History Main / BirthdayBuddies

* ''Webcomic/ElGoonishShive'': Susan and Diane are IdenticalStrangers (with the only real physical differences being magically induced on Susan's part) who go to different schools in the same town, and who are being watched over by the same immortal. The evidence they might be twins is heightened by the fact that they were born hours apart. Downplayed in that they don't technically share a birth''date'' (Diane was born before midnight on New Years Eve, while Susan was born after midnight on New Years Day) and [[spoiler: full-on subverted when it's revealed Susan's mother definitely only had one kid -- their birthdays were a RedHerring for the ''real'' reason they look so similar (sharing an immortal ancestor).]]

* ''Webcomic/ElGoonishShive'': Susan and Diane are near-IdenticalStrangers (with the only real physical differences being magically induced on Susan's part) who go to different schools in the same town, and who are being watched over by the same immortal. The evidence they might be twins is heightened by the fact that they were born hours apart. Downplayed in that they don't technically share a birth''date'' (Diane was born before midnight on New Years Eve, while Susan was born after midnight on New Years Day) and [[spoiler: full-on subverted when it's revealed Susan's mother definitely only had one kid -- their birthdays were a RedHerring for the ''real'' reason they look so similar (sharing an immortal ancestor).]]

* Series/TheBigBangTheory: In "The Birthday Synchronicity", Bernadette goes into labor with her first-born at midnight on Amy's birthday, which interrupts Amy's annual "birthday coitus" with Sheldon.

* PlayedWith in ''Literature/PercyJacksonAndTheOlympians:'' Thalia knows her birthday, but not her age. At 12 she was [[{{Transflormation}} turned into a tree]] for seven years, during which time she aged slower than usual. Apollo, with his [[PrescienceIsPredictable power of prophecy]], informs her that she's about a week shy of her DangerousSixteenthBirthday.

* On Series/TheBigBangTheory, Bernadette goes into labor on Amy's birthday.

Birthdays. A celebration of the individual and their continued existence on this Earth, a personal and special day for the birthday-person, a day all about ''them.'' Except that, with only 365-366 days in a year and billions of people on the planet, no birthday is unique to the individual. Everyone shares a birthday with ''someone''... and occasionally, a character may just run into someone else who has the same birthday as them.

This may be a cause for bonding, if the characters decide to celebrate together or, at the very least, realize they have one thing they can both relate to. This may also be a cause for a rivalry, or inflame a pre-existing rivalry, as both characters may want the spotlight, and compete to have their party be bigger and better than their enemy's. It may even mean both characters are special somehow, if the birthday they share is a SignificantBirthDate.

These characters, of course, should ideally be unrelated. Twins are inherently born on the same day, [[note]]with very rare exceptions[[/note]] so this trope concerns those who aren't twins... that is, unless the point is to foreshadow a SeparatedAtBirth twist, with the characters (and often the audience) not knowing right away. This also means other familial-relationships are allowed, assuming the emphasis is on the special shared date just as in a non-related-character example. They also don't have to be literally born on the same day down to the year, so long as they share the same birthday each year they're both alive.

** Kaguya and her ShadowArchetype/cousin Maki (and by extension Maki's twin brother Mikado) were born on New Years Day.

* ''Manga/TegamiBachiLetterBee'': Lag and Sylvette are both born on the Day of Flicker. Being born on the Day of Flicker caused Sylvette's legs to be non-functional from birth, while Lag has an eye missing. As one may guess, the Day of Flicker later turns out to have been the sign of something bigger going on.

* In ''Fanfic/UnexpectedSurprise'', Emma and Gabriel first meet when the little girl leaves her mom's office to cheer someone up during her birthday, and runs into the boss grieving, because it's also the birthday of his beloved late wife.

* In ''Literature/TheLordOfTheRings'', Bilbo and Frodo share a birthday, September 22. The story opens with their shared birthday party (Bilbo's 111st, Frodo's 33rd). After Bilbo leaves the Shire to go adventuring again, Frodo continues to refer to the date as "our birthday" and keeps up the tradition of joint birthday parties.

* In ''Literature/SnowFlowerAndTheSecretFan,'' Snow Flower and Lily ending up being chosen as each other's laotong in part because they share the same birthday.

* ''Series/{{Bunkd}}'': Both Tiffany Chen and Hazel Swearington were born on the same day. This was best exampled in "Boo Boos and Birthdays" when Hazel overhears Emma and Lou's party plans for Tiffany and believe they're for her and they remembered; matter of fact, ''no one'' remembers Hazel's birthday anyway.

* ''Series/HouseOfAnubis'': Joy and Nina were both born on July 7th, which is a SignificantBirthDate. Joy was believed to be TheChosenOne because of her birthday, but wasn't born at the exact right ''time''; this lead to the reveal that Nina, who had the same birthday, was the ''real'' Chosen One, being born at 7:00 AM. The two of them were, incidentally, born 12-hours apart.

* In the ''Series/SpaceCases'' episode "It's My Birthday, Too, Yeah", Radu lies and claims that he shares a birthday with Bova, because his species don't actually have birthdays and he's NeverHadABirthdayParty.
* ''Series/StuckInTheMiddle'': Louie and Beast have seperate birthdays, but did not know this. When Harley informs of them, they also choose to keep sharing a joint birthday.

* In ''VideoGame/DragonQuestXI'', the protagonist and his ChildhoodFriendRomance Gemma not only share a birthday, but they were born on the same day. As the game begins, they must climb a mountain as part of a coming-of-age ceremony, and it's remarked that it's almost unheard-of for more than one person to perform the ceremony at once (although Gemma hardly minds having a companion/bodyguard for the trip).

* ''WebVideo/TheLizzieBennetDiaries'': Lizzie Bennet is very close with her best friend Charlotte Lu, who was born on the very same day as she was. Lizzie jokes that they have been friends since fetuses because their mothers were friends who frequented the very same book club and went to labour at the same time. There's a rumour that Lizzie as a child behaved like a brat during Charlotte's 6th birthday party and wanted to open all of Charlotte's presents. During Q&A from fans, one person said they sensed lot of drama in that story, since it must have been Lizzie's birthday as well. Charlotte snarks that it's precisely it: Lizzie had her own presents to open.

* In ''WesternAnimation/AvatarTheLastAirbender'', it is revealed that the previous Avatar, and the Fire Lord that started the war (Roku and Sozin) were actually born the same day, and show that they were very close friends, even celebrating their birthday together. This all contrast with their later relationship as bitter enemies in their old age.

TruthInTelevision, obviously. Everyone shares their birthday with ''someone''. An interesting thing to note is that, according to the [[https://en.wikipedia.org/wiki/Birthday_problem birthday paradox]], it only takes 23 people to have a 50% chance of having a pair with the same birthday. In fiction, the fact that this trope is usually averted makes it similar to The OneSteveLimit. Even though it's common in real life, unless it has some sort of significance to the story, it would be weird for two characters to share the same name, just as it would be weird for them to have the same birthday.

** Both [[SitcomArchNemesis Fujiwara and Ishigami]] were both born on Hinamatsuri (March 3rd). [[SecretlySelfish Fujiwara immediately begins complaining upon hearing this because she doesn't want to have to share her birthday party]]. When their birthday is celebrated later in the series, Fujiwara spends the whole time whining.

* The ''WesternAnimation/{{Arthur}}'' episode "Arthur's Birthday", adapted from a book of the same name, deals with Arthur and his classmate Muffy having their birthday parties on the same day. Arthur and his friends aren't sure whose party to attend until they come up with a solution: [[spoiler:they turn it into a surprise party for Muffy at Arthur's house]].

* ''LightNovel/FullMetalPanic'': Though not mentioned until well into the series, all of the ''Whispered'' around the world were born on [[BizarreBabyBoom within the same three minute timespan]] (though local time frames mean some are on different calendar days).

* PlayedWith in ''Literature/PercyJacksonAndTheOlympians:'' Thalia knows her birthday, but not her age. At twelve she was [[{{Transflormation}} turned into a tree]] for seven years, during which time she aged slower than usual. Apollo, with his [[PrescienceIsPredictable power of prophecy]], informs her that she's about a week shy of her DangerousSixteenthBirthday.
* The first ''Literature/SeptimusHeap'' book opens with Septimus and Jenna both being born on the same day. Jenna's mother the Queen is killed, and she's adopted by the Heaps, who have just lost Septimus (they were told he died, but he was actually kidnapped for eleven years).

* Ayunda Risu of ''WebAnimation/{{hololive}}'' and Oga Aragami of ''[[SpearCounterpart holostars]]'' both have their birthdays on January 15th, and the two have collaborated to celebrate their shared birthday.
* ''WebVideo/TheLizzieBennetDiaries'': Lizzie Bennet is very close with her best friend Charlotte Lu, who was born on the very same day as she was. Lizzie jokes that they have been friends since fetuses because their mothers were friends who frequented the very same book club and went to labour at the same time. There's a rumour that Lizzie as a child behaved like a brat during Charlotte's sixth birthday party and wanted to open all of Charlotte's presents. During Q&A from fans, one person said they sensed lot of drama in that story, since it must have been Lizzie's birthday as well. Charlotte snarks that it's precisely it: Lizzie had her own presents to open.

* In ''[[https://incorrectsmashbrosquotes.tumblr.com Incorrect Smash Bros Quotes,]]'' Galeem and Dharkon share December 7th (the release date of ''VideoGame/SuperSmashBrosUltimate'', their debut game) as their birthday.

* ''Series/HowToRock'': Kacey and Nelson have the same birthday. When their friends plan a joint birthday party, Kacey's diva tendencies end up monopolising the event to her needs only. When she realizes what a self-centered jerk she is being, she changes the party to cater to Nelson's interests.

* In ''[[https://incorrectsmashbrosquotes.tumblr.com/ Incorrect Smash Bros Quotes]]'', Galeem and Dharkon share December 7th (the release date of ''VideoGame/SuperSmashBrosUltimate'', their debut game) as their birthday.

* ''Series/HowToRock'': Kacey and Nelson have the same birthday. When their friends plan a joint birthday party, Kacey's diva tendencies end up monopolising the event to her needs only. When she realises what a self-centered jerk she is being, she changes the party to cater to Nelson's interests.

* The reason ''WebVideo/CriticalRole'' castmates Creator/LiamOBrien and Creator/LauraBailey chose to make their first campaign character twins is because they share a birthday.

* PlayedWith in ''Literature/PercyJacksonAndTheOlympians:'' Thalia knows her birthday, but not her age. At twelve she was [[{{Transflormation}} turned into a tree]] for seven years, during which time she aged slower than usual. Apollo, with his [[ProphecyIsPredictable power of prophecy]], informs her that she's about a week shy of her DangerousSixteenthBirthday.

* ''Series/HowToRock'': Kacey and Nelson have the same birthday. When their friends plan a joint birthday party, Kacey's diva tendencies end up monopolising the event to her needs only. When she realises what a self-centered jerk she is being, she changes the part to cater to Nelson's interests.

* ''LightNovel/FullMetalPanic'': Though not mentioned until well into the series, all of the ''Whispered'' around the world were born on [[BizarreBabyBoom within the same three minute timespan]] (though local time frames mean some are on different calendar days).
* In ''Manga/LaidBackCamp'', Nadeshiko Kagamihara and Aoi "Inuko" Inuyama are both pleasantly surprised to find that they share a birthday on March 4.

* ''WebVideo/The8BitDrummer'' shares his birthday with his wife.

TruthInTelevision, obviously. There are eight billion people and only 366 possible birthdays, so everyone shares their birthday with ''someone''. An interesting thing to note is that, according to the [[https://en.wikipedia.org/wiki/Birthday_problem birthday paradox]], it only takes 23 people to have a 50% chance of having a pair with the same birthday. In fiction, the fact that this trope is usually averted makes it similar to The OneSteveLimit. Even though it's common in real life, unless it has some sort of significance to the story, it would be weird for two characters to share the same name, just as it would be weird for them to have the same birthday.

TruthInTelevision, obviously. Everyone shares their birthday with ''someone''. An interesting thing to note is that, according to the [[https://en.wikipedia.org/wiki/Birthday_problem birthday paradox]], it only takes 23 people to have a 50% chance of having a pair with the same birthday. In fiction, the fact that this trope is usually averted makes it similar to The OneSteveLimit. Even though it's common in real life, unless it has some sort of significance to the story, it would be weird for two characters to share the same name, just as it would be weird for them to have the same birthday.

TruthInTelevision, obviously. Everyone shares their birthday with ''someone''. An interesting thing to note is that, according to the [[https://en.wikipedia.org/wiki/Birthday_problem birthday paradox]], it only takes 23 people to have a 50% chance of having a pair with the same birthday. In fiction, the fact that this trope is usually averted makes it similar to The OneSteveLimit- while common in real-life, it's weird for fictional characters to have the same name, just as it's uncommon for them to have the same birthday.

** Kaguya and her ShadowArchetype/cousin Maki (and by extention Maki's twin brother Midado) were born on New Years Day.

These characters, of course, should ideally be unrelated. Twins are inherently born on the same day, [[note]]with very rare exception[[/note]] so this trope concerns those who aren't twins... that is, unless the point is to foreshadow a SeparatedAtBirth twist, with the characters (and often the audience) not knowing right away. This also means other familial-relationships are allowed, assuming the emphasis is on the special shared date just as in a non-related-character example. They also don't have to be literally born on the same day down to the year, so long as they share the same birthday each year they're both alive.