shinichi Kudo and Shiho Miyano's body by around ten years, causing two Teen Geniuses to live in first graders' bodies. On the other hand, APTX-4869 is intended to be a poison and is generally successful.
 * In Black Cat, Creed 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).
 * As I recall, it was the Doctor character who shot Train, or at least that was the case in the anime.
 * It was Creed in the manga. Doctor did it (on purpose) in the anime, but it ended up having the same effect in both versions.
 * In Mahou Sensei Negima, Weasel Mascot Chamo produces a jar of magical (and illegal) candy that can produce this effect as a sort of illusion (red candy for older, blue for this) both for fun on the part of the girls and as a Strangely Effective Disguise when they become wanted people. It's been implied that The Mind Is a Plaything of the Body, 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 adult forms behave like giddy teens.
 * A Black Lagoon non-Canon Omake has the main cast regress to adolescence and, in Balalaika's case, beyond. For the record, tiny Balalaika is the cutest thing ever.
 * The most shocking ones are Yolanda (the old nun), who was a stunner at 29, and Balalaika's underling Boris, who was Bishounen to the max.
 * England, at one point, dresses up in a toga, wings, and halo, calling himself 'Britannia Angel' before using a star-tipped fairy wand to turn South Korea back into a baby for a strip. It's even become a meme in the fandom.
 * An Ace Attorney doujinshi features Edgeworth turning into a cute little boy thanks to a Fey family recipe gone awry. Given that he was just about to take Wright's place in a case, Hilarity Ensues.
 * Ichinensei ni Nacchattara has this as part of its core concept, with main character Iori going from high school to elementary school, and getting gender-bent in the process. However, he retains his original personality, and he's not happy about becoming an elementary school girl.
 * Doraemon's Non-Serial Movie: Nobita in the Wan-Nyan Spacetime Odyssey 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 temporary.
 * One Piece:
 * 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?
 * Anime-only antagonist Ain from the 12th movie has a more limited version: Each use of her power can make a victim exactly 12 years younger, and she can potentially Ret-Gone a foe who is younger than that. Often she will use it once on a foe, then use the prospect of a second dose to convince the foe to surrender, lest they be erased from existence.
 * 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.
 * Sort of happens in Bleach:
 * The Korean manhwa series Horror Collector depicts Elizabeth Bathory as a young adult who frequently reverts back to her teenage self through her regular baths in blood.
 * In the anime sequel to the hit US cartoon "Lilo and Stitch" called "Stitch", Babyfier (a creature that can turn people into babies) makes 3 appearances.
 * In the first, "Rivals Stick Together", Babyfier is unleashed at a school and turns most of the students and adults into babies. In its second appearance, Babyfier turns the main character and her friends into little kids. Babyfier then pulled a Heel Face Turn and uses its powers to turn a couple of villians into babies.
 * 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, that their teacher 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..
 * In the episode "Ultra Hot Kid's Meal" of 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 The Mind Is a Plaything of the Body, the girls gave the twins a pretty hard time looking after them.

Comic Books

 * X-Men:
 * This was a favorite tactic of the extradimensional media mogul Mojo in the Claremont-era comics. Being Mojo, he's done a Spinoff Babies deal with this twice, called the X-Babies. And said X-Babies turned on him - both times.
 * 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 aged back to adulthood sometime in the 80s, putting his age firmly back in the traditional comic book "fucked if I know" category. This could've eventually become a problem for Charles Xavier, though, since his backstory is tied to a friendship with Magneto before either of them began their current careers... but then he's not in his original body anymore, either.
 * The DCU Fifth Week Event Sins of Youth combined Fountain of Youth and Overnight Age-Up, 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 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 remnants of Atlantis, where everyone is a child (and happy from it) after having drunk from an actual Fountain of Youth.
 * Three of The Smurfs were child-ified 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 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 Rip Van Winkle 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.
 * The Batman comics have Ra's Al Ghul's Lazarus pits. While not -exactly- the same thing, the pits are used at one point in Batman Beyond to restore elderly Bruce Wayne back down to his 40's (as part of a Ra's plot to put his mind into Bruce's body).
 * There was another story from the 60's in which Batman is turned into a toddler, but he retains his intelligence and strength.
 * Judge 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's 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.
 * Horrifically deconstructed with the character of Super Sally Sonic in Grant Morrison's Seven Soldiers of Victory. As a little girl, she was offered a magical artifact that let her grow up until she called off the magic. Eventually she kept the magic on all the time, never aging and retaining the physique of a twenty-something... even when her parents died and legally she could not get any help. It only got worse from there.
 * In The Incredible Hercules, Zeus gets reverted back to childhood, both physically and mentally, by drinking from the waters of the river Lethe.
 * In a "Gnuff" story in the Furry 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.
 * One 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 Etetnal Life in The League of Extraordinary Gentlemen New Traveller's Almanac. They fail to find it, and Alan dies on the trip. After an indecently short period of time, Mina hooks up with Alan Quartermain Jr. Really, that's what happened. It's in the Almanac.
 * In The DCU, the Fountain of Youth is what gave Detective Chimp the ability to speak to other animals and stopped his aging. It's either 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.

Fan Works

 * In Kyon: Big Damn Hero, Nagato provides this function for Kyon, Mikuru, and Kanae. Otherwise the  would make them age by over a year every night.
 * In With Strings Attached, 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 Youth Restoration Spell from My Little Alicorn 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 it works a little bit differently on Alicorns. Hilarity Ensues.
 * The Kids arc of the Mega Crossover fancomic Roommates where the resident magical troublemaker Schmuck Baits ("What does this glowing orb do?!") the other main cast members into it and we learn that some people changed a lot... others not so much. Thank god the magic only lasted thirteen hours.

Film

 * The MacGuffin weapon of the Big Bad in Sky High did exactly this.
 * The titular character in The Curious Case of Benjamin Button has a similar problem: he ages backwards. He is born as an old man, and dies of old age as an infant.
 * The Fountain involves a story within a story about a Conquistador's 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 17 Again.
 * Also the plot of the very early made-for-tv Keanu Reeves movie Young Again, from which 17 Again seems to be heavily drawn. 17 Again is practically an unoffical(?) remake of the film.
 * The Sequel Hook at the end of Pirates of the Caribbean: At World's End 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 MacGuffin in Nutty Professor 2. Professor Sherman Klump invents the fountain of youth formula which lasts temporary.
 * In the Three Stooges short "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 Cirque Du Soleil -- Journey of Man: When The Everyman 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 voice-over narration explains "Years turned to dust. I was young again."
 * The pool house in the movie Cocoon, by way of Alien Phlebotinum.
 * The planet Baku in Star Trek: Insurrection. 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 Not-So-Hidden Elf Village
 * Smurf essence becomes this in The Smurfs when Gargamel used it on Odile's mother, which makes Odile want to get her hands on it.
 * Smurf essence becomes this in The Smurfs when Gargamel used it on Odile's mother, which makes Odile want to get her hands on it.

Literature

 * In Diana Wynne Jones's House of Many Ways, the grown wizard Howl became the Deliberately Cute Child Twinkle partly as a disguise and partly (he said) because he felt he deserved a better childhood than the one he'd actually had.
 * Discworld:
 * Terry Pratchett did this in The Last Continent, combined with Overnight Age-Up, 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 Mrs. Whitlow... It wears off within a few minutes.
 * And in 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 subsequently, permanently becomes her.
 * In The Thief Lord by Cornelia Funke, there is an example of this trope in the form of.
 * In the Blackcollar books by Timothy Zahn, 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 Robert A. Heinlein'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 twenty years old again, complete with a fresh brain that's had the memories from the old one 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 Time Enough for Love and The Number of the Beast) is by far the oldest.
 * Glory Road, while set in a different continuity than the Future History series, also features medical rejuvenation, known on Center as "Long Life" treatment.
 * In Gilded Latten Bones, . 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 Left Behind 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 was used in Charlie and the Great Glass Elevator on Charlie's grandparents. Unfortunately,
 * Due to a quirk in their physiology, the Cheela in Dragons Egg can rejuvenate. Under particular conditions, when their body has been battered enough, it will revert to the plant the Cheela evolved from and heal itself, taking the best part of a lifetime than us 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 Something Wicked This Way Comes can function as either this or as an Overnight Age-Up, 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 A Dirge for Prester John. It's nothing like what the characters expected it to be, but it does the trick.

Live-Action TV

 * The Buffy the Vampire Slayer 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.
 * Star Trek: The Next Generation:
 * The episode "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 (communicator stuck to a toy car anyone?) rather than their usual methods.
 * 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
 * One of the few permanent examples comes from Kamen Rider Den-O which did this out of necessity. The actress who played female lead Hana quit unexpectedly in the middle of the series, but her character was too important to the story to write out. So the producers replaced the twentysomething actress with an eight-year-old. A subplot was added in which Hana was de-aged due to a time anomaly...and stayed that way. In a further subversion, none of the characters, including Hana herself, seemed to have much of a problem with this, and hardly any effort was made to find a cure.
 * 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 Hand Wave 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.
 * The Alien Rangers half-season of Mighty Morphin Power Rangers was an extended plot-arc in which all the regular characters were age-regressed to young children.
 * This also happened in a season 2 episode. In both cases, it seemed to be a strange mix of this and Time Travel- 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 Stargate Atlantis, 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.
 * The Goa'uld Sarcophagi in Stargate SG-1 also mildly 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 sarcophogus have a lifespan of about two hundred years.
 * The Mighty Boosh: 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. Hilarity Ensues.
 * The Doctor Who story 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. Hilarity Ensues.
 * "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 Master later uses the technology in reverse to make the Doctor old.
 * At the end of the 1998 Merlin series, when the titular character is a Cool Old Guy complete with beard,
 * In Sanctuary all of The Five had unnaturally long lifespans
 * Except for.
 * The Twilight Zone 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...
 * 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 LazyTown it occurs in the episode "Little Sportacus" where Sportacus is deaged 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 its never too early and children no matter how young are capable of amazing things.
 * The protagonists of The Legend of Dick and Dom 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 children.
 * In episode 16 of Kyodai Ken Bycrosser, the villains use a weird gun to revert a couple of children (Yeah, children of all people) to infancy, before turning 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.
 * A short-lived late-70s sitcom called Big John, Little John was about this guy who, having unwittingly taken a sip from the Fountain of Youth, was prone to turning into a twelve-year-old at inconvenient times.

Tabletop Games

 * Jhoira from the Magic: The Gathering 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.
 * Of course, Magic has also had the literal card Fountain of Youth for the longest time.
 * Which is how Jodah, Archmage Eternal of the Academy of the Unseen, came to be several thousand years old by the time he met Jhoira.

Theater

 * The finale of the early Cirque Du Soleil show Nouvelle Experience had the inhabitants of a Magical Land change The Everyman hero back into a child before he returned to the world he came from.

Video Games

 * Gilgamesh from 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 dog-kicking Knight Templar and Big Bad who wanted to ; when he reverts, he turns into a cute little boy that everyone loves.
 * A fountain of youth is present on Easter Island in the Sam and Max Freelance Police game Moai Better Blues, the reason that the island is populated by babies.
 * In The Curse of Monkey Island, Guybrush is age-regressed to the form of a young child when he is trapped in the Carnival of the Damned by Lechuck.
 * In Brain Lord, 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 Henry Hatsworth in the Puzzling Adventure grants youth to whoever wears it. Henry's in his sixties/seventies, so when he dons it, he is restored to young adulthood.
 * The "Babality" finishing moves in the Mortal Kombat 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.
 * in Drakengard, everyone who make a pact with a creature has to sacrifice something. Seere sacrificed his "time", which meant that he'd never age, and never grow up. This would possibly be considered Cursed with Awesome except Seere is six and will be so for his whole life. The fact that he's travelling with a pedophile and a cannibalistic elf with a specific taste for children does not help in the least.
 * At the end of Emerald City Confidential,.
 * Borf's weapon in the full-motion video game 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.
 * In the "King's Quest" aeries, there have been 2 cases of this trope.
 * In "King's Quest 2" you will stumble apon 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 villian she will become a young woman again (good or bad depends on what you do).
 * In "King's Quest VII: The Princeless Bride", the female villain is turned into a baby
 * Nightfall Mysteries: Asylum Conspiracy featured a character who was in her mid-thirties or so chronologically but had stopped aging completely at eight or nine. Unfortunately, this resulted in nobody but her normally-aging older brother taking her seriously at first.
 * Purah in The Legend of Zelda: Breath of the Wild; a "failed experiment" she used to make herself young (to prevent dying of old age before Link woke up) worked too well, regressing her age to that of a young child. Ultimately, though, the experiment was a success, as during the Time Skip between that game and Tears of the Kingdom, she has aged about ten years, now an attractive young adult.

Webcomics

 * When Mingmei in The Wotch 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 (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 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 Axis Powers Hetalia England de-ages Korea to make him less annoying.
 * In The Dragon Doctors, 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.
 * A Backstory chapter features a lake of youth that is responsible for the 'deaths' of several colonists.
 * Dream Tales has a whole section of Age Regression conics that feature characters getting younger or older.
 * Morgan of Gender Swapped after pestering Sven long enough to bend the rules for the two of them
 * In El Goonish Shive, Dr. Germahn invented one.
 * Ponce de Leon and his companion look for one in Oglaf, but only come across the fountains of Doubt, Death Water So Good Even Dead People Want It, and Girl (NSFW).
 * In Kevin and Kell the vulture family have a time machine where they sometimes travel to the past. But in some cases if used right can affect someone's age.
 * Dolly who is a clone of Corrie, begins to age faster then 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 that's probably not actually happening.
 * Pain Train has a rather insidious version.

Web Original

 * Happens to both Marie and Heather in Erika's New Perfume, each reduced to three years old. The sequel, Erika's Old Big Sister, centers around Marie regaining her adolescence, but because she so much time in an age that suited her bratty nature far better, she was incapable of readjusting . The epilogue has Heather returning to tweenager-hood, though only time will tell if she chooses to stay that way.
 * Whateley Universe example: retired U.S. Navy officer Sam Everheart was injured trying to save a Hot Scientist 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.
 * SCP Foundation-006.
 * In this Deviant ART animation, a guy ages down, presumably by trading ages with the girl opposite him who ages up.

Western Animation

 * The Emperors New School 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.
 * One episode of Lilo and Stitch involved an experiment known as the "Baby-Fier" that turned its victims into infants.
 * Spider-Man: The Animated Series: The aged crime lord Silvermane's long-standing goal was to find a way to restore his youth. Unfortunately, the Applied Phlebotinum 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.
 * In the Woody Woodpecker short Born To Peck,
 * One Star Trek: The Animated Series 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.
 * Two episodes of the original 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.
 * Codename: Kids Next Door had an episode about it. The Delightful Children from Down the Lane wanted to destroy it.
 * Peach got turned into a baby in Super Mario Bros.: Super Show after falling in The Fountain of Youth. To get her back to her real age, the brothers had to make the waterfall in the fountain go up instead of down and put her in the fountain.
 * In the DuckTales (1987) episode "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.
 * Donald Duck tries to trick his nephews into believing they've found the fountain in "Don's Fountain of Youth." Hilarity Ensues.
 * Quack Pack has the episode "Can't Take a Yolk" where Donald really is regressed to youth—represented here by an Art Shift to his original character design from the 1934 short "The Wise Little Hen".
 * In the Justice League 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.  Of course, one wonders if Morgan can't just cast it again... or just won't.
 * 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.
 * In SpongeBob SquarePants, Plankton develops both a super-aging ray and a de-aging ray. The latter ends up working a bit too well, turning him into an even smaller protozoa.
 * 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, and everyone but Leela (who opted out of the cure, in order to relive the childhood she never had) started regressing into early childhood.
 * And then the trope is parodied when they seek to be cured at the Fountain Of Aging.
 * An old episode of The Care Bears has this. One of the villains ends up turned into an infant and her partner has to watch after her.
 * In an episode of 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 Bump in the Night episode "Baby Jail," Bumpy accidentally swallows some baby formula while trying to feed a baby and becomes one of them.
 * 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.
 * Two instances happened in Kim Possible. The first was when in the Made for TV Movie "A Sitch In Time" where the teamed up bad guys, having possession of time traveling idol, used a device to make themselves toddlers so they could infiltrate the titular hero's youth.
 * The second was in an episode where Ron was continuously sent through a machine that turned adults into babies. He went through so many times that when he finally got back to his own age, he was wearing a diaper.
 * There have been a few episodes in "Darkwing Duck" that feature this.
 * An elderly villain attempted to actually make one of these so 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.
 * In Teen Titans Warp is reduced to infancy after his time suit malfunctions.
 * In one Betty Boop 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.
 * In one episode of the third season of Winx Club, 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 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.
 * The "Little Muriel" episode of Courage the Cowardly Dog has Muriel being turned into a mischievous little girl by a freak tornado.
 * Leave it to 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.
 * Happens to Batman in Batman the Brave And The Bold after he was zapped by Dr. Sivana starting as a teenager, then a toddler, and then a baby.
 * The Problem Solverz 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.
 * In The Mask 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.
 * In the cartoon version of Space Ace, the Infanto Ray made some appearnces; 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.
 * In an episode of "Adventures of Sonic the Hedgehog", Dr. Robotnink plans on defeating Sonic by making him so old, he wont be that 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 Robotnink is too turned into a toddler. At the end Robotnink is turned into an old man.
 * Rocko's Modern Life. 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.
 * A while ago, McDonald's released cartoons on VHS featuring Ronald McDonald and his friends having adventures. One such cartoon saw them go to an amusement park called Birthday world where him and his friends are turned into toddlers and babies.
 * In an episode of the cartoon "Yogi's Treasure Hunt" 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.
 * The final The Fox and The Crow 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.