Speak of the Devil

""Speak of the devil and he doth appear.""

You know how when you're in a crowd, you can tell whenever someone says your name? Well, some villains can do that anywhere.

The core trope is that saying the name of the villain summons him. Rarely, though, is he summoned surprised and vulnerable; be assured that saying the name of this guy is a bad thing. Though probably just for you; he'll usually disappear afterward. The question of why everyone in the world often knows this name, despite the massive taboo against saying it, is rarely addressed.

This makes talking about the villain problematic, as he has to be referred to as "The Enemy" or "He Who Must Not Be Named" or " You Know Who", or possibly just by a nickname, as with Satan, who may be called "Old Nick" or "Mister Scratch". Sometimes these nicknames are conspicuously positive, just in case they're listening anyway, as with The Fair Folk, because you do not want to face down a pissed-off faerie. If referring to him by any name summons him, well, then you're just screwed.

If attempting to talk to someone not in the know, this can easily lead to Poor Communication Kills. There also always remains the possibility of someone slipping up (especially when surprised or caught off-guard), or someone not in the know saying it. If you have another enemy you want to deal with, though, perhaps you can trick him into saying the name.

Another variation is that the villain's name must be said multiple times to summon him. In these cases, saying the name once is safe, so you probably don't need to worry about summoning him accidentally, or being tricked into doing so (unless you have no idea what's going on and just come across a piece of paper saying "Say Hastur 3 times.") (Okay. "Hastur three times.") Instead the villain is essentially Sealed Evil in a Can, and he'll be summoned either by someone who has no idea what's going on, or by someone who got his tropes mixed up and thinks he'll be able to control the villain this way, or at least bargain with him. Expect this guy to die horribly. Also expect this villain not to disappear.

The name comes from the old saying: "Speak of the Devil, and he will appear." Also known as He Who Must Not Be Named.

If saying the villain's name doesn't necessarily summon him, but may simply cause something bad, that's The Scottish Trope.

If knowing someone's true name instead gives you power over him, that's I Know Your True Name. If summoning him is not a bad thing, see Call on Me. See also Inadvertent Entrance Cue. When this is done for humor rather than being a supernatural ability, it's Right Behind Me. Related to the Sneeze Cut. When this is invoked for a murder, a Trouble Magnet Gambit is very likely the method used. Candle Jack was a recent pop culture variation.

Anime and Manga
"Aoba: I just hope they don't start using BC weapons! Things could get pretty ugly... Hyuuga: Yeah, that or N2 mines -- (BOOM) Aoba: Speak of the devil...! Hyuuga: Damn! Haven't they ever heard of moderation?! Fuyutsuki: That was a little much... (the JSSDF begins a Macross Missile Massacre on the Geofront)"
 * The Rail Tracer in Baccano!! is something of a subversion. At first, it's pretty obvious that it's a relatively harmless Urban Legend delivered by two Cloudcuckoolanders and a chirpy train conductor that had the misfortune of coinciding with a train hijack. Then episode 6 rolls along and shows the aforementioned hijackers getting picked off by this...thing, proving that it just might be Real After All. And then comes the Wham! Episode (Let's just say that )...
 * A subversion and running gag on Dinosaur King: Ursula always knows when someone calls her an "old lady" no matter where they are in the world and immediately, and loudly, takes exception. She won't know where you are, much less be teleported there, but she will be pretty P.O.'ed when she meets up with you. This was once used to determine if the Alpha Gang was in the area.
 * In The End of Evangelion, the JSSDF begin an assault on NERV HQ, and one of the Bridge Bunnies, Makoto Hyuga, states that he hopes they don't use non-nuclear mines. In the English dub, at least, Shigeru Aoba gives a Title Drop of this trope when the inevitable happens.


 * "It would be disastrous if an Angel turned up right now."
 * In Ranma ½, Old Master Happosai's name is treated as an invocation that will summon him. Seems to work that way, too, at least part of the time.

Comic Books
"Zatanna: Stranger things have happened. Phantom Stranger: Did someone just use a sentence involving the word stranger?"
 * In The Sandman, characters refer to the Furies as "The Kindly Ones", as the ancient Greeks did; in this case, it's also to avoid attracting their attention.
 * Also in The Sandman, there is one instance of summoning the title character by saying his preferred name (Morpheus). The character Rose Walker is given a piece of paper by her protector, Gilbert, and told that she must read the word aloud if she finds herself in grave danger; she reads it when another character attempts to rape and murder her, causing Dream to appear in the room and come to her rescue. It's not made clear why this works, however; it may be
 * Though remember that Glob warns Brute not to say the name "Morpheus", because that could give him immediate entry to their sanctuary. Otherwise, Morpheus needs to take the long way around. Again we have dream creatures involved, so it is hard to say what would happen if a mortal said it under normal circumstances.
 * In the story Ramadan, the Kalif of Bagdhad gets Dream's attention by addressing him by name and then threatening to release a horde of demons if he doesn't show. It seems that he knows where anyone is talking about him but doesn't have to take an interest, which suggests that Gilbert, knew a name for dream most mortals don't and that made him take an interest.
 * In the spinoff series Lucifer, the eponymous protagonist threatens the queen of the Japanese afterlife  with calling on the Dream King by merely saying his name. Since we know Lucifer doesn't lie but   we know that it's probably true, but not how it works, since Dream claims to no longer be.
 * In Young Avengers, Kang the Conqueror references this trope, and sort of uses it.
 * A heroic version, The Phantom Stranger occasionally waits to show up until someone says the word "stranger". This is less of a summoning issue, and due more to the fact that he has a sense of dramatic timing. This has, needless to say, been lampshaded and parodied.


 * In Brazilian comic Monica's Gang, two characters have it: Lady McDeath appears whenever someone says "death" or something related to the verb "die"; and whenever something absurd occurs and someone asks "who would be nutty enough..." Nutty Ned appears.
 * A more down-to-earth version of this is used for humor and to get around a real-world problem in the G.I. Joe comics. Hasbro created a character named Ghostrider, who is a stealth pilot. Nobody noticed that there was already a character in Marvel Comics with almost the exact same name before the figure went into production. Larry Hama worked around the issue by writing the character as being so stealthy that even his own teammates could never remember his codename.
 * In Zot, the assassin-for-hire 9-Jack-9 can be summoned by typing his name (actually spelled J9AC9K) into any computer terminal. Every single reader has tried it at least once... or considered it and then chickened out.
 * In an issue of Wolverine, it was revealed that perennial X-Men villain Spiral is aware (or alerted) whenever anyone anywhere mentions her. She used this to track Wolverine and Mystique, the latter of whom could not spit out the warning in time.

Film
"Even though I should be wary Still I conjure something scary Ghostly hauntings I turn loose, Beetlejuice, Beetlejuice, Beetlejuice!"
 * Beetlejuice is summoned by saying his name 3 times.
 * He's also sent back whence he came by saying his name three times.
 * The full rhymes (from the cartoon, at least), though rarely used, go:


 * for bringing him into our world, and:

"Knowing that I should be wary Still I venture someplace scary Ghostly hauntings now turn loose Beetlejuice, Beetlejuice, Beetlejuice!"


 * when Lydia wants to enter the Neitherworld.


 * Community used this for a stealth gag that ran over the course of three years. Watch behind Annie at the end of the clip.
 * The Candyman horror films: A tortured murderous spirit is summoned by saying "Candyman" five times in front of a mirror.
 * This hearkens back to the childhood myth of Bloody Mary.
 * In the V for Vendetta film,  is listening to a recording in which he talks about V (specifically about how he wishes he could fight him man to man) only for a Mirror Scare to reveal V standing there. Just for clarification, there is nothing magical in this case, and it is just a coincidence (or possibly the ever-theatrical V was waiting for the perfect moment,) but the look on the man's face suggests it might as well have been this trope.

Literature
""Do not speak of him!" she whispered. "Demons are often summoned by the sound of their names."
 * In The Belgariad, saying the name of Zedar allows him to listen in on your conversation. The protagonists eventually get around this by getting lots of storytellers to retell the tales of Zedar, so he won't notice them amidst all the noise.
 * In Robert W. Chamber's The King in Yellow, "Hastur" was originally a mysterious name, most likely a location, with only vague connections to the titular King. When August Derleth absorbed Hastur into the greater Cthulhu Mythos, he started using it as the actual name of The King in Yellow, and re-appropriated non-synonymous titles such as "Him Who Must Not Be Named," (likely another euphemistic name for Azathoth) and "The High Priest Not To Be Described" (a minion of Nyarlathotep who might actually be Nyarlathotep) as sobriquets. This spawned the idea in the Expanded Universe that referring to him in by name was a very bad idea. In particular, the 1980 Dungeons & Dragons Deities and Demigods Cyclopedia stated that naming Hastur aloud could result in his sending some Byakhee to kill you. If they failed, he might appear himself to finish the job. Tricking a player into doing so has long been a favorite means of ending a game that has gone sour.
 * Not a bad thing but in fact quite good: In Persona 2, saying "Hasturcomeforth" instead of your birth month to a fortune-telling girl would freak her out immensely and let you eventually summon him. (Hastur just loves hearing his name, basically.)
 * In the Web Comic User Friendly, Kuan is singing the Badger Song and Sid, annoyed, It looks like  as a result.
 * Someone has coined the term "hasturbating" to refer to the process of invoking this meme.
 * In the Incarnations of Immortality series, mentioning Satan by name will draw his attention. Lachesis and Chronos both mention this to the new incarnation of Death, when Death is investigating a suspiciously premature demise.
 * Author Ramsey Campbell created a god for the Cthulhu Mythos named Y', who could possess a host if they merely read his name. Not even out loud; he could possess a person if they sight-read his name on a printed page. Seeing as he's a god that represents every deed that could be viewed as defiling by individuals both sane and insane across the universe, this is not a pleasant fate.
 * Well, it's not clear whether merely reading the name or reading out of De Vermis Mysteriis will turn you into a slave of Y'.
 * The accepted version is that reading his name is fine unless you are reading his name from one of the 7 tomes of "The Revelations of Glaaki" which will cause him to appear and either eat or mind rape or enslave you.
 * In The Wheel of Time series, saying The Dark One's true name supposedly draws his attention, and certainly gives you a nasty fit of bad luck. He's the dark god, you know. So there exist many alternate names for him too - like "father of lies".
 * Heroic example: Chrestomanci, from the book series of the same name by Diana Wynne Jones, will appear wherever his name is spoken. Chanting his name three times can summon him to another world. His enemies refer to him as "August Personage" to avoid attracting his attention.
 * Used in Jonathan Strange & Mr Norrell with the Raven King, a human raised in faerie who is the bringer of magic to England, and who is considered the true ruler of those living Oop North who often make oaths by him. One Northerner, Childermass, declares himself loyal to the Raven King despite his absence, and later is shocked when he meets him and it's clear that The Raven King heard the oath
 * In the Harry Potter series Voldemort is literally called He-Who-Must-Not-Be-Named by those who are afraid of saying (or printing) his name, though those using less formal diction call him You-Know-Who. His followers simply call him The Dark Lord. In the earlier books this is portrayed merely as people being monumentally afraid of Voldemort (and a sign of reverence, in the case of his followers). In the last book.
 * In a more benign case, house elves automatically Apparate to the location of their owner when their name is called, regardless of any curses or protective magic that should prevent them.
 * In the Young Wizards series, speaking any of the Lone Power's nicknames has the danger of drawing Its attention. Even thinking its true name is guaranteed to get Its attention unless something is keeping It distracted.
 * Discworld:
 * In Lords and Ladies, it is mentioned that mentioning the Elves by name can draw their attention and even help them cross over from Fairyland, especially around certain times of year when crop circles appear. For this reason, the witches of Lancre refer to them by various pseudonyms (such as the Gentry, or the Lords and Ladies), and only feel (barely) comfortable saying their name aloud when in the presence of lots of iron.
 * Although if you're close enough to a portal even these pseudonyms will draw them.
 * This is actually based on old folk beliefs; there's a reason the trope's called The Fair Folk.
 * Another Discworld example is Igor (any Igor). When the master calls him, Igor will appear directly behind to answer. Makes no difference if Igor was in the basement or on the roof at the time, somehow he will also be out of sight behind his master when the master calls. Just part of the Igor service package.
 * Yet another Discworld example, especially in the early books such as The Colour of Magic, was never mentioning the true name of The Lady, the Goddess Who Must Not Be Named, which is . An inversion, since she's the only goddess who only comes when not called and flees when mentioned. The Discworld Companion adds that the Gamblers' Guild once tried worshipping her, and the result was that the building exploded. Not so surprising, since it is later established that Gambler's guild is always right across the street from the Alchemists Guild.
 * Inverted with the Auditors, which are instantly destroyed if they refer to themselves in the first-person singular.
 * Wizards are forbidden from saying the number eight because it draws the attention of the Eldritch Abomination Bel-Shamharoth, the Sender of Eight.
 * The Lord of the Rings offers a sort of half-example; the words "Sauron" or "Mordor" are often avoided, but it's never made clear what, if anything, the consequences of using them are.
 * There is also a case of inconsistent narration, since in the Fellowship of the Ring Aragorn claims that Sauron doesn't use his given name, and forbids his servants speaking or writing it (not really surprising when Sauron is elvish for "Abhorred"), but in the Return of the King we encounter a character called the Mouth of Sauron, who explicitly calls his master "Sauron the Great".
 * He might have been using the name for the benefit of the people he is talking to, since that it is the name they recognize for him. His original name of Mairon would not really have meant anything to the people of middle earth. Though it would have been funny to see the mouth refer to "Mairon The Great" only for Aragorn to reply "Who?".
 * Sauron was known by that name in Númenor (as the Númenoreans knew him from the Elves) and the Mouth of Sauron was a Black Númenorean, so he might have been using the name out of habit. Also, the taboo about not mentioning Sauron's name seems to be mainly a Gondorian thing ("He who we do not name" or "the Nameless Evil")
 * Let's not forget the whole Literary Agent Hypothesis.
 * I believe there is also magic involved when Gandalf calls Shadowfax.
 * This trope is used often in the books: Gandalf is unwilling to pronounce the ring's verse in the dark, especially in the black speech. There is generally a reluctance from all the characters to use words or names associated with evil things when it is dark.
 * Since the Ring's verse is essentially an evil spell, it's quite understandable why Gandalf doesn't want to speak it in uncontrolled circumstances.
 * Similar to The Lord of the Rings, the Chronicles of Thomas Covenant has the Ranyhyn, the wild, free and intelligent horses. They have special magic that days or weeks before you call them, they know it and head for where you will be so that as soon as you whistle for them, they are there.
 * And in the Second Chronicles we meet the Sandgorgons, who instantly know when their names are mentioned, even a great distance away, and will run at incredible speeds to find the person who did it
 * A rather literal variant in the Thursday Next series, Acheron Hades can hear his name if it's spoken within a hundred-mile radius.
 * In the David Drake fantasy novel The Sea Hag, The Hero is able to defeat the villain by tricking him into naming Serdic, his old (dead) master...who then promptly appears and drags the villain away to a Nightmare Fuel fate, since he had promised the hero earlier this would happen the next time he was named.
 * In Snakecharm, the second of Amelia Atwater-Rhodes' Kiesha'ra series, an unfortunate falcon, masquerading as a serpent, asks Zane if the falcons' ambassador, Syfka, is in town. Syfka pops up almost immediately, telling the rogue falcon "You were foolish enough to use my name, not once, but twice." The "...And then you're in deep trouble" aspect is subverted, as Syfka gets into a heated argument with Zane, and when she turns around a moment later, everyone realizes that the man who said his name had run away during the argument.
 * In Romance of the Three Kingdoms, Cao Cao had a tendency to show up whenever his name was being mentioned - so the saying goes, "Speak of Cao Cao, and Cao Cao is at the gates." Ironically, at one point, this was happening to the man himself - everytime he tempted fate by mentioning some character on the opposing side, that man would shortly show up.
 * In John C. Wright's Chronicles of Chaos, Echinda can detect anyone saying her name; the children resort to refering to "the fishmonger."
 * Similar to the Sandman example above in the Percy Jackson and The Olympians series by Rick Riodan, the use names of various mythological figures or places causes bad things like thunder and darkening of the skies to happen, so the characters tend to avoid using them.
 * It's stated that this is because it gets their attention, and the lightning is only if they're upset with you.
 * Unless you're Dionysus, who responds to Zeus's thunder with a bored "Blah, blah, blah."
 * Mentioning the in Turn Coat is a very bad idea, since it grows stronger with fear and infamy. So Harry renames it "Shagnasty," which lacks the same intimidation factor.
 * Evie Scelan threatens people who seem like they are about to call the Bright Brotherhood by their proper name, . For someone who doesn't mind handing out her true name, she seems surprisingly worried about this.
 * In Jack of Shadows, by Roger Zelazny, Jack's powers include the ability to hear any person who speaks his name in shadow, and to continue listening in until they move out of it.
 * In Zelazny's Dilvish the Damned stories, the evil wizard Jelerak won't himself show up if you speak his name, but one of the demons that serve him may, mistaking your use of his name for Jelerak summoning them. They'll be "unhappy" to be accidentally summoned that way, and may demonstrate this upon your person....
 * Jack Chalker's The Changewinds begins with the female protagonists learning that they are being threatened by an evil wizard. A mercenary to whom was entrusted the girls' safety decides that the villain is likely to pay better and attempts to attract his attention by saying his name now and then. The girls, discovering this, try to call on the wizard who brought them to this world by saying his name over and over. Of course, with a name like "Boolean", the girls just wound up giggling after a while. It should be noted that neither wizard was summoned, no matter how much their names were dropped.
 * In Robert E. Howard's Conan the Barbarian novel The Hour of the Dragon, Zenobia fears it, even though it's a man being spoken of.


 * The Bloody Mary version is weaponized in Seanan McGuire's short story Dying With Her Cheer Pants On
 * Nearly used in the Solomon Kane story The Blue Flame of Vengeance, except that Solomon shows up right as the Fishhawk is about to say his name.
 * In The Kingkiller Chronicle, the Chandrian can tell when and where their name is spoken.
 * In The Empire of the East, the arch-wizard Wood (itself an alias) is too afraid to say the demon-prince Orcus' name, or even think it. He still proposes to release him, though.
 * In The Griffin's Daughter Trilogy, the Nameless One's true name had been stricken from elven records and lore, to keep others from trying to invoke I Know Your True Name and claim the Nameless One's power, either becoming as big a threat as The Nameless One or inadvertently resurrecting him.

Live-Action TV
"Alton: All right, which one of you at home said "Nutritional Anthropologist"? Deb Duchon, Nutritional Anthropologist: That guy, there... naugahyde chair, green pants. Alton: Yeah, well, (through megaphone) thanks a lot, Mr. Talks-to-his-television!"
 * The Spanish Inquisition, whom nobody expects.
 * "Say my name and I appear. Why have you summoned Quagmire here?"
 * In an early episode of Supernatural, the boys fight Bloody Mary. Needless to say, this trope comes into effect.
 * Good Eats; not a villain but a Running Gag:
 * Good Eats; not a villain but a Running Gag:

"Johnny: Who am I?! "
 * Rick and Neil on The Young Ones once summoned the demon Futumsch to their flat by saying his name, which had been printed in a newspaper article for no readily-apparent reason. Not that they ever noticed Futumsch was there, mind...
 * In Brazilian sitcom Toma Lá, Dá Cá, whenever the apartment manager's name is mentioned, she knocks at the door and comes in. At a certain point of the show, the Genre Savvy characters would try to stop whenever someone started saying her name.
 * In Scrubs mentioning "Johnny the tackling Alzheimer's patient" will result in JD being tackled by Johnny at least once that episode.


 * The Tales from the Darkside episode "Seasons of Belief" has a couple on Christmas Eve telling their kids the story of a monster who's so full of himself, if he hears anyone say his name, his ears will transform into wings and he'll hunt them down and squeeze the life from them, (often while singing a song about himself). Supposedly, the only way to get rid of him is to finish telling the story about him.
 * WWF/E wrestler The Undertaker does a very Candle Jack-ish variation of this. Basically, if his name is brou
 * Sorry about that; the previous troper should have known better. As he was saying, if his name is brought up in an offensive way while he's around (or even if he isn't), a gong will sound, and the lights will go off. Then he will appear behind the offender and usually chokeslam or Tombstone Piledrive them to the mat.
 * Sometimes, Taker's name doesn't even need to be spoken—as heel manager Paul Heyman learned at the end of a Smackdown match, just telling someone that "there's not a man alive who's going to stand in my way" can be enough to bring the Deadman's wrath down on you.
 * In Raising Hope, the Dog-Head Man knows when people are talking about him. At least, according to Jimmy.
 * In Nikita, Birkhoff gets an alert whenever anybody online runs a search on his name.
 * The Muppet Show:
 * Mentioning any word associated with bombs and explosions will cause Crazy Harry to appear, detonation plunger in hand and BOOM! Kermit once had the misfortune of causing this three times in a row on the Ben Vereen episode.
 * In one episode the Newcaster reports that the temple of an ancient Egyptian crocodile god named Rezal-evad-gib (the name of which he actually says twice for emphasis) has been discovered, and that said god would "wreak a terrible vengeance" upon anyone entering the tomb or even saying his name aloud. Well, you can probably guess what happens. He gets an excuse that time, but in the very next scene, where Beauregard tries to warn Lynda Carter that they've discovered a dangerous word, but can't remember the hard-to-pronounce name, the Newscaster runs in and says it again.

Music
I hope your bullet holes become mouths that say my name, cuz I'm the-*GUNSHOT*"
 * In the song "Black Fox" whose artist varies, some bored foxhunters mention that if the devil himself showed up, they'd "run him such a race." Out of nowhere appears a black fox with red eyes, which the exited hunters chase all over the countryside. Eventually, the fox swims a river, and upon reaching the other side, reveals itself to be Satan, who more or less exclaims "Surprise, ******* !" The terrified hunters flee back to town.
 * For some odd reason, in Lupe Fiasco's The Cool, whenever The Game is mentioned, someone dies (unintentional. Maybe.). You don't even hear him say it in his own song due to this reason:
 * " If you die, tell 'em that you played my game

Oral Tradition, Folklore, Myths and Legends

 * As mentioned above, Satan is the Trope Namer.
 * Depending on how strict their adherence to the 3rd Commandment is, some people refrain from saying God's name as well, though that's less out of fear of summoning Him (seeing as He's already, you know, omnipresent) and more because to do otherwise is seen as blasphemous.
 * Various old folklore: Not only the Devil, as mentioned above, but Cao Cao in Chinese folklore, wolves in France, and various predators in various places.
 * An especially interesting case is bears. "Bear" is itself a euphemism for the creature, a word (meaning "the brown one") used instead of their name to avoid drawing their attention. The substitution happened so long ago that we have no idea what the real name was though.
 * Actually, we sort of do. Based on reconstructed Indo-European, the old Germanic word for bear would be "urþaz" (or something similar, from Proto-Indo-European hrtkós); given that the current word in English has cognates in the other Germanic languages (for instance, the German "Bär"), the change probably occurred at the proto-Germanic stage, and the ancestors of the original English speakers stopped using the old word.
 * Similarly, the Slavic term for a bear is medved, meaning "one who knows where the honey is." Which itself has been known to get substituted with euphemisms like "furry one".
 * And Finnish has roughly fifty different terms for a bear, the euphemisms ranging from "dew palm" to "the apple of the forest".
 * This actually continues to this day. In Central America, Mayans will never refer to the jaguar by its name ("balam") for fear of invoking its presence. They refer to it as "chac mool", which means "red paw"
 * This was so prevalent when it came to wolves in Sweden that the most common euphemism ("varg", meaning killer or strangler) became the proper name.
 * The fairy Puck will appear if you say his name, in folklore and in Shakespeare's works.
 * An unlike in the Bard's play, encountering jolly old Robin Goodfellow in the older folklore tended to get you into far worse fates than growing some donkey ears.
 * One old wives' tale is that of Bloody Mary, who supposedly appears and very violently murders anyone who says her name three times while looking in a mirror.
 * Or seven times, and maybe you have to do it by candle light, or maybe you have to taunt her that you killed her baby. Myths are like that.
 * Hades of Greek Mythology is a good example. The Greeks believed saying his name drew his attention, so they called him by all sorts of nicknames and titles, like "The Wealthy One" or "The Host of Many."

Tabletop Games

 * Dungeons & Dragons:
 * In early editions, saying the name of a demon could cause it to turn its attention to the speaker and attack him if possible, and speaking the name of a devil (which was inscribed on its talisman) would call forth that devil. And although they aren't villains, in the "Forgotten Realms" campaign setting, saying the name of any of the Seven Sisters would allow them to hear the next nine words uttered by the speaker.
 * 3.5 has Truenaming, which around level 18 gives a feat that allows a character to do this with a use-name of their choice. Speaking the use-name, afterward, allows the character to know where you are, what the general situation is, and lets them decide whether or not to be teleported into the area. Depending on the character in question, this can either be an example of this trope, or Call on Me. Or, in some cases, both at once.
 * Also from Dungeons & Dragons: any good or neutral creature that speaks Pazuzu's name three times will catch his attention. He sometimes offers to aid such a creature if they're in trouble... but accepting a boon from a demon lord is guaranteed to pull you into evil.
 * No, just towards Chaos. Evil is only eventual inevitable.
 * also in the 3.X Deities and Demigods Handbook it states that Deities are generally aware if anyone says their name, anywhere or any of their common titles. This generally won't summon the deity to you of course, but that does make it hard to mount an assault on the gods....
 * One DnD sourcebook (likely The Book of Vile Darkness) relates the story of a particularly huge prick of a merchant who would take advantage of this rule by selling a parrot to rich-looking individuals. When they got out of town and onto a deserted stretch of road, their new pet would fly away and start shrieking the name of Orcus—a freaking demon lord—who would appear and murder the poor saps. After Orcus had teleported back to the Abyss, the merchant would then gather up his dead victims' gear. That he would pull this trick repeatedly says something horrible about the merchant and a little pathetic about Orcus, who apparently has a lot of free time on his hands.
 * Well, he does just sit around on his throne all day.
 * Why doesn't Orcus kill the parrot?
 * Because if he does, Demogorgon will begin reciting the dead parrot sketch at him.
 * More importantly, how did that merchant manage to teach the parrot to say "Orcus" without being killed?
 * Although its been referenced in several other tropes, the legend of the Serpent's Coil still (sort of) counts. A 2nd edition myth that made it into 3.0 before being retconned out at the end of 3.5, the myth went that Asmodeus, the king of Hell, was actually a very advanced illusion or perhaps an avatar of some sort; his true shape was a miles-long monstrosity of utter, incomprehensible evil. When he was hurled from the celestial planes into Hell, this form crashed through the dimension's reality - creating the nine levels of Hell - and came to rest in a deep, spiraling crater at the very bottom of The Pit. In an aversion of this trope however, telling someone this story didn't summon Asmodeus: it simply caused the storyteller to die within 24 hours (by unspecified means). Which is about on par for drawing the attention of overwhelmingly powerful evil uberdeities.
 * Points of Light has an interesting reversal. The god that Asmodeus rebelled against in this setting is known only as "He Who Was". This is because Asmodeus literally erased all record and memory of the deity's name from history, fearing that if it was spoken just once, the slain god would regain his powers.
 * In the Planescape setting Cerlic, the Ferryman of the Styx (known as Charon to most mortals) is a unique yugoloth and one of the safest ways to travel through the Lower Planes, and simply saying his name on the shores of the River Styx will summon him in at most, a half-hour. Being a yugoloth, however, he is Only In It For The Money and requires payment up front (which is astronomical) and anyone who summons him and refuses to pay is attacked; he's incredibly powerful, on par with a minor demon lord.
 * Another example of this that was legitimate is the Demon Lord Fraz-Urb'luu, who is notorious for using a unique talent to use the names of other Demon Lords to trick them into thinking they have been summoned. His usual strategy is to do this, and then teleport away right before the victim appears, assuring that the angry demon will take out his anger on whoever Fraz-Urb'luu had been fighting. This strategy naturally has made Fraz-Urb'luu universally hated among other Demon Lords.
 * Kibo, mentioned below in the Real Life section, was used by Mage: The Ascension. In the digital web, he set up magic tracers so whenever anyone said his name, he would instantly be able to appear, as a real person, in front of them.
 * The Antediluvians in Vampire: The Masquerade are like this, or at least their vampiric descendants are afraid that they might be. At various points, it comes up that the names we have for them aren't their real names, just pseudonyms that are used to refer to them without the possibility of drawing their attention via Speak of the Devil.
 * It also shows up in Demon: The Fallen. Using a demon's Celestial Name automatically opens a remote channel of communication with them; use it unaware of that connection, and they'll be listening to everything you say...
 * Call of Cthulhu (tabletop game) supplement Terror Australis, adventure "Old Fella That Bunyip". The investigators are forced to say the phrase "Eleanba Wunda" to drive Bunyip upstream. Unfortunately for them, it's the name of a spirit worse than Bunyip, which will appear if its name is chanted too often. The second time the investigators do so they feel a cold wind, and the third (and final) time Eleanba Wunda almost appears.

Video Games

 * In the Devil May Cry series, the ruler of the underworld and Big Bad of the first game is named "Mundus". Oddly, he is almost never referred to by name in other products, either being referred to as "the Devil King" or "the Devil Emperor".
 * Parodied (and used) in Kingdom of Loathing: if you select 'Say "Guy Made Of Bees"' five times as a choice when you encounter a bathroom mirror, you will encounter the Guy Made Of Bees. And unless you have a certain in-game item and use it in the first round of combat, the Guy Made Of Bees will hit you with as much force as the Incredible Hulk's weight in bees.
 * During a perfect Pacifist Run in ''Iji', Elite Krotera will mention Vateilika and how he'll deal with her after you're dead. He really should have spent the time saying goodbye to Mr. MPFB Devastator, as his flight off this mortal coil just arrived.
 * In Ultima V, the Shadowlords could be summoned to your location by yelling their name (Eg, Yell Astaroth).
 * Gaia Online NPCs sometimes comment their own fanthreads during events. One wonders what they make of all the dirty-minded fans.
 * A possible inversion of this trope (overlapping in aspects with I Know Your True Name) occurs in Breath of Fire IV. Along with straight treatment of I Know Your True Name, General Yohm hunts down Fou-lu—even at one point explicitly commenting that the mere act of uttering Fou-lu's name is sufficient to send ripples in the world that can lead someone sensitive to those ripples to find him. (Yes, this is justified—Fou-lu is not only a God-Emperor but a rare case of a Physical God that was explicitly summoned to be the King in the Mountain of a dying empire.)
 * A straighter version ALSO exists. In a part of the game, Fou-lu refrains from revealing his name to Mami explicitly to keep this from happening, and merely goes by his nickname "Ryong"—this eventually gets blown to hell when he tells her his story via a historical legend (and HAS to use his real name in it).
 * In RuneScape, saying 's name (how fun, the fact he exists is a spoiler) gives him power. He's weakened that much - in fact, most NPCs (and other Gods) refer to him as "The Nameless God".
 * In Red Dead Redemption people who usually play free roam with their friends, have probably encountered a cougar. Because of that it's common to hear someone mention a cougar (example: 'Did I just hear a cougar?') and see or hear their demise. It gets better when you are in areas of the map where cougars never should/usually spawn, and you hear someone mentioning it. Hilarity Ensues.
 * In Dead Space 2,
 * Liquid Snake from Metal Gear Solid is a variation: His real name isn't stated not due to fear of him being summoned, but rather because the SAS and the US Government had highly classified his real name to the extent that not even someone within the highest rank of the command pyramid is allowed to know it, as mentioned by Roy Campbell.
 * Neverwinter Nights 2 inverts this initially, when an Affably Evil devil willingly tells you his true name so you can banish him back to Hell. Later played straight when knowing his true name from your previous meeting with him lets you summon him for a Deal with the Devil.
 * In the Discworld adventure game, saying the word "monkey" will cause the Librarian to appear and punch you, because he is an ape and does not like the M-word. This is occasionally mentioned in the books, but the game turns it into a Running Gag instead.

Web Comics

 * This creature (well, the creature this demon is shapeshifted into) in UC: Deviating from Normality.
 * This Xkcd strip features an abuse of Bloody Mary. Explaining it would ruin the joke.
 * Don't say Ironman in Austin, TX as shown why in Rooster Teeth's webcomics, Michael "Burnie" Burns will be groundpounded.
 * In Order of the Stick, saying "mind flayer" or "illithid" will bring down copyright lawyers upon the speaker. Actually, pointing out any copyrighted material can do this, as Vaarsuvius realizes to his advantage when confronting a (supposedly good-aligned) drow wizard armed with two swords.
 * In Goblins, the "Guide within the Well of Darkness" appears whenever someone says his name and answers a yes/no question. The catch? At the fourth summoning, he kills everyone. Incidentally, his name is Noe. Pronounced as "no".
 * K'seliss invokes this trope and rips Noe's throat out right as he appears. It's just as cool as it sounds.
 * In Chasing the Sunset, speaking the name of the evil wizard Malvenicus causes lightning and a crack of [Kra-ka-tow!] thunder. Just like that. Malvenicus [kra-ka-tow!], as it turns out, is not all that evil; he just put an enchantment on his own name back when he was younger because he thought it would be funny.
 * In User Friendly, Sid deals with an annoying intern by tricking him into saying "Hastur" three times.
 * And Stef manages to avoid being shredded by an angry Indian god by calling upon Hastur, and letting the two duke it out.
 * This Girl Genius comic averts it. Not subverts, but averts. This is a trope-heavy world with Genre Savvy people (as a survival trait), and the named individual is a genuine Hero.

Web Original

 * Fooby, the Kamikaze Watermelon, appears in The Demented Cartoon Movie every time someone says "kamikaze watermelon."
 * It is theorised that Slender Man might have these properties; other theories state that you can only see him if you know about him. So if you've read this example...
 * asdfmovie: I like trains. *hit by a train*
 * Pianos! *Piano Drop* Whose idea was this?!
 * The Binder of Shame; El Disgusto's character is caught stealing from the other characters and killed. His last words are "You'll pay for this! You'll all pay for this! Hastur! Hastur! Hastur! Hastur! Hastur!" Fortunately (or unfortunately as it turns out), the wizard NPC resurrects the group.
 * The Makeover Fairy from The Nostalgia Chick can do this, appearing in a puff of sparkleswhenever somebody says her name. Either it's a new ability or the others didn't know about it yet, since at one point Chick comments that she wasn't sure if it would work.
 * Earlier in the show's run, The Nostalgia Critic appeared to bitch her out for reviewing Transformers when she said the word "manchild".

Western Animation

 * Freakazoid! had the villain Candle Jack who would appear randomly and kidnap whoever said his name out loud.
 * Candle Jack himself says,"Not a very bright group, are you?"
 * Freakazoid! also spoofed this in a Credits Gag: "Interesting Fact: If you spin around while saying 'Huggbees' three times real quick, Pierre Salinger will appear. Only he'll have... a beard!"
 * In a South Park episode, saying Biggie Smalls' name three times while looking into a mirror will summon his ghost, which really pisses him off when he's got things to do.
 * In Harvey Birdman, Attorney at Law, saying Mentok the Mind Taker's real name, Mufti, summons powerful magical winds.
 * Said by one of the bad guys in Jonny Quest episode "Skull and Double Crossbones," after his captain referred to the possibility of the Coast Guard showing up ... and they promptly did.

Real Life

 * Kibo originally became known on UseNet for searching for any occurrences of his name (whether they refer to him or not) and responding to them. Naturally, this became rather less possible once he became something of a Usenet celebrity.
 * You are allowed.
 * Google has a tool that lets you track the entire Web for instances of a certain phrase, such as your name. Knowing this does not make it any less creepy when one of its users suddenly materializes in your forum discussion of them.
 * Warren Ellis has a tendency to do this when his name is mentioned on the Internet.
 * Troy Hickman on the City of Heroes official forums prides himself on it.
 * Twitter codifies this, providing you a whole new tab for when your @username appears in someone else's tweet.
 * An AVGN ripoff, who shall remain nameless; he Googles his name and flips out at those who don't love his stuff and proceeds to plug his links.
 * The Chinese general Cao Cao (3rd century AD) was so well known for his rapid marches, the Chinese term for this trope since the time was "Speak of Cao Cao, and Cao Cao will appear." (And this was way before he could Google it. Impressive.)
 * A once-popular internet meme says this of Candle Jack, who kidnaps whoever speaks his name.
 * icycalm of Insomnia.ac keeps track on reactions of his articles in a forum topic made for this purpose, and sometimes rants about who he feels has misintrepretted whatever he said. Some people say that he may also show up whenever he's mentioned and end up in a flamewar about it, but he doesn't seem to bother doing that much these days.
 * This may be even subverted as he has recently made a thread about his potential impostors.
 * As stated on this page, people of old didn't dare saying "bear", fearing that it would summon one.
 * Actually, bear meaning 'the brown one' was the equivalent of 'He Who Must Not Be Named', the name that people used so as not to attracted the animal by using their real name. We don't know what the original name was as it has been replaced by the euphemism.
 * The old Swedish had a similar fear about wolves. It became so prevalent and went on for so long that the most popular nickname stopped being a nickname and became the proper name, though thankfully the fear fell into obscurity before it happened again.
 * Mafioso Vincent "The Chin" Gigante was so feared in the mafia underworld that people would tap their chins rather than say his name out loud.
 * More likely, that was done to bypass FBI wiretaps and whatnot.
 * Ben Mack, author of Poker Without Cards (among other things), has been known to do this on forums which discuss his book. He shows up and plugs it and whatever his current project is like mad. One forum specifically refers to him as "Men Back" or He-Who-Must-Not-Be-Named for fear he'll show up again.
 * Will Shetterly sometimes does this by Googling his name, so some people refer to him as "Will Sh*tterly" or "Will Shitterly."
 * A certain fundamentalist with a "4 step proof of God" is known to regularly google his name and spam any forum on which it is posted with said "proof".
 * In the AI field, there's a crank who goes by Mantifax (replace the As with Es) whose obsessive self-promotion efforts include appearing on any site that mentions him.
 * My Cage creator Ed Power was known to appear wherever his strip was mentioned, back when it was new.
 * Another comic author who's notorious for this is Bobby Crosby, especially when he gets criticized.
 * Demonologists usually advise people to not speak about the demon while in a demonically infested house. Some activities, like listening to recordings of exorcisms for instructional purposes, are also considered "opening doorways" that could attract the wrong kind of attention.
 * Tagging somebody's name in a Facebook post alerts that person to the post. It's not uncommon for people to post the name on its own to get their attention.