I Know Your True Name

""Fear names. Names have power in identity. Others can use names as weapons. Names are a hook that can be used to track you... Remain nameless, and you shall be safe. I am the Nameless One.""

- Planescape: Torment

""The name is the thing, and the true name is the true thing. To speak the name is to control the thing.""

- The Rule of Names, Ursula K. Le Guin

This is a version of Functional Magic that revolves around the use of "true names." A true name perfectly describes something's essential nature; knowing a true name gives one power over the owner of the name. True names are frequently words in a Language of Magic, but they don't have to be. In some portrayals, using a person's true name forces them to obey your commands. In others, a true name gives you a connection to the name's owner that allows you to work magic on it from a distance. Sometimes, a person's true name is needed if you want to work any magic on him at all.

In some stories, all creatures have true names, while others limit the use of true names to certain kinds of creatures, such as fairies, demons, or dragons. As a rule, objects do not have true names.

A person's true name might be self-determined, or bestowed on him by someone else -- possibly in a religious or magical ritual. In works which feature true names prominently, people tend to guard them jealously, and will even have a second name (or two or three or more, depending on the character's age) for everyday use.

Audiences might think that having a very long or difficult-to-pronounce true name might provide one with a shield against being enspelled, but it never occurs to characters. Except for demons. Demonic names are frequently impossible for humans to pronounce.

Contrast with Speak of the Devil, where saying a name summons the named entity, but doesn't confer any power or control over it. Compare Sympathetic Magic, where you need some other part of a person to work magic on them.

Compare Words Can Break My Bones and Language of Magic.

Anime and Manga

 * In the manga Isuca the main character has the ability to reveal the true name of any magician and demon or otherwise supernatural being through… mouth contact. Yes, it's that kind of manga.
 * In the Vampire Princess Miyu OAV, the Dark Magical Girl must first learn the name of the Shinma she's chasing after and then use her flames in a spell that writes the kanji of said enemy's name in the air. Only then, she can seal the enemy away.
 * The titular Death Note requires that you write the true name of your intended victim, hence some of the characters using aliases whenever possible.
 * The definition of 'true name' beyond 'the name a shinigami's eyes see floating over your head' is not provided, but in the majority of cases it appears to be the legal name provided at birth. Meaning L apparently had fucking loonies for parents, unless he was named in unusual circumstances.
 * Light does not appear to have lost too many marks to name changes, probably because he concentrated his efforts on persons already investigated thoroughly by the police, and Japan has a pretty tough name-record system in place with the family register. Modern record-keeping generally makes complete identity change much harder. A Death Note user in Japan a couple hundred years earlier would have had an interesting time working out which of a man's names was 'true.'
 * Bleach: Knowing the name of an attack increases its power significantly. Unless you have also achieved bankai, using shikai requires the user to say the sword's name. Calling the sword another name that it doesn't like will cause it to refuse to use its special ability. Yumichika does this deliberately, because its kido-based ability would embarrass him in front of his squad mates.
 * This trope goes far further than weapons and attacks. "Zaraki Kenpachi" is a title more than a name (meaning, roughly, "master swordsman from the Zaraki district"); the man was never given a proper name. His lieutenant, Yachiru, was named by him. His sword, which carries no name, is treated as nothing more than a tool. In a few sparse scenes these characters relate the pain of not having a name. Though Kenpachi has no interest in achieving bankai, he states that he would like to learn his sword's name so that he could communicate with it. Likewise has no name, and claims his name does not matter.
 * Very early in the series, Renji, out of curiosity, asks Ichigo the name of his sword. At the time, Ichigo did not know that the swords were sentient, and replies that he hasn't given the sword a name, and that the concept of naming an object is silly. Renji is incredibly offended and mocks Ichigo's ignorance.
 * This idea is enforced, expounded, and several other adjectives starting with 'e' by xxxHolic, particularly by one of the main characters, Ichihara Yuuko. No, that's not her real name, and she . The series also deals a fair bit in Words Can Break My Bones.
 * Tsubasa Reservoir Chronicle, due to it being linked to xxxHolic although it isn't stated here as explicitly.
 * Cardcaptor Sakura once featured this when the only way she could seal the power of one of the Clow cards was to discover its name, given only the clues that it seemed to appear as a duplicate of Sakura, and that it held a relation to the Shadow, Water and Illusion cards.
 * Spirited Away has characters whose independence depends on them not forgetting their actual names. Chihiro is reminded not to forget hers (although the witch tries to take it away from her), and Haku is enslaved until he rediscovers his name late in the film.
 * Worth noting is the fact that only one other character introduces himself without being prompted or hearing the name from someone else.
 * The pharaoh in Yu-Gi-Oh! was unable to reclaim his world of memories from Zorc Necrophades until Yugi and the others learned his true name,.
 * In Fruits Basket, Hanajima's brother Megumi claims to be able to curse people if he knows their names; Hanajima had warned them not to say their names in the house; then he reveals that he knows them.
 * True names play a big part in Loveless as they determine who your partner will be.
 * When Soubi fights with Ritsuka he goes against his name since he and Ritsuka don't share names, which not only weakens their power as a whole but causes his name to bleed.
 * The Zeroes "...We control that name..."
 * Nodoka Miyazaki in Mahou Sensei Negima requires at least a name for her mind-reading book to take effect. Recently, with the help of a dungeon-crawling adventuring party, she's gained two Shonen Upgrade accessories (both supposedly useless, but Game Breaking in her hands): the auris lectans, an ear-piece which immediately reads out words on paper to her mind, and the comptina daemonia, which can read a target's name (in a sense) to her. While less powerful and discreet than the shinigami eyes, it's much cheaper.
 * Also, at least one opponent, at the sight of the book, wondered if it was the Death Note.
 * Interestingly, it has been revealed that one's True Name is the name that they think is their True Name. Also, if you name, say, any of a crazy person's multiple personalities and so on, it would still work. It gets kinda complicated regarding the specifics on true names and souls and all that.
 * The Devil May Cry manga says that a demon's name is so important to him that by taking it away, the creature can be sealed for eternity.
 * In Mononoke the name ("katachi" in the original Japanese, which also means 'form') of the mononoke is one of the three things the Medicine Seller needs to kill it.
 * A central part of Natsume Yuujinchou. The main character owns a book filled with true names of spirits and is constantly accosted by spirits who want their names back or spirits who want to steal his book for themselves.
 * In Ayakashi Ayashi, the protagonist can reveal the true name of anything he comes in contact with and use it's power. The 'name' usually manifests as a tool of some sort, and is the most effective way to fight the monsters the heroes are meant to hunt down. Alternatively, destroying a Youi's name, will destroy the Youi itself.
 * In Wild Rose, Mikhail knowing Kiri's true name, Kazekiri, is both proof he is his master and gives him total control over Kiri.
 * In Yu Yu Hakusho, Roto is able to escape almost certain death by saying "I own your mother's life... Shuichi Minamino", and revealing that he has a demon able to kill Shiori Minamino if he so commands.
 * Played for Laughs in Houshin Engi during a battle where the enemy's Paopei was a megaphone that could freeze a person in place by shouting them to do so, as long as the user knew his target's real name. Taikoubou has fun with this.

Comic Books

 * Variant: In The Invisibles, all new Invisibles take on a 'magic name' upon joining the organisation. This name is tied to their personality, and strongly influences their powers and lives (as poor Tom O'Bedlam discovered the hard way).
 * Relatedly, in the same series, the English language has far more then 26 letters. Being knocked out is just the least of the possibillities with the new words.
 * Superman has "Mister Mxyzptlk", an imp from the 5th dimension who is sent back when he says his name backwards. As he's invulnerable otherwise, the only way to get him out of your hair is to trick him into saying his name backwards.
 * No longer an example of the trope since the Crisis on Infinite Earths -- ever since the John Byrne Re Boot of Superman, it's just been Mxyzptlk being sporting. On the other hand, Grant Morrison revealed in a storyline of JLA that Johnny Thunder's Thunderbolt is actually a being from the same dimension Mr. Mxyzptlk hails from, and Johnny's old magical phrase ("Cei-U" or "Say You") used to call his Thunderbolt is in fact the being's name (Yz) pronounced backwards... which doesn't actually make a lot of sense when considering that Mxyzptlk has to be made saying his own name backwards; and yet, Yz himself saying a combination of his own name and that of his rival Lkz ("Ylzkz") somehow made them merge into a new being. Therefore, it's strongly implied that the power to control and manipulate these beings somehow lies in their names. You get the idea.
 * That said, despite their common plane of origin, Mxyzptlk and the Thunderbolt are different classes of beings (an imp and a genie respectively), so the rules governing each of them may be different.
 * In the same storyline, a group of fifth dimensional imps reins in another by intimidating him into saying his name backwards.
 * In the "Emperor Joker" storyline, however, the Joker tricks Mxyzptlk into revealing his "secret imp name," allowing the Joker to steal 99.9% of Mxy's power.
 * In Action Comics #273 (February 1961), Superman decides to pay Mxyzptlk back for his pranks by visiting HIS home dimension and playing pranks on him (Fridge Logic would say that Supes, being vulnerable to magic, would have been even MORE helpless there, but anyway...) Mxy then tries to trick Superman into saying his name backwards (Namrepus) to send him back to Earth. When he finally succeeds, it FAILS. This is because Superman's real name is Kal-El/Clark Kent, a fact Mxy was unaware of!
 * In an episode of Superfriends, they record Mxyzptlk saying his name and then play the recording backwards, which banishes him. For some reason.
 * If Silver Banshee knows a person's real name, then her scream will instantly kill them if they hear it. Because she doesn't know Superman's real name is Kal-El, her scream can only hurt his ears, much to her frustration.
 * In one comic Superman tries this and it doesn't work because Mxy had his name legally changed.
 * The justification for Libra being able to kick the Spectre's ass in Final Crisis was that the Spectre didn't know Libra's True Name. Up to this point the Spectre was portrayed as an unstoppable embodiment of the Wrath of God (or the Presence, the closest thing to God in the DCU). Considering the shitty job Crispus Allen had been doing since becoming the Spectre, it's actually not all that surprising. Especially since Libra was working with... you know... Darkseid.
 * Final Crisis: Revelations instead implied the reason to be that Spectre only delivers justice to those God wants justice delivered to via him - he is the hammer of God. He smites what God wants him to smite. Libra's fate (and that of Darkseid) had apparently already been decided, and it didn't involve Spectre. As a result, Spectre wasn't allowed to interfere with that particular issue. Either that, or since Evil won the war between the New Gods, Darkseid was dragging the entire multiverse into the Forever Pit and receiving massive amounts of Villain Anti-Decay, at this point he had more power over the multiverse than God. Neither the Spectre nor the Radiant could feel God's presence at the time, despite being aspects of Him.
 * In Elf Quest, the telepathic Wolfrider elves all possess "soul names", the knowledge of which gives another elf access to the owner's most intimate thoughts and feelings. Therefore all Wolfriders guard their soul names carefully from all except their closest friends and lovers. However, the involuntary mating urge called Recognition sabotages this by forcing the affected couple to exchange soul names. On one occasion Big Bad Winnowill learned Dewshine's soul name and attempted to use the knowledge to coerce her, which only went to show how evil Winnowill was. On another occasion, Nightfall unilaterally gave her lovemate Redlance her soul name before placing herself in danger, so that if she died her soul would still be joined to his. She later brought Redlance back from the verge of catatonic shock by persuading him to give her his soul name, causing their souls to become one.
 * This was a favourite trick of Con Man/Occultist Igor Bromhead in the Hellboy comics. Most memorably used in the "Box Full of Evil" storyline to enslave H.B.'s demon-cousin Ualac, and then to . It backfired, though, since Hellboy's "True Name", Anung Un Rama, means "World Destroyer, The Great Beast"--a role Hellboy had long since renounced. When Hellboy realized this, Bromhead's hold over him was broken. Most recently, he used the true name of the human component in Hecate's replacement body to imprison her.
 * Specifically in Box Full of Evil, this is done thrice: first with Igor Bromhead commanding the demon Ualac using its true name, secondly with Bromhead commanding, and finally with Hellboy commanding Ualac using.
 * It is mentioned in multiple issues of The Books of Magic that names have power, particularly in the Otherworld of Fairyland. When the Manticore asks Timothy Hunter his name, the one he gives is "Jack Bone". In the original four-issue run, Rose makes the Baba Yaga back down by claiming she knows her true name, and threatening to shout it to the world.
 * Tim also takes control of a clay golem by giving it a name, and drawing a face on it. His current companion, Leah, comments that such a thing is considered impossible.
 * The Zombie Priest, Big Bad of The Goon, can be controlled by anyone who knows his true name. One issue heavily implies that he's Rumpelstiltskin.
 * A Marvel example: The Elder god turned Demon Cthon, prior to leaving the physical plane, penned the Darkhold, the first book of magic ever written. He did it because "to name something is to hold power over it". As a result, Cthon effectively rules over all the magic of the Marvel Universe.
 * Reversed in the case of The Unnameable, a demonic entity from Marvel Comics' The Defenders series. Anybody who found out its true name fell under its control!
 * The recurring Cosmic Horror of Hellblazer during Mike Carey's run was one of the animals that Adam never got around to naming during his time in Eden. And, as he never named it, he never gave it purpose, meaning, or definition -- leaving it to become shapeless, formless, and ever hungering...
 * Hawk & Dove #15 (1990) features a subversion of this. The protagonists find themselves stranded in Druspa Tau, a place of magic, different from their superheroic place of origin. There is a magical liquid metal called "tridic metal". It can be made to form any object the wielder can imagine but only if the wielder knows that object's True Name. One master does amazing things with the True Names of "staff" and "sword" and "morningstar" etc. Hawk? Figures out that if you know every last detail of an object, you don't need the True Name. So he picks up a blob of tridic metal and goes "Trigger. Muzzle. Safety catch ..."
 * In Proposition Player, Bill the Angel of the Lord claims that a whole slew of terrifying first-testament things will happen if his True Name was uttered, so he sticks with a simple nickname. It's never made explicit whether it's true or he's just bragging, though either is equally plausible.

Fairy Tales

 * In "Rumpelstiltskin", the title character offers to let the princess keep her firstborn child if she can guess his name within three days.

Fan Fic

 * In Barack Obama and the Thunder Zepplin, Obama conjures the sylph Plame using her real name and offers her a new name in exchange for transport. This is a reference to Valerie Plame, who had to leave the CIA after her name was leaked to the public.
 * In .hack//G.U.: The Staircase To Nowhere, if an Epitaph user learns the true name of another Epitaph User, he/she can control their fellow user and make them do anything.
 * In the Eyrie Productions Unlimited story "Raven/The Demon Halloween Special," after an "eventful" Halloween date between Teen Titan Raven and Etrigan (the titular demon), realizing that he may be forced against his will again to do the will of the underworld, Etrigan tells Raven his true name - giving her the power to stop him completely. (While this is certainly an effort to prevent him from being forced to commit any actions to which he personally objects, it is also an attempt to atone for his involvement - against his will - in just such an act when he kidnapped her on behalf of her father Trigon earlier.)
 * Used several times in the Dresden Files fic Fair Vote. Exploited spectacularly so near the end.

Film

 * Warlock, the MacGuffin is a book that contains the true name of God. Saying his true name backwards will cause The End of the World as We Know It.
 * In The a Team, the CIA contact is known as Lynch, which it soon becomes obvious is a pseudonym, as various military figures recalls all the CIA agents named Lynch that they've known..

Literature

 * In Poul Anderson's Operation Chaos, the narrator does not give his real name as a POW, only the official name he's using; when his daughter is born, affairs are more organized, and she is issued both a name she can use and a secret, real name.
 * In Elizabeth Bear's Promethean Age series, names have power, as is demonstrated in the Wham Chapter of Blood & Iron; Elaine  She occasionally still answers to the name, though; magic is magic, but you still need a way of getting someone's attention across a crowded room.
 * In Tithe, by Holly Black, Kay forces one of The Fair Folk to tell her his true name, not quite realizing that when she uses the name he has to do anything he's commanded to do.
 * Specifically, Roiben promises to tell her any three things she asks. After he plays literal genie with her out of habit/to protect her ("Shall I consider that your second question?") she asks for his name to piss him off. She only knows that fairies don't like to share their names, and finds out WHY when she uses a poorly worded insult.
 * This trope is referenced in A Connecticut Yankee in King Arthur's Court - the protagonist/narrator once fools the people into thinking he has done magic, by claiming to command an evil spirit by "thine own dread name" and then just making up a long nonsensical word.
 * In Jim Butcher's The Dresden Files ordinary names work like true names. However, you not only need to know a person's full name, you must also pronounce it in precisely the same way the owner does. So no using a telephone directory for instant magical smackdown--in order to use somebody's name against him you need to hear it from his own lips. Fortunately for human beings, their names tend to "go stale" after a while, because humans constantly change their self-images, and thus their own identities, which in turn reduces the effect of the connection using their names. You have to constantly "refresh" the name over time to keep it "current" so it can affect them. Wizards' names do not change quite as quickly as those of other humans. Wizards can mispronounce their names if they choose, and only other wizards can tell. Most supernatural enities are static enough that their names do not 'change' over time, making knowledge of them very powerful. Harry himself specifically has four names (his two middle names being Blackstone and Copperfield), and he makes sure to always keep one in reserve so that no one can know his full True Name.
 * As an aversion, Harry meets  Ferrovax at a costume ball, and doesn't tell him his full name (going by just "Harry Dresden"). The incredibly powerful Ferrovax is able to force him to his knees with only the two names.
 * There's also another issue with using an entity's true Name: when you use their Name, you create a connection between yourself and the entity in question. Unfortunately, when you do that, the connection works both ways, and if you try to invoke the Name of something very powerful, it can affect you right back. That's why Harry's Badass Boast mentions his name in full, and then adds the addendum that you should "conjure by it at your own risk."
 * Also, as the first book demonstrates, there is something more stupid than revealing your true name to your enemy: Letting him hear the true name of the demon you just summoned to kill him.
 * Harry's habit of giving nicknames proves unexpectedly powerful as the names he gives them influence the very nature of beings like a skullbound spirit of intellect, the embodiment of all recorded knowledge, and the psychic imprint of a fallen angel.
 * This somewhat backfires when he casually calls the archangel Uriel "Uri," and is told in emphatic terms to never do it again - that "el" is the part of Uriel's name that refers to God (the name as a whole means "Light of God" or "God is my Light") and he doesn't appreciate having it left off.
 * Keeping one's names in reserve doesn't help when dealing with angels. Thanks to their intellectus, they automatically know the True Name of anyone they're dealing with, letting them flatten any mortal who tries to stop them from completing their tasks.
 * Ted Chiang's SF short story Seventy-Two Letters uses this trope as one of its themes. In the story scholars engage in research to discover new names to give to clay golems that will imbue them with the ability to perform various tasks.
 * In Meredith Ann Pierce's The Firebringer Trilogy, knowing someone's true name doesn't necessarily give you complete power over them - it just makes them a lot more vulnerable to other spells.
 * In Glen Cook's Black Company series, particularly in the third book, "The White Rose", speaking a person's True Name nullifies their powers. Guessing wrong about which ancient wizard you're naming can be hazardous to your health...
 * The Wiz Biz/Wizardry series by Rick Cook; this also semi-averts people not realizing the best protection, as the hero is from another world and after a near-brush with revealing his true name, only goes by two different convenient nicknames. Other wizards also go by a nickname, or only a portion of their name, for the same reason.
 * This comes in particularly handy when a bad guy sics an ultra-powerful demon onto the hero; said demon is dangerous because it can hunt and kill anyone whose name has ever been spoken in that world. This would be a perfect plan except for the "from another world" thing.
 * Diane Duane's Young Wizards series has the wizardly Speech as the Language of Magic. Knowing someone's true name does not let you control them, but it is needed to perform some types of spells on them. Wizards must "sign" spells with their name in the Speech, which comprise not only spoken names but personality and sense of identity. And writing the name of something differently in the Speech changes the thing so named, so they must be treated with extra care.
 * Nita exploits this in the climax of So You Want to be a Wizard when she's reading from The Book Of Night With Moon:
 * Another example occurs in A Wizard Abroad where to repay a debt, one of the Sidhe whispers what is presumably his true name to Nita, instructing her to speak it to call for aid one time if she needs it. It comes in handy when they encounter creatures that are immune to their spells and speaking it calls out said fey and The Cavalry (literally).
 * All of the words in the Language of Magic are the true names of the things they stand for. Which makes sense, since it was the language with which reality itself was written.
 * The Door series, also by Diane Duane, also uses the trope. People have powerful, secret true names, though most don't know what theirs is.
 * At one point in the Malloreon, Ce'Nedra was possessed by Zandramas. Polgara forces Zandramas to admit her name, and by doing so is able to banish her. Polgara mocks Zandramas for "not knowing the power of a name."
 * It eventually becomes apparent that Polgara was lying about this. Zandramas is better at messing with minds than Polgara is at spotting her, but is aware of her inferior education and (relatively) enormous inexperience, and is inclined to run in any direct confrontation. Polgara's bluff played to this.
 * Eddings also played a different version of this game in the Tamuli, in which the Child Goddess Aphrael speaks the true name of the Elene God to Patriarch Bergsten, to prove that she's not a demon.
 * In Michael Ende's The Neverending Story, the Fantastica side of the plot begins with the Childlike Empress getting sick because she "needs a new name." Bastian becomes a Fantastican hero because he has the ability to name things. This is natural, as words have obvious importance when the entire world exists in a story.
 * In the second film based on the book, Bastian is called back to Fantasia in order to name the new threat ("The Emptiness") which should give them the power to fight it properly.
 * According to The Tough Guide to Fantasyland by Diana Wynne Jones, avoiding this is the real reason so many Fantasylanders have apostrophes in their names.
 * Diana Wynne Jones again: in The Dalemark Quartet books, saying the lesser name of one of the gods causes an island to come up out of the sea and break your enemy's ship in half. "What happens if you say his big name?"  Unsurprisingly, he's known by his nickname, the Earth Shaker. His wife's names also have dramatic effects.
 * Diana Wynne Jones again: In Power of Three, a major threat to the Dorig and Lymen is to simply mention that one has the name of an enemy in mind, as having a person's name allows you to curse them. Ceri scoffs at the 'giants' for giving out their names so freely.
 * Katharine Kerr's Deverry sequence, where it applies to dragons.
 * Ursula K. Le Guin's Earthsea series is probably the Trope Codifier. Each person is given his or her true name (which is a word in the language of dragons) by a Wizard. People keep their true names secret, and have other names for common use. A woman who lost her true name was rendered semi-catatonic. It is implied by the books that one can't be given an unpronounceable true name.
 * In one of her short story precursors to the series, "The Rule of Names", two supposed wizards get into a battle that involves lots of shapeshifting. The wizard Blackbeard invokes this when his opponent turns into a dragon, naming him and forcing him into his true form. Turns out
 * And it's not just people that have names; everything, from rocks to trees to sheep to the earth(sea) itself has a name, and can be controlled by one who knows it. Unfortunately, said control affects EVERYTHING that shares the name, as shown by the story of the man who accidentally turned an ocean of saltwater to fresh, when he only wanted a section of it to change. He was cursed by the gods to endlessly shovel the deposited salt back into the ocean, without being able to die.
 * A Wind in the Door by Madeleine L'Engle does not treat names themselves as being important, but the very state of being Named and of having someone know your Name is extremely important (as the cherubim Proginoskes put it, "He calls them all by name, and someone has to know who He's talking about.") This is the job of Namers, because without being Named, a person cannot know who they are, and are vulnerable to someone else pushing them around. The secret to naming? Love.
 * Reversed by the Echthroi, the closest thing L'Engle had to monsters: they can "X" a person, un-Naming them.
 * In The Lies of Locke Lamora by Scott Lynch, mages can mentally puppeteer anyone whose true name they know. The Bondsmage finds out the hard way that
 * In Patricia A. McKillip's The Bell at Sealey Head, when Ridley Dow is caught in the magic, Emma's calling "Mr. Dow" does not lead him to the Cool Gate, but Miranda Beryl's use of "Ridley" does.
 * In Robin McKinley's Sunshine, vampires use name magic. One laughs at the narrator for asking him his name, and later reveals it as a gesture of trust. Unlike most works, in Sunshine, the name is the name -- or names -- you use. The narrator is as vulnerable through her nickname "Sunshine" as through her name "Rae," and more vulnerable through either of those than through her long-disused birth name "Raven Blaise."
 * In Graham McNeill's Warhammer 40000 Horus Heresy novel False Gods, Temba whispers Horus's name to his warp-tainted sword before fighting with new skill.
 * In the later novel Prospero Burns, a demon is able to control all the Space Wolves present by learning pulling their names from Kaspar Hawser's brain. Only one marine, called Bear, is immune to the control. In a moment that could be a Crowning Moment of Funny, when Hawser later asks why the demon couldn't control Bear, he learns that the demon pulled the names from his mind, and Hawser's gotten Bear's name wrong from day one. Bear's name is actually Bjorn.
 * One series where the wizard does have a huge, unpronounceable name is Larry Niven's The Magic Goes Away.
 * In Andre Norton's Witch World novels, name magic is routine, and so powerful than the witches of Estcarp hide them from everyone.
 * In Scott O'Dell's Islandofthe Blue Dolphins, the protagonist's father accidentally introduced himself to the captain of the hunters' ship using his secret name rather than his common name. He later fell in battle, and his people blamed the public use of his secret name for it.
 * In The Gift by Patrick O'Leary, dragons can be commanded by their true names... except that, as it turns out, they all have the same one (the ancient word for "dragon"). They were purposely conditioned that way centuries ago by wizards who wanted to keep them in line.
 * In Christopher Paolini's The Inheritance Cycle, knowing the true name of someone lets you control them. They also have Elvish as a Language of Magic.
 * Also, this is a case of every animal/object having a true name. Though the only example thus far has possibly been
 * Also, a person's True Name isn't set in stone. As they grow and mature, and their personality changes, their true name will also change to reflect this. This can come in handy, since if someone is using your true name to enslave you, you can escape by changing yourself enough for your name to change. It isn't easy, but it's possible.
 * Galbatorix combines the ability to control someone through their True Name with the fact that the Ancient Language is a Language of Truth to force people to swear unbreakable oaths.  Galbatorix also cast a spell so that anyone who attempts to use his True Name against him will die.
 * In Barbara Hambly's Winterlands series, everything, even inanimate objects, have true names. Any spell stronger than basic telepathy (which can be used to discover someone's true name) requires you to Know Your Target's True Name, and you have to power the spell by "sourcing" energy from things you know the true names of. Our Dragons Are Immune To Magic because nobody can figure out what their true names are.
 * In Terry Pratchett's Discworld novel Mort, it's briefly mentioned that, in the old days, students at Unseen University had to "memorise the true names of everything until the brain squeaked". It's not made clear that there's any magical advantage to doing so, however. Considering the attitudes of the Unseen University faculty, it's quite likely that most of the 'learning true names' curriculum was to keep the students too busy to bother them.
 * In The Last Continent, however, it's stated that the Librarian has removed all mention of his own name from University records to prevent anyone trying to turn him back into a human. Rincewind knows it, and so the Librarian dissuades him from telling anyone -- by holding him over a ten-story drop.
 * Though knowing the staff of UU, this might just be a case where they go by titles so much that they can't remember which "Librarian" became THE Librarian in order to change him back.
 * In Pyramids: "All things are defined by names. Change the name, and you change the thing. Tere is a lot more to it than that, but paracosmically that is what it boils down to..."
 * A slight variation involves the fact that giving a name to something changes its nature, as in Interesting Times (with regards to Magitek Hex) "We should never have given you a name. A thing with a name is a bit more than a thing." Also comes into play when Agnes names her alter ego Perdita. She then develops a magical form of multiple personality disorder, as Perdita becomes an actual person living in Agnes' head with her and being everything Agnes wishes she could be.
 * Similarly used in the Neil Gaiman collaboration Good Omens where the Anti Christ, having been accidentally brought up by a normal middle-class family, is sent a Hellhound. The Hellhound has a bit of internal monologue all about "The Naming," saying that its master's name will give it its purpose. When said Hellhound is simply named "Dog" since that's all the boy wants, however, it ends up becoming... a dog, and all that the name implies. It's a happy-go-lucky, cat-chasing, normal, everyday dog.
 * Another example of names shaping things in Good Omens: Pepper's proper name is Pippin Galadriel Moonchild. "There are only two ways a child can go with that name, and Pepper had chosen the other one."
 * Spider Robinson once wrote of a wizard so ancient that he guided the evolution of humanity in such a way that modern larynxes simply can't form the sound of his True Name.
 * In Emily Rodda's The Key to Rondo, giving the Blue Queen your true name gives her power over you, and she can command you to do anything, up to and including suicide. In her first appearance she gains control over the heroine's beloved dog through this means; however, she doesn't gain control over the heroine, first because she believes the heroine to be someone else (and thus uses the wrong name), and then because the hero knows the heroine only by a nickname and therefore, despite calling her by her name repeatedly, doesn't reveal her real name.
 * In the final showdown, the Blue Queen learns the hero's name, and controls him as a hostage from that point on, effectively removing him from battle and threatening his life for a "Friend or Idol?" Decision.
 * In the third book, The Battle for Rondo, it's how they managed to defeat the Blue Queen.
 * In another of Emily Rodda's books, Deltora Dragons, the dragons believe that knowing a fellow dragon's name gives you some type of power over them.
 * Jonathan Stroud's The Bartimaeus Trilogy: Magicians lose their names when they start training and choose new ones to be called by later on.
 * Unfortunately, unlike most examples, this still doesn't work -- the new names aren't nearly as powerful as their birth names for magical purposes, but can still be used to mess with them.
 * Demons are also summoned and controlled through their names, though its revealed that this is less because it's their true name, but that when a magician first summons a demon he gives it name, and that name can then be used to call them. Bartimaeus and many other demons also have many names, but only Bartimaeus actually seems to have power over him.
 * Although no specific reason is given, The Ents in Lord of the Rings are likewise surprised at people giving out their real names, though the long-winded Entish language probably makes it moot for them (an Ent's true name can go on for days). Gandalf also complains that Bilbo was smart enough not to tell Smaug the dragon his name, but could have avoided rather more trouble if he hadn't told Gollum.
 * While not exactly magic, calling Smeagol/Gollum by one name gets a very different reaction than calling him by the other.
 * The protagonists also rarely speak Sauron's name out loud, usually using his title "Dark Lord", instead. Though it isn't explicitly stated, it's implied that speaking it too often in wrong situations could make him aware of the speaker. Also, when Pippin uses a Palantír and accidentally makes contact with Sauron, the first thing the Dark Lord does is demand his name, which Pippin refuses despite the resulting mental torture - again, it's implied that telling your own name to Sauron could make you fall under his power.
 * Tom Bombadil teaches Frodo Baggins an extended verse which will bring Tom to the aid of anyone within his territory who utters it, and this verse includes his name.
 * Dwarves in Tolkien are described as having true names in Khuzdul, which they never reveal, not even on their gravestones. The names they are known by (Thorin, Balin and so on) are by-names.
 * Book of Amber series by Roger Zelazny, in Guns of Avalon, when Strygalldwir comes to Corwin's window. He offers his name but says "Conjure with it and I will eat your liver." Only seems to apply to that certain brand of demon, though.
 * In The Changing Land, also by Roger Zelazny, one of the characters is a demon named Melbriniononsadsazzersteldregandishfeltselior. Usually conjurers trying to summon him messed up his name during the summoning and binding ritual - which left the demon free and ready to have fun. Unfortunately for the demon, another character, wizard Baran, was from a land with very complex language - so the name of the demon was quite manageable for Baran.
 * The Death Gate Cycle, in one of its appendices, describes rune-magic in terms of true names. What a rune-magic spell does is change an object's name, thus causing the object itself to change. The Sartan and Patryn (battling Witch Species who use this magic) are each affected by it in different ways:
 * Sartan magic emphasizes the spoken runes; as such, a Sartan's true name in their own language can be used to control them. Most Sartan go by pseudonyms as a result, and when Samah introduces himself to a stranger by his true name, this is a sign of both his power and arrogance (since it shows he doesn't fear magical attack).
 * Patryns emphasize the written runes, which they tattoo on their bodies. A Patryn's true name is therefore not the spoken form but the "heart-rune" inscribed in the center of their chest. Messing with this rune can seriously screw up a Patryn's ability to work magic.
 * A major part of the mythology of Skulduggery Pleasant, and the reason why the magically inclined go by self-referential nicknames. In the Skulduggery Pleasant books, everyone has a True Name (theoretically; the only known listing of them was destroyed) and a Given Name (your full given name, e.g. on a birth certificate), and may also take a Taken Name. Anyone mixing with magic is well-advised to pick a Taken Name, because it protects you from having your Given Name used against you. If you only have a Given Name, many mages can simply command you once they know it.
 * This is quite prominent in the Warhammer 40000 universe. A few examples include:
 * Zygmunt Molotch, the villain of the Ravenor books in the Warhammer 40000 universe, can subdue an opponent by speaking their full name using a Chaos skill called "Enuncia." (He can also briefly stun them using less than their full name, but this is much less effective.)
 * Toros Revoke, of the same series, is much better at using Enuncia as a weapon. He's able to shatter bones, burst internal organs, and drive back a daemonic assassin using it.
 * In the Warhammer 40000 novel Grey Knights,  gibberish is actually the True Name of , and   It pays off.
 * Saying the name of a Greater Daemon while in it's presence will send them instantly back to the warp. Their true name, mind. If a Greater Daemon of Khorne says his name is "Bob", it's probably lying. And about to kill you.
 * A Greater Daemon of Khorne is always about to kill you.
 * The Grimoire of True Names. Incredibly rare and potent artefacts, guarded by the Deamonhunters (who else?). In-game, a Deamonhunter that fights a Deamon in close combat while equipped with a Grimoire cuts the Deamon's Weapon Skill (ability to strike blows in close combat) in half. Hey, it can't kill you if it can't hit you!
 * In the Grey Knights novel, finds such a Grimoire - known as the Codicium Aeternium, thought to have been lost for centuries - after the capture of a rogue Inquisitor, which sets the Grey Knights off on the quest featured in that book.
 * The Star Wars Expanded Universe novel New Jedi Order: Traitor has an interesting bit of philosophy that seems to be the inversion of this trope: its proponent states that in naming a thing, you limit it, and in doing so you are saying a half-truth, or worse, a lie.
 * At least superficially, this view of words somewhat matches up with a few religions and philosophies, like Zen. If the universe is One whole, then the mere act of trying to describe the Oneness, or one's experience of it, divides and diminishes it into misleading categories.
 * There is also the Firrerreo race introduced in the novel The Crystal Star, who have a superstition about speaking someone's name out loud in order to have authority over them.
 * In the (A)D&D novel Pool of Darkness, a demon, due to a curse or another, had to speak his true name backwards, as a Verbal Tic. He used his backwards name as an alias in human form.
 * In fact, that had a second fiend (a succubus) whose human form also went by an anagram of her real name, and who was forced back into her natural shape when called by the latter (though it didn't seem to otherwise interfere with her power).
 * In John C. Wright's The Titans of Chaos, a god casts a spell on the title characters who have three sets of names apiece; he fails because one of them hid one set from him. Granted, someone named Quentin Nemo should have been a clue.
 * The Name of the Wind focuses heavily on this. Actually learning the names of things, though, is regarded as really, really difficult, and unless a person actually understands the name, he will only hear the common name for the object. Kvothe badly wants to study naming, but is refused by the somewhat-loopy but brilliant Master Namer.
 * Make Way For Dragons concerns the proper name for things. Renaming means reshaping. It's a very tricky situation, as reversing is impossible.
 * Evie Scelan is surprisingly casual about using her true name for someone who knows that magic exists and names can be used in it.
 * This was sometimes the case in Forgotten Realms. Ariel Manx in the Avatar Trilogy, for example, usually uses the pseudonym Midnight as a protective measure.
 * The Yn shamans from Janet Kagan's Hellspark use name magic. The protagonist uses this to talk one down, pointing out that she doesn't actually know the true name of her target and her curse is likely to go awry.
 * In The Iron Dragon's Daughter, knowing someone's - or even something's - true name can give you almost total power over that someone. Main character Jane, being a human not of that realm, doesn't have a "true name".
 * Vernor Vinge wrote an early Cyberpunk story, True Names, in which the dangers of using your real name on the Internet is a major plot point.
 * The reason why it's so hard for the title magicians in Jonathan Strange and Mr. Norrell to find and summon the Raven King is that they have no idea what his real name is.
 * In Neil Gaiman's Anansi Boys, Mr. Nancy (Anansi) and his sons apply this trope in a few ways, one of which being the humiliation of a major villain.
 * In the Mercy Thompson books, The Fair Folk can use someone's true name to control them. True names aren't any sort of magical secret knowledge, although older entities seem to prefer using nicknames and aliases for this reason. In Hunting Ground a fae greets Anna with her full name and the name of her pack in order to subtly threaten her. Later in the same book, a fae addresses one man with the name he was given at birth and his parents' names, and uses that power to issue him an order he can't resist.
 * In The Demon's Lexicon by Sarah Rees-Brennan, demon-summoning requires knowledge of the demon's true name.
 * Susan Cooper's novel The Dark Is Rising (part of The Dark Is Rising series). Merriman Lyon defeats Maggie the witch-girl (an agent of the Dark) through his knowledge of her true name.
 * In Cate Tiernan's series Sweep, everything has a true name, from plants to people. One of the main characters actually finds out her fathers true name and
 * Low caste Goreans frequently hide their true names from others due to a fear of this trope.
 * In A Name to Conjure By, a Summon Everyman Hero spell brings the protagonist to another world where his full, exceedingly long name is a powerful spell. A magician tries to learn the name with a spell, but fails because he can't read the English alphabet.
 * In Melusine, Mildmay warns Ginevra not to use her real name when they go to meet Vey Coruscant. At one point she says his name out loud, but at the time she only knew him by an alias.
 * In The Book of Three, the first volume of the Prydain Chronicles, Prince Gwydion is the only one who can defeat the Horned King because he's the only one who knows his real name,
 * In Simon Green's Nightside series, the second book features the Speaking Gun that can unmake anything ever created by saying its true name backwards. It's touted as the only actual item that can destroy an angel, whether nefarious or holy. (Little difference between them. Nefarious angels will destroy you because they are evil and enjoy it. Holy ones will destroy you because you're either in the way of the Plan, or simply because you're flawed.)
 * Quantum Gravity: True Names exist and work on all sapient species...while in Alfheim, home to the elves. They work on elves anywhere, but especially in Alfheim. It's the type of power that makes the target do something, though the exact power has yet to be confirmed: It made a target do something he didn't want to, but was worded very specifically and whether the action went against his nature is unknown.
 * In Robin Hobb's Realm of the Elderlings series, no dragon could lie to someone who demanded the truth with her true name or used it properly when asking a question. Nor could a dragon break an agreement if she entered into it under her true name.
 * George R. R. Martin's book Dying of the Light has a line that invokes this, when the viewpoint character's ex-girlfriend, explaining how she disliked the pet name he'd given her, says (approximately), "Give a thing a name and it will somehow come to be. All truth is in naming, and all lies as well, for nothing distorts as a false name can, a false name that changes both the appearance and the reality...."
 * Paranormalcy's Faeries run by this trope, which, when combined with Adults Are Useless (or Adults-Are-Too-Pigheaded-To-Realize-The-Consequences) leads to some serious trouble. Especially since some of the Faeries are resentful about it and are all to willing to get revenge in any way they can. A good example is Reth, who does a pretty spectacular job at twisting every command given to him, though he's not particularly nasty...
 * Inverted in the Doctor Who Expanded Universe Eighth Doctor Adventures and Faction Paradox novels. During the Second War in Heaven, the Time Lords battle a race of entities referred to as 'the Enemy'. The Enemy does have a true name, but the Time Lords almost never use it, as by naming the Enemy, they create the risk of the listener misunderstanding the Enemy as a physical alien race fighting the Time Lords in a physical war. The system of time we know (a steady progression of entropy, cause and effect, Timey-Wimey Ball, etc) is an invention of the Time Lords, and the Second War in Heaven is fought to prevent the Enemy from replacing it with whatever system they would impose on reality. Thus, the War is so surreal and metaphysical by normal standards that naming the Enemy causes non-Time Lords who cannot understand the principles at work to view the Enemy as a hostile invading force (false), rather than a fundamentally different and opposing system of time. Thus, the Enemy is a process, an unnatural force of nature, a series of events, rather than anything concrete.
 * Elizabeth Haydon's Symphony of Ages novels live on this trope. Especially in her first three books of the series, true names are bandied about or kept secret so they can't be abused as plot points practically every five pages.
 * In The Lost Years of Merlin series, by T.A Barron, names are very important, magically; Naming is even one of the Seven Songs of Magic. If someone knows the true name of someone or something, they have control over it (only Merlin knows the true name of, so he's the only one with total control over it. Merlin also learns his own true name at the end of the last book.
 * The Horus Heresy novel Prospero Burns has this as a second-half plot point that turns out to have a major implication near the end.
 * In the first book of The Kane Chronicles, this is how the heroes.
 * In Artemis Fowl, the Butlers don't reveal their true names to their charge in order to prevent attachment, and thus will only tell them when they are about to die. In the third book, Butler's real name is revealed to be . This becomes important in the next book as a safe word in order to break the inflicted on Butler.
 * Actually an important point in the Chronicles of the Emerged World, where the Orcish-like Fammin serving the Tyrant all have names which are actually magical words used to force them to obey the orders. This is the Wrong Ones' main source of fear and Angst.
 * In Salamander, the name a wizard uses must be their true name (or a shortened form of it), or else their magic fades. A superstition in-story is that naming a child after a dead wizard will give him some of that wizard's power.
 * The short story "True Names" by Harry Turtledove is a parody of this trope. It's set After the End in "Eastexas", where the remnants of the American people have reverted to ignorant barbarism. A tribal shaman finds a book about taxonomic classification and believes the scientific Greek names given for animals to be their 'true names' that grant the one who knows them power over them.
 * In Krabat. Fortunately, The Hero doesn't know the real name of the girl who's able to save him. (Another one wasn't that lucky.)
 * Stina Leicht uses both this and Words Can Break My Bones in "Of Blood and Honey". Using someone's true name gives you power over them; you can call them to you or command them.
 * In Teresa Frohock's Miserere an Autumn Tale, telling your name is dangerous. And you need to force a demon to tell you its name to exorcize it.

Live Action TV
"Townfolk: "If you can get a spirit to reveal his true name, you'll render yourself impervious to his charms! What is your true name?" The Doctor: "I haven't decided on one yet.""
 * One of the few ways to break Jasmine's control in Angel is to hear her true name spoken.
 * More specifically, hearing her name spoken stripped her of much of her power, and one of the abilities she lost was her ability to brainwash people. She also suffered permanent Glamour Failure.
 * The Carrionites of Doctor Who, who are implied to be the inspiration for the witches in Macbeth and possibly this whole true-name thing. Unfortunately, with them, It Only Works Once. Apparently it also works in reverse, as the Carrionites try to overcome the Doctor by this means, but are unable to discover his true name. Inverted in the Series 4 episode "Silence in The Library" when the Doctor finds out that archaeologist River Song knows his real name (not just "The Doctor"). He flat-out says that "there's only one reason" why he would ever tell anyone his name, with their conversations and River's comments to Donna making the implication (but only the implication!) that River could be.
 * He also adds that there is only one 'time' when he could tell anyone his name. This, plus River's use of the Tenth Doctor's grim Catch Phrase for people he knows are going to die ("I'm sorry, I'm so sorry") leads to the theory that she will be present at his death.
 * In the classic serial "Silver Nemesis", Lady Peinforte claimed to know the Doctor's true name.
 * Paige from Charmed has the power to 'orb' objects by focusing on and verbalising them. This proved to hold a prominent weakness in the episode 'Sense and Sense Ability,' where the Crone rendered her unable to speak, and, hence, use her power.
 * On So Weird Bricriu could only be banished if you know his name. When he possesses Fi's brother, he challenges her to figure out his name, at three guesses, giving her almost no hints. Near the end of that episode, Fi renegotiates and he lets her have as many guesses as she needs for one hour. She then uses a program to goes through every possible letter combination until it gets his name; how she got her computer to do that is unknown. In his (and her) final episode, his name is wiped from her memory when Fi's connection to the spirit world is removed. However, she didn't need it this time: he was in her computer, so she just traps him on a floppy drive.
 * Subverted during his second appearance, when he possesses Molly. He manages to trick Fi into letting him stay for 24 hours. Her agreement to this constitutes a Magically-Binding Contract, so even his true name can't be used to banish him during that period.
 * In Stargate SG-1, the team is looking for the Holy Grail. They are warned that part of the quest will involve battling a dragon and that the only way to stop it, is to speak the name of the one who controls it. Daniel theorises that this is based off this trope, but his actual explanation is that the dragon is a machine of some kind and that the name is some kind of code word.
 * They are told they will need to speak "the guardian's name." They assume this means they have to guess the name of the dragon; it is not until they are being attacked by it that Daniel figures out "the guardian" is the person who set up the whole quest: Morgan Le Fay (or Ganos Lal, as it was her true, Ancient name that beat the dragon.)
 * A minor sketch on The Young Ones showed two demons in Hell complaining about their own names being too weird. Apparently they could only be summoned to Earth to collect souls if a mortal said their names, and this unlucky pair were called Orgo and Futumsch.
 * In the Star Trek: Voyager episode "Spirit Folk", holograms of superstitious townfolk try to apply this trope and fail.
 * In the Star Trek: Voyager episode "Spirit Folk", holograms of superstitious townfolk try to apply this trope and fail.

""I can't. It... it knows I'm here. It knows my name!""
 * In an episode of Babylon 5 where Ivanova was using an alien supermachine to telepathically Google the First Ones, she accidentally astrally ran into the Shadows. She tried to escape, but had trouble:


 * In a sketch on Alexei Sayle's Stuff involving a Masonic Lodge style religious cult based around pencils, mention is made of "The Great Architect of the universe, whose name we cannot say... for it was written in pencil and got a bit smudged."
 * In an episode of NCIS: Los Angeles, the episode's villain, an information broker, manages to coerce Callen (whose first name is unknown by all, including him, with the exception of the fact that it starts with G) to obey his instructions by saying "I know what the 'G' stands for". The instructions nearly get Callen killed because the broker ordered him to stand in for the broker in dealing with some troublesome clients. Later, when Callen and the team find the broker's hideout, Callen gets the chance to learn for himself what the G stands for when he finds a file labelled "Callen, G" but is forced to abandon the file when the broker's security measures trigger explosives/incendiary devices that destroy all the files and equipment in the base.
 * In the eighth season of 24, Dana Walsh receives a call from her ex-boyfriend revealing that he knows that her true name is Jenny Scott, and forces her to work with him under threat of revealing it. Since she's a convicted felon, she does as he says in order to keep him quiet.

Music

 * Nightwish's "Nemo" may or may not use this.

Mythology

 * Older Than Dirt: Ancient Egyptians actually believed in the spiritual power of names, especially of one's own soul and those of the gods; for example, Isis (Au-set/Aset) once tricked the high god Ra into giving her a great deal of power by creating a serpent whose venom only she could counteract and having this viper bite him. He suffered but as a god was unable to die. She wrangled his True Name from him in exchange for the antidote which ended his suffering.
 * There was also the belief that if you destroy all records of someone's name, their 'Ka' would no longer exist. This has been attempted on unpopular pharaohs (like Akhenaten by everyone, and Hatshepsut by her successor and stepson).
 * Likewise, in the Egyptian Book of the Dead, the names of a number of guardians of gates in the netherworld are listed; by knowing them, the deceased gains power over them and will be able to pass through those gates.
 * A major part of Egyptian magic and religion generally related to the knowing and stategic use of names.
 * Furthermore, the goddess/incarnation of justice, Ma'at, has a true name that is not written anywhere because of the danger that someone might decide to speak it backwards.
 * In the original writings of The Bible, God's name is written around 7,000 times; the four letters that make it up are called the Tetragrammaton. Later on the Jews became superstitious regarding the name and would not say it, and since the original written form of the Hebrew language only consisted of consonants, the original pronunciation was lost. Another theory is that, according to Wikipedia, four letters of the Hebrew alphabet can double as vowels, ie mater lectionis, including Yodh "Y, I, J, or a vowel"; He "H, silent, or a vowel"; and Waw "W, V, or a vowel"; which all make up the Tetragrammaton. That is why in Gnostic literature, one of the names of the demiurge is Iao, Jao, Yao, or any other derivative form you can get from using the mater lectionis method. Either way, the loss of the correct pronunciation of the name of God in the present can make others to mistakenly believe that the name of God was used in this manner by those who did know it, while actually the name was well known and often used during Bible Times. It was a crime for the Jews to practice magic.
 * Actually, God has many names in scripture, and the four-letter name is only one of them. It isn't even used until several chapters into Genesis. Legend has it that different names of God represent different attributes, which is why Jews invoke several names, traditionally the ones aligned with mercy and compassion, in prayer.
 * Like the word "God" itself, those are simply just titles, the Tetragrammaton is the actual name. To illustrate the difference, in Bibles that use the Tetragrammaton, it is left as Yahweh, Jehovah, or something similar; whereas all the titles are translated into the native language.
 * The Jewish legend that changing the name of a gravely ill person can hide him from the Angel of Death.
 * Shemyaza, one of the Grigori/Watchers (the angels who were enamoured by human women and came down to earth to take them as their wives) was seduced by Istahar into revealing God's true name. He regretted it later, and threw himself into the constellation Orion.
 * In Homer's The Odyssey, Polyphemus the Cyclops is tricked by Odysseus/Ulysses. Odysseus claims his name is "no man," causing the Cyclops to be thought insane or cursed when he says that "no man" blinded him. However, Odysseus seals his fate after escaping when hubris prompts him to announce his True Name, allowing Poseidon, the Cyclops' father, to take revenge by sending a storm to destroy Odysseus' ships.
 * In Norse Mythology, specifically some re-tellings of the story of Sigurd, telling a dying person (and particularly a dying Dragon) is a bad idea, because if a dying person (or Dragon) curses you by name, that curse is guaranteed to be carried out.
 * Traditional Shinto beliefs include a form of magic called kotodama, in which you can compel your target to do almost anything if you know their true name. Series that feature this include Wagaya no Oinari-sama., Tactics, and Her Majesty's Dog.

Newspaper Comics

 * In a German Tabletop RPG fan comic, the gay priest of a group converts a demon in order to free said demon from the evil mage who caught the group. Reason? With the conversion, he got a new name, and as you know, the control over a demon depends on knowing his true name.

Tabletop Games

 * In Mage: The Awakening, knowing a person's real name makes using magic on them from a distance much, much easier. As a result, mages take "shadow names", sharing their true names only with their closest allies (as sometimes having someone be able to cast spells on you is beneficial).
 * The Awakening itself is supposed to result from a prospective mage metaphorically travelling to a Supernal Realm and inscribing their name on its Watchtower.
 * The Old World of Darkness version, Mage: The Ascension, had something similar with several of the Traditions - the Order of Hermes mages had a 'True Name', which was an Enochian phrase that described them. They concealed it in a Shadow Name, and many higher-powered mages found ways of inserting traps into the shadow name that would harm enemies trying to determine their True Name. Knowing a Hermetic's true name had a similar effect as in the new game. The technomantic Virtual Adepts had something similar with their Internet handles - but someone who goes by the name pronounced 'Coyote' could well be C0y0t3, (oy0t3, or any other 1337 variant.. good luck figuring out which would be their True Name...
 * Mummy: The Resurrection uses an Egyptian-influenced truename magic system called "Nomenclature." One of the system's ultimate powers is the ability to erase someone or something's name, removing them from existence (by making the universe forget they exist).
 * On the Old World of Darkness note, the Art of Naming from Changeling: The Dreaming no doubt caused many a Storyteller endless distress. The ability to rewrite someone's true name (essentially, the core of their being) does come with the risk of the Fates noticing you...
 * Continuing on with the oWoD name craze, Demon: The Fallen gives characters three names. A Fallen has whatever name or alias they are using in the real world. They also have a Celestial Name, which gives them remote communication and viewing with anyone who knows it. And finally they have True Names, which can be used to summon, bind, and exorcise them. Guarding one's names against hostile parties could be a very important part of the game.
 * And then there were the Tremere in Vampire: The Masquerade, whose projects included studying the Human Genome Project and the human genealogical records of the Church of Latter Day Saints in conjunction with one another in order to discern the true name of the human species.
 * Dungeons and Dragons
 * 1st edition.
 * Several spells usable against creatures from other planes (Banishment, Binding, Planar Call and Torment) required the use of the creature's true name.
 * The Call and Truename spells were usable against any living creature with a true name, not just otherplanar creatures.
 * The Prison of Zagyg magic item required knowing the target's true name in order to capture it.
 * The Oriental Adventures supplement said that in Oriental lands a person's secret name is given to them at birth and never revealed to others. Learning a person's secret name gives you magical power over them.
 * 2nd edition AD&D claimed that knowing a lich's true name conferred power over it.
 * 3rd Edition supplement Creature Collection. In order to destroy an Unhallowed, its True Name must be learned and spoken aloud to attract the attention of the gods before attacking it.
 * Edition 3.5 had a character class called the "Truenamer," who used this style of magic by learning the language of creation. A truenamer can technically use any utterance (spell) he knows any number of times per day, limited by the fact that the universe hates being screwed with, so spells get progressively harder each time per day they're used. That, and they screwed up the main way to use it so badly that it's nigh impossible to say it more than once.
 * Daemons of Chaos in Warhammer 40000 and Warhammer Fantasy Battle The Ordo Maleus maintains those which are known in The Grimoire of True Names. Sometimes Greater Daemons and Daemon Princes will go so far as to announce their true name, just to point out how doomed whoever stands against them is.
 * Works mechanically in two Dark Heresy supplements. Knowledge of a Daemons True name gives the player bonuses to summoning and commanding that particular daemon. It Is also featured in the "Thy Name I Keep" background where a character starts knowing a daemon's true name (or at least a fragment of it).
 * In Black Crusade player characters can receive a Daemonic name from their patron Chaos God. This brings them additional Infamy but should an opponent discover the name they gain an additional Infamy/Fate point (which can be spent to reroll failures, enhance successes or even avoid death) when fighting said player.
 * In GURPS Magic the alternate rules suggest that knowing someone's true name (which can be things like DNA or Social Security Number) give a very large bonus on targeting them with a spell. It also makes it easier to control summoned creatures.
 * The supplement book Mythic Egypt, written for both Rolemaster and the Hero System, naturally discussed true names. For purposes of magic in that setting, many spells meant to affected others required knowledge of their true name first (though there was also a spell to discover that by observing somebody directly which naturally didn't have that prerequisite) or otherwise simply wouldn't work, and one of the supernatural races of the setting had the explicit weakness that all of them shared the same true name...that had gotten out long ago.
 * In Legend of the Five Rings, the "Lying Darkness" had avoided being named at the creation of the world. This left it undefined and without limitations, and it tried to unmake the world. The world's heroes were finally able to stop it by gaining the power to name it, thus fixing its nature and imparting the qualities of the (previously existing, but no longer used) name Akodo.
 * Also, name-based magic is practiced by non-rokugani. Within Rokugan, it is practiced by the nezumi (rat people) and an angered nezumi shaman can cause a minor Cosmic Retcon to Unperson you if he snatches your true name away.
 * Oni can do something similar. They are nameless in their native realm and can't remain in the mortal world unless someone lends them a name. If the oni ever fully wrests the name from its original owner, the now-nameless victim is forced to obey the oni's commands.
 * Exalted features a reversal with She Who Lives In Her Name. Anyone who hears her true name becomes a drone who can only meditate on the inherent harmonic perfection of it.
 * Almost all magic in the Earthdawn system is based off of Names. The importance of Names in the system is emphasized by the fact that the collective term for all sentient races is "Name-Givers."
 * Shadowrun. Knowing a free spirit's true name allows it to be more easily summoned, controlled and banished.
 * Amber Diceless Role-Playing game (based on Roger Zelazny's Amber stories).
 * Using the target's true name is necessary or helpful when using certain Power Words.
 * Including the target's true name makes the Power Word "ASKIIR!" (Psychic Disrupt) much more effective on it.
 * It is necessary to use a target's true name when using the Power Words "KROLAK!" (Neural Disrupt) or "SCHANG!" (Resume True Form) against it. If the target does not have a name, the user must have a higher Psyche score to use those Power Words against it.
 * Hot Chicks RPG. When casting the Bind Spirit spell, using the spirit's True Name reduces the spirit's chance to resist the spell, as well as making the caster the spirit's hated enemy.
 * Witch Hunter: The Invisible World.
 * Knowing a creature's True Name allows the casting of or enhances the effect of the spells Spirit Son, Bond of Blood, Spirit Brother, Spirit Father, Magician's Mark, Sigil of Warding, Mark of the Minion, Mark of Dominion, Summoning of the Unseen, Exorcism, Exchange of Hurts, Strip Power, Compel Truth, Breath of Crom Slough, Compel Spirit, Eye of the Avenger, Circle of Summoning, The Unseen Hand, Séance, Trap Ghost, Raise the Dead, Charm and Scry.
 * Creatures can have the Mystical Price called True Name. If another being uses the creature's True Name while conversing with it, the speaker gains a bonus on the use of personality-based skills against the creature. It is also more difficult for the creature to attack someone who has spoken its True Name.
 * The Ven (the dominant species) in Houses of the Blooded all have three names: 1. A public name known by all with no power. 2. A private name with limited power (required for certain spells) given to allies, and 3. A true private name, known to the Ven and their mother (who gives them that name) which removes almost all spell resistances given only to the most trusted of allies and usually only needed for Unbreakable Vows.

Video Games
"Now, what has she sent in this envelope? Ah, of course. How droll. The child has uncovered what she thinks is my true name, and now believes she can blackmail me into telling you what I know. Well, maybe I'll tell you, but not because of her."
 * One of the bosses in Paper Mario: The Thousand-Year Door, a shapeshifting ghost in a party hat, can only be defeated if his true name is stated. A talking crow explains that there always has to be someone in the world who knows the ghost's name, or he would cease to exist.
 * In Neverwinter Nights: Hordes of the Underdark, it is possible to defeat in combat, but you can skip the fight entirely if you discover his true name and bind him with it.
 * And once he is bound, you can order him to do anything from killing himself, going back to Hell forever, or even handing control of Hell over to you and becoming your lackey! Your choices will alter the after-game epilogue considerably.
 * You can also find out the true names of all of your party members, which come in handy later.
 * Learning the true names requires you running all across the eight layer of hell to find the one being who seems to know them, innately. Knowing a person's true name is implied to give one complete power over them. Annoyingly, in the sequel, true names are much easier to acquire, and aren't nearly as effective as they once were.
 * Specifically, in Neverwinter Nights 2 . This Nerf is made somewhat worse (or mitigated) by the fact that only two of your party can read and pronounce it.
 * Towards the end of Simon the Sorcerer, you must banish two demons to back to hell. One requirement for the ritual to do so is knowing their true names. Strangely enough, they want to go back to Hell, but still refuse to give out their names to you. Though this could have something to do with their true names being "Belchgrabbit" and "Snogfondle".
 * An interesting twist on the theme occurs in Planescape: Torment, in which the main character is the Nameless One. His utter lack of a name prevents mages, demons, Big Bads, and anyone else from scrying upon him, and makes it next to impossible to find any history related to him.
 * The trope is twisted even more egregiously if the Nameless One attempts to take a name. Calling himself "Adahn" to NPCs results in an unusual focus of belief in the world; he's certainly not Adahn, but people start to believe that there is an Adahn wandering around that looks and acts just like you. Do it enough times, and eventually enough people assume that Adahn exists that... well, you can meet him yourself in a bar, proving that words can not only break your bones, they can make them, too!
 * This is all based on the game universe, as defined by the D&D sourcebooks. Sigil is a city where, if enough people believe it, it exists/occurs/whatever. A strong enough will can change the world. In fact, one of the main character's memories is of an argument he entered into with an unknown man. By applying apparently credible logic (it's never shown), he proves that the man doesn't exist. The man then reveals that if he were to believe it, he'd...and then he disappears from existence.
 * In Achaea, the Occultist class has the ability to take a "true name" from a player's corpse. They can later use the true name in a very strong attack against that player.
 * The "No one ever seems to realize this" bit is pointedly averted in the MUCK game SouthernCross, as those taking the flaw 'Bound by Superstition', among other significant quirks, have a True Name. This is so common in the setting's fae cultures, that a deep-set tradition is to either name an afflicted child with a difficult and esoteric name, then give them a new name by which they're addressed normally, or for the afflicted character (if they have one) to see to it that people always call them by the name of their domain (the concept or element many fae-blooded characters embody). 'Course, it's also played straight in that another part of said culture is the intrinsic value placed in knowledge of one's true name, and so just forgetting what your True Name is and having done with it is rather frowned upon.
 * The Elder Scrolls universe states that all Daedra have both a neonymic and a protonymic. The neonymic is their true name that they can change. It holds a certain amount of power, but is hard to use against them because they can change it at any time. However, the protonymic is their true name that they cannot change. It is heavily implied that through use of the protonymic mortals can do horrible things to even the most powerful of Daedric princes. The player character in Battlespire managed to banish Mehrunes Dagon through using them both.
 * Played with in Skyrim, where shouting a Dragon's name in Thu'um (dragon language) is viewed as a challenge to that dragon; it will seek out whoever made the shout, but more out of curiousity and a sense of honor than mental compulsion.
 * In the Nintendo 64 Game, Aidyn Chronicles: The First Mage,
 * In Warcraft universe, knowing a demon's true name gives you some power over it. This is presumably how warlocks controll their demon minions, as enslaving a random demon will only allow them to controll it for a few minutes and the two warlock minions without an individual name (Doomguard and Infernal) will only stay summoned for a limited time (they used to break free and attack the player, but now they just despawn).
 * City of Villains brings us the voodoo-themed Mr. Bocor. At the behest of a contact, the Player Character can attempt to blackmail Mr. Bocor into working with them by threatening to publish his true name. In classic trickster form, though, Mr. Bocor implies Hello, Insert Name Here has the wrong true name.


 * Knowing the true name of the Envoy of Shadows is the only way to get rid of him as he just keeps coming back every time he is killed.
 * In Gensokyo, the shopkeeper of Kourindou, Rinnosuke, has the power to determine the True Name and purpose of objects, but not how to use them.
 * In Chapter 14 of Curiosities of Lotus Asia, the canon material in which he is encountered, Reimu brings Rinnosuke a bone that is so old the ancient creature it belonged to has no True Name.
 * Your  co-workers in Deus Ex are two difficult cookies to crack if you end up fighting them straight. However, some snooping, hacking, and risky bets will net you their respective killswitches. The results of speaking their "True Names" are... impressive.
 * In the SNES Shadowrun game, a jester spirit challenges you to learn his true name; if you succeed, he tells you how to find the Big Bad, and will assist you during the fight.
 * In Dragon Age Origins,  mentions that the Desire demon he unwittingly summoned   refuses to tell him its name, since "names hold power".
 * In Star Control 3, you can find an object that contains the true name of the Eternal Ones, a mysterious evil race. If you let the robotic Daktaklakpak learn this true name, they will first essentially orgasm and then self-destruct.
 * In Breath of Fire IV this is used in a particularly brutal fashion by General Yohm to track down King in the Mountain (and eventual Woobie, Destroyer of Worlds) Fou-lu. Fou-lu is a half of a draconic deity that was Split At Birth, but was still so powerful that he became God-Emperor of the Vestigial Empire that summoned him; unfortunately for him, this causes a bit of Cursed with Awesome as the mere act of speaking Fou-lu's name creates such ripples in the universe that anyone who is psychically active can use these to track them down like a bloodhound following a scent. Oh, and Yohm is not only sensitive to these vibrations but is also The Dragon to The Emperor who sees the reawakening of the King in the Mountain as an Unwanted Revival and wants Fou-lu dead. Hilarity does not ensue.
 * This even results (at one point in the game) with Fou-lu essentially pulling Speak of the Devil on himself. Unfortunately, at one point he decides (in a fit of despondency) to tell Mami his life story in the form of a historical legend...which involves the use of his name. Things go rapidly to hell from there.
 * Invoked in Metal Gear AC!D - Hans Davis  However,   his true name in order to be put under Neoteny's control.
 * In Tales of Symphonia: Dawn of the New World, if
 * Also brought up to a smaller degree in the original game. Sheena says that everyone in Mizuho hides their real name and uses another name and no one besides their family and the chief know it. Although it's just a tradition and nothing magical or significant beyond that.
 * Hannar (jellyfish people) from Mass Effect have "Face names" and "Soul names". They usually refer to themselves as "This One," however. This is just a matter of courtesy, and when asked about it they mention it is rude to use one's soul name with someone they don't know very well. At no point is it suggested that knowledge of the soul name is connected (or is believed to be connected) to some sort of power or control.
 * In Sam And Max: What's New, Beelzebub?, Sam can thwart an illusion created by Peepers by saying his true name. Unfortunately, Sam does not know his true name, and all parts of it wind up being censored by the censorship branch of Hell (turns out it's .) He can also reveal Girl Stinky's true form by stating her true name... which stops making any iota of sense when the third season completely retcons Girl Stinky's origins.

Web Animation

 * In one Strong Bad Email episode, Strong Bad reveals that getting Bubs to say his name backwards minus the first 'b' (Sbu) will force him to give you a free lunch special.

Web Comics

 * "True Names" are a heavy theme in Shadowgirls. First, Becka gains the respect of a sea monster by telling it her name. After that monster tells her there is power in names, Becka is then able to summon her full power by saying the real name of the Shadowchild within her.
 * Played with in Goblins. According to a house rule, the pit fiend can be forced to serve any mortal who speaks his true name. Incidentally, his true name is definitely not Richard, Francis, Leslie, Winkypoop the Slippery Monkey, or Walter.
 * No doubt will be a huge theme in Namesake especially since one of the characters has "sold their name."
 * Elf Blood's sympathetic magic works best with these. The knowledge of a true name drove the entire Sister, Sister arc.
 * In Sinfest, Satan sneers at Criminy's claim to the book because he doesn't even known its true name.
 * In Sinfest, Satan sneers at Criminy's claim to the book because he doesn't even known its true name.

Western Animation

 * American Dad had Steve playing an MMORPG where his character dies when someone says his name backwards. His sister Hayley uses this little-known fact to humiliate him in front of his friends, who instantly go from praising him to constantly belittling him. When this happens, Hayley's boyfriend convinces her to go with him on a long quest for an item to revive Steve. After he comes back, he goes to take revenge on his friends for maltreating him, only for them to just say his name backwards the second they see him.
 * Family Guy employed a similar gag when, in a cutaway scene, Adam West writes down Jeopardy! game show host Alex Trebek's name backwards, thus banishing Trebek "back to the fifth dimension where he belongs."
 * Someone actually tried this in a real game of Jeopardy. Unfortunately, Trebek was not banished.
 * Only because they did it wrong. They should have written "" (Trebek's real RL name courtesy of That Other Wiki)
 * "Swiper no swiping!"
 * In Minoriteam, Fasto had to stop a Galactus expy from eating the world. So, he threatened him with his real name. The real name was so embarrassing that it worked.
 * In Ben 10: Ultimate Alien, Charmcaster explains that in the Magical Land of Ledgerdomain, to know someone or something's true name is to have power over it. The villain Adwagia has the Alpha Rune, the true name of magic itself, making him an unstoppable Physical God/Reality Warper. At one point, Kevin taunts Charmcaster about how she told him her name was Caroline, but she retorts that "Caroline" is just an alias.
 * For the record, Charmcaster's real name is

Real Life

 * Used in bizarre fashion in the House of Commons, where members are only referred to by one of a variety of titles. Only the Speaker uses the name (always the Full Name) of the members, and explicitly "naming" someone is either an insult, a reprimand, an enormous faux pas, or is calling for them to speak - depending entirely on context.
 * In the United States Senate only the presiding officer may be directly addressed in speeches; other Members must be referred to in the third person. In most cases, senators do not refer to each other by name, but by state, using forms such as "the senior senator from Virginia" or "the junior senator from California."
 * Thanks to the Internet, putting a real name to a screen name or e-mail address can lead to all sorts of unpleasantness coming to light.
 * Unless your name is exceptionally generic such that there are twelve people in your home country alone with your exact combination and spelling of first name and last name ("Robert Smith" in the United States for instance). But if they also have a general location...
 * On Myspace, there is an option you can enable that requires people adding you to know your last name or e-mail address.
 * Encyclopedia Dramatica, for all its moral ambiguity, doesn't allow you to show them your pokemans either.
 * General consensus is that the best way to make a troll stop is to call them out by their full name. more thorough retaliation involves phone numbers, addresses, class schedules, friends and relatives, and photos. Collectively these are known as "dox" and to release this information is to known as "dropping dox."
 * Whether a type of organism is assigned its own species-level taxonomic name or not can be the deciding factor in whether it is entitled to protection under the Endangered Species Act. The future of the North American red wolf grew far less secure when it was mistakenly suspected to be a hybrid of timber wolf and coyote, hence not necessarily an endangered "species" in its own right.
 * A variety of cultures still believe that names have power, and often people are given a name for daily use in order to keep their "true" name sacred.
 * In certain rural locales in the Philippines, sickly children are believed to be targeted by The Fair Folk, and as such are given a "second baptism" in an attempt to throw the Fae off. This ends up sometimes with a person being known by his legal name in the city and by his second name to his folks who stayed on the farm / island.
 * This is true of some Native American peoples. Some give a child an unpleasant name at birth (to trick envious spirits), and then a more appropriate name later on. The Dineh (Navajo) have a true name ('war name') - known only to family - and the name they use for everyday purposes.
 * In the United States, one's Social Security Number is effectively a True Name. They are designed to be unique, used only when unambiguous identification is necessary, and if someone else gets it they can cause some problems.
 * And in many countries who practice ID cards, the ID card number.
 * If you call someone by their name, they will usually stop for a moment to hear what else you have to say. However, if this power is abused, it will become less effective.
 * Because religious intolerance has and still exists, part of Gerald Gardner's "Old Laws" for Wicca touches upon persecution and the need for secrecy and the usage of names at rites. "And while there, none shall say whence they come, or give their true names."
 * In programming, if you know the full name of any object, you can force it do whatever you want that's within its power. What's more, if you know the full name of a class, you can extend it or create a subclass of it to give it the power to do whatever you want, create an object, and - using the full name of the object you've created - force it to do whatever you want that's within the power that you've given it.