%% This list of examples has been alphabetized. Please add your example in the proper place. Thanks!

* ''WesternAnimation/AdventureTime''
** The Earl of Lemongrab is an interesting version of this. Physically he's eighteen at the youngest, but because he was born in a laboratory, he's only about one year old chronologically. He acts like a bratty little kid trapped inside the body of an adult, mainly because he IS a very young brat who happens to be an adult, too.
*** He and his brother/clone/[[AmbiguouslyGay boyfriend]] have kids together... and they're STILL immature manchildren.
** Jake also very much resembles this at times, to the point where one wonders if he's an English Bulldog, as he closely resembles physically, or if he's a [[BigFriendlyDog Golden Retriever]]. His son Kim Kil Wan even says that Jake acts like a child.
** Ice King also acts like this as he throws tantrums and treats being grounded literally
** Cinnamon Bun is shown to be "basically 30" yet he owns a night light and cries a lot like a child. He becomes less of this when he meets Flame Princess and starts working for her
* Richard Watterson from ''WesternAnimation/TheAmazingWorldOfGumball''. If anything, he's even ''more'' immature than his own offspring.
** Justified in that this was how his mother raised him. After [[spoiler: his father, a conman and literal rat]] left, Jojo Watterson raised Richard to be unable to do anything himself and instill a fear of everything in him, hence why he is the way he is today. We learn the latter when she attempts to do the same with her grandchildren in an episode (but Nicole put a stop to that.)
* ''WesternAnimation/AmericanDad'':
** Stan Smith as he is 42 years old but he has shades of acting childish at times. He said that he wanted a pony and then there was an episode where Stan decided to relive his childhood as it was once ruined by his father, who left him and his mother on Stan's 8th birthday
** Also Roger the alien. He was revealed to be over 1600 years old yet he throws tantrums and some of his personas and disguises are that of children.
* Sterling Archer in ''WesternAnimation/{{Archer}}'', despite being a world-class secret agent, it also a brainless and immature MommasBoy who is often more interested in things like pirate lacrosse or ''Film/{{Aliens}}''-style space robots than the safety of his companions.
* ''WesternAnimation/BatmanBeyondReturnOfTheJoker'': ComicBook/TheJoker points out that for all the fear he invokes being TheCowl, Batman is really this trope:
--> "I must admit, it's sadly anti-climactic. Behind all the sturm und batarangs, you're just a little boy in a playsuit, crying for mommy and daddy! It'd be funny if it weren't so pathetic... Oh, what the heck, I'll laugh anyway! ''([[LaughingMad Mad Laughter]])''"
** Years later the second Batman, Terry [=McGinnis=], throws the Joker's insults right back at him by pointing out that the Joker himself is also this trope as his fixation with the original Batman was childishly pathetic and, once you take away all the garish make up and fancy props, the Joker was really nothing more than a stupid, overgrown kid trying to make people laugh at a joke that wasn't all that funny to begin with, angering the Clown Prince of Crime greatly.
* Several characters in ''WesternAnimation/BatmanTheBraveAndTheBold,'' most notably ComicBook/PlasticMan.
* The animated version of ''WesternAnimation/{{Beetlejuice}}''. The majority of the inhabitants of the Neitherworld are fairly mature. Beetlejuice most likely expired in his late 30s, but he's mentally about eight, and a childish prankster who hangs around with a twelve-year-old Lydia in an IntergenerationalFriendship.
* Jerry in ''WesternAnimation/TomAndJerry'' is mentally about four. To be fair he's a mouse, but Tom has the intelligence of a teenager.
* TheEeyore of ''WesternAnimation/ChalkZone'', Mr. Wilter. Lampshaded in his EvilTeacher roles.
* Mr. Delmas of ''WesternAnimation/CodeLyoko'' has shades of this--plays games on his computer, for instance.
* Dexter's Dad from ''WesternAnimation/DextersLaboratory''.
* Captain Hero from ''WesternAnimation/DrawnTogether'' is revealed in the pilot episode to be a 28 year old superhero yet he wears diapers, wets the bed, and throws tantrums. He also crosses into a psychopathic version of this frequently and is considered to be very dangerous through this tripe.
* ''WesternAnimation/TheFairlyOddparents'': Timmy Turner will apparently become this in the future, according to his show's LiveActionAdaptation.
** Every adult in Dimmsdale is this.
** Cosmo, despite being thousands of years old he acts immature at times, and still wears diapers.
* Peter Griffin from ''WesternAnimation/FamilyGuy'' wavers between this and PsychopathicManchild.
--> "I wanna be the baby!"
* While he technically isn't this yet, Debbie Douglas expresses hope that her son, Duncan becomes one of these in ''WesternAnimation/{{Freakazoid}}'' because he's not exactly opposed to it.
-->'''Debbie:''' "You'll be a big strong man-child, still lifting weights in your room when you're forty!"
-->'''Duncan:''' "Cool! That way I can ''really'' buff up, and save some money!"
* Philip J. Fry from ''WesternAnimation/{{Futurama}}'' has since the beginning of the series been the epitome of Generation X (or Y perhaps): A big 20-something man-child. He plays video games, watches TV, drinks soda by the gallon, does anything if he's dared to do it, and has no ambition in life except for one... love. He's that flat mate that you knew who just can't seem to truly grow up (...and is often fully aware of it. Refer to his one ambition for why this is a source of gloom for him often), but at least he's cool to hang out with.
** The new season reveals that Fry is 35. Adult Child, ho!
** Actually, he might be as old as 31 since in one episode, he and the Planet Express crew [[spoiler: were affected with chronotons that reversed their aging and then they negated the effects by going into the Fountain of Aging.]] And they, sans the Professor were [[spoiler: reborn in the series's revival.]]
** [[spoiler: Fry is his own grandpa]] and that caused genetic damage, which caused his brain to develop abnormally.
** Also, 'cause of that whole [[spoiler:Lars is an alternate Fry plot point]] in [[TheMovie Bender's Big Score]], this puts Fry's age at just older than '''''2037 years old'''''.
** Doctor John A. Zoidberg also qualifies as he is over 80 years old yet he plays with toys such as a slinky and cries and throws tantrums whenever Hermes is mean to him.
** Bender also has shades of this too as he throws tantrums and even went as far as "running away" from the company he works for when the crew insults his cooking.
** Also, Zapp Brannigan, though that's more disturbing as he is in a position of power, with the authority to get people killed in mass amounts. Which he fully utilizes to do just that.
** Lrrr, ruler of Omicron Persei 8 also has some traits of this as he is a wannabe alien overlord yet he throws tantrums, loves eating junk food, and at some point has a childish love for animals, which his wife likes.
* ''WesternAnimation/GravityFalls'' character Soos is described as this by the show's promotional material and website. Given that he's a semi-CloudCuckoolander who's OneOfTheKids, this is a given.
** Even said so by Grunkle Stan in the season 1 finale, saying "you're a good man...child, Soos".
** Deputy Durland and Sheriff Blubs also qualify as they both love reading spooky ghost stories and making friendship bracelets and went candy hunting on Halloween. They also giggle like children a lot. Dorland is shown to be a bigger one than Blubs.
* Glickenstein and King Malbert from ''WesternAnimation/{{Igor}}''.
* Lucius from ''WesternAnimation/JimmyTwoShoes''.
* The titular character of ''WesternAnimation/JohnnyBravo''. He's in his mid to late 20s, still lives with his mother, throws temper tantrums when he doesn't get what he wants, spends much of his time playing with toys, has a lot of childlike interests, and he sleeps with a teddy bear and baby blanky often while sucking his thumb, on the other hand he's pretty perverted and constantly hits on women.
* ''WesternAnimation/JohnnyTest'':
** Dukey is an 11 year old dog ( he should be 77 in dog years) yet he sounds like a 20 year old. He plays video games, cries whenever he thinks his birthday is forgotten, dresses like a teenager, and often whines.
** Hugh Test, Johnny's dad has some traits of this as he freaks out over the smallest things, obsessively cooks meatloaf, and is revealed to secretly love video games
** Mr. Black and Mr. White are federal agents in their 30's yet they both love candy and are very irresponsible as whenever they screw up in something, they rely on the Test family to help fix whatever messes Mr. Black and Mr. White themselves create
** Most of the citizens of Porkbelly also fit into this.
* Luanne Platter from the later episodes of ''WesternAnimation/KingOfTheHill'' when she began dating and eventually married a moronic, middle aged, hillbilly "Lucky" to the point where she acts like a five year old most of the time.
** Peggy Hill was once described as a woman-child, possibly due to her self-centeredness.
** [[AdultsAreUseless Most of the adults are immature in some way]], to the point where ''[[TheDitz Bobby]]'' snaps after his grandpa and step-grandma leave him to care for grandpa's infant son and Luanne and Lucky prove to be ridiculously irresponsible parents (I think Luanne is pregnant at this point).
** Hank's boss, Buck Strickland, is so childlike to the point where Hank always have to bail him out whatever trouble he gets into.
* ''WesternAnimation/KingRollo'''s daily schedule is indistinguishable from that of a five-year-old boy. His kingdom doesn't seem to suffer too much from his behaviour, though.
* ''WesternAnimation/TheLegendOfKorra'': Despite having grown up an orphan living on the streets, Bolin is pretty immature for his age and circumstance. Justified in that his older brother Mako has done a lot to shelter him from the worst aspects of their lives, and essentially raised him on his own. There's a tinge of deconstruction to Bolin's treatment because it shows the consequences of raising a manchild on the person who shelters them from reality. Mako is emotionally stunted due to having fixated for so long on raising Bolin. His romantic relationships feature him playing the part of [[DeclarationOfProtection a protective figure]], and when a girl proves she doesn't need his help he loses interest. [[CharacterDevelopment They both eventually get better.]]
** Also Aang and Katara's son Bumi although he's a middle aged man he acts like a hyperactive, childish prankster, his sister Kya lampshades this at one point:
-->'''Kya''': Even though you're the oldest you've always acted like the youngest
* WordOfGod on ''WesternAnimation/{{Madagascar}}'' and ''WesternAnimation/ThePenguinsOfMadagascar'' is that RidiculouslyCuteCritter Mort the mouse lemur, who looks and acts like a child, is [[OlderThanTheyLook the lemur equivalent of a thirty-five-year-old]]. Julien has tendencies this way as well; he's constantly demanding attention and throws tantrums when he doesn't get what he wants, but at the same time gets very upset and starts talking to his plush toys when he's lonely, and [[spoiler:it's revealed via the magic of the Golden Squirrel that his greatest desire is simply to have his friends near him]].
* While it's not clear how old the Ferocious Beast in ''WesternAnimation/MaggieAndTheFerociousBeast'' is, he appears to be relatively physically mature. However, he acts more like a four-year-old, and six-year-old Maggie is far more levelheaded and responsible in comparison.
* Peppermint Larry from ''WesternAnimation/TheMarvelousMisadventuresOfFlapjack'' became this in the second and third season. Heavily lampshaded [[spoiler: during his BiggerBad, EvilAllAlong, TheDitz and TookALevelInDumbass roles]].
** Captain K'nuckles is also a good example of this in addition to be a huge CloudCuckoolander. He is addicted to candy, throws some tantrums, and sometimes acts Flapjack's age. He is even revealed to be illiterate and can't count to four.
* Toki Wartooth from ''WesternAnimation/{{Metalocalypse}}''. He has a teddy bear, eats candy, collects model airplanes, says "Wowee", and has a childish naivety for certain subjects such as sex. He also drinks, swears, and [[spoiler:goes on the occasional murderous rampage]].
* ''WesternAnimation/MoonbeamCity'': [[CanadaEh Canadian-born]] police officer [[TheRival Rad Cunningham]]. [[PsychopathicManchild So]]. [[NotAllowedToGrowUp Very]]. [[UpToEleven Much]], to the point that it actually becomes weaponized by several characters in multiple episodes in order to resolve the plot.
* Texas ''and'' Tooley in ''WesternAnimation/{{Motorcity}}''. When the former is telling the latter about "his" exploits, Tooley even lies down like a kid would.
* ''WesternAnimation/MrBogus''.
* The main characters of ''WesternAnimation/MyLittlePonyFriendshipIsMagic'' are all responsible young adults, more or less, setting aside when they need to be relatable to young children. That said:
** Pinkie Pie [[GenkiGirl acts like an excitable six year old]] and seems [[{{Cloudcuckoolander}} incapable of holding a serious conversation or actually reading the mood]]. She can be surprisingly neurotic and [[InnocentlyInsensitive insensitive]] whenever events aren't as exciting as possible or if she isn't getting the kind of attention she wants.
** Rarity has DramaQueen tendencies that are usually PlayedForLaughs, but, at their worst, they'll cause her to lock herself in a room and refuse to come out like a petulant child and sometimes breaks down and cries with little provocation. Her younger sister can hold it together a lot better than her most of the time.
** Princess Luna tries to assert an air of cool authority, but it doesn't take much for the mask to break and this trope to come out. Endlessly enthusiastic about everything, she has a HairTriggerTemper and will sulk endlessly if she doesn't get her way. She is desperate for authority, but tends to resent it when it is actually given to her. Appropriately she [[OneOfTheChildren gets along very well with children]].
* Oggy from ''OggyAndTheCockroaches''.
* Kyösti Pöysti in ''WesternAnimation/{{Pasila}}''.
* Dr. Doofenshmirtz from ''WesternAnimation/PhineasAndFerb'' is physically in his 40s, but mentally around 10.
* The Mayor from ''WesternAnimation/ThePowerpuffGirls'' eventually wound up becoming this.
* Ray Stantz, one of ''WesternAnimation/TheRealGhostbusters'', is a more subdued version of this trope. While mature and perfectly capable of looking after himself, Ray still possesses an almost childlike idealism and enthusiasm for life. Ironically, this actually helps the Ghostbusters lure the Boogieman when they learn that the monster is attracted to people who think like children.
* Pops from ''WesternAnimation/RegularShow'', save the fact that he's the opposite of LiteralMinded.
** Rigby is this too. He may be 23, but he acts like an out of control teenager most of the time.
** Mordecai, to a lesser extent. He's a lot more level-headed and less impulsive than Rigby, but just as eager to slack off and do childish things.
* Homer Simpson from ''WesternAnimation/TheSimpsons'',. Originally he was just a stereotypical BumblingDad but eventually developed into, in the shows own words "a drunken, childish buffoon". A combination of low intelligence, emotional immaturity brought on by a neglectful father and absent mother, and simple CharacterDevelopment turned him into a ManChild.
** Bart encounters a former student of Springfield Elementary who's basically an adult version of him. He never matured beyond being a 10-year old prankster. He still lives with his mother well into his late teens, doesn't have a job, dresses like a child, and spends all his time and energy on childish pranks. Bart attempts to help him by getting him a job for Krusty The Clown, but what really turns him into a mature person is [[spoiler: getting a girlfriend.]]
* Randy Marsh, Stan's father from ''WesternAnimation/SouthPark'', has become this in recent years.
* ''WesternAnimation/SpongebobSquarepants''. He's old enough to hold down a job and live on his own, but doesn't drive, doesn't pay the electric bill, doesn't have any money of his own, and he's been referred to as a kid on multiple occasions.
** & Patrick Star [[UpToEleven even more so.]]
* The Warden of ''WesternAnimation/{{Superjail}}''. Even lampshaded by the Mistress.
* ''WesternAnimation/SuperNoobs'':
** Memnock and Zenblock look like brutes as they are aliens and virus warriors who are apparently in their early 20's yet they are shown to be very immature and childish. They both love going to amusement parks to ride rollercoasters, went on a kids monorail ride at the space zoo, become very excited when going on rides, especially in situations that were not rides at all. They went trick or treating, love eating candy and junk food, went to a build a bear knockoff store to craft their own plush puppies, played with dog toys, played a cooking sim video game meant for little kids, which they got addicted to, throws tantrums, and [[VitriolicBestBuds fought and bickered at each other very immaturely]]. Of course some of this is understood as they have a desire to understand Earth culture and Memnock in particular appears to be the more childish of the two as he seems to [[CampStraight not care whether a particular activity is masculine, feminine, or childish]]. Zenblock in particular also likes taking naps and sleeps with a teddy bear in his arms occasionally.
** General Blorgon, Hedies, and Tecknut also have shades of this as they love Earth culture as much as Memnock and Zenblock do
** Count Venamus literally goes into his 12 year old self in "Noob vs Venamus 12. Because of this, he gets fascinated with light up sneakers and candy.
* Amethyst from ''WesternAnimation/StevenUniverse''. Some of her antics are reminiscent of a teenager acting out. Her yelling "I don't wanna!" when Garnet tells her to go back to the temple in "Tiger Millionaire" is a good demonstration. [[spoiler:She's actually quite young in comparison to the other Gems, having been created on Earth instead of hailing from Gemworld.]] This is further enforced by the fact that during Greg's flashback in "Story for Steven" she's much younger in appearance than she is now.
** Greg was definitely this in his earlier years, refusing to work to support himself and mooching off other people for food. He's matured somewhat, but still prefers living in a van to a house and keeping a relatively unkempt appearance.
* ''WesternAnimation/{{Thundercats}}'': At the beginning of the series, Lion-O was placed as a child in a stasis pod to keep him from aging while Jaga drove their spaceship to the third planet. His pod was damaged and functioned imperfectly, so unlike the others he still physically matured inside and he eventually left it as an adult, thus making it a case of JustifiedTrope.
* ''WesternAnimation/TheRidonculousRace'':
** Surfer dudes Geoff and Brody are 19 years old yet they both act like children
** Owen becomes this in the show as he is also 19 yet he carried a teddy bear around with him until he accidentally ate it
** Daters Ryan and Stephanie are said to be in their 20's yet they both throw tantrums and it was exaggerated after they became the haters in which their insults towards each other were immature
** Step Brothers Chet and Lorenzo are said to be 17 years old, yet their nonstop bickering is very immature. Another contestant, Junior, who is younger than Chet and Lorenzo even asks how old they both are.
** Josee, the ice dancer is an Olympic figure skater in her 20's who is a silver medalist yet she shows affection towards her lucky rabbits foot and she throws tantrums whenever she finishes legs in places other than 1st much to the chagrin of her racing partner, Jacques.
** Rock and Spud, who form the Rockers team are said to be in their late teens yet they are implied to be rehearsing music in the garages of their families and Spud in particular is shown to be very lazy and motivated by junk food such as Choco oinks.
* ''WesternAnimation/TimeSquad'': Buck Tudrussell is shown to be a man somewhere in his 30's yet he frequently acts much like the age of his 8 year old time traveling partner, Otto as Tudrussell sometimes throws tantrums, sleeps with a teddy bear, and sucks his thumb. His other time traveling partner, Larry 3000 even calls Tudrussell a man child in " Ex Marks The Spot".
* ''WesternAnimation/TotalDrama'':
** Chris, the host of the show is revealed to be a 30 year old man, yet he is a {{Narcissist}} who throws tantrums and sleeps with a teddy bear in his arms at night while sucking his thumb, and comes up with challenges that look as if a toddler created them. He is literally a grown up SpoiledBrat.
** Brick also has shades of this as he is a military cadet who refuses to leave anyone behind but he ScreamsLikeALittleGirl, wets his pants, and sleeps with a night light on.
* ''WesternAnimation/UncleGrandpa'' takes this to extremes. He's shown be a [[{{Cloudcuckoolander}} very bizarre]] man who lives in his large R.V. and takes children on adventures to solve their problems.
* ''WesternAnimation/XiaolinShowdown'':
** Jack Spicer is a young man who is apparently in his early 20's there have been many signs of him acting very childishly. These hints include [[ScreamsLikeALittleGirl girly screaming]] , constant whining, and he was revealed to often sleep with a night light on. He also plays with the shen gong wu as if they were toys. This is mostly due to the fact that his rich parents did not raise him as much as they should as they often send him money in a vain attempt to make up for this.
** Kimiko's Dad is a child on the inside. Or so she once told her friends.
* As with the comic example above, Captain Marvel in ''WesternAnimation/YoungJustice'' is really a kid. However, none of the teens know his real form, so he definitely comes off as being this trope.