Any skill or ability that only a select few know how to/can use, from magic to martial arts to metallurgy techniques. Even the art ''itself'' might be unknown to the world at large, but the crux of the trope is that the know-how to use it is limited to a relatively isolated group or person. Some Secret Arts aren't even particularly jealously guarded and only remain secret via their sheer obscurity.

Sometimes the technique is similar to LostTechnology being a SupernaturalMartialArts techniques, [[FunctionalMagic magical spells]] or just [[YakitateJapan bread-making techniques]] that were invented eons ago but have been lost/buried/forgotten/not quite destroyed for a variety of reasons.

Perhaps their [[AndManGrewProud civilization collapsed]] or these techniques were simply were too powerful and/or dangerous and needed to be [[SealedEvilInACan sealed away]]; the point is, no one has seen and/or heard about them in a very long time. They will always, however, be superior to their modern counterpart, which will often make them the subject of a lengthy search quest by heroes or villains to further the plot.

Usually, one of the benefits of joining TheOrder. Can be (or encompass) the DangerousForbiddenTechnique. TheDarkArts are often this due to being outlawed. Often taught by a type I or III ObsoleteMentor.

Compare SupernaturalMartialArts, SuperEmpowering, OnlyTheKnowledgableMayPass, and TheChosenMany. Contrast EveryoneIsASuper.
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!!Examples:

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[[folder:Anime]]
* ''TriangleHeart 3'': The Fuwa-ryuu sword style, exclusive to the Takamachi family.
* ''{{Naruto}}'' has a few forbidden Jutsu sealed away in scrolls kept heavily guarded due to them being either {{Dangerous Forbidden Technique}}s or TheDarkArts. The series also has Secret Jutsu, which are usually carefully guarded techniques passed down a clan as part of their ThemeDeck.
* The ''Hokuto no Ken'' in ''FistOfTheNorthStar'', a series of seven punches that results in the instant death of the opponent, is known only to Kenshiro and Raoh.
** This is actually enforced by the practitioners of the style, as Hokuto Shinken is only allowed to have one successor.
* There is a fighting style known as "Rokushiki" in ''Franchise/OnePiece'' that utilizes six techniques. The members of [=CP9=] were practitioners of this style. There are a couple of high-ranking Marine officers that can use some of them, as well. But, this trope truly comes into play in the case of [=CP9=]'s Rob Lucci, who knows a hidden seventh technique known as Rokuougan. Only those who have completely mastered the six other techniques can learn it.
* In ''Manga/FairyTail'', the dragon slayers all have Secret Arts: for example Natsu's "Crimson Lotus: Exploding Flame Blade", Gajeel's "Karma Demon: Iron God Sword", or [[spoiler:Wendy's "Shattering Light: Sky Drill"]].
* In ''TheSlayers'', cooking dragon meat is apparently a secret art, and you have to endure a harsh apprenticeship from an OldMaster to learn how to do it. It turns out it's incredibly difficult to catch dragons and slay them with kitchen implements, and it's even harder (and incredibly time-consuming) to cook their meat properly and remove all poison from it.
* In ''Manga/FullMetalAlchemist'', Mustang's flame alchemy is shown to be this in a flashback sequence, with the formula for it being tattooed onto the back of a flame alchemist's chosen second (in Mustang's case, it's Hawkeye) and never written down so that only the rightful heir to flame alchemy can ever learn it. Probably a good thing, considering how enormously destructive flame alchemy is demonstrated to be throughout the series.
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[[folder:Film]]
* ''StarWars'': TheForce, though the ''StarWarsExpandedUniverse'' shows that the Jedi Order doesn't have quite as strict a monopoly on Force abilities as they'd perhaps like.
* Five ''Point'' Palm Exploding Heart Technique from KillBill which even Bill was surprised was taught to someone else by Pai Mei.
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[[folder:Literature]]
* ''TheDestroyer'': Sinanju. Only two people in the world know it.
** Within the first hundred or so books or so (literally; its a long series), we've run across a few others. In the history of the Korean village the art's home to, there have been a few rogue students and at least one second son who received surreptitious training and chose self-exile. In fact, Sinanju actually turns out to be in Remo's ''genetic'' heritage... but still, it's a pretty well-kept secret and there are probably at most three masters of it alive at any given time.
* Literature/{{Discworld}}[[spoiler:'s Lu-Tze. Deja fu.]] Of course the monks don't know it, he hasn't taught them!
* EarthsChildren: The Sharamudoi people have a secret technique for making chamois skin very soft and pliable, and only members of their cave are allowed to know it. This is done for economic reasons--soft chamois is a valuable commodity and other tribes trade things they want for it.
* In the ''YoungWizards'' series, every entity in existence (people, planets, universes, etc) has a "kernel", a wadded-up line of symbols from the LanguageOfMagic which both describes and ''is'' the laws by which that entity operates. Since letting any random wizard who felt like it alter a planet's kernel would be a Bad Idea, the knowledge and training of how to manipulate kernels is provided on a strict need-to-know basis. On any given planet populated by sentient beings, there's probably only one or two wizards who can do kernel manipulation.
* In ''Literature/AnInstinctForWar'''s story ''A Sword is Drawn'', the emperor gives a story how sword manufacture used to be known by a few who kept their methods secret. As it turned out, these "sword masters" knew their art as a ritual than a craft. If they missed one step, the swords turned into abominations and no one knew why. When the art of swordmaking was finally known, it was realized that there was nothing special about the art--anyone could make them. More and better swords were able to be made. The emperor uses this story to support his point that a disgraced general is not a craftsman of war, but an unimaginative follower to the principles of war.
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[[folder:TabletopGames]]
* This extends to the entire field of mechanics in Warhammer40K, where basic repair procedures are turned into complex rituals (burning incense before oiling a gear, for example). The techpriests get mighty miffed when people get stuff working without their assistance.
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[[folder: Video Games]]
* ''Franchise/DragonAge'': The Templar's anti-magic abilities are exclusive to them among the Ferelden warriors. Also, BloodMagic.
** The golem-making.
* ''Franchise/TheElderScrolls'': Necromancy tends to become this in times and places when it is illegal.
* ''StreetFighter'': The Ansatsuken fighting style
* In ''VideoGame/TheLegendOfZeldaTwilightPrincess'' (and possibly other Zelda games), Wolf Link can find a golden wolf spirit, which is actually an ancient warrior, who teaches him various forgotten sword techniques which greatly boost his effectiveness.
* Somewhat toyed with concerning the Early Summer Rain Jab in the last case of ''AceAttorney Investigations''. [[spoiler:After Larry's blunder with the Samurai Spear, the studio puts a gag order on the incident and tries to pretend the move doesn't exist. Kay comments that it seems like a lost art because of that.]]
* In ''TheLegendOfSpyro'' the Old Ways of dragon combat, particularly the [[LimitBreak Fury Wave attack]], fall under the almost lost/destroyed category. It's implied that only the Elder dragons can teach the techniques, and there just aren't many Elder dragons (or any other dragons for that matter) left due to a years-long war
* In {{Pokemon}}, many Pokémon, mostly Legendaries, have an attack only that Pokémon can use (under normal circumstances). Bulbapedia lists the article as "Signature Move", but it's not to be confused with the trope SignatureMove.
** Additionally, only the started Pokémon can learn the elemental Pledge moves, and only their final forms can be taught the strongest Grass/Fire/Water moves (Frenzy Plant, Blast Burn, Hydro Cannon). Draco Meteor can only be taught to Dragon-types with a high enough friendship.
** ''VideoGame/PokemonXAndY'' introduces Mega Evolution, which fits this trope for both Pokemon and trainers. It is a temporary boost in power only available to certain Pokémon, and then only if they are holding their species' specific Mega Stone (meaning they can't hold any other item), and their trainer has a Mega Ring to activate the transformation, which only a select few trainers have (including the PlayerCharacter, after reaching a certain point in the game).
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[[folder:Web Video]]
* ''WebVideo/YuGiOhTheAbridgedSeries''' explanation for why nobody could summon Exodia until Yami did: "This game makes no sense and nobody could figure out how to do it!"
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[[folder: Western Animation]]
* ''WesternAnimation/AvatarTheLastAirbender'': In need of gaining firebending Aang and Zuko travel to the city of the first firebenders and discover ancient dragons who teach them an ancient form of firebending (or at least the philosophical underpinnings of it; fire as life and energy, rather than simply rage and destruction). There are also some more specialized examples:
** Lightning-bending, the ability of a few high-end Firebenders to, well, blast people with lightning. In the original series, only Ozai and [[spoiler:his daughter Azula]] know how to do this; by the time of [[WesternAnimation/TheLegendOfKorra the sequel series]], the ability appears to be commonplace. Iroh develops his own counter to this: a lightning-''redirecting'' ability, which he teaches to Zuko, who later teaches it to Aang.
** Chi-Blocking, a pressure-points sort of technique that temporarily disables your opponent's bending powers. Only Ty Lee can do this at first; but, [[WitchSpecies since it doesn't require inherited magicalness]], this skill is also relatively common in the sequel, making it much more feasible for non-benders to fight benders.
** Bloodbending, an [[TheDarkArts evil version]] of Waterbending that allows you to control your opponent's body--making them helpless, since all the magic powers in their world are SupernaturalMartialArts. It was invented by an imprisoned waterbender who had nothing available to bend but the blood of her captors. Katara learns it from her, but [[DangerousForbiddenTechnique is reluctant to use it]]. This one is still rare in the sequel, but nonetheless important, since [[spoiler:Amon combines it with Chi-Blocking to ''permanently'' disable people's bending.]]
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[[folder: Real Life]]
* Martial Arts: Many forms, such an Ninjitsu, were traditionally taught in secret by a very few masters. The fact that they were explicitly forbidden and/or illegal forced them to remain underground. Sometimes prospective students were bound by an oath of silence, especially when this was a weapon of [[LaResistance rebels]]. These days, though, secret techniques don't remain secret for very long.
** Some techniques were developed by particular martial artists, who died without passing them on. But those arts are not so much Secret as they are Forgotten.
** [[Literature/{{Blossfechten}} Liechtenauer's school of German swordsmanship.]] In its time it was very exclusive, and it became entirely lost at some point in the 18th century. It's been brought back from the dead thanks to the finding of a handful of Medieval and Renaissance combat manuals, but it remains highly obscure.
* In Vajrayana Buddhism and presumably many other religions, certain teachings are only passed down from master to student.
** One of the major draws of esoteric traditions (including esoteric sects in mainstream religions) is the assumption that they are unknown because most PunyHumans can't handle them.
* In the old days it was stage magic. In the 1800s, it was much harder to learn how to do magic even if would-be magicians were serious about learning because other magicians were so reluctant to teach newbies back then. Nowadays, there are hundreds of books available for learning the art--but even today it's still frowned upon by most magicians to reveal a secret to a layperson. Also, if one wishes to join a group such as the The Magic Castle or The Magic Circle, one usually has to prove that they're at least somewhat competent with magic by demonstrating decent ability and take an oath swearing that they will never reveal magic secrets to anyone not serious about learning the art--failure to follow this oath can get you [[SeriousBusiness banned]] from most groups
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