People procreate. [[MassiveNumberedSiblings Some do it a lot.]] [[MyBiologicalClockIsTicking Some really want to do it before time runs out.]] [[ChildHater 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.



[[folder: Anime and Manga ]]
* 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.
* 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.
* 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.
* 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.
* ''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]].
* 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).
* 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.
* 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.
* In ''Manga/OnePiece'', Boa Hancock is the only major character known to have biological siblings [[spoiler:besides Sanji, who left behind a whole SiblingTeam when he ran away as a child]], as it eventually is revealed Ace is Luffy's adopted brother. 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.
* 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.
* Most lead Pretty Cures from the [[Anime/PrettyCure franchise]] are only children, with the exception of [[Anime/FutariWaPrettyCure Nagisa]] 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 and Iona]].
** 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]], 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.
* In ''Manga/PokemonAdventures'', there is a rotating cast of 21+ main characters, yet only one is confirmed to have a sibling: Green and his older sister Daisy, and she's most likely only there because she exists in the games. 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.
* Among the major characters in ''Manga/KaguyaSamaLoveIsWar'', only Kaguya is known to be an only child (Shirogane has a younger sister, Fujiwara is the middle child of three girls, and Ishigami's has an older brother). It plays into her LonelyRichKid status.
* 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.
* 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). Though it's somewhat ironic that Hori would be the one to point it out, considering that she spends most of her time outside of school taking care of her little brother.
* 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.

[[folder: Comic Books ]]
* Franchise/{{Batman}} and all of his protégés except for [[Comicbook/{{Batgirl}} Barbara]] fall under this trope, though since he's adopted most of the Robins and [[ComicBook/Batgirl2000 Cassandra]], they consider themselves siblings ([[BigBrotherMentor for better]] [[CainAndAbel or worse]]). There's also Batman's older brother, Thomas Wayne Jr., who's existed in various alternate continuities (and possibly in the Comicbook/{{New 52}} as well). Also, for a while he actually thought Comicbook/{{Bane}} was his half-brother, but that didn't pan out in the end.
* ComicBook/GreenArrow and all of ''his'' protégés...until his ComicBook/DCRebirth series, where a long-lost half-sister showed up.
* Franchise/{{Superman}} is doubly so - he was the only child of the Jor-Els (though granted, they might have had more if it weren't for the [[EarthShatteringKaboom slight impediment of being dead]]), and he's the only child of his adopted parents. Understandably justified as his birth parents died along with his entire planet when he was a baby, and the Kents couldn't have kids of their own.
* Franchise/WonderWoman:
** Diana's birth / creation into a league of immortals doesn't raise as many eyebrows as to why few children are born. Since they don't die, if they had new children showing up as often as humans do, their home island would be standing room only after a few centuries.
** Granted, Pre-Crisis Diana had a black twin sister. [[ No, really]].
** Diana usually ''treats'' ComicBook/DonnaTroy as her younger sister--[[ContinuitySnarl whether they're actually related is...]][[MultipleChoicePast debatable]]. Various explanations include her being a sort of magical clone of Diana or being a normal {{Muggle}} girl adopted by Hippolyta and given superpowers after Diana had already left the island.
** As of 2017, ComicBook/WonderWomanRebirth is apparently introducing Diana's long-lost ''brother.''
* An unusual number in Marvel Comics:
** 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.
** Tony Stark (Comicbook/IronMan) is an only child [[spoiler:except for the brother he never knew about.]]
** Bruce Banner (Comicbook/TheHulk) 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).
** Matt Murdock (Comicbook/{{Daredevil}}) is an only child.
** Peter Parker (Comicbook/SpiderMan) is an only child. 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.
** All the 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.
** 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 also mentioned two younger siblings early on, but over ten years 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]]
** Averted once more 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 have two children.
* One thing Franchise/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 Jason and Cheryl Blossom, who are about as far from role models as you can get.

[[folder: Fanfiction]]
* 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.
* 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.

[[folder:Film -- Animated]]
* Almost all of the Franchise/{{Disney Princess}}es are only children. However, in the original poem ''The Ballad of Hua Mulan'', Mulan has a younger sister, an older sister and a little brother ([[MythologyGag which is who they named they dog after in the movie]]) who is not old enough to join the army, but old enough to kill pigs by the time she comes home. Also, the real Pocahontas probably had many brothers and sisters as Powhatan had quite a few wives. Belle is given an unwanted suitor instead of the two jealous sisters from the original tale. Cinderella still has her mean stepsisters, though. Early drafts of {{Moana}} made her the youngest and the only daughter in a family with several sons, with a stronger "girls can do anything" theme; this was dropped in favour of focusing on a "follow your heart" message, with Moana an only child expected to become chief of her tribe. Rapunzel is [[JustifiedTrope justified]] by the fact that her mother's pregnancy almost killed them both. The exceptions are Ariel, who has [[MassiveNumberedSiblings six older sisters]], [[WesternAnimation/{{Brave}} Merida]], who has three younger brothers (triplets), and [[Disney/{{Frozen}} Anna and Elsa]].
* It's glaringly noticeable in ''Disney/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 ''Disney/TheLionKingOneAndAHalf''. 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. Nala was also supposed to have a 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]]
* Almost all of the major characters in ''Film/HarryPotter'', including the title character and protagonist himself, are only children.
* ''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.
* 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 sibling 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.
* 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.

* ''Literature/{{Animorphs}}'': [[TheLeader Jake]] has [[GrandTheftMe Tom]], [[DarkActionGirl 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.
** 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.
* ''Literature/HarryPotter'':
** Of the three main characters, we have Harry, whose parents died when he was a year old, Hermione, who has no siblings, and the Weasleys who are easily a case of MassiveNumberedSiblings. Then again, maybe that's why Harry and Hermione marry who they do.
** Interestingly, Hermione was supposed to have a younger sister, but [[WordOfGod Rowling wasn't able to fit her in.]]
** Death Eaters only have one child if any--just enough to satisfy plot needs: Nott, Malfoy, Crabbe, Goyle, Rosier, Mulciber, and Avery all have only one son. And these lines never go into three generations like real life would suggest. None of the original Death Eaters (Tom's era) have grandchildren in Harry's era, while none of the younger Death Eaters (Lily's era) have confirmed fathers who were Death Eaters (although there are some surnames that appear in both eras as Death Eater names).
*** Wizards live longer -- much longer -- than Muggles, though, so it may be that not enough time has passed for the third generation of Death Eater names to show, or they [[PutOnABus went to Durmstrang]], or simply attended Hogwarts during some time period between Tom's school days and Harry's and then got out of the family business.
* 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.
* 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, 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''. Most of the 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.
* ''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 have played important roles in his back-story and his older brother becomes a major player in Season 2, though the sister has yet to figure), while Koenig appears to have a suspiciously well-stocked army of [[BackupTwin Back-Up Twins]].
** 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.
* Averted in ''Series/Runaways2017'', 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.]] The ''rest'' of the cast are still only children.
* Very much averted in ''Series/TheBigBangTheory''. Howard grew up an only child, but discovered a half-brother. Sheldon has an older brother, George, and a twin sister, Missy; Leonard has an unnamed older sister and a younger brother, Michael; Penny has an unnamed brother and sister; and Raj has a younger sister, Priya, three unnamed brothers, and another unnamed sister. Bernadette, Amy, and Stuart have an unspecified number of siblings as well. Numerous aunts, uncles, cousins, nieces, nephews, and grandparents are also mentioned throughout the series.
* ''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 I'm almost certain 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) 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 parent's 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 because 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 her mother's only child in ''Series/GilmoreGirls'' but that might be because Lorelai made sure she didn't have another child out of wedlock. Of course, the basic premise of the whole series is that it focuses on a mother-daughter team.
* 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.
* 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, Thirteen, Taub and Kutner. It takes a while to mention Cameron's brother, Foreman's brother, Wilson's brother and Cuddy's sister.
** 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.
* ''Series/HowIMetYourMother'': Out from the five main characters, Lily is the only one who does not have siblings considering that [[DisappearedDad her dad is not doing his parental responsibilities very well]]. Ted has a younger sister [[ChuckCunninghamSyndrome who more or less appear 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 an older half-brother who is black 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.
* 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/{{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]].)
* 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.
* 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 child. 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/{{Zoey 101}}'', 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: Theatre]]
* Romeo Montague and Juliet Capulet from ''RomeoAndJuliet'' are both only children. Tybalt and Benvolio are presumably only children as well, although Mercutio has a brother only mentioned in passing.

[[folder: Video Games ]]
* ''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.
* In the ''[[Franchise/ShinMegamiTenseiPersona 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/{{Persona 3}}'' has a party mostly composed of only children, except for Akihiko, whose younger sister died years ago.
** ''VideoGame/{{Persona 4}}'' 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/{{Persona 5}}'' [[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]].
* Most of the rivals and protagonists in ''Franchise/{{Pokemon}}'' 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=]''), and Trevor from ''VideoGame/PokemonXAndY'' having an older sister.
* 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 by her brother.

[[folder:Western Animation]]
* 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.
* ''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.
* Curiously, every child who had a prominent appearance in ''WesternAnimation/DannyPhantom'' is shown as being an only child. The only one who isn't is Danny himself. He has an older sister and, if you wanna stretch it, an OppositeSexClone whom he treats like [[BigBrotherInstinct a little sister]].
-->'''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 both 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 step brother 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 sister, and Cosmo has a 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'', [[BlackBestFriend Gerald]] has [[AloofBigBrother two]] [[AnnoyingYoungerSibling siblings]] and [[JerkassWoobie Helga]] has [[ParodySue a sister]], but otherwise all the kids seem to be only children.
* 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 two half-brothers, though (one born in his father's old age, 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]].
* Five of the eight main kinds on ''WesternAnimation/TheMagicSchoolBus'' are only children (these are Ralphie, Tim, Arnold, Phoebe and Keesha). Dorothy Ann has a younger sister named Evan while Wanda and Carlos both have younger brothers--Wannda's brother is named William and Carlos's brother is named Mikey.
* In ''WesternAnimation/{{Metalocalypse}}'', Pickles is the only member of Dethklok with a sibling.
* 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'': 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; 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 is the only one confirmed to be an only child, while Starlight Glimmer's, Spike's, and Scootaloo's families have yet to appear (although a TieInNovel shows that Scootaloo stays with her aunts, as her parents are usually away on business).
* ''WesternAnimation/PhineasAndFerb'' seem to play this halfway--there's the title characters and their sister [[UnknownRival Candace]], [[SingleWomanSeeksGoodMan Jeremy]] / [[EnfantTerrible Susie]] and [[LoonyFan Irving]] / [[AloofBigBrother Albert]] as siblings, but [[TheChick Isabella]], [[BollywoodNerd Baljeet]], [[JerkWithAHeartOfGold Buford]], [[AsianAirhead Stacy]] and [[MadScientistsBeautifulDaughter Vanessa]] all get lots of screen time and give no indication of having a sibling. Adults having siblings seems to be more common--Lawrence has at least one (Ferb has [[MassiveNumberedSiblings six cousins]] from what we know to be Lawrence's brother, and Scottish cousin whose relationship to Lawrence has not been revealed), Linda has Tiana and [[MadScientist Doofenshmirtz]] has Roger.
** Technically, Ferb would be an only child in a [[HappilyAdopted strictly biological sense]].
** WordOfGod has apparently confirmed that Stacy and Ginger (the Fireside Girl) are siblings, as are [[GranolaGirl Jenny]] and [[DemotedToExtra Django]].
* 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, and Spinelli mentions having an older brother in jail.
* 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.
* Most of the babies in ''WesternAnimation/{{Rugrats}}'' were only children, but this changed after the respective releases of the first two movies: [[TheDeterminator Tommy]] gained [[TheVoiceless Dil]] as a younger brother after the first movie, and Chuckie gained Kimi as a stepsister after ''Rugrats In Paris.'' Among the main kids, Angelica is the last only child remaining (Phil and Lil are twins, and Susie is the youngest of four siblings).
** Angelica's being an Only Child was actually made the plot of one episode, where she became ''upset'' at being the only one like this (an unusual turnabout, since in previous episodes she was ''glad'' to have no siblings). The resolution came when Tommy pointed out that [[CrowningMomentOfHeartwarming with the way she occasionally picks on them but still cares, Angelica's really like a big sister to all of the younger kids]].
* Aside from WesternAnimation/{{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 child.
** 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 Star herself (Which is strange considering how many extended family members she has). Ludo and Pony Head both have MassiveNumberedSiblings, and as of season 3 [[spoiler: Marco is soon to have a younger brother]].
* ''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 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 a younger brother), all of the main Titans are only children. (The comics would eventually state that Raven has many half-siblings through her demonic father, but that became canon after the show ended.)
* {{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 only children, but about half of the original cast have siblings mentioned.
* Caitlin Cooke's the only one of the main six in ''WesternAnimation/{{Sixteen}}'' confirmed to be an only child --
** Jonesy and Jen both have siblings (Jen has an older sister while Jonesy has two younger brothers), are stepsiblings to each other (due to Jen's mom and Jonesy's dad getting married) and end up having baby half-sister.
** Jude and Wyatt have never mentioned having siblings, although Wyatt's mentioned to come from a large family--whether this means a large immediate family or a large extended family is uncertain.
** A couple of early episodes suggested that Nikki has siblings, but later episodes (including the series finale) seems to suggest that Nikki's probably an only child like Caitlin is.

[[folder:Real Life]]
* Since 1979, UsefulNotes/{{China}}'s one child policy has 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 [[ Little Emperor Syndrome]] to describe the social implications of such a phenomenon when it has an effect on a nationwide level. The multi-generational aspect of this trope is averted, however, as parents who were both only children themselves are allowed to 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. At the moment, there are [[ 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.