History Main / OnlyChildSyndrome

** Rainbow Dash couldn't bear being near her parents because they gave her too much attention as their only daughter, as shown in "Parental Glideance". They are just proud of her accomplishments, but they can't stop bragging about her in public.

** Rainbow Dash couldn't bear being near her parents because they gave her too much attention as their only daughter, as shown in "Parental Glideance". They were just proud of her accomplishments, but they couldn't stop bragging about her in public.

* ''Film/{{Adam}}'': Beth tells her Dad that she must scare people off because of being an only child.

Only children are often seen as having the best of both worlds. Not only do they get all of their parents attention and love, they don't also have annoying younger siblings to take care of or bossy older siblings to listen to. However, this isn't always the case.

* Muffin Heeler from ''WesternAnimation/{{Bluey}}'' is Stripe's only child. She is also an absolute nightmare.

* The Literature/{{Discworld}} of Creator/AAPessimal sees two only daughters, each born to Grand Ducal families in what is left of the Discworld's UsefulNotes/{{Russia}} after its version of TheGreatPoliticsMessUp. Olga Romanoff and Natasha Romanoff are cousins. If they agree on one thing, it is that as only children they were deprived of a chance to fight TheGloriousWarOfSisterlyRivalry with an actual sibling. Therefore they have no choice other than to fight at one step removed, as cousins.

* ''Literature/TheBabysittersClub'': Stacey is an only child, and it shows during the books where she and Mary Anne accompany the Pike family on their summer vacations to Sea City. It's very obvious that she's used to not having to show consideration for siblings, as she keeps prioritizing her own plans over Mary Anne's and even over minding the children. Incidentally, Mary Anne is ''also'' an only child (until her father marries Dawn's mother partway through the series), but averts the trope; the fact that she had only one parent and that parent was quite strict and is implied not to have been around as much due to a demanding work schedule is likely the reason for this.

* ''Series/NewGirl'': Schmidt's mother micromanaged the hell out of his childhood since he was her only son and now he's a micromanager himself.

* ''Literature/TheBabysittersClub'': Stacey is an only child, and it shows during the books where she and Mary Anne accompany the Pike family on their summer vacations to Sea City. It's very obvious that she's used to not having to show consideration for siblings, as she keeps prioritizing her own plans over Mary Anne's and even over minding the children. Incidentally, Mary Anne is ''also'' an only child (until her father marries Dawn's mother partway through the series), but averts the trope; the fact that she was raised by a single parent who was pretty strict with her and also wasn't around as much due to working a job with a demanding schedule is likely the reason for this.

* ''Literature/TheBabysittersClub'': Stacey is an only child, and it shows during the books where she and the more considerate Mary Anne[[note]]who was raised an only child, but by now has grown used to having stepsiblings[[/note]] accompany the Pike family on their summer vacations to Sea City. It's very obvious that she's used to not having to show consideration for siblings, as she keeps prioritizing her own plans over Mary Anne's and even over minding the children.

* ''Series/{{Charmed 1998}}'': Paige is an only child and dd not take well early on to moving in with the others and dedicating herself to becoming a Charmed One. She got used to it after her past life destroyed her loft.

** In the season six episode, "Top Bolt", The pegasus Vapor Trail was an only child whose parents piled attention on her, barely giving her a second to herself. Because of this, Vapor Trail developed an aversion to being in the spotlight, and was content with acting as the "wing pony" to her best friend Sky Stinger.

[[WMG:[[center:[[AC:This trope is [[https://tvtropes.org/pmwiki/posts.php?discussion=1581133049099388900 under discussion]] in the [[https://tvtropes.org/pmwiki/posts.php?discussion=13222107430A61495000 Trope Repair Shop]].]]]]]]

All this is in spite of the fact that it has been repeatedly shown in scientific studies that there is no measurable difference in the personalities of only children compared to those with siblings (at least not most of the time - there are a lot of perfectionists in the only child world). Only children also tend to mature faster.

!!Examples

[[folder:Film]]

[[folder:Live Action TV]]

[[folder:Webcomics]]

[[folder: Western Animation]]

[[/folder]]

!Examples

[[AC:Fan Works]]
* The Literature/{{Discworld}} of Creator/AAPessimal sees two only daughters, each born to Grand Ducal families in what is left of the Discworld's UsefulNotes/{{Russia}} after its version of TheGreatPoliticsMessUp. Olga Romanoff and Natasha Romanoff are cousins. If they agree on one thing, it is that as only children they were deprived of a chance to fight TheGloriousWarOfSisterlyRivalry with an actual sibling. Therefore they have no choice other than to fight at one step removed, as cousins.

People procreate. [[MassiveNumberedSiblings Some do it a lot]]. [[MyBiologicalClockIsTicking Some really want to do it before time runs out]]. [[NotWantingKidsIsWeird Some don't want to do it at all]].

Yet, in fiction, people only procreate [[LawOfConservationOfDetail if it's relevant to the plot]], and that includes {{Backstory}}. Most fictional characters do not have canonical relatives at all, and far fewer have siblings unless they are required by the plot. Authors employ this trope for every reason between heightening the angst of ParentalAbandonment and excusing romance {{Genre Blind}}ness.

This is even more true in adoptive families. Fictional characters rarely adopt more than one child, {{happily|Adopted}} or [[OrphansOrdeal otherwise]], unless the plot calls for it. Families with both adopted and biological children are even rarer.

In a WorldOfNoGrandparents, all parents are also usually only children, which means no one can raise orphans except butlers, strangers, or [[OrphanageOfFear the school of hard knocks]]. Usually, the orphan in question is also an only child.

In shojo romances, the PluckyGirl heroine has seemingly avoided all interaction with the opposite sex until meeting the TroubledButCute school bully. In most cases, PluckyGirl doesn't have any brothers. If she does, they are too young to provide any model of what she is dealing with, or old enough to either be in the parenting role or live far away.

{{The Chosen One}}s, [[LastOfHisKind Last of Their Kind]] and other such fulfillers of ancient prophecies not only suffer from Only Child Syndrome, their entire heritage suffers from it. When a man curses a family's name or [[SinsOfOurFathers goes after descendants for revenge]], don't be surprised if 100, 200, 1000 years later, [[SingleLineOfDescent there is only one descendant]]. All generations previous must have felt bad for the eventual fate of TheHero and only had one child each to make the revenge short. Presumably in a more realistic story, if being the descendant of some ancient ruler means that one has a right to the throne, for every FarmBoy who becomes king, there are 373 cousins who MissedTheCall. One wonders how they feel about this.

Most examples of ParentalAbandonment in a WorldOfNoGrandparents also feature Only Child Syndrome. Oh, the {{Wangst}}.

Expect some people with Only Child Syndrome to have a few subtleties. Such as, for example, most people who can point out Only Child Syndrome in RealLife can say an only child is often used to never having to compete with anyone else for parental attention, or feeling like they're the only person against the world. Or even a subtle disrespect or having never truly learned to live or communicate (in the worst cases) with others their age. This is in spite of the fact that it has been repeatedly shown in scientific studies that there is not a measurable difference in the personalities of only children as compared to siblings (at least not most of the time - there're a lot of perfectionists in the only child world). Sometimes this also happens with MiddleChildSyndrome, too. Only children also tend to mature faster.

Some stories use HaremGenre situations to replace the character's lack of a family.

This trope tends to affect {{fanfic}}s in two ways: writers may convert a [[LikeBrotherAndSister sibling-like bond]] onto unrelated characters, or create OriginalCharacter siblings.

Contrast MiddleChildSyndrome, MassiveNumberedSiblings. May result in SiblingsWanted.

!!Examples:

* In the first season of ''Anime/{{Bakugan}}'', the only main character who is definitely not an only child is Julie, who has an older sister. The other brawlers don't seem to have any siblings. The second season introduces Mira, whose older brother Keith [[spoiler:is actually Spectra]], and Baron, who has [[MassiveNumberedSiblings several younger siblings]], but we don't know anything about Ace's family. In season 3 there's Fabia, whose older sister is the queen of the planet Neathia. In total, there are 12 main characters in 3 seasons and only 4 of them are confirmed to have siblings.
* Averted in ''Manga/BlackJack''. You would think that an AntiHero Doctor with notable ParentalAbandonment issues would be an only child, right? Well... no, actually. He has a half-sister from his father's second marriage. They just don't keep in touch because she doesn't like him very much.
* Zig-zagged in ''Anime/{{Doraemon}}''. Gian has a younger sister, but all the other human kids (including Nobita, Shizuka, Suneo, and Dekisugi) appear to be only children. Suneo actually has a younger brother but he lives in America and very rarely appears (and is almost never mentioned). As for Doraemon, he also has a younger sister but she isn't seen very often.
* Miaka and almost all the Suzaku Seven in ''Manga/FushigiYuugi'' have siblings, while Yui and the Seiryuu Seven (sans Amiboshi and Suboshi) were only children (we're not exactly sure about Tomo, Miboshi, and Ashitare, though). However, the Suzaku Seven's siblings were either dead, killed off halfway through the story, or unimportant and thus were never mentioned. Miaka's older brother Keisuke had a minor role in the manga but played a more important role in the anime.
* Lampshaded in ''Manga/{{Horimiya}}'' when Hori points out how weird it is that most members of the cast are only children (only four recurring characters actually have siblings, and one of said siblings is dead).
* Justified in ''Manga/JoJosBizarreAdventure'' - Joestars, whether by blood or by marriage, have a ''really'' unfortunate tendency to die before having more than one child. Even when they aren't killed, ''something'' gets in the way (Jotaro's father is a famous musician who's always on tour - and when we say "always", we mean "he never appears in the series"). Averted with Joseph Joestar, who had a legitimate child (Holly, Jotaro's mother)... and then had an affair with a Japanese college student that resulted in Josuke. His wife was ''pissed'' when she found out.
* Averted in ''Manga/KaguyaSamaLoveIsWar''. All but one of the student council members (Miko) have at least one sibling. This even extends to the supporting cast, where only Osarai and Hayasaka are confirmed to be only children. And even those three are justified since Miko and Hayasaka's parents constantly being busy with work ties into their backstories, while Osaragi's parents are implied to be divorced.
* Averted in ''Franchise/LyricalNanoha''. Given how strong a theme family is throughout the franchise, most characters have at least one sibling (adopted or otherwise), even if those siblings have nothing to do with the plot or are only mentioned in supplementary material. The ones who don't are justified by either being orphans or {{Artificial Human}}s who were never officially adopted.
** Just to put in perspective how prevalent this is: the second ''[=StrikerS=]'' Sound Stage has a scene where two minor characters are talking about their families. Both of them mention having multiple siblings, none of who are ever seen or even mentioned outside of this one conversation.
* This seems to be the case in ''Manga/MahouSenseiNegima''. Of the class of 3-A, only four characters have a confirmed sibling - the Narutaki twins (each other), Makie (younger brother), and [[spoiler:Zazie (twin sister)]]. Ayaka would have had one, but he died at birth, and Natsumi has to pretend Kotaro is her little brother, but she doesn't see him this way. Negi has Nekane, though it is revealed she is actually his cousin. This does imply Nagi had one though, most likely an elder brother.
* Every mermaid in ''Manga/MermaidMelodyPichiPichiPitch'' is either an only child or they're all sisters. Because most of the other races are off doing their own thing and mermaids have a thing about not revealing their identity to humans, the only way that most of them reproduce is by having their [[MineralMacGuffin pearl]] create a new mermaid when they die. Caren and Noel refer to themselves as twins despite never even having met before the story starts just because they were born two minutes apart, and some of the songs refer to Aqua Regina as a symbolic "mother", but the FridgeLogic says they must all be only children.
* In ''Manga/MyBrideIsAMermaid'', [[AlwaysInClassOne Class 2-1]] has 8 cast members in it (Nagasumi, Sun, Mawari, Saru, Lunar, Class President, Kai, Akeno). Of them, only Saru and Akeno have any siblings (just one each) and four are explicitly only children.
* ''Manga/{{Naruto}}'':
** Of the 12 Konoha genin, only Kiba, Sasuke, and Hinata have any siblings, and then it's only one (an older sister, an older brother, and a younger sister respectively), while Gaara, Kankuro, and Temari are all siblings. A strange occurrence, considering that their clans are supposed to produce [[ChildSoldiers new soldiers]] to defend their ''entire'' nation. Of course, we know nothing about the family life of many of them, and there is a high number of [[ParentalAbandonment dead parents]] so it's likely a lot of them didn't even have the ''chance'' to have many kids.
** This even persists into the next generation in ''Manga/{{Boruto}}'', this time without the dead parents excuse. Of all the members of Naruto's generation, only [[spoiler:Naruto and Hinata]] have two kids, with every other couple having only one. Shikamaru stated in Part 1 that he wanted a son and a daughter when he grew up, however he only ended up having [[spoiler:a son with Temari]].
* In ''Manga/OnePiece'', the only major characters with biological siblings are Boa Hancock (two younger sisters) and [[spoiler:Sanji (who left behind a whole SiblingTeam when he ran away as a child)]]. Nami and her sister were adopted orphans, Luffy's brother turns out to have been adopted, and the rest of the Straw Hats are known or assumed to be only children. There are a few minor siblings like the Nyaban Brothers, the Decalvan brothers, Hotori and Kotori, etc. The series does much to say that [[TrueCompanions it's not necessarily your]] [[HappilyAdopted blood that makes you family]], though.
* Most lead Pretty Cures from the [[Anime/PrettyCure franchise]] are only children, with the exception of [[Anime/FutariWaPrettyCure Nagisa]], [[Anime/GoPrincessPrettyCure Haruka]], [[Anime/HugttoPrettyCure Hana]], and [[Anime/FutariWaPrettyCureSplashStar Saki]]. However, [[spoiler:[[Anime/HeartcatchPrettyCure Tsubomi]] gets a newborn sister in the final episode]] and [[Anime/FreshPrettyCure Love and Setsuna]] become adopted sisters after the first half of the season. [[Anime/SuitePrettyCure Hibiki]] is actually the only lead Cure who suffers from being an only child while [[Anime/SmilePrettyCure Miyuki]], [[Anime/DokiDokiPrecure Mana]], and [[Anime/HappinessChargePrettyCure Megumi]] don't seem to care.
** Most Pretty Cures are only children. The only Cures who have siblings are the five mentioned above, [[spoiler:[[Anime/FutariWaPrettyCure Hikari]]]], [[Anime/FutariWaPrettyCureSplashStar Mai]], [[Anime/YesPrettyCure5 Rin, Komachi]], [[Anime/FreshPrettyCure Miki]], [[spoiler:[[Anime/HeartcatchPrettyCure the whole Heartcatch Team]]]], [[Anime/SuitePrettyCure Kanade]], [[Anime/SmilePrettyCure Akane, Nao, Reika]], [[Anime/DokiDokiPrecure Alice]], [[spoiler:[[Anime/DokiDokiPrettyCure Aguri]]]], [[Anime/HappinessChargePrettyCure Yuko, Iona]], [[Anime/GoPrincessPrettyCure Towa, Minami]], [[Anime/HugttoPrettyCure Emiru]], [[Anime/StarTwinklePrettyCure Lala, Elena]], [[spoiler:[[Anime/HealinGoodPrettyCure Chiyu]]]], and [[Anime/HealinGoodPrettyCure Hinata]].
** This means the remaining Cures who don't have siblings are (besides the mentioned lead Cures) [[spoiler:[[Anime/FutariWaPrettyCure Honoka]]]], [[Anime/YesPrettyCure5 Urara, Karen, Kurumi]], [[Anime/FreshPrettyCure Inori]], [[spoiler:[[Anime/HeartcatchPrettyCure nobody of the Heartcatch Team]]]], [[Anime/SuitePrettyCure Ellen, Ako]], [[Anime/SmilePrettyCure Yayoi]], [[Anime/DokiDokiPrecure Rikka, Makoto]], [[Anime/StarTwinklePrettyCure Madoka, Yuni]], [[Anime/GoPrincessPrettyCure Kirara]], [[Anime/HugttoPrettyCure Saaya, Ruru, Homare]], and [[Anime/HappinessChargePrettyCure Hime]]. [[Anime/YesPrettyCure5 Urara]] and [[Anime/SmilePrettyCure Yayoi]] are {{Justified| Trope}} due to having a dead [[MissingMom mother]] and [[DisappearedDad father]] respectively before their parents could conceive a second child. [[Anime/HugttoPrettyCure Ruru]] is justified since she's a robot.
* In ''Manga/PokemonAdventures'', there is a rotating cast of 21+ main characters, yet only two are confirmed to have a sibling: Green has his older sister Daisy, and she's most likely only there because she exists in the games. Moon has a yet-to-be-revealed older sister. That said, in ''Pokemon Emerald'' the rival has a younger brother, however Sapphire never got one most likely due to it being odd if [[RememberTheNewGuy a previously unknown sibling popped up]]. Platinum should also have a younger sister, but it's explicitly stated almost immediately that she's an only child. [[spoiler: It is heavily implied that Platinum is Moon's older sister, meaning that Moon must've been born sometime after the events in Sinnoh.]]
** By contrast, the main characters of the ''Anime/{{Pokemon}}'' tend to avert it. Only Ash, Dawn, Iris, Serena, Sophocles, and Goh are confirmed or implied to be only children, while the rest have at least one known sibling. [[note]]Misty has Daisy, Violet, and Lily, Brock is the eldest of ten, May and Max have one another, and so do Clemont and Bonnie, Cilan is triplets with Cress and Chilli, Lillie has Gladion, Mallow has Abe, Kiawe has Mimo, and Lana has Harper and Sarah. [[/note]]
* The Sailor Soldiers of ''Franchise/SailorMoon''. Usagi has an AnnoyingYoungerSibling... and that's it, she's the only one with any siblings whatsoever. Also, it's flat-out stated at the end of the series that Neo Queen Serenity only ever has one child in the future (Chibi Moon).
* In ''Manga/StrawberryMarshmallow'', Matsuri and Miu are the only ones who are ''explicitly'' only children; Nobue and Chika are, of course, sisters, and Ana... well, who knows? In episode 16, Nobue mentions this in connection with Matsuri's parents knowing to get her the new ''Literature/HarryPotter'' book. In episode 22, Nobue reflects on why Miu often feels left out.

[[folder:Comic Books]]
* One thing ''ComicBook/ArchieComics'' often got criticized for was that despite the attempt at depicting a "typical teenage" group of friends, an unrealistically high proportion of them were only children. Archie, Reggie, Veronica, and even minor characters like Chuck, Nancy, Moose, Midge, and Dilton are all only children. Betty is actually the youngest of three children, but only the most hardcore of fans know that; her sister Polly makes single-digit appearances per ''decade'', and her brother Chic is almost never mentioned even when Polly is. For all storytelling purposes, Betty may as well be an only child. And Jughead gained a baby sister fifty ''years'' after his debut, and it's a coin-toss whether most writers remember Jellybean's existence nowadays. The only significant siblings in the ''Archie'' cast are the twins Jason and Cheryl Blossom, who are about as far from role models as you can get.
* Creator/DCComics:
** The Franchise/{{Batman}} corner of the universe is filled to the brim with only children. Bruce himself is an only child, though he used to have a brother named Thomas Jr. before he was retconned out of existence; his father Thomas has become an only child after his brother Philip and sister Agatha were likewise retconned (Philip is now Martha Wayne's brother); and Dick Grayson, Jason Todd, Tim Drake, and Stephanie Brown are all only children as well. The aversions are Barbara Gordon, who has a younger brother; Cassandra Cain, who has two known biological siblings; and Catwoman, who has a sister and [[DependingOnTheWriter sometimes]] a brother. Also averted by Batman's four adopted children and one biological child, who consider themselves siblings, [[BigBrotherMentor for better]] [[CainAndAbel or worse]].
** ComicBook/GreenArrow and all of ''his'' protégés...until his ComicBook/DCRebirth series, where a long-lost half-sister showed up.
** Franchise/{{Superman}}
*** Clark Kent/Kal-El is the only child of his biological parents Jor-El and Lara as well as the only child of his adoptive parents Jonathan and Martha. {{Justified}} since Jor-El and Lara might have had more children if they weren't [[EarthShatteringKaboom dead]] shortly after his birth (and usually do, in alternate universes where they survived), and the Kents are usually established as having been unable to have children through biological means.
*** Kara Zor-El, his cousin, is also an only child, but she was a teenager when Krypton was destroyed and her parents Zor-El and Alura were seemingly capable of having more children.
* An unusual number in Creator/MarvelComics:
** Steve Rogers (Comicbook/CaptainAmerica) was an only child. [[spoiler:The Paradise-X storyline shows he just wasn't aware of an older sibling...]]
*** As was his archnemesis, the Comicbook/RedSkull (probably due to his mother dying in childbirth and his father killing himself immediately afterwards). Red Skull's daughter Sin is also an only child.
** Matt Murdock (Comicbook/{{Daredevil}}) is an only child.
** Averted by the ComicBook/FantasticFour; Reed Richards is the only member to be an only child. Jonny and Sue are siblings and Ben had an older brother who died when they were teens. Reed and Sue also end up having two children.
** Bruce Banner (Comicbook/IncredibleHulk) is an only child, as is his cousin Jennifer Walters (Comicbook/SheHulk), his wife Betty Ross (Red She-Hulk), and his father-in-law Thunderbolt Ross (ComicBook/RedHulk).
** Tony Stark (Comicbook/IronMan) is an only child [[spoiler:except for the brother he never knew about.]]
** All the original Comicbook/{{Runaways}} are only children, but this is justified because each set of parents agreed to give their designated place in paradise to their offspring. Because there were only six places, the six couples had one child apiece. [[SixthRanger Victor]] is an only child for [[RidiculouslyHumanRobots obvious reasons]]. The same can't be said for Xavin and Klara, but then again, it's never been explicitly stated that they didn't have siblings back on Tarnax VII or in 1907.
** Peter Parker (Comicbook/SpiderMan) is an only child--in his case, his parents had disappeared when he was a little kid (usually around the age of 4 to 6), so they didn't really get the chance to have another kid. And in the case of Peter's Aunt May and Uncle Ben, they (similar to Superman's adoptive parents) are sometimes portrayed as having been unable to have children of their own thru biological means.
. In this case, his parents died a short while after he was born, so they didn't even have the chance to have another kid.
** Notably averted with [[Comicbook/XMen the Guthries]]. [[MassiveNumberedSiblings All twelve of them]].
** ''ComicBook/YoungAvengers'': [[ComicBook/KateBishop Kate]] has an older sister, and it's implied that Eli comes from a large family. Billy and Tommy are twin brothers...via reincarnation (it's complicated). Billy mentioned he had two little brothers in the first arc, but over a decade later they've failed to appear in any capacity whatsoever. Teddy is an only child, which isn't too surprising given his parents were on opposite sides of an interstellar war. Same goes for Cassie, as her parents have split up and her father was [[DeathIsCheap dead for a while.]]

[[folder:Fanfiction]]
* The plot of ''Another Fairly Oddbaby'' is Poof feeling rather lonely as an only child, so he wishes to have a baby brother. Fortunately, Cosmo is willing to give birth to another child, who his parents name Puff. Unfortunately for Poof, [[SamusIsAGirl not only does the baby turn out to be a girl]], [[FoolishSiblingResponsibleSibling but she also turns out to be more mature than he is]], meaning that they don't share the same interests. Fortunately, much like their parents, they ultimately learn to love each other despite their differences.
** Not long after in the fanfic, Anti-Cosmo and Anti-Wanda give birth to Puff's anti-fairy counterpart, Huff. However, unlike Poof, Foop is horrified to learn that he has a younger sibling, as he actually enjoyed being an only child since he got all his parents' love and attention. Since they're both the opposites of Cosmo and Wanda's children, their relationship as the FoolishSiblingResponsibleSibling is reversed, similar to Anti-Cosmo and Anti-Wanda's relationship compared to their fairy counterparts.
* In ''Fanfic/EmpathTheLuckiestSmurf'', Papa Smurf reveals to Empath that he is Papa Smurf's only begotten son. However, Empath's mother did have another child through another father, which turned out to be Brainy, giving Empath a half-brother.
* In ''Fanfic/MyHuntsmanAcademia'', Izuku is an only child, which leads to some awkward interactions with Weiss and Shouto when he starts making assumptions about what it's like to have siblings.

[[folder:Film — Animated]]
* Except for WesternAnimation/{{Cinderella}} (who has two stepsisters), [[WesternAnimation/TheLittleMermaid Ariel]] (who's the youngest of seven daughters) and [[WesternAnimation/{{Brave}} Merida]] (who's the oldest and only daughter of four kids), all the Franchise/{{Disney Princess}}es are only children -- although you could consider Cinderella an only child in a strictly biological sense (since she's the only child her dad had through his first wife and he didn't have any more biological children after he and Lady Tremaine got married). And for Rapunzel, her status as an only child is [[JustifiedTrope justified]] in that her biological mother's pregnancy almost killed them both--it also very well could've rendered Queen Arianna (Rapunzel's biological mother) unable to have more children through biological means.
** In the original poem, ''The Ballad of Hua Mulan'', Mulan had two sisters and a brother ([[MythologyGag which is who they named the dog after in the movie]]), the latter of whom wasn't old enough to enlist in the military when Mulan left (but old enough to kill pigs by the time she came home).
** The real-life [[WesternAnimation/{{Pocahontas}} Pocah]][[UsefulNotes/{{Pocahontas}} ontas]] probably had many brothers and sisters, as her father had multiple wives.
** In the [[Literature/BeautyAndTheBeast version of the fairy tale]] that ''WesternAnimation/BeautyAndTheBeast'' is based on, Belle had two older sisters who were very similar to Cinderella's stepsisters--and in early drafts of the movie, Belle was originally going to have a younger sister named Clarice.
** Just like with Belle in WesternAnimation/BeautyAndTheBeast, early drafts of ''WesternAnimation/{{Moana}}'' were originally going to give the TitleCharacter siblings--in Moana's case, she would've been the youngest and only daughter of ''[[MassiveNumberedSiblings ten children]]'' and the movie would've had a stronger "girls can do anything" theme. This was dropped in the favor of focusing on a "follow your heart" message, with Moana as an only child who's expected to become the chieftess of her tribe.
** For those who consider [[WesternAnimation/Frozen2013 Anna and Elsa]] to be Disney Princesses, they would obviously be an exception to this trope since they're sisters.
* It's glaringly noticeable in ''Franchise/TheLionKing'' that lion cubs are born as individuals when in real life litters are the norm. Even Timon, a meerkat, is presented as an only child in ''WesternAnimation/TheLionKingOneAndAHalf''. [[WesternAnimation/TheLionKingIISimbasPride Kiara]] was [[WhatCouldHaveBeen originally]] written as being a pair of twins but they scrapped the brother in development. Over a decade later she finally got a younger sibling in Kion from ''WesternAnimation/TheLionGuard'' though. [[WesternAnimation/TheLionKing1994 Nala]] was also originally supposed to have a younger brother named Mheetu, but he was likewise cut. On the other hand, Mufasa and Scar are brothers so avert this.
* ''WesternAnimation/MeetTheRobinsons'' has Wilbur living in a [[TheClan large, extended family]] that includes aunts and uncles, great-aunts and great-uncles, cousins once removed and two people whose relationship nobody's even sure of...but no siblings, first cousins or other children. (Though, for that matter, no one else in his parents' generation seems to be married.) His parents almost adopt Lewis as a second child, before realizing [[spoiler:he's actually Wilbur's own father from the past]].

[[folder:Film — Live-Action]]
* ''Film/CatchMeIfYouCan'' portrays Frank Abagnale, Jr. as an only child. In RealLife, he had three siblings.
** A background event later in the film hints that his mother has had another child, although it's not made clear if it's his half-sibling or step-sibling.
* Ron, Hagrid, Sirius, and Dumbledore are the only major characters in the ''Film/HarryPotter'' films who have siblings. Some of them have siblings in the books who are AdaptedOut. However, this averted in the ''Film/FantasticBeasts '' prequel series where the only major character who doesn't (or rather isn’t confirmed either way) is the BigBad Grindelwald. Although, Credence had adopted sisters and is told he has biological siblings but it came from an unreliable source and remains to be seen if it's true.
* Noah and Allie from ''Film/TheNotebook'' are both only children.
* Bootstrap Bill only had one kid in Will Turner, something that makes the plot of ''Film/PiratesOfTheCaribbeanTheCurseOfTheBlackPearl''.
* From book to the first movie of ''Film/TheSisterhoodOfTheTravelingPants'' they removed one of Tibby's younger siblings so that she only has one, Bridget's brother so that she's an only child and Lena's sister so that she can go to Greece by herself. Lena's sister who we see in the second movie must have been jealous.
* ''Franchise/StarWars'': Anakin in ''Film/ThePhantomMenace'' is his mother's only child, although by the time of ''Film/AttackOfTheClones'' his mom has married, giving him a stepbrother.
** This also appears to somehow apply to the Jedi in general. It is canon that the Jedi Order took Force-sensitive children from their families to sever emotional attachments. But it is unclear how this would work if a given family produced more than one such child. How the Jedi would have handled twins like Luke and Leia is unexplained, since the films (unlike the Expanded Universe) strongly imply that all Jedi children were raised communally in the Temple on Coruscant.
* Bella Swan, the protagonist from ''Film/{{Twilight}}'', is an only child. Although Edward Cullen has adoptive siblings, Edward is biologically an only child as well.
* ComicBook/{{Thor}}, ComicBook/DoctorStrange [[note]] His sister Donna was in a few scenes that got [[DeletedRole cut out of the final film]] [[/note]], and ComicBook/BlackPanther are the only main heroes in the Franchise/MarvelCinematicUniverse who have siblings.
* Almost none of the characters in the ''[[Franchise/DCExtendedUniverse DC Films]]'' franchise have siblings. ComicBook/WonderWoman had a brother in her [[Film/WonderWoman2017 first film]] but she kills him at the end. ComicBook/{{Aquaman}} has a half brother but he didn't find out about his existence until his [[Film/Aquaman2018 own first film]]. ComicBook/{{Huntress}} from ''Film/BirdsOfPrey'' had a brother but he died when she was a kid.

[[folder:Literature]]
* ''Literature/{{Animorphs}}'':
** [[TheLeader Jake]] has [[GrandTheftMe Tom]], [[ActionGirl Rachel]] has two younger sisters and [[TokenNonHuman Ax]] has [[AlwaysSomeoneBetter Elfangor]]. The other three protagonists, over half of the humans, are only children. The same is true of [[TheWoobie Melissa Chapman]] and [[SixthRangerTraitor David]], the only other kid characters to get significant development. Also note that, for each of those groups of siblings, [[spoiler:one is dead by the series' end]].
** Ironically, most of the important Andalites (Elfangor/Ax, [[ActionGirl Aldrea]] and [[JerkassWoobie Alloran]]) have siblings, despite a throwaway line implying that their species has some sort of legalized population control.
* In the ''Literature/{{Belgariad}}'', Riva Iron-Grip's family has a tendency to produce only children, due to [[BecauseDestinySaysSo divine intervention]]. Garion, at least, is only alone because his parents were killed when he was an infant. (It's implied at the end of the ''Malloreon'' that he'll break the tendency - by having one son and ''legions'' of daughters. After all, the Prophecy stated the Rivan King would have only one son. It said nothing of daughters...) ''Belgarath the Sorcerer'' lampshades this.
** In Polgara the Sorceress, it's [[{{Retcon}} stated several times]] that the line of hidden kings on occasion had multiple children (but not necessarily multiple males). Polgara presumably was only concerned with the eldest male child.
** The main line itself flows through the only survivor of the Nyissan massacre, the king's "youngest grandson." Hopefully this was a one-off and all other all-male lines are extinct. We don't need another random challenger.
* The book ''Charley'' by Jack Weyland has a typical Mormon son (except that he has no siblings) who marries an only child and together they have exactly one child.
* In ''Literature/CharlieAndTheChocolateFactory'', not one of the ''five'' Golden Ticket finders has siblings. (This also seems to be the case with Willy Wonka, who states he has "no family at all.")
* Creator/TerryPratchett and just about all of his protagonists. Though considering how [[Literature/{{Discworld}} the Disc]] runs on narrativium, this may just be because the universe is aware of the trope. Meanwhile, Esme Weatherwax has an EvilTwin, and Tiffany Aching has about six older sisters and an AnnoyingYoungerSibling. Oh, and Mustrum Ridcully has a brother too.
* ''Literature/TheElenium'' takes a humorous twist to the "never had to compete" bit mentioned in the trope description. Patriarch Bergsten is big and impressive [[note]]''Sparhawk'' decides he'd really rather not fight Bergsten, thanks anyway [[/note]] because he was an only child and didn't have to worry about sharing food with other siblings.
* In ''Literature/GeorgesSecretKeyToTheUniverse'', both George and Annie start out as this, but this is later subverted as George's baby sisters Juno and Hera are born between the second and third books and [[spoiler: Nimu from the last book is Annie's half-sister.]]
* In the original series of ''Literature/{{Goosebumps}}'', sixteen protagonists of the 20 books are only children. The specific books featuring these protagonists are all four of the ''Monster Blood'' books (since all of them feature the same protagonist), both ''The Curse of the Mummy's Tomb'' and ''Return of the Mummy'' (for the same reason as the Monster Blood books), ''Welcome To Camp Nightmare'', ''Piano Lessons Can Be Murder'', ''My Hairiest Adventure'', ''A Shocker On Shock Street'', ''The Haunted Mask II'', ''The Headless Ghost'', ''Attack of the Jack-O-Lanterns'', ''Vampire Breath'', ''Calling All Creeps'', ''Beware, the Snowman'', ''How I Learned To Fly'', ''The Blob That Ate Everyone'', ''The Haunted School'', and ''Werewolf Skin''. Gretchen in ''How To Kill a Monster'' could be considered an only child from a biological standpoint. Subverted in ''I Live In Your Basement'', [[spoiler:in which the protagonist, Marco, actually dreamed he was the only child to his single mother while comatose from his head injury courtesy of a baseball bat during a softball game and that the girl that he dreamed doing the damage, Gwynnie, is revealed to be his younger sister.]]
* Most of the characters in Creator/JohnGreen's books don't have any siblings. He jokingly said that it's his way of telling his brother Creator/HankGreen that he doesn't exist in his mind.
* ''Literature/HarryPotter'':
** Harry Potter's parents died when he was fifteen months old. At one point, Harry wonders what his life would have been like if his parents had lived, and imagines that he might have had younger siblings. He did live with his cousin Dudley, also an only child, but they do not have a sibling-like relationship.
*** Dudley is a fairly extreme example of Only Child Syndrome since his parents [[SpoiledBrat spoil him rotten]]. It's never said why Dudley is an only child, but it may be that the parents felt that having more than one child was unseemly, or it could be them further spoiling Dudley by keeping him as the sole center of their attention.
*** Harry's father James was also an only child, but in his case, his parents Fleamont and Euphemia struggled for many years with infertility and only had James in the twilight of their lives. This led to James becoming a SpoiledBrat due to his parents' overindulgence and his own brilliance and talent.
** Hermione Granger was supposed to have a muggle younger sister, but she got cut from the series when she had nothing to do, leaving Hermione an only child.
** Like Harry, Neville had the option of having siblings taken away from him when he was only a toddler. His parents are still alive but were tortured into madness right after the first fall of Voldemort and are institutionalized.
** Harry’s godson Teddy is an orphaned only child like him but it’s clear that Harry’s three kids see him as their old brother.
** Remus Lupin, Severus Snape, Luna Lovegood, and Draco Malfoy are also only children, but in their case, there is no explanation. Draco is a particularly odd case as the only child of his parents and the father of one child himself, leaving readers to wonder how the Malfoys expect to preserve their precious bloodline with only one child a generation. Some more minor characters who appear to be only children include: Seamus Finnegan, Pansy Parkinson, Crabbe, and Goyle.
** Some of the Hogwarts staff are questionable because they're Harry's teachers so family just doesn't really come up. The only teachers Harry for sure knows have siblings are Dumbledore who has a brother and deceased sister and Hagrid who has (at least) a half-brother. Even the former was mostly found out posthumously since he only ever directly mentions his brother in front of Harry once and never mentions his sister. [=McGonagall=] was confirmed to have two brothers whom she never mentions in the books but everyone else remains a question mark.
** The Weasleys are an aversion with [[MassiveNumberedSiblings seven children]], as is their mother, who has two (deceased) brothers. Mr. Weasley also been confirmed to have two brothers, one of whom briefly appears without being named in the last book when he thinks Harry in disguise is his son. The Black family are also reasonably filled out, with Sirius having a brother and Narcissa, Bellatrix and Andromeda being sisters.
* Both Lyra and Will in ''Literature/HisDarkMaterials'' are only children. Very few characters are stated to have siblings, with the Costa family being the only notable exception.
* The only characters in ''Literature/TheInfernalDevices'' who aren't only children are Tessa, whose search for her brother Nate [[spoiler: who eventually betrays her, and is actually her cousin]] kicks off the plot, the Dark Sisters, Gabriel, whose siblings aren't seen until at least the second book, and Will [[spoiler: whose younger sister comes to the Institute at the end of ''The Clockwork Prince'']]. Aunt Harriet, who was Tessa and Nate's mother's sister, is dead. Everyone else's parents are either [[ConvenientlyAnOrphan deceased]] or [[ParentalAbandonment simply not there]], leaving them only children.
* Steve in ''Literature/KingOfTheBench'' is the only child in his family. As a result, his mother is a "[[MyBelovedSmother turbo-hyoer-worrywart]]" about all his athletic activities.
* Protagonists and major characters in the ''Literature/KushielsLegacy'' series tend to be only children or have otherwise odd family situations. Of the three narrator-protagonists in the series, Imriel and Moirin both play the trope straight, while Phedre's situation is more complex (she has a sibling she never meets due to ParentalAbandonment, but later gains a foster brother who is himself an orphan). Of the protagonists' main love interests, only Sidonie has a traditional sibling relationship; Joscelin has brothers and sisters but doesn't know them well because he was sent to a monastic order at the age of ten, while Bao was sold into slavery by his destitute parents as a young child before his sister was born. Other characters explicitly stated to be only children: Delaunay, Hyacinthe, his mother Anastaizia, Ysandre, her father Rolande, Snow Tiger, and the Rani Amrita's son. Others, such as Jehanne, are heavily implied to have no siblings.
* Averted for [[TheNarrator Saleem]]'s family in ''Literature/MidnightsChildren'', but played straight almost everywhere else. (And even in his case, his grandparents were both only children.) Parents tend to be pretty rare too. This was likely a necessity to keep the LoadsAndLoadsOfCharacters under control; if Saleem's father's family was as complex as his mother's, the book would probably have to be twice as long.
* ''Literature/TheReynardCycle'': This is justified in the case of [[spoiler: Hirsent.]] She had three children, but the first two ''died''.
* The majority of kids born to the characters in ''Franchise/StarWarsLegends'' are lone children or part of a [[UntoUsASonAndDaughterAreBorn male-female twin set]]. Wedge had two girls and Leia and Han had twins and then a boy, but they're the exceptions; for that matter, those lone children are overwhelmingly boys. Actually, a lot of ''Franchise/StarWars'' characters fit that pattern.
* ''Literature/TortallUniverse'': The protagonist of ''Literature/SongOfTheLioness'' quartet has a plot-significant [[HalfIdenticalTwins twin]], but her royal and noble supporting cast are almost all only children. In the case of Jonathan and Roger, it's explicitly for medical reasons: the Queen could bear no more children, and Roger's mother [[DeathByChildbirth died]], a condition stated to be very common. The follow-up series ''Literature/ProtectorOfTheSmall'' averts this trope and has siblings up the wazoo.
* ''Literature/TheWheelOfTime'' contains a particularly JustForFun/{{egregious}} example. Throughout the first three volumes, Perrin never mentions any siblings and he explicitly says that he had no sisters. Then in the fourth book [[spoiler: the trollocs come in and kill his entire family]], including a boatload of siblings, [[RetCon some of whom are indeed female]]. Basically, they didn't exist until they became necessary to the plot.

[[folder:Live-Action TV]]
* Justified in ''Series/The100''. Many characters were born on The Ark, a space station constructed from 12 original stations to shelter the remnants of the human race after a nuclear war. To conserve resources, the Ark has a [[PopulationControl strict one-child policy]], so everyone in the main cast is an only child with the exceptions of Bellamy and Octavia Blake, the latter of whom is an illegal second child who was kept hidden for most of her life.
** Though no such justification exists for the many non-Ark characters, who have plenty of resources and yet very few siblings are ever seen. The few exceptions are Emori's brother Otan, who gets little dialogue before dying and is [[ForgottenFallenFriend rarely mentioned since]], and Kaylee and Daniel Lee, who were only clarified to be siblings and not a couple several episodes after they were KilledOffForReal.
* ''Series/AgentsOfSHIELD'':
** Most of the titular agents seem to be only children: Fitz explicitly states that his only relative is his mother, and Skye was raised in an orphanage and never kept a foster family long enough to gain siblings that way. Simmons mentions her parents often enough to make it seem like that's the extent of her family unit, particularly since when she thinks she's about to die her wish is to pass messages on to her parents and Fitz, but no-one else. Coulson and May's parents are, respectively, frequently mentioned and featured in cameos, without any siblings in the picture, and Coulson later described as a classic only child. Meanwhile, Triplett appears to be the sole heir to his legendary grandfather's stash of cool vintage S.H.I.E.L.D. tech.
** The only aversions are Ward and Koenig. Ward mentions two brothers and a sister: the two brothers played important roles in his back-story and both eventually appeared on-screen, though the sister was never mentioned again and may have been retconned out of existence. Koenig, meanwhile, appears to have a suspiciously well-stocked army of identical [[BackupTwin Back-Up Twins]] [[spoiler:and one sister. Turns out they weren't clones or Life Model Decoys after all, just a bunch of brothers who looked a lot alike. TheUnreveal is PlayedForLaughs after several seasons of speculation.]]
** {{Averted}} for Mack, who turns out to have a younger brother, but they're not all that close, to the point that he's initially unaware Mack is a SHIELD agent at all.
** Also {{averted}} for Simmons in the comics, where it's mentioned that she has a brother and a sister (and is TheUnfavorite to her dad). It's unclear whether this is true for her in the show or not.
** This is all possibly {{Justified}} in that S.H.I.E.L.D. has a reputation for hiring loners, and lacking an extended family network surely helps in this regard. Note that Ward, the only main character to mention having siblings, makes it explicit that they no longer have anything to do with one another.
* ''Series/BeverlyHills90210'': Played with in both the original and the reboot.
** At the start of the original series, twins Brandon and Brenda were seemingly the only ones with siblings. Eventually, it's revealed that Dylan has a half-sister and much later, a half-brother; Kelly and David become stepsiblings and gain a half-sister (see below) through their parents' marriage (additionally, Kelly has another half-sister through her dad); Steve has two half-brothers; and Donna has a half-sister ([[spoiler: her cousin Gina, who was the product of an affair her aunt had with her father]]). This would leave Andrea the only one of the iconic eight-member lineup without a sibling. Even in later seasons, most of the new characters were only children with the exception of Matt, whose brother dies offscreen anyway, and Noah.
*** It’s actually mentioned in one episode that Andrea has a sister, though she is never mentioned again nor does she ever appear in the series (even at her sister’s wedding, where Andrea’s parents are present for in their sole appearance in the show).
** In the reboot: Annie and Dixon are adoptive siblings, Silver is the half-sister of Kelly and David, Naomi has an older sister, Navid has several younger siblings, Ethan has a brother, and Teddy has a sister. Liam, Ivy, and Adrianna appear not to have siblings.
* ''Series/BuffyTheVampireSlayer'' / ''Series/{{Angel}}'':
** Almost all the main characters on both shows seem to be only children: Buffy ([[CosmicRetcon pre-Dawn]]), Xander, Willow, Cordelia, Fred, Faith, Spike, and Wesley all seem to have no siblings. Only Angel (sister), Gunn (sister), Tara (brother), and Andrew (brother) are known to have had siblings - and two of those four were either already dead or were killed off straight away!
** Andrew, interestingly, originally had to keep being introduced as "Tucker's brother", even though Tucker was a [[MonsterOfTheWeek villain of the week]] who wound up being much less important to the series and only appeared in one episode.
* ''Series/{{Carnivale}}'' provides a [[JustifiedTrope justified]] case of this, at least according to [[AllThereInTheManual the "Gospel of Knauf"]] that outlines the series' mythology. One of the pitfalls of coming from a line of historic [[TheChosenOne Avatars]] (one of the super-powered humans at the heart of the series' mythology) is that a woman is rendered infertile after giving birth to an Avatar--who, as per the rules of the universe, can only be the firstborn male child of his family. Hence, Avatars can only have older female siblings and are very often only children.
* Most of the main characters of ''Series/{{Community}}'' seem to be only children, with the exception of Annie (younger brother), Jeff (younger half-brother), Pierce (half-brother), and Chang (brother and twin sister, [[ItMakesSenseInContext whom he ate in utero]]).
** Abed mentioned that Britta having a brother who works with disabled kids in the pilot, and Troy mentioned having siblings.
* In ''Series/{{Degrassi}}'', the vast majority of the LoadsAndLoadsOfCharacters that have appeared over the years are only children: Snake (older brother), Liberty (younger brother), Craig (half-sister), and Holly J (older sister) are some of the few exceptions.
** They seem to be averting this in the post Season 10 episodes. Out of the characters still on after season 13, Drew had a stepbrother, Alli has an older brother, Miles has a brother and sister, Tristan has a stepbrother, Maya has an older sister, etc.
* ''Series/DoctorWho'':
** Nearly all companions in both the classic and revived series are only children. The exceptions are Martha (a brother and a sister), Yasmin (a younger sister), and technically Captain Jack (who, as it turns out, had a brother, but this fact is only revealed in his spin-off ''Series/{{Torchwood}}'').
** Adric had a brother. [[spoiler:Emphasis on had.]]
** Rose was an only child for her tenure as a full companion, but had a baby brother by the time of [[Recap/DoctorWhoS30E13JourneysEnd "Journey's End"]] due to [[spoiler:Jackie and alt-Pete getting together.]]
** River has a younger brother, although, like in Rose's case, we only hear about him in what is the [[Recap/DoctorWhoS33ShortPS epilogue]] for her parents' story arc and it's unclear if they ever met. Then again, given her parents' dangerous, unsteady lifestyle and how it got, you can understand why her parents might have refrained from having another kid until their space travel days had come to an end.
** Sort of justified, however, in that someone with little ties to their place of origin to begin with would simply be more likely to follow an extraterrestrial oddball on a joyride through time and space than someone whose siblings or parents would get worried.
* This is discussed in an interesting way in ''Series/EverybodyHatesChris''. Chris is jealous of Greg when he comes to stay with them because he's an only child and he expects all of the attention and does everything by himself, whereas Chris usually has to take care of his younger siblings. Near the end of the episode, Chris confronts Greg, and Greg says that the reason why he does everything by himself is not that he wants to, but because he has to, being an only child.
* Averted in ''Series/{{Friends}}'': Joey has seven sisters, Rachel has two sisters, Phoebe has a twin sister and a half-brother, Monica and Ross are brother and sister, leaving Chandler as the only only-child. And that's justified seeing as his parents hated each other, his Dad was gay and they [[{{ParentalNeglect}} barely noticed the son they did have.]]
* Rory is an only child in ''Series/GilmoreGirls,'' but that might be because Lorelai made sure not to have another child out of wedlock. Of course, Lorelai is ''also'' an only child, as is Rory's father, her best friend Lane, her frenemy Paris... The major exceptions seem to be Luke ([[{{Nephewism}} so that he can have a nephew]], Jess, who has no siblings) and two of Rory's main {{Love Interest}}s, Dean and Logan, each of whom has one sister.
** Rory eventually gets a half-sister, Gigi, born to Chris and his fiancée Sherry during season three.
* Most main characters in ''Series/{{Glee}}''. Only Puck, Blaine, Sam, Quinn, Sue, and Jake have known siblings (though in Quinn's case, her sister is only mentioned, never seen). Finn and Kurt later become stepbrothers.
* In ''Series/TheGoodPlace'', Eleanor is an only child, her parents having divorced when she was eight. Chidi and Jason don't mention any siblings they could potentially have. Tahani ''does'' have a sister, but spent her life on Earth amounting fame and fortune so she could become more successful than her (she failed). Janet and Michael don't have siblings due to being celestial beings without families.
* The fact that Claire from ''Series/{{Heroes}}'' is both adopted and an aversion, having a little brother Lyle, produced vast speculation over his origins because it's so rare for a family with adopted children to have more than one.
* ''Series/{{House}}'' has the title character and as far as we know Chase, Taub, and Kutner. Ultimately averted with most of the other series regulars as even though it's not stated from the beginning, it ultimately comes out that they have siblings.
** Since ''House'' is based on SherlockHolmes, WordOfGod states that House [[WhatCouldHaveBeen was originally intended to have a brother representing Mycroft]], played by Hugh Laurie's comedy partner Creator/StephenFry, no less. The character was cut due to a combination of scheduling conflicts and not being able to find room for the character in the show's dynamic.
** Adams (who only joins the cast in the final season) also appears to be an only child or at least doesn't mention any siblings during her run on the show.
* ''Series/HowIMetYourMother'': Out from the five main characters, Lily is the only one who does not have siblings considering that [[DisappearedDad her dad didn't do his parental responsibilities very well]]. Ted has a younger sister who appears once in the show. Robin also has a younger sister. Marshall has three older brothers [[BigBrotherBully who are more or less jerks to him]]. And Barney has a black older half-brother from his mother's side and three half-siblings from his biological father's side.
* Most of the characters on ''Series/{{Lost}}'' are only children (or raised as only children) with the exception of Charlie (who has a brother), Hurley (who has a brother), Juliet (who has a sister), and Mr. Eko (who has a brother). Desmond has three unnamed brothers who are never seen, and Charlotte has two unnamed sisters. Boone and Shannon are step-siblings. [[spoiler:Jack and Claire are half-siblings but neither are aware of this.]]
* ''Series/{{Merlin|2008}}'' zigzags the trope. At first, the core four characters (Arthur, Merlin, Gwen, and Morgana) are all apparently only children. Arthur's mother died in childbirth, Merlin's father was run out of town before he ever knew he had a son, Gwen's mother is nowhere to be seen, and Morgana has a dead father and a MissingMom. [[spoiler: Arthur and Morgana are half-siblings through their father]], and Gwen has a brother named Elyan who's spent the majority of his life running around, leaving Merlin the only one without siblings.
* ''Series/TheMunsters'': Eddie Munster is an only child, in spite of his parents having been married over one hundred years.
* Evidently averted in ''Series/MurderSheWrote'', as Jessica Fletcher seems to have a different niece or nephew in almost every episode.
* In an exception to the vaunted realism of ''Series/MySoCalledLife'', five of the seven youth characters (Brian, Sharon, Rayanne, Rickie, and [[FullNameBasis Jordan Catalano]]) are only children, and the remaining two (Angela and Danielle) are each other's only sibling. These characters would have been born c. 1980, which was the beginning of the "Echo Boom", when Boomers settled down and started having families, and the birthrates rose.
* ''Series/OurMissBrooks'': Teenagers Walter Denton and Harriet Conklin are only children.
* ''Series/Runaways2017'':
** Averted, despite it being an actual plot point in the original comics. Here, Nico had an older sister who died in mysterious circumstances, and Gert and Molly are foster sisters, Gert's parents having adopted Molly after [[DeathByAdaptation hers died]]. Karolina, Alex, and Chase are still only children, though. [[spoiler:At least until Karolina's mother gets pregnant again towards the end of Season 2.]]
** However, this ''does'' still mean that five out of the six friends were the only children in their original family units, which is pretty rare by real-life standards.
* Sabrina Spellman has many aunts, but only a couple of cousins and no siblings in ''Series/SabrinaTheTeenageWitch''.
* ''Series/TheSarahJaneAdventures'':
** Every protagonist is an only child including Sarah Jane herself. Her son is a special case, as he was grown in a lab by aliens.
** Sky — Luke's new adopted sister in Series 5 — has similar-though-not-matching reasoning for being an only child (biologically, anyway). On top of that, Sarah Jane's parents died when she was a baby, which justifies her lack of siblings. Meanwhile, Maria's dad and Clyde's mum are divorced from partners with whom they didn't work out [[spoiler:and Clyde's dad ran off with his wife's sister, whom it's revealed he impregnated, giving Clyde an unseen half-sibling/cousin.]] The only one with no excuse whatsoever is Rani, and to be fair not all parents in the present-day want more than one child anyway.
* In ''Series/SavedByTheBell'', Kelly and Slater are the only children to have siblings. Jessie does end up gaining a stepbrother. Zack, Screech, and Lisa are all only children.
* ''Series/SchittsCreek'': David and Alexis's love interests, Mutt, Tedd, Stevie and Patrick, all appear to be only children. Mutt later gains a much younger brother, Roland Jr. Stevie is eventually de-facto adopted by the Roses, culminating in the renaming of the motel. Patrick being Clint and Marcie's only child has made Patrick very close to them and thus makes it harder to come out to them.
* ''Series/{{Smallville}}'' begins with the lonely Clark. Lex has also grown up without siblings. Lana's parents died when she was young. Pete and Chloe also appear to be without siblings. There is no reference to Kara having had any. Lois might be the one exception having grown up with a sister.
** Jimmy has a younger brother. ([[spoiler:Also named Jimmy]].)
* ''Series/StrangerThings'': Mike and Nancy are siblings, and also have a toddler sister. Will and Jonathan are brothers, and Season 2 shows that Lucas has a younger sister, Erica. However, Dustin and Steve have not been shown to have any siblings, and Eleven's biological mother fell into a catatonic state several years after she was born, preventing her from having any more children. Also, in Hopper's backstory, his [[LittlestCancerPatient deceased daughter]], Sara, was also an only child.
* Of all of the main cast of ''Series/TheSuiteLifeOfZackAndCody'', London Tipton is the only one without a sibling. The titular twins have each other, Maddie has her younger brother Liam and is mentioned to have a sister as well, Moseby is revealed in one episode to have an older (yet much shorter) brother named Spencer, and in the same episode, Carey mentions she has a sister she recently doesn't talk to.
** In its sequel series ''Suite Life On Deck'': Bailey mentions having nine sisters in season 1 ([[ContinuitySnarl though oddly none of them are seen nor mentioned in the episode where the gang goes to Bailey's home in Kansas, in season 3]]) while Woody has a sister and states "being the youngest of nine" ([[{{Retcon}} though aforementioned sister is stated to be younger than him]]). Marcus appears to be an only child.
* Almost all of the core characters on ''Series/TeenWolf'' are only children. Scott, Stiles, Allison, Lydia, Kira, Jackson, Malia, and Liam are all only children. Derek and Isaac have siblings, but Isaac's brother is dead, and Derek's two sisters were either murdered or PutOnABus to South America. If Derek had any other siblings, they likely died in the fire along with the rest of his family before the series began.
** Technically, Malia had a younger sister when she was a child, but she died in a car accident. And since Malia turned out to have been adopted, she wasn't biologically related to the girl anyway.
* ''Series/That70sShow'' had Hyde, Jackie, and Fez as only children. Eric had sister Laurie and Kelso eventually had brother Casey make an appearance, while Donna had a [[EarlyInstallmentWeirdness sister]] but was retconned into being an only child.
** Actually, Kelso is mentioned to have 7 brothers and sisters, Fez mentioned at least one sister, and Hyde eventually gained a half-sister (Angie) through the discovery of his biological father William Barnett. Technically, this would make Jackie the only only-child.
* Almost every main character on ''Series/TheVampireDiaries'' is an only child with the exception of Stefan, Damon, and Matt. Caroline, Bonnie, Tyler, and Jeremy are all only children. Elena is technically an only child as well even though she grew up with Jeremy as an adopted brother (Jeremy is actually her biological first cousin)
* On ''Series/Zoey101'', Zoey is the only one of the main characters to have a sibling, her brother Dustin. Lola mentions a younger sister in passing (season three's "Surprise") who is never mentioned again and never seen, and none of the other characters seem to have siblings at all.
[[/folder]]

[[folder:Roleplay]]
* ''Roleplay/DawnOfANewAgeOldportBlues'' features a cast of roughly forty teenagers, only a scant handful of which have siblings. While not all of the non-player characters have had focus turned on their family life, meaning it's possible they have relatives behind the scenes, it still leaves about thirteen out of sixteen main characters without siblings- the exceptions being Irene, who has three; Jenna, who has a little sister (ironically, given Jenna's new TheWormThatWalks form, she's terrified of bugs); and Ciro, who has two younger siblings which are important to his background and development.
[[/folder]]

[[folder:Theatre]]
* Romeo Montague and Juliet Capulet from ''Theatre/RomeoAndJuliet'' are both only children. Tybalt and Benvolio are presumably only children as well, although Mercutio has a brother only mentioned in passing.
[[/folder]]

[[folder:Video Games]]
* Surprisingly {{averted}} in ''VideoGame/Dishonored2'', which sees Corvo (or his daughter Emily) return to his native Carnaka, where he'll reveal that he has a sister Beatrici who was also an adventurous type, and who he hasn't seen or heard from in several decades. [[spoiler:She later shows up in the tie-in novel series.]]
* ''Franchise/DragonAge'':
** The noble families of Ferelden in ''VideoGame/DragonAgeOrigins'' are strangely small:
** The Cousland family has two children, both of them grown, and a single grandson. All of them save the elder son (and possibly the second child, one of the possible origins) are killed in the prologue. By the end of the game, Fergus is the heir and sole member of the family.
** The Guerrin family consists of two brothers, one of them unmarried, and a son barred from succession because he is a ChildMage.
** Rendon Howe has three adult children: one becomes a Grey Warden and thus is unable to procreate; his only daughter has one son; and his second son is dead by the end of the game.
** Loghain Mac Tir has an only daughter, the Queen.
** Queen Anora never had any children with her husband, King Cailan, who was likewise the only son of King Maric, who was the only son of Queen Moira, who was the only daughter of King Brandel, who was the only son of King Vanedrin. And, of course, [[spoiler: Alistair]] is the last scion of the Theirin family, which does not bode well since he [[spoiler:is a Grey Warden.]]
** Even the minor families of Ferelden seemingly have only one or two children, and some even appear unmarried or childless. How this feudal, hereditary monarchy can survive such an impending power vacuum is never addressed. It's possible that, because this is a video game where the focus is not dynastic politics, many of these families are actually larger, or have extended, female-line branches that are simply not seen, but for a series that revels in creating a huge codex of extraneous lore, that would be a strange oversight.
** ''VideoGame/DragonAgeInquisition'' has Dorian Pavus, the only son of the noble House Pavus of Tevinter. His only-child status is both justified, as his parents despise each other and married for political reasons and thus only cared to have the necessary heir, and problematic, as Dorian is gay and refuses to hide it, preventing him from carrying on the bloodline, driving his father to [[CureYourGays desperation]] that led to Dorian leaving the family altogether.
* Anila of ''VideoGame/GranblueFantasy'' experiences this as the crew met her. Since she’s an only child, she wonders what it is like to have siblings at the end of her second Fate episode. Lyria suggests calling the player character brother/sister and Anila tries but finds it weird. Vyrn then observes that Andira and Lyria act more like sisters instead and they eventually bond over that.
* Link and Zelda from ''Franchise/TheLegendOfZelda'' have been portrayed as only children in almost all of their [[EternalHero various incarnations]]. The exceptions are ''VideoGame/ZeldaIITheAdventureOfLink'', where the sleeping Zelda had a cruel brother whose evil wizard adviser was responsible for putting her into her slumber, and ''VideoGame/TheLegendOfZeldaTheWindWaker'', where Link's younger sister Aryll gets kidnapped by the Helmaroc King and must be rescued.
* ''VideoGame/LifeIsStrange'':
** In a game that delves into a lot of family drama, it's noteworthy that Max, Chloe, and Rachel - the protagonists of the first two games - are all only children.
** {{Averted}} with many of the minor characters at Blackwell Academy, however. Kate Marsh has two sisters, which can become a minor plot point. Drew and Mikey North are brothers who share a roughly equal amount of screen time. Then there's an interesting case with Nathan Prescott, who has an off-screen older sister who emails him during the game and seems to be a rare positive influence in his life, but who never becomes plot-relevant.
** Chris, the protagonist of ''The Awesome Adventures of Captain Spirit'', is also an only child. {{Justified}} (if such a thing needs justification) by the fact that his mother died when he was quite young, so it's possible his parents would have liked more children but circumstances intervened.
** Completely {{Averted}} with Sean and Daniel Diaz, the brothers who are co-protagonists of ''Life is Strange 2''.
* In the ''Franchise/{{Persona}}'' series, this is fairly common. Virtually all party members and most Social Links are only children, and among the few that have siblings, those siblings are usually dead or much older/younger than them.
** ''VideoGame/Persona3'' has a party mostly composed of only children, except for Akihiko, whose younger sister died years ago.
** ''VideoGame/Persona4'' also has only children in the party, although the main character's young cousin, Nanako, sees him as an older brother. One of the Social Links, Naoki, is the younger brother of the second murder victim, while Kou's adoptive parents have a two-year-old biological daughter.
** ''VideoGame/Persona5'' [[RuleOfThree follows the preceding two games]]. Makoto is the only party member who has siblings, and in her case, her significantly older sister [[PromotedToParent acts more as Makoto's legal guardian, raising her after the death of their father]].
* ''Franchise/{{Pokemon}}''
** Most of the rivals and protagonists are only children. The exceptions are: Blue from ''VideoGame/PokemonRedAndBlue'' having an older sister named Daisy, May/Brendan from ''[[VideoGame/PokemonRubyAndSapphire Pokémon Emerald]]'' having a younger sibling (though they lack a sibling in ''Ruby'', ''Sapphire'', ''[=OmegaRuby=]'', and ''[=AlphaSapphire=]''), Hugh from ''VideoGame/PokemonBlack2AndWhite2'' having a younger sister, and Trevor from ''VideoGame/PokemonXAndY'' having an older sister.
** If you include spin-off titles, then the protagonists of ''VideoGame/PokemonXD'' and ''[[VideoGame/PokemonRanger Pokemon Ranger: Shadows of Almia]]'' have younger sisters who are minor characters. Tim Goodman from ''VideoGame/DetectivePikachu'' apparently has a younger sibling, but he/she only briefly appears in a photograph.
* Out of roughly two dozen members of the Van Der Linde gang at its peak in ''VideoGame/RedDeadRedemption2'', only three are confirmed to have siblings, Micah, Javier, and Hosea. Micah has a brother and Hosea's dad was a bigamist whom he figures had roughly [[MassiveNumberedSiblings 100 children]]. Javier laments early on that since he can't go back home to Mexico, he missed his sister's recent wedding. They had a pair of brothers that ran with them prior to the events of the game who died in the botched Blackwater ferry heist. Justified somewhat as the game takes place in 1899 when a lot of women died in childbirth (like John Marston's mom) and a lot of people died in childhood, some of them may have had siblings who died as kids. Also, the reason they're all together is that they had rough childhoods and Dutch picked them all up. Neither Arthur the protagonist of this game nor John the protagonist of the sequel ''VideoGame/RedDeadRedemption'' has confirmed siblings.
* Protagonist Nathan from ''VideoGame/{{Uncharted}} '' is the only main character who has a sibling. Even then he thought his brother was dead for the first three games in the series and never brought him up.
[[/folder]]

[[folder:Western Animation]]
* While most of the main characters in both ''[[Franchise/AvatarTheLastAirbender Avatar]]'' series have siblings, we've never known of an actual Avatar that did: [[WesternAnimation/AvatarTheLastAirbender Aang]] and all previous Air Nomad Avatar (like Yangchen) come from a society with NoBloodTies. [[WesternAnimation/TheLegendOfKorra Korra]], Roku (the Avatar before Aang), Kyoshi (Roku's predecessor), and Wan (the first Avatar) are all only children. The most recent Avatar who hasn't been confirmed either way is Kyoshi's predecessor, Kuruk. Plus, on the non-Avatar side, there's Toph, whose only childness coupled with her blindness has led to her parents being too overprotective for their own good.
* Caitlin Cooke's the only one of the main six in ''WesternAnimation/{{Sixteen}}'' confirmed to be an only child.
** Jen and Jonesy both have siblings (Jen has an older sister while Jonesy has two younger brothers) and the two are stepsiblings to each other (due to Jen's mom and Jonesy's dad getting married). They also eventually end up gaining a baby half-sister.
** While Jude and Wyatt are never confirmed to have any siblings, they're also never confirmed to be only children like Caitlin is--Wyatt's mentioned to come from a large family, but whether this means a large ''immediate'' family or a large ''extended'' family is uncertain. It seems likely that Jude's an only child because while he's mentioned his parents quite a few times, he's never mentioned any potential siblings.
** Nikki's a strange example because a couple episodes in the first season pretty much explicitly state that Nikki has siblings (in "Dude of the Living Dead," Jen claims that Nikki has a sister and in "The Fake Date," Nikki mentions having a nephew). However, later episodes (such as the SeriesFinale) imply that Nikki's an only child like Caitlin is.
* On ''WesternAnimation/TheAdventuresOfJimmyNeutronBoyGenius'', none of the main characters are shown having siblings--Sheen was sometimes mentioned as having a younger sister, but she was never actually seen in person. Jimmy's lack of a brother was even the impetus of the plot of the episode "I, Brobot", where he makes one.
** Another curious case is that of Libby. In "Make Room for Daddy-O", a young boy acts as the legs to Libby's "cutting-person-in-half" magic trick and runs after Libby and her dad after the trick is completed. It can be inferred that the boy is her brother, but he never appears after that episode nor is it directly ever stated that the boy is Libby's brother (in fact, she never mentions any siblings during the show). For what it's worth, the show's wiki labels him as Libby's brother.
* ''WesternAnimation/TheAmazingWorldOfGumball'': The main character's family has three children, but of his approximately twenty classmates, only Penny, Tobias[[note]]His sister, Rachel, [[ChuckCunninghamSyndrome ceased appearing]] even in scenes of his family after season one.[[/note]], and Idaho are known to have any siblings while many of the rest are shown to be only children. Colin and Felix are very similar but not confirmed to be brothers. Among the rest of the school and Elmore's [[LoadsAndLoadsOfCharacters many citizens]], the only ones with known siblings are Margaret, Louie, Hot Dog Guy, and a few very minor characters, while Richard, Nicole, and Rocky are only children.
* ''WesternAnimation/{{Arthur}}'': Most of Arthur's friends are only children, with only a handful having at least one sibling. In the earliest seasons, it seemed like Arthur, Francine and Prunella were the only ones who had siblings. Later ones would introduce siblings for Muffy, Binky, Molly, and Rattles, and also introduce more characters who have siblings from the get-go, but that's still only a fraction of the cast.
* ''WesternAnimation/CodeLyoko'', aside from Yumi ([[AnnoyingYoungerSibling one younger brother]]) and Odd ([[MassiveNumberedSiblings five]] [[OutnumberedSibling older sisters]]), most of the children in Kadic are shown to be only children.
* ''WesternAnimation/DannyPhantom:'' Danny and Jazz are siblings, and if you wanna stretch it, he treats [[OppositeSexClone Dani]] like [[BigBrotherInstinct a little sister]]. However, ''every other secondary character''--[[LoveInterest Sam]], [[ExtravertedNerd Tucker]], [[DatingCatwoman Valerie]], [[JerkJock Flash]], [[AlphaBitch Paulina]], etc.--seems to be an only child.
-->'''Sam:''' If you don't mind, we'll be over there doing the "glad-I'm-an-only-child" dance."
* Out of all the main children of ''WesternAnimation/{{Doug}}'', the ones who are only children are Patti, Roger, Boomer, Willie, Beebe, and Connie. Doug has his older sister Judy (and later, a baby sister in the Disney series), Skeeter has his little brother Dale, Ned has MassiveNumberedSiblings as revealed in the Disney series, Chalky is revealed to have a(n) (unseen) older brother, and Al and Moo Sleech are twin brothers.
* On ''WesternAnimation/EdEddNEddy'', Ed and Sarah are brother and sister, Eddy has an older brother, and the Kankers are sisters. Double D, Rolf, Kevin, Jimmy, Johnny, and Nazz are all presumably only children -- Double D's the only one confirmed to be an only child, while none of the other characters mention having siblings.
* In the early days of ''WesternAnimation/TheFairlyOddparents'', the only ones shown to be siblings were [[EvilRedhead Vicky]] and [[{{Meganekko}} Tootie]]. Since then, a character is an only child unless a story involving siblings is written. Several seasons later [[AmbiguouslyGay Sanjay]] was revealed to have a stepbrother that hasn't been mentioned since, and Timmy wished for an older brother [[StatusQuoIsGod that he inevitably unwished]]. In season six Timmy got a godbrother in [[CousinOliver Poof]]. Up in Fairy World, Wanda was eventually revealed to have a twin sister, and Cosmo has an older brother.
* Of the main three characters of ''WesternAnimation/HarveyBeaks'', the title character has a younger sister (Michelle, who was just an egg when the show started), and Foo and Fee are brother and sister (and half-adopted into Harvey's family). The only siblings of the supporting cast are Claire's [[TheGhost unseen]] BigSisterBully, Rooter's younger brother, and Dade's [[MassiveNumberedSiblings many younger siblings]]. This leads to Fee looking for advice on being an "honorary sister" to Michelle, but finding [[TheBlindLeadingTheBlind no one with experience to speak of.]]
* On ''WesternAnimation/HeyArnold'', Gerald has [[AloofBigBrother two]] [[AnnoyingYoungerSibling siblings]] and [[JerkassWoobie Helga]] has [[ParodySue Olga]], but otherwise all the kids seem to be only children.
* ''WesternAnimation/{{Hilda}}'': None of the protagonists (Hilda, Frida, and David) have siblings.
* In ''WesternAnimation/KingOfTheHill'', the three main kids -- Bobby, Connie, and Joseph -- are all raised as only children, as were Hank and Luanne. Hank eventually gets or discovers two half-brothers, though (one [[PracticallyDifferentGenerations born in his father's old age]] and one he just never knew about); Joseph also has at least one half-sister through John Redcorn, but [[ObliviousAdoption still doesn't realize that he's related to either of them]].
* In ''WesternAnimation/TheMagicSchoolBus'', only three of eight main kids are confirmed to have siblings:
** Dorothy Ann ("DA" for short) has a younger sister named [[GenderBlenderName Ev]][[TomboyishName an]] while Wanda and Carlos both have younger brothers -- Wanda's brother is named William and Carlos's brother is named Mikey.
** Ralphie, Tim, Arnold, Phoebe, and Keesha are never explicitly stated to be only children, but whenever we see or hear anything about their families, we only ever see (or hear about) their parents rather than any potential siblings.
* In ''WesternAnimation/{{Metalocalypse}}'', Pickles is the only member of Dethklok with a sibling.
* In ''WesternAnimation/MiraculousLadybug'', the two main characters, Marinette and Adrien, are both only children. Among the main cast, Alya is shown to have three sisters (an older sister and two younger twin sisters), and Nino has a younger brother named Chris.
* In ''WesternAnimation/MuchaLucha'' Rikochet, Buena Girl and the other characters have no brothers or sisters. Only The Flea has a baby sister named [[TheVoiceless Pulgita]].
* Averted for the most part in ''WesternAnimation/MyLittlePonyFriendshipIsMagic'', with some of the characters' siblings being important supporting characters and [[ADayInTheLimelight even having episodes focusing primarily on them.]] Rainbow Dash is the only one of the Mane Six to be an only child, although she does have a sisterly bond with Scootaloo (who's presumably an only child like Rainbow Dash is). Starlight Glimmer's presumably an only child as well and the only relative of hers that we ever see is her dad.
** Rarity has a younger sister named Sweetie Belle.
** Pinkie Pie has three sisters named Limestone, Marble and Maud.
** Twilight Sparkle has an older brother named Shining Armor--he also has a wife named Cadance and they eventually have a daughter named Flurry Heart. Twilight Sparkle and Shining Armor also have Spike the Dragon, who they essentially see as their adoptive younger brother--we never see or hear anything about Spike's biological family, so we don't know for sure if he has any biological siblings.
** Fluttershy has a younger brother named Zephyr Breeze.
** Applejack comes from a rather large family and thus has numerous siblings--but the ones we see (and hear about) the most are her older brother, Big Macintosh, and her younger sister, Apple Bloom.
* In ''WesternAnimation/PhineasAndFerb,'' the title characters' three main friends ([[TheBigGuy Buford]], [[BollywoodNerd Baljeet]] and [[TheChick Isabella]]) are all only children, as is [[MadScientistsBeautifulDaughter Vanessa]]. [[AsianAirhead Stacy]] and [[ScoutOut Ginger]] are [[ConnectedAllAlong revealed to be sisters]] once, but otherwise it doesn't come up, while WordOfGod say that [[OutOfFocus Jenny and Django]] are siblings. Interestingly, all of the major adult characters (Linda, Lawrence, and Doofenshmirtz]] have siblings. [[AnimalSuperhero Perry]]'s status is unknown.
** Ferb could be considered an only child in a strictly biological sense, as he's presumably the only child that Lawrence had through his first wife.
* On ''WesternAnimation/ReadyJetGo'', all of the kids -- Jet, Sean, Sydney, Mindy, Mitchell, Lillian, and Zerk -- are only children. In "So Many Moons", Mindy says that her parents are thinking about having another baby, [[AbortedArc but that arc was soon dropped and forgotten about]].
* Of the six main characters in ''WesternAnimation/{{Recess}}'', three (Gretchen, Gus, and Mikey) are only children. TJ and Vince have elder siblings who have appeared in the show. Spinelli mentions having an older brother in jail but considering how she actually lied about her parents to make them seem cooler, it might also be made-up.
* Mostly averted in ''WesternAnimation/RocketPower''. Out of the main cast, Sam is the sole only child in the series.
** Reggie and Otto have each other.
** Twister has an older brother named Lars--the brothers also have a little cousin named Scottie, who's an only child but looks up to Twister as an older brother.
* ''WesternAnimation/{{Rugrats}}'': [[HalfIdenticalTwins Phil and Lil]] are the only characters to have had siblings from the start of the series [[CaptainObvious (since they're fratenal twins).]]
** Susie's established as having siblings since her introduction on the show (she's the youngest of four kids).
** Tommy eventually gained a younger brother named Dil (after the first movie) while Chuckie eventually gained both a step/adoptive sister named Kimi and a step/adoptive mother named Kira (after the second movie).
** Angelica's the only one of the kids to remain an only child throughout the entire series--she's usually thankful for her status as an only child, but she has sometimes expressed a desire for a sibling.
* ''WesternAnimation/{{Rupert}}'': Except for the Fox twins and Bill and his baby brother, every single child in Nutwood is an only child.
* ''WesternAnimation/SheRaAndThePrincessesOfPower'': Castaspella is the sister of Glimmer's father Micah, Bow has [[MassiveNumberedSiblings one dozen]] [[TheGhost unseen]] older siblings, and [[spoiler:Horde Prime and his [[CloneArmy many clones]] (including Hordak)]] refer to each as [[ArtificialFamilyMember "brothers"]]. Siblings are not otherwise mentioned, though Adora, Catra, and several other characters from the Horde are orphans who wouldn't know if they had biological siblings.
* ''WesternAnimation/TheSimpsons'': Aside from the Simpsons family, The Flanders', Apu and Manjula, the Hibberts and Sherrie and Terri's family the rest of the couples have one child only. With the exception of the above, most of the kids from the elementary school are only children. This is justified in an issue of ''Simpsons Comics'' that ends with all the adults in Springfield becoming sterile.
* ''WesternAnimation/SouthPark'': Most of the minor characters seem to be only children (except for Craig, who has a younger sister), and out of the five "main boys", Butters and Cartman grew up as only children. ([[spoiler:Except that Cartman actually has an older half-brother]]). "Reverse Cowgirl" states that [[TheGenericGuy Clyde]] has a sister, but she's never (explicitly) appeared.
* Most of the characters in ''WesternAnimation/StarVsTheForcesOfEvil'' don't appear to have any siblings, including [[MagicalGirl Star]] herself (which is a little odd, considering how many extended family members she has), [[OurDemonsAreDifferent Tom]], [[ActionGirl Kelly]] and [[NightmareFetishist Janna]]. [[MuggleBestFriend Marco]] is an only child for most of the series, though his parents have another child later. In contrast, [[StarterVillain Ludo]] and [[ItsAllAboutMe Pony Head]] both have MassiveNumberedSiblings.
* ''WesternAnimation/StevenUniverse'': Steven is an only child because he could only be born by his mother giving up her physical existence. Full gems don't have biological family on account of their BizarreAlienReproduction, though the Diamond Authority have a sibling-like relationship, and Amethyst considers the gems made on the same planet as her "[[{{Portmanteau}} Famethyst]]". Of the human characters, only six are expressly shown to have siblings: Peedee and Ronaldo are brothers, Jenny and Kiki are twin sisters, and Sour Cream and Onion are half-brothers with a wide age gap. Connie, Lars, Sadie, Buck, Kevin, and all the adults are either only children or their siblings are never mentioned (though we do eventually meet a cousin of Greg's).
* In ''WesternAnimation/TeenTitans'', with the exception of Starfire (who has [[CainAndAbel an older sister]] and, [[ComicBook/TeenTitansGo in the tie-in comic]], a younger brother), all of the main Titans are only children.[[note]]The comics would eventually state that Raven has many half-siblings through her demonic father, but that became canon after the show ended. Robin traditionally has several "Bat-siblings," but presumably they won't come until he [[LegacyCharacter stops being Robin]].[[/note]]
* {{Averted}} in ''WesternAnimation/TotalDrama''--taking both the show and [[AllThereInTheManual supplementary materials]] into account, only three characters ([[TheChick Zoey]], [[ExtravertedNerd Cody]] and [[{{Geek}} Beth]]) are confirmed to be only children, but about half of the original cast are mentioned to have siblings.
* Zigzagged in ''WesternAnimation/VoltronLegendaryDefender''. Lance, Pidge, and Hunk are all shown as having at least one sibling. Meanwhile, Allura and Keith are both only children (though justified in the latter's case since his parents were only together for a few years), and Shiro's family goes unmentioned altogether.
[[/folder]]

* From 1979-2016, UsefulNotes/{{China}}'s one-child policy prevented urban married couples from having more than one child[[note]]With numerous exemptions, such as: you can have two kids if you live abroad, if you've divorced and remarried, or if you're an ethnic minority.[[/note]]. This has led to coinage of the term [[http://en.wikipedia.org/wiki/Little_Emperor_Syndrome Little Emperor Syndrome]] to describe the social implications of such a phenomenon when it has an effect on a nationwide level. The law was slowly walked back over time, first couples where both spouses were only children could have two, then if one spouse was, and now all couples can have two children.
** It's also led to a fairly significant gender disparity; sons have always been more desirable than daughters, and all the more so when a couple is only allowed one child, so many parents aborted female fetuses or gave daughters up to orphanages to be put up for adoption so they could have a boy. At the moment, there are [[https://www.nytimes.com/2017/02/14/world/asia/china-men-marriage-gender-gap.html 33.59]] ''million'' more men than women in China, with the result that a whole lot of men in a family-oriented culture are unable to marry. This was part of the reason China expanded the limit to two children starting in 2016 and is reportedly even considering ending family restrictions altogether.
[[/folder]]

----

** The Weasleys are an aversion with [[MassiveNumberedSiblings seven children]], as is their mother, who has two (deceased) brothers. The Black family are also reasonably filled out, with Sirius having a brother and Narcissa, Bellatrix and Andromeda being sisters.

** Some of the Hogwarts staff are questionable because they're Harry's teachers so family just doesn't really come up. The only teachers Harry for sure knows have siblings are Dumbledore (who has a brother and deceased sister) and Hagrid who has (at least) a half-brother. Even the former was mostly found out posthumously since he only ever directly mentions his brother in front of Harry once and never mentions his sister. [=McGonagall=] was confirmed to have two brothers whom she never mentions in the books but everyone else remains a question mark.

** Some of the Hogwarts staff are questionable because they're Harry's teachers so family just doesn't really come up. The only teacher Harry for sure knows has siblings is Dumbledore (who has a brother and deceased sister) but even that was mostly found out posthumously since he only ever directly mentions his brother in front of Harry once. [=McGonagall=] was confirmed to have two brothers whom she never mentions in the books but everyone else remains a question mark.

** Remus Lupin, Severus Snape, Luna Lovegood, and Draco Malfoy are also only children, but in their case, there is no explanation. Draco is a particularly odd case as the only child of his parents and the father of one child himself, leaving readers to wonder how the Malfoys expect to preserve their precious bloodline with only one child a generation. Some more minor characters who appear to be only children include: Seamus Finnegan, Pansy Parkinson, Crabbe, and Goyle. Some of the Hogwarts staff are questionable because they're Harry's teachers so family just doesn't really come up. The only teacher Harry knows has siblings is Dumbledore (who has a brother and deceased sister) but even that was mostly found out posthumously since he only ever directly mentions his brother in front of Harry once. [=McGonagall=] was confirmed to have two brothers whom she never mentions in the books.

** Remus Lupin, Severus Snape, Luna Lovegood, and Draco Malfoy are also only children, but in their case, there is no explanation. Draco is a particularly odd case as the only child of his parents and the father of one child himself, leaving readers to wonder how the Malfoys expect to preserve their precious bloodline with only one child a generation. Seamus Finnegan, Dean Thomas, Pansy Parkinson, Arthur Weasley, Crabbe and Goyle all appear to be only children too, as appear to be almost all the Hogwarts staff (except for [[spoiler:Dumbledore, with a brother and deceased sister]].

** Remus Lupin, Severus Snape, Luna Lovegood, and Draco Malfoy are also only children, but in their case, there is no explanation. Draco is a particularly odd case as the only child of his parents and the father of one child himself, leaving readers to wonder how the Malfoys expect to preserve their precious bloodline with only one child a generation.
** The Weasleys are an aversion with [[MassiveNumberedSiblings seven children]].

* Averted for the most part in ''WesternAnimation/MyLittlePonyFriendshipIsMagic'', with some of the main character's siblings being important supporting characters and even having their own [[ADayInTheLimelight focus episodes.]]
** Rarirty has a younger sister named Sweetie Belle.

** Twilight Sparkle has an older brother named Shining Armor (who has a wife named Cadence)--Shining Armor and Twilight Sparkle also have Spike the Dragon, whom they essentially see as their adoptive younger brother.

** Applejack comes from a rather large family and thus has numerous siblings--but the ones we see and hear about the most are her older brother, Big Macintosh, and her younger sister, Apple Bloom.
** Rainbow Dash is the only one of the main six to be an only child, though she does have a very sisterly-relationship with Scootaloo (who's presumably an only child as well). Starlight Glimmer's presumably an only child (and we only ever hear about her dad) and we never see or hear anything about Spike's biological family.

** Twister has an older brother named Lars--the brothers also have a little named Scottie, who's an only child but looks up to Twister as an older brother.

* Except for WesternAnimation/{{Cinderella}} (who has two stepsisters), [[WesternAnimation/TheLittleMermaid Ariel]] (who's the youngest of seven daughters) and [[WesternAnimation/{{Brave}} Merida]] (who's the oldest and only daughter of four kids), all the Franchise/{{Disney Princess}}es are only children -- although you could consider Cinderella an only child in a strictly biological sense (since she's the only child her dad had through his first wife and he didn't have any more biological children after he and Lady Tremaine got married). And for Rapunzel, her status as an only child is [[JustifiedTrope justified]] in that her biological mother's pregnancy almost killed them both--and, also because of that, Queen Arianna (Rapunzel's biological mother) may have been rendered unable to have more children through biological means.

** Jen and Jonesy both have siblings (Jen has an older sister while Jonesy has two younger brothers) and the two are stepsiblings to each other (due to Jen's mom and Jonesy's dad hooking up and eventually getting married). They also eventually end up gaining a baby half-sister.

** While Ralphie, Tim, Arnold, Phoebe, and Keesha are never explicitly stated to be only children, whenever their families were shown, we only ever see their parents and no siblings of any kind.

* Averted for the most part in ''WesternAnimation/MyLittlePonyFriendshipIsMagic'': Rarity has her younger sister Sweetie Belle; Pinkie Pie has her sisters Limestone, Marble, and Maud; Twilight has her older brother Shining Armor and sister-in-law Cadance, as well as Spike the dragon, whom she and Shining see as essentially their adoptive brother; Fluttershy has her younger brother Zephyr Breeze; and Applejack has her large family, including her older brother Big Macintosh and her younger sister, Apple Bloom. They are pretty important supporting characters and even have a few [[ADayInTheLimelight episodes]] of their own. Of the main cast, Rainbow Dash, Scootaloo, and Starlight Glimmer do not have siblings, while Spike's biological family has yet to appear.

* Mostly averted in ''WesternAnimation/RocketPower''. Out of the main cast, Sam is the sole only child in the series. Sister and brother team Reggie and Otto have each other. Twister has his older brother Lars, and even his little cousin Scottie, who is an only child himself and looks to Twister as a surrogate brother.
* ''WesternAnimation/{{Rugrats}}'': Originally, [[HalfIdentitcalTwins Phil and Lil]] were the only main characters with siblings. The show eventually introduced Susie, who had older siblings, while Tommy got a little brother, Dil, and Chuckie got a step-/adoptive sister, Kimi. Angelica is the only one to remain an only child throughout the series; usually she's happy about that, though there was a SiblingsWanted plot in one episode.

* {{Averted}} in ''WesternAnimation/TotalDrama''--taking both the show and [[AllThereInTheManual supplementary materials]] into account, only three characters ([[TheChick Zoey]], [[ExtravertedNerd Cody]] and [[{{Geek}} Beth]]) are confirmed to be only children, but about half of the original cast have siblings mentioned.