History Main / ClapYourHandsIfYouBelieve

* ''VideoGame/GloryOfHeracles'' does this to Iphicles [[spoiler: who was given a fragment of Heracles's soul to be revived from the dead. He gets amnesia from the experience and believes himself to be Heracles. When Iphicles learns the truth, that he's actually dead, he fades into ether.]]

* ''Series/OnceUponATimeInWonderland'': Referenced. Alice and Will clap in order to summon the fairy Silvermist to help them out when [[IncrediblyLamePun they need a ferry]].

* ''Series/OnceUponATimeInWonderland'': Referenced. Alice and Will clap in order to summon the fairy Silvermist to help them out.

** The Orks subconsciously generate a mild psychic field, its strength directly proportional to the amount of "boyz" present, so if enough Orks believe in something then reality is given a swift kick in the balls and told to follow the proper, Orky way of doing things. Ork belief that "[[RedOnesGoFaster da red ones go fasta]]" really ''does'' make vehicles painted red move slightly faster, and because Orks believe that [[LargeAndInCharge the biggest Ork is in charge]] an Ork will ''actually grow'' in response to other Orks following him, and while Orks can't make a stick fire bullets, their powers are able to make a lot of things that shouldn't work shoot bullets. Most of their "shootaz" are little more than boxes filled with gears and bullets that are in the general shapes of guns, and Orks have been known to make ships without fuel fly across solar systems.

* ''LightNovel/TheMisfitOfDemonKingAcademy'':

* ''ComicBook/TheLegendOfZeldaALinkToThePast'': With no way to reach Ganon's floating castle, Roam goes a little nuts and surrenders to his eagle form. Back on the ground, Zelda says a prayer to the maidens, who magically float her and Link into the structure.

** In ''VideoGame/{{MOTHER|1}}'', [[spoiler: Giegue]] is defeated by the use of the [[spoiler: Sing command, singing Queen Mary's lullaby]] that Ninten and friends learned over the course of their adventure.

** In some cases, even the inhabitants of Gensoukyou have stopped clapping their hands. E.g., things from the outside world sometimes slip through the barrier, and one of the things that slipped through in the past was a scientific magazine that explained how echoes are actually just sound waves bouncing off surfaces. As a result of people learning this, the Yamabiko, mountain-dwelling spirits born from humans ascribing echoes to the Yamabiko shouting people's words back at them, are currently facing extiction via PuffOfLogic.

** In ''VideoGame/{{Earthbound}}'', the only way to beat the BigBad Giygas is the liberal use of the "Pray" command... and the prayers of everyone who you met on your quest, culminating in ''the player''. [[TheFourthWallWillNotProtectYou These prayers actually do physical damage to him.]]

* Mundanes are largely immune to being attacked by maleficaria in the ''Literature/{{Scholomance}}'' books by Naomi Novik, because if they spot them at all, they don't believe they're seeing a dangerous magical beast, and the mal loses both its magic and its danger. El's gym teacher once spotted a creature that was trying to get the jump on El, thought it was a rat, and killed it with a cricket bat. El, who is prophesied to destroy wizard society with her apocalyptic magic, says that she could not kill even a small mal with a piece of wood.

* One of the types of superpowers in ''Literature/{{Brennus}}'' is Contrivers, who have the ability to create object or inventions that completely defy the laws of physics - [[AchievementsInIgnorance because contrivers are all delusional and believe that their inventions actually work on a different set of rules from everything else.]] Proving to one that their inventions ''shouldn't work'' can end very badly. They generally fall under two broad subcategories: [[MadScientist Mad Scientists]], who make technological inventions that they believe others aren't smart enough to understand, and Sorcerers, who believe their creations are magical (this one includes Hecate, one of the main characters). Obviously, they are ''highly'' sought after by various groups, heroes and villains alike.
* In one ''Literature/DearAmerica'' book, a faith healer attempts to invoke this after he fails to cure the protagonist's sister of her PTSD-related mutism, claiming that his "treatment" failed because the sister didn't have enough faith. The protagonist's father is quick to call the man out for blaming his "patients" to avoid revealing that he's nothing but a charlatan.
* In ''Literature/ForLoveOfEvil'', [[spoiler:Jehovah — the Jewish God]] says the number of believers in an Office determine the strength of the Office. Therefore, Satan's Office is extremely powerful because many people believe in Hell, but the powers of other deities wax and wane with the number of their believers.
* Subverted in F. Paul Wilson's ''[[Literature/TheAdversaryCycle The Keep]]'', in which a "vampire" ''pretends'' to be affected by a Christian cross, but not a Star of David in order to cause a Jewish professor to question his faith. [[spoiler:Later it's revealed that the vampire is actually affected by the symbol of a magical sword, and the Christian cross just happens to be very similar to this sword symbol.]]

* Laurel K. Hamilton's Literature/AnitaBlake novel: Religious symbols will only harm vampires if the person wielding it actually believes in it.

* In ''TabletopGame/InNomine'', the Marches, the land of dreams separating the corporeal realm (Earth and the rest of the physical universe) from the celestial realm (Heaven and Hell) is populated by the power of human imagination with pagan gods and creatures of myth.
* The Memory playbook from ''TabletopGame/InterstitialOurHeartsIntertwined'' relies on this to survive - if it loses all its Links, which represent one's memories of another character - then everyone forgets about them and they cease to exist.
* The card game ''TabletopGame/{{Munchkin}} Bites'' has an item ''The Yarmulke of Religious Obfuscation'' which gives the wearer an extra bonus against ''The Vampire Hunter'' and ''The Meddling Cleric''.
* In ''TabletopGame/LittleFears'', your characters are children who have access to Belief magic, which gives power to childish fancy and superstition. For example, if a child honestly believes that their toy gun can shoot monster-melting lasers or that stepping on a crack can in fact break their mother's back, then that's exactly what will happen does. [[GrowingUpSucks The older your character is, the less Belief you have]].
* In the ''TabletopGame/NewWorldOfDarkness'':
** In ''TabletopGame/MageTheAwakening'', the disbelief of normal humans ''can'' unravel magic, but only because their souls bear a fragment of the nothingness which stands between the sources of magic and reality.
** In ''TabletopGame/ChangelingTheLost'' a magical effect preys on the beliefs and psychological expectations of mortals and other supernaturals to make Changelings and Fae Tokens appear as mundane people and objects, rather than the (sometimes flagrantly) magical things they are.

*** ''LightNovel/FateApocrypha'': UsefulNotes/VladTheImpaler says that in life he was an ordinary human warlord, but because so many people believe he was {{Dracula}}, he can become a vampire. Semiramis says that she had nothing to do with the Hanging Gardens of Babylon, but can summon and control it because so many people believe she built it.

* ''LightNovel/ACertainMagicalIndex'':

* ''Lightnovel/FullMetalPanic'': the Lambda Driver reacts to the user's mental state. The first time Sousuke uses it, Kaname instructs him that he must believe in it for it to work.

** Elan creates his own god, Banjo the puppet ([[DontExplainTheJoke so called because he has a banjo]]) for when he multi-classes to Cleric. When Roy tells him his opinion, Elan calls for Banjo to smite Roy. A tiny storm appears and throws a tiny lightning on Roy, which has no effect. Elan comments that maybe Banjo needs more believers. In a later story Banjo actually did gain some more followers briefly, although they ended up worshiping another puppet instead.

** Because he has a planetful of worshipers who see him as a TricksterGod, Loki can't come clean and [[spoiler:tell Hel that he's only acting against her plot to get all the dwarven souls in this world because there's a once-in-forever chance to stop the Snarl for good]], no matter bad he feels to keep lying about it. He is allowed to be honest with Thor as long as it takes the form of [[EvilGloating rubbing things in his face]].
** The goblinoid god The Dark One [[DeityOfHumanOrigin became a god after death]] from the devotion his followers had to to his memory. The murderous rampage in his name against the nations that betrayed and murdered him acting as a gigantic blood sacrifice to him also helped.
* This is the entire plot of ''Webcomic/ParallelDementia''.

* ''Film/WarGod'' have this happening in the DarkestHour; all of humanity's best weapons, including the prototype DeathRay from Chao's labs, has failed against the Martians. Mr. Chao, still insisting on believing his faith in his precious statue of Guan Yu, starts kneeling to the War God while the city is being destroyed all around him while his daughter Li-Yu pleads him to leave the statue and run. But his fate isn't in vain, as the UsefulNotes/GuanYu statue suddenly comes to life, enlarges to kaiju size, and battles the invaders.

* Film/SantaHunters: Santa's sled, sans reindeer, only flew because the children believed it would do so. This was after things started to disappear due to the lack of belief, but of reliance of physical evidence of Santa's existence. Even gets invoked by Zoey.

%%* Creator/AndreiTarkovsky is fond of this one: ''Film/{{Stalker}}'', ''[[Film/Solaris1972 Solaris]]'' (1972}

* Belief in ''WesternAnimation/RiseOfTheGuardians'' is presented as a power that humans have that fuels spirits, with the belief that children possess being a strong motivating MacGuffin. Belief in the existence in certain spirits (Jack Frost, Pitch Black and the Guardians) and what they contribute to the world (Fun, Fear, Wonder, Hope, Dreams, etc.) is what gives them their power, the Guardians becoming ineffective and helpless after Pitch nearly snuffs the world's belief in them. Belief in that particular spirit also allows the believer to see, hear and touch the spirit in question.

* The Creator/DisneyChannel MadeForTVMovie ''Film/DontLookUnderTheBed'' invokes this trope by name as part of a key plot point. [[ThingsThatGoBumpInTheNight Boogeymen]] are actually imaginary friends who are unwillingly turned into what they are when [[ForgottenChildhoodFriend the children who created them stop believing in them too soon]]. The only way to reverse the transformation is by [[IKnowYoureInThereSomewhereFight reaffirming belief in them]]... [[spoiler:which is exactly how the movie's BigBad is dealt with.]]