Sometimes, [[HatShop the type of hat a person wears can tell you a lot about their personality]]. However, ''these'' hats go a step beyond and noticeably alter the personality of their wearer.

The hat may be a form of personality-altering AppliedPhlebotinum. Particularly bad cases may function more like DemonicPossession, with the hat completely overwriting the wearer's personality. Or the hat may simply be a MagicFeather, giving the character the boost of self-confidence necessary to alter their behavior. However it works, the character's behavior is markedly different when they wear it.

A subtrope of ArtifactDomination. If the hat alters the wearer's behavior for the worse, then it's also an example of ClothesMakeTheManiac. If it's used by someone else to control the wearer it's also a HypnoTrinket. If the hat grants special powers to the wearer, it's a HatOfPower. It has very little relationship to PlanetOfHats.




[[folder: Advertising]]
* A bumper for Creator/{{Syfy}} had a woman try on a dress, only to be taken over by it.

[[folder: Anime and Manga ]]
* One episode of ''Anime/KirbyOfTheStars'' was about an evil hat that can corrupt whoever puts it on.

* ComicBook/DoctorFate's Helmet of Nabu would cause him to be possessed by the spirit of the deceased wizard, Nabu.
* The Serpent Crown in the MarvelUniverse which grants the wearer various abilities. These abilities can include superhuman strength, the power to read and control the minds of others, the power to levitate oneself and other persons or objects, the ability to cast illusions, the power to project destructive bolts of mystical energy and even the mental ability to manipulate matter and energy. However, use of the crown usually leads the wearer to fall under the mental domination of Set, who then has the wearer perform various tasks which would help facilitate its physical return to the Earth dimension.

* In ''Literature/{{Discworld}}'', both the crown of a king and the Archmage's hat exert their own influence upon the wearer.
** According to Cohen, so does the turban conventionally worn by the GrandVizier. "Give 'em a turban with a point in the middle and it just erodes their moral wossname." This could just be a metaphor, though, as opposed to the Archchancellor's hat that ''literally'' has magical influence.
* The ''Svarog'' series by Alexander Bushkov mentions in passing an artifact called the "Black Crown". Presumably, it gives one great powers but burns their soul, making them instantly ChaoticEvil.
* In the second book of the ''Literature/{{Larklight}}'' trilogy, the mysterious hats are actually [[spoiler:shapeshifting, mind-controlling, thought-eating aliens in disguise.]]

[[folder: Live Action TV ]]
* There's a largely-forgotten ''Series/NormanWisdom'' sitcom from the 70s where his entire personality would change according to what hat he was wearing.
* Linda's magic hat from the ''Series/RoundTheTwist'' episode "Copy Cat", which [[HatOfPower grants the wearer the power to fly]] but also starts changing the wearer's personality.
* In the original ''Series/TheTwilightZone'' episode "Dead Man's Shoes", a homeless man finds the body of a gangster's victim, puts on his shoes, and is possessed by the victim. The '80s remake did a gender flip, "Dead Woman's Shoes", in which the trinket is a pair of shoes belonging to the murdered wife of a rich corporate type.

[[folder: Other Sites ]]
* ''Wiki/SCPFoundation'', [[ SCP-1510 ("The Tarnished Legionnaire")]]. A Roman legionnaire was affected by a curse that caused his body to rot away and his mind/soul to be bound to his helmet. Whenever a man between 28 and 35 years old puts on the helmet, [[HypnoTrinket the legionnaire's personality possesses them]].

[[folder: Tabletop Games ]]
* ''TabletopGame/DungeonsAndDragons''
** Helm of Opposite Alignment. Instantly changes the wearer's CharacterAlignment to its opposite (e.g. LawfulGood to ChaoticEvil).
** The Crown of Souls will eventually change the wearer's alignment to NeutralEvil.
** The ForgottenRealms Horn of Crowns causes its wearer to act in a crazed and violent manner.
** Hat of Command: The wearer feels an overwhelming desire to take charge.
** Hat of Occupation: Wearer thinks and acts as if he's a member of another class, but isn't.
* Parodied in ''TabletopGame/{{Munchkin}}'' with the Helm of Courage. [[FearlessFool It has no visor.]]

[[folder: Video Games ]]
* The Helm of Dark Magics in ''VideoGame/{{Arcanum}}'' permanently raises your magical aptitude and lowers your alignment each time you put it on.
* The Peak Point helmets from ''VideoGame/ApeEscape''. The most notable example is [[BigBad Specter]], who goes from a cute and adorable monkey to a scheming, megolamaniac supergenius. The only exception to this is Pipotchi from ''2'', who wears a special pipo helmet designed by the Professor which [[HatOfPower increases his intelligence]] but keeps his lovable personality intact.
* While not shown when in Moga or Tanzia, the Shakalakas who accompany you in ''[[VideoGame/MonsterHunter Monster Hunter Tri (Ultimate)]]'' change personalities depending on the mask they wear. Cha-Cha acts like a BadassGrandpa with the Ancient Mask, while Kayamba in the False Felyne behaves like a WebOriginal/{{Lolcat|s}}.

* In one ''WebComic/SkinHorse'' comic, an avian-humanoid freaks out because Tip put on a hat. She believes that hats make you evil and instantly worthy of hate.
* ''Webcomic/GirlGenius''
** When Agatha returns to [[GeniusLoci Castle Heterodyne]], the only way for humans to communicate with the castle's central brain is for the Seneschal to wear a helmet that inserts probes into his brain, allowing the Castle to take control of his body.
** In the "Trelawney Thorpe: Spark of the Realm" short story, the MacGuffin is the crown of KingArthur, which is supposed to give the wearer the power of King Arthur. [[spoiler: What it actually does is give King Arthur the body of the wearer.]]
* In a EGS:NP storyline in ''Webcomic/ElGoonishShive'', John Toutman gets a detective hat [[ placed on his head]], he claims wearing a detective hat [[MagicFeather does not actually help]] make him any more of a detective and yet he is [[ immediately able to deduce where Susan ran off to]] when he wasn't able to [[ before]].

[[folder: Western Animation ]]
* The ''WesternAnimation/LooneyTunes'' cartoon "Bugs' Bonnets" has WesternAnimation/BugsBunny and Elmer Fudd switching personalities as various hats blow past and land on their heads.
* In ''WesternAnimation/TheCareBearsAdventureInWonderland'', Grumpy Bear changed personalities every time he put on one of the Mad Hatter's hats.
* In one episode of ''WesternAnimation/TheNewAdventuresOfSuperman'' cartoon, a possessed hat causes anyone who dons it to commit evil acts.
* WesternAnimation/DarkwingDuck several times had to fight alien, sentient mind-controlling hats.
* ''WesternAnimation/RubyGloom's'' Skull Boy has problems with this thanks to a "Shakespearean Love Hat." It causes him to speak proper Shakespearean when wearing it and also makes Iris & Misery fall for him.
* In ''WesternAnimation/TotalDrama: Revenge of the Island'', Mike (who has multiple personality disorder) puts on a slouch hat and suddenly becomes an adventurer called Manitoba Smith.
* ''WesternAnimation/RockyAndBullwinkle'' has the Kirwood Derby, which makes its wearer the smartest person in the world.
* Doctor Fate's helmet (see ComicBook examples above) appears in ''WesternAnimation/YoungJustice''. It eventually ends up completely taking over the mind of [[spoiler:Zatara]].
* ''WesternAnimation/{{Spliced}}'': In "Follow Your Dreamworms", Entree snatches Joe's top hat and replaces it with a flowery sunhat. Joe's normally angry voice immediately becomes much more girly and singsong.
* ''Characters/MeetTheRobinsons'''s Bowler Hat Guy could only dream of exacting revenge [[spoiler:on his boyhood pal Lewis for ruining his chance at baseball stardom,]] until he was accosted by the robotic bowler hat DOR-15 "Doris", and he became the arch-villain of his dreams. [[spoiler:Dream on, Goob.]]
* An episode of ''WesternAnimation/SheriffCalliesWildWest'' centers around one character receiving a new wardrobe to turn him into a gentleman. Wearing [[HighClassGlass the monocle]] transforms the wearer's voice and mannerisms to that of a high-class man, complete with the stereotypical Queen's English accent.

[[folder: Real Life ]]
* Creator/TerryPratchett was so associated with wearing his fedora, that when he wasn't wearing it at conventions, he officially ''[[PaperThinDisguise wasn't him]]''.