History Main / DoesntKnowTheirOwnBirthday

* [[Characters/HololiveEnglishGenerationOneMyth Gawr Gura]] from ''WebAnimation/{{Hololive}}'' has been around long before the modern Gregorian calendar was invented, indeed longer than before humans began recording the passage of time. She also doesn't remember [[VagueAge exactly how old she is]] anymore, but knows it's somewhere after 9000 years. For this reason, she declared June 20th as a SignificantBirthDate because it's the day when ''Film/{{Jaws}}'' was released in theaters.

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* ''Manga/ChainsawMan'': Denji says he "thinks" he's sixteen years old, suggesting he doesn't know his exact birthday. It's implied basically getting abducted into slavery by mobsters at a young age [[TheSpook has made his existence largely undocumented]].

[[quoteright:350:[[WesternAnimation/BobsBurgers https://static.tvtropes.org/pmwiki/pub/images/tumblr_inline_po25pvoerk1r5ioas_540.png]]]]
[[caption-width-right:350:"Today's my birthday?"]]

* ComicBook/HoneyBadger doesn't know her date of birth, being a clone. The Stepford Cuckoos have a similar predicament, but decided to arbitrarily pick a day based on the birth date of their favorite actor.

May lead to VagueAge. If the character doesn't remember their birthday, this often relates to a MysteriousPast. One of the reasons a character may have NeverHadABirthdayParty. Often caused by the same reasons a character was NeverGivenAName. Compare ForgottenBirthday for when a character's friends/family forget their birthday. This may also go along with a BirthdayHater.

* A variation occurs in ''Series/FindingCarter''. The eponymous protagonist ''thought'' she knew her birthday, but the day that she had celebrated as her birthday for most of her life was actually the day that her "mom" kidnapped her from her real family.

* A variation occurs in ''Series/FindingCarter''. The eponymous protagonist ''thought'' she knew her birthday, but the day that she had celebrated as her birthday was actually the day that her "mom" kidnapped her from her real family.

* In ''Literature/LoskutikAndTheCloud'', Loskutik, a poor orphan who has lived her entire life as a servant to abusive masters, doesn't know when her birthday is.
* In the ''Literature/ModestyBlaise'' series, Modesty was orphaned very young and doesn't know her real birthday (or anything else about her birth family; even her name is one she acquired later). In ''The Impossible Virgin'', when Sir Giles says that at his age he doesn't bother celebrating birthdays, she says that she uses it as an excuse to celebrate her birthday three times a year.

* ''VideoGame/TheIdolmasterSideM'' has Kei, a man so [[{{Cloudcuckoolander}} listless]] he doesn't know when his birthday is, let alone his age. The Producer and others know enough to help him celebrate every year, so they'll remind him when the time comes.

* In ''ComicBook/AllStarSuperman'', our hero doesn't know when his biological parents' birthdays are, so he's arbitrarily marked two dates six months apart as the days that he'll celebrate them. Since he's the only one observing them[[note]]Clark's cousin [[{{ComicBook/Supergirl}} Kara]] isn't mentioned, so it's unclear if she even exists in this continuity.[[/note]], it doesn't really matter.

* ''Series/AgentsOfSHIELD'': Daisy Johnson[=/=]Skye spent her whole childhood frequently changing among foster families without ever knowing her biological parents, therefore she never knew her exact birthday. [[spoiler:When she manages to reunite with them she learns that her birthday was on July 2nd and that she was born in 1988, and not in 1989 as she believed.]]

* A ''RWBY'' fanfic written before it was revealed that Blake isn't an orphan revolved around Blake being a BirthdayHater because she didn't know her own birthday.

[[folder:Web Comics]]

* Mosuo writer Yang Erche Namu has no known birthday and does not even know her own birthday, as Mosuo traditionally do not record them.
* Technically the case for anyone who was a [[DoorstopBaby foundling (excluding those who had obviously been born the same day they were abandoned); they do have a official birth date but usually it's just an educated guess in order to have something to put on the paper work that's based on how old they're estimated to be when found.

* ''VideoGame/FireEmblemThreeHouses'' a disguised example. While Byleth's date of birth is chosen by the player, they do have a canon birthdate as well. [[spoiler:As in, one that's always canon, revealed as part of the plot. It's hinted the player-chosen birthdate actually belongs to Sothis, which Byleth osmosed thanks to SharingABody.]]

* ''WesternAnimation/TheTransformers'': One episode reveals that Ultra Magnus dosen't remember the date of his own creation so Wheelie and Daniel set out to find it.

* ''WesternAnimation/StevenUniverse'': In "So Many Birthdays", as Garnet and Pearl were born on another planet, Amethyst lived alone for a long time, and [[TimeAbyss all of them predate modern calendars anyway]], Steven makes up a birthday for the three of them.

* In ''ComicBook/AllStarSuperman'', our hero [[{{CaptainObvious}} doesn't know when his biological parents' birthdays are]], so he's arbitrarily marked two dates six months apart as the days that he'll celebrate them. Since he's the only one observing them[[note]]Clark's cousin [[{{ComicBook/Supergirl}} Kara]] isn't mentioned, so it's unclear if she even exists in this continuity.[[/note]], it doesn't really matter.

* In ''WesternAnimation/StevenUniverse'', as Garnet and Pearl were born on another planet, Amethyst lived alone for a long time, and [[TimeAbyss all of them predate modern calendars anyway]], Steven makes up a birthday for the three of them.