Outgrowing Their Childish Name
A character stops using an immature sounding nickname or shortened version of their name as a sign of maturity
Often, diminutive versions of names are used for children; however, their usage may diminish as the child ages, sometimes at the child's own request. If this occurs to a character in-series, it's usually either a sign of Character Development or the character trying to seem more mature than he really is. The character's childhood nickname may end up becoming an Embarrassing Nickname as an adult. Compare to Meaningful Rename, which includes cases in which the character's name actually changes when they become an adult.
- X-Men: In the "Days of Future Past" storyline, the future Kitty Pryde goes by "Kate" and sees the nickname "Kitty" as a relic of her childhood.
- In the film Under The Same Moon (La misma luna), the protagonist's mother comments that he is growing up so quickly that she will soon have to start calling him "Carlos" instead of "Carlitos". He stays Carlitos for the duration of the movie, though.
- Fantastic Four: Rise of the Silver Surfer: The Human Torch is known as Johnny Storm for all of the first film. In the second, he has embraced the money that comes with sponsorship, and because "focus groups say Johnny skews young", decides to go by John Storm instead since he doesn't want "hero to children" to outweigh "ladies' man".
- In the To Kill a Mockingbird sequel, Go Set a Watchman (which was actually written first and thus has much Early Installment Weirdness to the point where it's considered an Alternate Universe book), Scout no longer goes by her tomboyish childhood nickname. She goes by "Jean Louise".
- Subverted with Ravenpaw in Warrior Cats. He fled ThunderClan not soon after becoming an apprentice, when he was still the cat equivalent of a teenager. He never became a warrior and thus never received his 'adult name' (all apprentices are called "[x]paw"). Ravenpaw however continued to use that name even after becoming a loner.
- Billy the Werewolf is a recurring character in The Dresden Files from the second book onward. He enters the story as a teenager who gains shapeshifting powers with his friends, the Alphas. As time goes on, Billy begins going by "Will", which the Alphas also call him. It's a significant turning point in his and Harry's relationship when Harry finally shifts from "Billy" to "Will" himself.
- The belief in this is used as a sign of immaturity in Otherwise Known as Sheila the Great, where the image-obsessed Sheila hates the fact that her father goes by "Buzz" and tries to convince him to go back to "Bertram", even though even she admits to preferring "Buzz".
- In the Little Women series of books, nicknames were needed for the twins John Brooke, Jr. and Margaret Brooke (sharing their parents' names requires the nicknames). Eventually Demi (short for Demijohn, he's half a John) and Daisy (a common nickname for Margaret) were chosen to fulfill Theme Twin Naming requirements. Upon reaching adulthood Demi went back to John (his father being dead by this point prevents confusion), but Daisy remains Daisy.
- In Star Trek: The Eugenics Wars by Greg Cox, Khan Noonien Singh is mainly referred to as "Noon" when he's younger, and working for Gary Seven. After the Union Carbide disaster in Bhopal, he resigns from working for Gary, telling him, "Stop calling me Noon. That was a child's name. My name is Khan."
- Jimmy Olsen in Supergirl is presented several years older than he usually is and is far more mature than most depictions. He goes by "James" instead of "Jimmy".
- The Suite Life of Zack and Cody: In "Super Twins", a wish on a star turns Zack and Cody into superheroes, and Mr. Moseby into a supervillain; at one point, Moseby turns Bob into a suit-wearing adult who prefers to be called Robert.
- Implied in an episode of Law & Order: SVU, when Stabler asks about his son by a nickname, and his wife tells him that he hasn't been called that for years (making it clear how little time he spends with him).
- Inverted in Doctor Who. Amy Pond was named Amelia as a child, but grew to dislike it for being sounding too much like it was out of a fairy tale.
- In the final season of Rizzoli & Isles, Frankie is having something of a crisis of identity. During a heart-to-heart with Korsak, Korsak suggests that maybe he should stop going by Frankie, which is what his family has called him since childhood. By the end of the series, he has started going by Frank.
- One episode of Girls in Love has Ellie persuade her father to cease calling her "Elly Belly".
- On Supernatural, Sam objects to being called Sammy, correcting anyone who calls him by that nickname. Eventually, he concedes the nickname to his older brother, but it becomes a Berserk Button for anyone else using it. However, he also dislikes anyone calling him Samuel, the long form of his name.
Sam: You know, Sammy is a chubby 12-year-old, OK? It's Sam.
- In episode 3453 of Sesame Street, Baby Bear decides to change his name to "Not-a-Baby Bear", because he isn't a baby anymore and doesn't want his friends to get the wrong impression. He soon finds out the disadvantages of changing his name, such as not getting a package of instant porridge from his Grandma, and how different his fairy tale, "Goldilocks and the Three Bears", sounds. He soon learns from his friends that your name doesn't always have to mean what you are, and that Papa Bear went through a similar experience in his childhood, as his name was also "Baby Bear" once. These persuade Baby Bear to be proud of his original name.
- In Animal Crossing: New Leaf, if you upgrade their shop to T&T Emporium, Timmy and Tommy will start going by their full names (Timothy and Thomas) on the town billboard.
- In Valkyria Chronicles, Welkin dislikes being addressed as "Welkies".
- Kenta from No Need for Bushido at one point gets mocked for having "a baby name" but this turns out to have a tragic origin, since his entire clan was wiped out when he was a child so he was never able to receive a "proper" adult name. It symbolizes how he's never moved on from the tragedy and how it's stunted his emotional maturity.
- In Alice Isn't Dead, the episode "The Factory" has the narrator enter the titular factory and meet a young man named Jackie, except every time she loses sight of him and finds him again he grows several years older, and when she addresses him as "Jackie" after he becomes middle aged, he requests to be called "Jack" instead.
- In the Foster's Home for Imaginary Friends episode "The Bride To Beat", Bloo fears that Mac is outgrowing him and decides to act like an adult. This includes changing his name from "Bloo" (short for "Blooregard") to "Bob".
- SpongeBob SquarePants:
- In an episode where SpongeBob begins wearing longer pants, and thus seems more like a mature adult rather than a Manchild, his sophisticated peers begin referring to him as "SpongeRobert".
- In another episode, Barnacle Boy does a Face–Heel Turn because Mermaid Man keeps treating him like a kid, despite both of them being elderly, and demands to be known as Barnacle Man.
- There's a woodchuck character on Animaniacs who wants to be taken seriously as an actor and insists on being called Charleston instead of the Embarrassing Nickname Baynarts.
- The Flintstones: Whenever Fred tries to act sophisticated, he tends to calls himself and Barney "Frederick" and "Bernard".
- After starting college in Ben 10: Omniverse, Gwen starts going by "Gwendolyn".
- Referenced at the end of the Teen Titans episode "The Beast Man". Beast Boy mentions that, after what he experienced in the episode, maybe he should change his superhero name to "Beast Man".
Hello, Unknown Troper. You'll need to get known to lend a hand here.