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[[quoteright:350:[[Music/WeirdAlYankovic http://static.tvtropes.org/pmwiki/pub/images/weirdalfoil_2322.jpg]]]]
[-[[caption-width-right:350:[[MindControlDevice Thought control rays]], psychotronic scanning\\
Don't mind that, I'm protected cause I made this hat]]-]

->''"I seem to recall it was your bright idea to spend billions of credits on those orbiting mind-control lasers!"''\\
''"How was I to know that tinfoil hats would become the latest fashion?"''
-->-- '''Plan 7 of 9 from Outer Space'''

When a writer wants to establish a character as a ConspiracyTheorist, a CrazySurvivalist, or another kind of paranoid {{Cloudcuckoolander}}, they usually give them hats made out of tinfoil to wear, ostensibly to protect themselves from TheGovernment's MindControl rays.

As Wiki/TheOtherWiki can tell you, however, aluminium actually has very little shielding effect and covering just the top of the head with it leaves the rest of the body (including the bottom of the head) "unprotected", anyway. (In fact, if improperly made, the tinfoil could amplify any radiation reaching the head.) So whoever is wearing it must be... [[{{Cloudcuckoolander}} funny in the head]] to begin with. Or the more sinister interpretation: the whole idea that tinfoil will protect you is Just What They Want You To Think.

To elaborate: To shield off radiation, you need steel. Electromagnetic waves consist of alternating areas of electric fields and magnetic fields. To reflect them, you need a material, that shorts both electric fields and magnetic fields. In terms of shorting electric fields, any metal (being conductors) does an adequate job (aluminium (which so called tinfoil is usually made of, despite its name) is even a very good conductor), but to short magnetic field you need a ferromagnetic metal, like iron, nickel or cobalt. As iron is seldom used nowadays, the best choice is steel (an alloy of iron, carbon and tiny amounts of other components). Just take a look at a video-recorder: Videorecorders may have fancy chassis made of aluminium, but if you look inside, you will see a small box behind the coaxial connectors, there the aerial is connected, containing the high frequency circuitry. This box is made of steel in order to shield the radiation.

For when a Tinfoil Hat actually ''does'' protect the ProperlyParanoid wearer, see also ArtisticLicenseNuclearPhysics and FantasticRadiationShielding. This trope includes both properly paranoid and simply paranoid examples. Compare also ManifestoMakingMalcontent, where manifestos are used as a similar material shorthand for potentially dangerous weirdos.



[[folder:Films -- Animation]]
* The ''WesternAnimation/{{Futurama}}'' movie ''Into the Wild Green Yonder'' featured a cult-like group of hobos called the Legion of Madfellows who all wore such hats to prevent the Dark One from reading their thoughts, and indoctrinated Fry into their practices.[[note]]Fry's hat in particular would be in different shapes for different scenes (it's foil, after all), depending on the occasion. E.g. it became a stereotypical police officer hat when he was posing as a security guard.[[/note]] They were, of course, ProperlyParanoid. The hat also serves to block Fry's own mind reading powers as [[PowerIncontinence he can't turn them off of his own accord]].

[[folder:Films -- Live-Action]]
* Most of the main characters in ''Film/{{Signs}}'' wind up wearing one at some point before the end of the movie. The scene gets parodied in ''Film/ScaryMovie 3'', where the hats are giant Hershey's Kisses.
* More of a hat in spirit, in ''Film/Series7TheContenders'', the ceiling of competitor Franklin's trailer is lined with tinfoil, and his personality follows suit (YMMV on whether it's played straight--along with the rest of the movie).
* The crazy conspiracy theorist in ''Film/NoroiTheCurse'' takes it one step further and wears an ''outfit'' made of tin foil.
* A variation on this trope is used in the film ''Film/ConspiracyTheories''. In it the main character lines walls of his house with tin foil to block out government surveillance tools. [[spoiler: However this, (like many conspiracies in the film) are subverted and proven right. It's revealed that government tools struggle to penetrate his aluminum defenses.]]

* In the early ''Literature/ArtemisFowl'' books, the paranoid centaur Foaly always wears a tin-foil hat. In the second book he throws it away in frustration after being trapped in his own hermetically sealed command center.
* The novel ''Idiots In The Machine'' by Edward Savio portrays a character who believes that tin foil keeps harmful gamma rays away and becomes a media sensation, marketing a successful line of foil hats to Chicago.
* In ''Franchise/TheDarkTower'', Randall Flagg has one of these. Allegedly, it actually works against most forms of mind control magic, but it doesn't work on the villain he's facing, Mordred.
* Inverted in ''Literature/TheSalvationWar'', where demonic mind control and illusion powers can be blocked by foil and the story gets much mileage out of this, including the line "There will always be eccentrics who deny that the tin foil hat is absolutely essential to prevent baldricks taking over your mind."
* In the ''Franchise/{{Mistborn}}'' books, aluminum cannot be affected by [[FunctionalMagic Allomantic powers]], so adding it to a hat in ''Literature/TheAlloyOfLaw'' protects the wearer against EmotionControl.
* In the ''[[Literature/TowerAndTheHive Pegasus]]'' trilogy, one character wears a metal skullcap to block out mind-reading. This is actually effective against telepaths in this 'verse. [[spoiler: Doesn't help much if the psychic has made skin-to-skin contact, though.]]
* When [[ConspiracyTheorist James]] of ''Literature/TheChroniclesOfSteveStollberg'' suggests that Mickey Mouse faked his death, Miss Jackson implies that he likes to wear tinfoil hats.
* In ''Literature/EverWorld'', Senna gets into a mentally-ill homeless man's head, telling him he should have remembered to wear his tinfoil hat as she makes him go yell disturbing things outside Jalil's house.
* Averted in ''Literature/TheWarAgainstTheChtorr''. The protagonist is discussing how hundreds of people have been secretly implanted by the Telepathy Corps. If you find out about it, the only way to prevent them reading your thoughts is to wear an iron cap for the rest of your life.

[[folder:Live-Action TV]]
* ''Series/{{Eastenders}}'' character Joe Wicks was briefly portrayed constructing and wearing his own tin-foil hat as part of a storyline which saw him suffering from schizophrenia.
* In ''Series/TheXFiles'', Series/TheLoneGunmen wear them occasionally. Also, [[JustForFun/JohnMunch a policeman]] suggests they all get one in their OriginsEpisode when he realizes what kind of kooks he is dealing with.
* On an episode of ''Series/{{Fringe}}'' Walter wears a tinfoil hat at Massive Dynamic headquarters to defend against mindreading/MindControl projects, and convinces Astrid to do the same. In context, it's actually a credible concern.
* ''Series/NYPDBlue'': While on desk duty Sipowicz gets a call from a psychotic ConspiracyTheorist. Sipowicz suggest (in as close to SincerityMode as possible) that he make a tin foil hat in order to block the rays the government is allegedly sending to his head.
* In an episode of ''Series/TheFinder'' the Finder wears an aluminum foil hat. The client (Hodgins from ''Bones'') mocks him, but it really does help block the government from interfering with your brain waves so you can move.
* In the fourth season of ''Series/{{Farscape}}'' a Sheriff (or deputy) encountered by Moya's crew when they land on Earth in 1985 via time travel turns up again showing off a tinfoil-lined baseball cap on TV in 2003 when the crew returns. In his defense, he did receive several doses of one of Noranti's potions during the first visit.
* Oliver does this in ''Series/HannahMontana'', but it's really more of a parody, because he wants Joanie to think he's insane and dump him.
* ''Series/{{Dollhouse}}'': Senator Perrin goes public accusing the Rossum Corporation of unethical practices, hoping that it will encourage witnesses to come forward. The following episode he's griping that the only witness so far is a guy in a tinfoil hat claiming that Rossum mailed his liver to Saturn.
* ''Series/TheGlades'': The VictimOfTheWeek of the "Close Encounters" episode was a millionaire who believed that he was abducted by an UFO and had a few foil hats scattered through his mansion.
* On ''Series/GoodEats'', Alton wears a foil fedora and a metallic suit, while he's inside of a grill, explaining how a grill works, how it can be a problematic method for cooking chicken, and how to get around these problems. Unlike most examples, it's not worn to keep radio signals from messing with his head or anything along those lines, but simply [[RuleOfCool because it's cool]].
** In an earlier episode about pot roast, Alton wants to use some foil for braising the meat while cooking pot roast at his neighbor Chuck's trailer home. There's no foil to be had in the kitchen, but there's plenty of it on the roof of the trailer, formed into a satellite dish. When questioned, Chuck responds that he got the idea from a neighbor of his who wears foil on his head to block mind-controlling signals from the government. Alton tells him to take the satellite dish down so they can use the foil for the pot roast.

* In Music/DoctorSteel's web video, "Reality Engineering", Steel is shown wearing a tinfoil hat when he's labeled a conspiracy nut.
* Music/WeirdAlYankovic's "Foil" (which provides the trope picture and is a parody of "Royals" by Music/{{Lorde}}) has Al claim to have cracked the code on conspiracy staples such as TheIlluminati, {{Black Helicopter}}s, the MoonLandingHoax, and more, which is why he crafted a handy hat from foil, to protect himself from alien AnalProbing and mind reading. It doesn't do him much good, because TheMenInBlack just tranquilize him and drag him away. The music video ends with the director (played by Creator/PattonOswalt) unmasking himself as a [[TheReptilians lizard person]].

[[folder:Tabletop Games]]
* ''TabletopGame/{{GURPS}} Illuminati'' actually gives a bonus on resisting Mind Control Lasers to people wearing a tinfoil hat.[[labelnote:fnord]]It's just +1 though, so it doesn't make much difference.[[/labelnote]]
* The ''Occult Adventures'' companion book for ''TabletopGame/{{Pathfinder}}'' introduces the "tin cap" item, which grants its wearer a bonus to resisting mind-altering effects and divination spells that gather information about them, but saps the mind of the wearer and induces paranoia that makes the player throw a saving roll against ''any'' effect, including harmless ones. The book also introduces a more powerful "stannum crown", which provides complete immunity to the aforementioned effects, but can only be removed by the wearer and requiring a saving throw that grows more difficult the longer the crown is worn.

[[folder:Video Games]]
* The tin-foil hat was an April Fool's Day item created by Blizzard to parody player paranoia about their character information being searchable on the ''VideoGame/WorldOfWarcraft'' armory.
* ''VideoGame/LANoire'' features a street mission in which Phelps has to chase down a tinfoil hat-wearing conspiracy theorist.
* Dogen Boole in ''VideoGame/{{Psychonauts}}'' wears a tinfoil hat he claims prevents him from accidentally [[YourHeadASplode making people's heads explode]] with his PsychicPowers.
* In ''VideoGame/DestroyAllHumans'', you occasionally encounter humans wearing tinfoil hats... [[TheCuckoolanderWasRight and Crypto can't read their minds because of it.]]
* Some ''VideoGame/NetHack'' variants include these; wearing one blocks both incoming and outgoing telepathy.
* In the second Special Operation for ''VideoGame/MarvelAvengersAlliance'', which introduced Emma Frost (one of the game's first truly psychic heroes), one of the random daily rewards was a Bauxite Interference Helmet, which could be used as in item to prevent psychic attacks on the character it was used on. Bauxite is the ore from which aluminum is extracted, making it a (very high-tech-looking) tinfoil hat.
* ''VideoGame/ThimbleweedPark'' has a pirate hat wrapped in tinfoil. It doesn't protect against mind control, but it does reflect some real lasers used by [[spoiler:the [=PillowTron=] AI.]] Chet, on of the characters in game, goes far further than a tinfoil hat: He tinfoils the entire inside of the giant novelty pizza costume he's wearing.
* In ''VideoGame/{{Deponia}} Doomsday'' it's shown that a tinfoil hat stuffed with straw will provide RippleEffectProofMemory necessary for a time traveler. Rufus, luckily, has a de facto built-in version thanks to a metal plate in his head.
* In ''VideoGame/TheDarksideDetective'', one of Dooley's conspiracy theorist colleagues believes that wearing a tinfoil hat will help keep the Man from tracking him down.

[[folder:Web Animation]]
* Deconstructed in ''Machinima/FreemansMind'', where [[BadassBookworm Freeman]] reasons that, assuming mind reading is possible despite not showing up on any known spectrum, a tinfoil hat would conduct any signal that the wearer is concerned about. He concludes that you'd have better chances with a lead helmet coated in rubber.

[[folder:Web Comics]]
* In ''Webcomic/{{Sinfest}}'', [[http://www.sinfest.net/archive_page.php?comicID=3498 Squigley's protection from the Illuminati.]]
* In ''Webcomic/{{Freefall}}'', [[http://freefall.purrsia.com/ff1900/fc01863.htm Edge's protection from the lobotomizing program.]] Subverted in that in this case, since he ''is'' an AI and the program would be coming in on the com-net (basically wi-fi) since he has disabled all other means of communication except speech, aluminum foil covering his receiver ''would'' be enough to weaken or distort the signal enough to protect him from its effects.
* In ''Webcomic/TheGreeningWars'' Hatchet's old "friend" Codex was wearing a tinfoil hat when they visited his bunker. But then again his former employers had [[http://www.drunkduck.com/The_Greening_Wars/5345899/ put a tracking chip in his head.]]
* Karl from ''Webcomic/FreakAngels'' wears one at all times to block his telepathic link to the rest of the group, because they mostly seem to use it for inane bickering, {{Seinfeldian Conversation}}s and complaining about how crap their sex lives are. AMindIsATerribleThingToRead indeed...
* In ''Webcomic/SkinHorse'', Jonah has the "attenuator", a colander with wires sticking out of it, which he believes is why he and Nera were unaffected when the WeirdnessCensor suddenly went nationwide. (Other evidence, however, suggests that being regularly in contact with the weirdness increases your chance of not being affected somewhat anyway.)

[[folder:Web Original]]
* SJ Games used to (still does?) run a site cataloging weird things you might find in a SecretGovernmentWarehouse. One of them was a crate of instruction booklets on how to make a tin-foil hat. They were all stamped "obsolete" and there was a note in the inventory saying that the mind-control system had been upgraded since printing, so tin-foil hats were no longer effective. (Elsewhere in SJ Games's paranoia-inducting line of games is the note that ''aluminum'' foil beanies do not work against mind-control devices, but ''tin'' foil beanies did. This fact is behind the switch from tin to aluminum foil in the mid-20th century.)
* A guy wearing a tinfoil hat is the symbol of the WildMassGuessing section of Wiki/ThisVeryWiki.
* The [[http://zapatopi.net/afdb/ Aluminum Foil Deflector Beanie.]]
* WebVideo/VenetianPrincess mentions wearing one in her ''The End Is Nigh'' (spoof of Music/LadyGaga's "You and I") to protect against solar flares.
* The "dear athetits" meme parodying excessively spurious claims to have disproven atheism -- for whatever reason, its most iconic image is of [[http://i.imgur.com/J66GZWj.jpg a dog wearing a tinfoil hat.]]
* ''Literature/WhateleyUniverse'': A [[MagicPoweredPseudoscience Devisor]], Dr. Herbolt, used his powers to make tin foil hats that blocked psychic intrusion, but because they are powered by his power, they might not work for anyone else. There's no info on that latter point.
* The [[FanFic/FirstMembranes 1st Membranes]] have tinfoil helmets as part of their standard gear. It helps block out the Warp from the Guards' minds.
* Episode 32 of ''WebVideo/HalfInTheBag'' has a paranoid Jay surmise that Mr. Plinkett has become wise to his and Mike's schemes and placed a tracking beacon in their heads, and wears one of these to block it. The hat winds up interfering with a media satellite, causing ''Film/{{Battleship}}'' and ''Film/DarkShadows'' to be downloaded directly into his brain. [[spoiler:When Mr. Plinkett tries to download Creator/KenBurns documentaries by wearing one of these, he gets a burst gamma radiation and becomes dumber.]]
* An episode of [=OutsideXtra=] had host Luke decking his baseball cap in tinfoil to prevent being possessed by [[VideoGame/SuperMarioOdyssey Mario throwing his hat and possessing people.]] His co-host Ellen thinks that ridiculous, only for third co-host Andy to show up talking like Mario wearing the plumber's trademark hat. Ellen then steals the tinfoil hat so Luke can be possessed.
* Subverted in ''Podcast/WelcomeToNightVale'': the Sheriff's Secret Police advise (through Cecil) that tinfoil hats are useless against mind-scanning helicopters, which could scan someone's brain even if they were behind twenty feet of lead. Mostly, the Secret Police are sick and tired of everyone believing this works and wearing such silly things in public.
-->'''Cecil:''' ... It draws unnecessary attention to yourself. It's pathetic and paranoid. The Secret Police are ''embarrassed'' for you.

[[folder:Western Animation]]
* {{Exaggerated|Trope}} in an episode of ''WesternAnimation/TheSimpsons'', "Brother's Little Helper", Bart becomes paranoid after taking an ADD drug called Focusin, leading him to believe that Major League Baseball is spying on him and begins donning a tin foil bodysuit. At the end of the episode, Bart turns out to be right when he shoots an MLB satellite out of the sky.
* In the ''WesternAnimation/{{Futurama}}'' movie "Into The Wild Green Yonder," Fry gains mind reading powers, and immediately gets [[PowerIncontinence bombarded with brain-chatter from everyone around him]]. A member of a secret society of mind-readers teaches him to wear a tin foil hat to block out other people's thoughts, and to keep other telepaths from reading his mind.
* On ''WesternAnimation/RegularShow'', Mordecai and Rigby make foil hats when using Pops' '80s era cell phones, after he warned them that they cause tumors.
* Being a paranoid cuckoo girl, Sticks of ''WesternAnimation/SonicBoom'' inevitably references this in "My Fair Sticksy". She mentions one of her town defense system modes is meant to counter people trying to read her thoughts. According to her, it's a series of tinfoil-lined paddles to smack away telepathic signals. Or maybe just smack the mind readers themselves.
* In ''WesternAnimation/TheAmazingWorldOfGumball'', Mr. Small wore this when he says he's aware of many things in Elmore disappearing like Janice. It turns out he was right when Gumball and Darwin noticed Molly was missing and they all went to the Void to rescue her and Janice. Tinfoil hats were worn so they are aware of the existence of the Void and at earlier times, change one's luck like in "The Helmet".
* A variant in ''WesternAnimation/HarveyBirdmanAttorneyAtLaw'': the cops arresting Mentok the Mindtaker wear helmets lined with aluminum as that blocks Mentok's mindtaking powers. Metal plates also block them, as he found out when he tried taking daredevil Ernie Devlin's mind.
* In an episode of ''WesternAnimation/StrokerAndHoop'' entitled "Tinfoiled Again (a.k.a. Star Crossed Livers)", Stroker wore a tin foil hat to protect himself from being psychically manipulated by Creator/RonHoward.
* In "Olivia and Her Alien Brother" from ''WesternAnimation/{{Olivia}}'', Olivia wears one and has her friend Julian do the same, under the mistaken impression that her "older bother" Ian is an alien studying intelligent life forms on Earth and plotting to get rid of all little sisters.
* A variation on this trope is used in ''WesternAnimation/GravityFalls''. In the episode "The Last Mabel Corn" it is revealed that Uncle Ford has lined his skull with metal to prevent the series antagonist Bill Cipher from possessing him or entering his mind without realizing it.

[[folder:Real Life]]
* "CAT Scans" (properly called CT scans) are an incredible diagnostic tool for measuring changes in activity in the body, specifically the brain. But one class of people present a problem: those who for one reason or another have had restorative surgery involving replacement or reinforcement of bones with metal plates. The CT scan is ineffective for those who have had part of the skull replaced with a metal plate as this blocks the ability of the machine to observe brain activity in areas adjacent to the implant. So there may be a little TruthInTelevision operating here. But would even the most determined paranoiac have their entire skull replaced with metal? Read more [[http://www.action.org.uk/our-research/picture-clear-ct-scans-patients-metal-implants here.]]
* One of the more ludicrous claims made by WW2 propaganda broadcaster [[https://en.wikipedia.org/wiki/Lord_Haw-Haw Lord Haw Haw]] was that the British government was issuing hats made of very thin metal to protect against shrapnel from the Blitz. No doubt he was taken no more seriously at the time than other practitioners of this trope are now.