Man in Black: No one of consequence.
Inigo: I must know.
Man in Black: Get used to disappointment.
This character hides some secret, and their name is a part of it. To keep this secret buried and cut all ties to it, this character withholds the name associated with that secret from their friends and allies. While the character is hiding their name, admitting that they refuse to share their name is at least telling the audience that there is a secret to be learned and this secret is often revealed in the story.
The character may have abandoned their old name in favour of a new name, adopted a name that reflects their lack of a name, decided they don't need a name, or just use part of their name because the rest of their name is embarrassing. They may also be called by a nickname, and only a nickname.
If I Know Your True Name is in effect in the work, a person may hide their True Name to prevent their enemies from using it against them.
Sub-trope to The Nameless (the character seems to have no name). Contrast with Code Name and Nom de Guerre: this trope is only in play if the character refuses to share their name, not if they disguise their name by using another. Compare to the Sister Trope No Name Given, where the author avoids naming a major character in their work.
- In Accel World, the female lead is Only Known By Her Nickname of "Kuroyukihime" (Princess Snow Black). She claims that it's not that far from her real name, but refuses to say what it is, even going so far as to hack her student ID to read Kuroyukihime (something that other characters had previously thought to be unhackable).
- Black Butler is careful not to reveal the true name of "Ciel Phantomhive", who actually stole the identity of his dead twin brother, the real Ciel Phantomhive. Even after this is revealed, the other characters are careful to only refer to him as "Earl Phantomhive" or "Young Master" as he prefers to not go by his old name.
- Bleach: The zanpakuto of the Soul Reapers (the swords are sentient spirits who are created with their own identity) withhold their names from their owners until a Secret Test of Character is passed. They withhold it because I Know Your True Name is very important in this universe; affecting the power something or someone has.
- Coffee Shop Anemone: Raizō Sumizome keeps his real name a secret and prefers to go by just "Rai". This is because his full name gives away the fact that he is a Miko, which he has been bullied about.
- Inverted and Played for Laughs in Cromartie High School: Hokuto's lackey frequently gets cut off before he can say his name. The background and author notes in the manga finally does reveal his name to the reader, but the whole cast of the series admits that it's better that he just continues to go by "Hokuto's Lackey" because they've built up their friendships and familiarities with him around it. Learning his name would be a rather jarring change to that relationship.
- Fullmetal Alchemist: The Ishvalan known as Scar underwent a Meaningful Rename, and tossed away his old name in his quest for revenge.
- In the manga, Yoki asks Scar's name. Scar responds that to Ishvalans, a person's name is the most important thing; the name is regarded as a gift from God. So Yoki asks again, and Scar's response is "I threw it away. I threw away my own name." Yoki doesn't dare ask him again. At the end of the series, he still refuses to give his name and says you can just call him whatever you want to.
- During the 2003 anime, Scar's name is never given, even when he's about to die. When Lust asks him his name, he answers that his body once had a name, but "that person died a long time ago." Lust, who'd only called him "scarred man" up to this point, finally uses the "name" Scar as he dies: "Goodbye... Scar."
- Moriarty the Patriot's William James Moriarty assumed the identity of the real William James Moriarty after murdering him as a child, and the protagonist known as William makes a point to keep his birth name hidden from nearly everyone. The only characters who seem to know for certain what it was are his brothers and Sherlock, when William gives him his birth certificate. And all of them still call him "William" exclusively.
- Naruto: Most characters in the series go by a single name, with the tradition originating from a time of constant clan warfare where revealing your clan's name could get you killed by anyone from a rival clan.
- Yuuko Ichihara from Xxx Holic never reveals her true name, as that would give others power over her so she only uses a pseudonym.
- 'The Dog' in Footrot Flats has such an Embarrassing First Name that he never allows it to be said or revealed in any way in the comic, and holds a grudge against Aunt Dolly for giving him the name.
- Warren Ellis' breakout series, Nextwave, features a protagonist named only "The Captain". Due to his abusive childhood, depression, and alcoholism, he refuses to divulge his real name; his teammates theorize that he may not even remember it.
- Ghost of Thunderbolts erased all record of his original identity after he became Ghost. When he recounts his origin, every mention of his original name is blacked out.
- V from V for Vendetta underwent a Meaningful Rename, where they discarded his old name/identity to become a symbol of revolution. When asked, V states: "I do not have a name. You can call me V."
- Zatanna: Everyday Magic: When Zatanna makes Nimue swear off her Deal with the Devil, she uses her Nom de Guerre of Nimue Ravensong, thus making the whole thing invalid. Zatanna only realizes this later and manages to save Constantine from the Trade in the nick of time by swearing by Nimue's true name of Mary-Ann.
- Jaune Arc, Lord of Hunger: While showing Jaune memories of his past, Darth Nihilus censors any mention of his original name. Whenever someone in the flashbacks mentions Nihilus' real name, they are either cut off at the last second or their words become unintelligible to both Jaune and the reader.
- The Fourth of July: When Sharon Carter is assigned to work with Steve Rogers, she initially refuses to give her actual name telling him to refer to her as Agent 13. Steve eventually tries throwing random names at her to see if he can guess what her real name is with Sharon agreeing to answer truthfully if one of his guesses is correct. In You and I Were Fireworks, she gives Steve her first name and Arnim Zola informs Steve of Sharon's surname and thus relation to Peggy Carter. When Steve confronts Sharon about why she didn't tell him who she was, Sharon explains that she kept her relation to Peggy a secret to most of SHIELD, not wanting her career to be based on being the founder's great niece and that she didn't tell Steve out of fear of it ruining their partnership.
- In the Marvel Cinematic Universe fic A Little Red and Blue, Sharon is inadvertently sent to the year 1944 by Wanda and is later found by the past Steve and Bucky, introducing herself to them as simply "Kate" to hide the fact that she's from the future.
- Played for Laughs in The Hitchhiker's Guide to the Galaxy (2005), where Slartibartfast initially refuses to give his name because it's embarrassing.
- Mad Max: Fury Road: Being a paranoid loner of the post-apocalyptic landscape, Max Rockatansky refuses to reveal his name, until after the climax of the film. As such, Furiosa refers to him as "fool". It's only after his Character Development near the end, as he's giving his blood to her to save her life that he finally says his name.
- Star Trek III: The Search for Spock: Commander Kruge's name is only spoken once early on by Valkris (whom he then kills); his troops only address him as "My Lord" or "Sir", and he flat-out refuses to tell Kirk his name.
- In V for Vendetta, V refuses to share their name because they discarded their old name/identity to become a symbol of revolution.
- Artemis Fowl: Only Butler and his mother know his birth name, for security reasons. Thus when faced with impending death, Butler tells Artemis his first name, Domovoi, a type of Russian Fair Folk. This comes in handy later when (a recording of) Artemis uses it as proof of their having been through truly harrowing experiences together, allowing Butler to defeat the fairy mind-wipe.
- In Darkness at Noon, No. 402 refuses to give his name when Rubashov asks. No, we don't know their name, either.
- The title character in Frederick Forsyth's The Day of the Jackal assumes several identities over the course of the story, but we never learn his real name and only a few hints about his background. Much of the plot hinges on a Red Herring, with investigators assuming he's another man (Charles Calthrop) with shady ties to international arms dealers.
- A Dozen Black Roses by Nancy A. Collins: The main character Sonja Blue is referred to as "the stranger" throughout the whole book, when asked for her name, she either refuses to give it, or is cut off. She finally reveals it at the end to one of the few surviving characters.
- In The Crew of the Copper-Colored Cupids, the Queen of the Black Market placed her real name under a Curse of Silence: it can only be revealed to those she wish, otherwise people's minds will simply not retain the name even if they see it written down. She explains that she underwent the costly procedure to protect herself against I Know Your True Name-type attacks, although she is also observed to keep other private details about herself, such as her species and world of origin, a secret.
- The short story "An Encounter and an Offer" has a nameless fae boy, whose name was stripped from him by the fae courts. He refuses to reveal why.
- Played With by Seerdomin from Malazan Book of the Fallen, who goes by the title of his former military rank to show that he won't hide from his crimes under the Pannion Domin. It is later revealed that his real name was Segda Travos, but nobody alive remembers it.
- The main villain of The Mental State goes to extreme lengths to conceal his real identity from the rest of the world. It is even suspected that he joined a black-ops group just for that purpose. He has a variety of different pseudonyms but no one ever finds out his true name.
- Nettle & Bone: The dust-wife is only ever referred to by her profession, a polite epithet, or, at her suggestion, "ma'am". Fenris doesn't get anywhere when he asks for more.
Fenris: Do you have a name, Lady Fox?
- The fairy tale Rumpelstiltskin has as one of its main points the queen trying to find the name of the eponymous dwarf as the escape clause out of the Deal with the Devil she had made with him in order to keep her child. He gives three chances to correctly guess his name, and it takes all three nights for her to find out what it was. When she says his name, he throws such a tantrum it actually kills him.
- In The Southern Reach Trilogy, expedition members are explicitly forbidden from telling each other their names. None of the characters in Annihilation are named, referring to each other only by their job titles: the biologist, the psychologist, the anthropologist, and the surveyor. While most of them Subvert the trope by sharing their names over the course of the next two novels, the biologist refuses to ever give her real name, insisting that she be called by the nickname "Ghost Bird".
- Servants of the Spells, Swords, & Stealth dark god Kalzidar give up their names as part of their service to him. One such nameless priest is the primary antagonist of the second book. Upon meeting a rogue in the third, the party is immediately wary when she initially refuses to give her name. In that case, it's just a case of the rogue, Elora, being cautious.
- On Angel, "The Host of Caritas" was not given an official name (even to the other characters) until late into the second season. The explanation, when their name is revealed, is that it's too embarrassing. Krevlornswath of the Deathwok Clan.
- Doctor Who: When a Time Lord graduates, they choose an alias that they will be known by, and keep their personal names secret. This overlaps with Meaningful Rename and Naming Ceremony. The Doctor prompts the Title Drop when people try to ask him his name, and he insists on the title instead.
- Once Upon a Time: The motorcycle rider who suddenly comes into Storybrooke partway through the first season reveals hardly anything about himself, not even his name, for the first few episodes he appears in. Eventually, he introduces himself as August W. Booth, but that's just what he goes by. His real name is Pinocchio.
- The Janitor from Scrubs makes a point of never revealing his name to anyone. When J.D. is leaving for another hospital, he finally reveals that his name is Glen Matthews. But when J.D. leaves, another character addresses him by a completely different name.
- Stargate Atlantis is Playing With this trope. When telepathic Wraith get captured for interrogation or just become recurring characters, Colonel Sheppard randomly assigns human names to them so they can be called something other than "that Wraith". The Expanded Universe novels reveal that Wraith have names that they use among each other, but they're apparently based on their roles in society and/or how their minds "feel" to each other telepathically, which means they have no way of communicating their names to humans even if they wanted to.
- Superstore: The pilot episode features one character who always wears a name tag with someone else's name so that customers won't know her real name. While all the other workers know her name, she doesn't tell it to Naïve Newcomer Jonah until near the end of the episode. Her name is Amy.
- Douglas Adams had said that in The Hitchhiker's Guide to the Galaxy (1981) he came up with the name Slartibartfast because the character bearing the name had a hidden sorrow, something to be ashamed of. So Adams came up with an embarrassing name for him.
- The Bible:
- In the Book of Genesis, when Jacob wrestles with an Angel and prevails over Him until the Angel gives Jacob a limp and blesses him, Jacob asks for the Angel's name, and the Angel refuses, asking "Why do you ask My name?"
- In the Book of Judges, Maon and his wife, the parents of Samson, ask an Angel for His name, He refuses, saying "Why do you ask My name, seeing that it is wonderful?" (Some translations have Him say that it is "beyond understanding.")
- Azure Striker Gunvolt: After Gunvolt fights him as a boss, he asks for Copen's name. He refuses, saying that he won't share his name to "abominations" like Gunvolt, but then added, "But when God sends me to judge you, you may hear Him whisper, 'Copen'...".
- Rival Schools has Chairperson, who refuses to reveal her real name and would rather prefer other characters refer to her by her title.
- Fire Emblem: Three Houses: As suggested in the Cindered Shadows DLC, Claude's real name isn't actually "Claude". While his real name is never revealed in-game, Word of God confirms that it's "Khalid", a name befitting his homeland of Almyra.
- Super Robot Wars 30: While Banagher Links' name is clearly displayed during Intermissions, he chooses not to divulge it to anyone, even when asked for it. As such, the party is forced to address him as just "you."
- Overwatch: Cole Cassidy kept his name a secret for years, if not decades, and it's implied that he never told anyone it during his initial stint in the titular heroic organization. When the time comes for Putting the Band Back Together, one of the first things he does upon rejoining is to admit his true identity to finally let go of his outlaw past.
- Hatred has a playable antagonist whose narration starts out that his name is not important.
- Seen at the end of Hitman (2016) when the Constant approaches Diana during a train ride (and addressing her by name despite her traveling using an alias).
Diana: I didn't catch your name.Constant: No. You didn't.
- Vermintide II: Downplayed. Kerillian claims to have many names, which she refuses to share even with her True Companions when asked, but concedes that the name Kerillian is "real enough".
- Gunnerkrigg Court: One of the fairies refuses to share their name with the other characters because her best friend gave it to her. Her name is <Snuffle> (her friend was a jackelope) but it has to be said/done in a specific way or it sounds completely different.
- Magick Chicks: If the mysterious girl who is the spirit of the wand has a name, she has yet to reveal it and has evaded the question both times she was asked about it. She's only known by the nickname: "fade-out girl"note or FoG for short.
- Medium Awareness version: Daigo in The Order of the Stick, having discovered that giving his first name offered him enough Nominal Importance to survive in a bad situation, is keeping his last name secret in order to use it as a Get Out Of Horrible Doom Free card later.
- In El Goonish Shive, the Crystalline Turtle Frog refused to give Mr. Verres their real name because it could be used to summon them. When he gives them the nickname "Steve", they accept.
- Inverted and Played for Laughs in the case of Rookie from Combat Devolved, who often tries to tell the others his name, but no one cares so they call him Rookie instead.
- Critical Role: Campaign Three: Deni$e gives an admittedly fake name when she becomes a Guest-Star Party Member because she's meeting a strange group of people under highly dubious circumstances. She accidentally reveals her real name within the day.
Laudna: But first, what's your name?
Laudna: I felt like you had to think about that for a second.
Deni$e: Yeah, I got to think about it. I'm not going to tell you my real name yet. I don't know you that well.
- Kate, in KateModern, revealed in episode 4 that her name wasn't really Kate. Her actual first name wouldn't be revealed until episode 88. It's Genevieve, by the way.
- In Fen Quest, the first person Fen meets outside his home forest introduces herself as "Nonyour Bizniss".
- In The Penumbra Podcast, Peter Nureyev is notorious throughout the galaxy as "the Nameless Thief"; he provides each of his contacts with a different alias, and it's likely that Juno is the only person alive who knows his true name. It's later revealed that he abandoned his birth name because he's a former freedom fighter who, after he successfully stole the reactor powering the floating city of New Kinshasa, became the Icon of Rebellion for the Brahmese Revolution. As of season 3, he seems to have struck a middle ground - as a member of the Carte Blanche, he goes by "Peter Ransom", his real first name and his mentor's last name.
- In the SpongeBob SquarePants episode, "Good Ol' Whatshisname", Squidward and SpongeBob compete in against each other to learn the names of all the customers in the Krusty Krab. When Squidward gets down to the last customer, it seems like the customer doesn't want to tell Squidward his name, as it sounds like he tells him "What's it to ya?". After Squidward takes the customer's wallet from him, getting himself arrested as a result, Squidward finds out the customer's real name is "What Zit Tooya".
- The last member of the Yahi tribe of Northern California could only have his name known after a friend from his tribe introduced him to an outsider. Since he was the last one of his tribe, there was no one to introduce him, and he became known as "Ishi", "man" in his language. His real name will never be known.
- Cracked had an article about a guy who filmed a porn movie on short notice. The director didn't give his name, but for the sake of clarity told the author to address him as Mr. [Name of the street they were on].