->''"You were expecting a book. An ancient tome filled with the secrets that you seek. But instead, you have found me."''
-->-- '''Dyus''', ''[[VideoGame/TheElderScrollsIVOblivion Shivering Isles]]''

When GreatBigLibraryOfEverything is just too large and a GreatBigBookOfEverything is too impersonal, these characters are trained or [[NeuralImplanting modified (by science or magic)]] to retain (nigh-)superhuman quantities of knowledge, and then wait around until their memories are called on.

Whether the Human Hard Drive is capable of doing anything with the knowledge (except recite it when queried) will vary. Whether they're [[MySkullRunnethOver left capable of]] doing anything ''else'' will also vary. A Human Hard Drive isn't necessarily human, [[WhatMeasureIsANonHuman but they are considered a person]], so some androids and AI programs still count.

Very often overlaps with LivingMacGuffin, since a character like this will often become a point of conflict due to the knowledge they have. If they are instead (or also) part of the FiveManBand, they will be TheSmartGuy. If the Human Hard Drive bears the burden of exposition, this trope may overlap with both MrExposition and {{Expositron 9000}}, simultaneously.

* EncyclopaedicKnowledge, where the knower isn't necessarily ''intended'' to store information (nor have they surpassed human capacity), but they know something about ''everything''.
* GibberingGenius, if the modification has left them a little worse for wear, or at least prone to trip over their own words.
* NeuroVault, where the knower doesn't know that they know. Err, that is, the character is unaware of the information stored in them.
* WetwareCPU, one possible method of modifying a human to be (part of) a Human Hard Drive.



[[folder:Anime & Manga]]
* Index Librorum Prohibitorum from ''LightNovel/ACertainMagicalIndex'', who has memorized the complete contents of 103,000 magical grimoires, giving her a near-complete knowledge of all magic.
* Disk from ''Manga/{{Needless}}''.
* Dantallian from ''LightNovel/BibliothecaMysticaDeDantalian'' is technically a gateway to an actual library, but the net result is still this trope.
* Yuki Nagato from ''LightNovel/HaruhiSuzumiya'', a "data entity" who remembers every irrelevant detail of [[spoiler:[[GroundhogDayLoop 595 years of summer vacation]]]], and presumably everything else.
* In ''Anime/MoribitoGuardianOfTheSpirit'', one of the ''Mikado's'' elite memorizes a book of delivery tickets by flipping through it.
* All the Persocoms in ''Manga/{{Chobits}}'', although it's implied that the Chobits series of androids can do much more.
* In ''Manga/FullMetalAlchemist'', after the central library burns down, we learn that a former librarian named Sheska has memorized the entire contents of all of the books in the library. She is then paid by the Elric brothers to recreate books from the library.

[[folder:Comic Books]]
* Layla Miller in ''ComicBook/XFactor''. [[CatchPhrase She knows stuff]]. At first it seems that "knowing stuff" is her mutant power, but in fact [[spoiler: Future!Layla downloaded all the knowledge into Past!Layla's brain]].
* ''ComicBook/XMen'': in the "Age of X" alternate timeline, Rogue's code name was Reaper and it was her job to save all the memories of fallen mutants.
* In ''ComicBook/DoomPatrol'', a doomsday cult is looking for something called the Book of the Fifth Window. It turns out to be a young man with writing all over his skin.

[[folder:Films -- Live-Action]]
* The lead character in ''Film/JohnnyMnemonic'' has an 80 Gb hard drive implanted in his brain for the purposes of carrying sensitive infodata.
* Mr Memory, in the Creator/AlfredHitchcock film ''Film/{{The 39 Steps|1935}}'', is a man with perfect memory who travels around the world answering trivia questions from the audience. He is also the "39 Steps" organization's human database and file cabinet. He knows every last detail reported to him and is able to recite it instantly at will. He's used to smuggle stolen governmental and military information between international borders, as no amount of searching by security can find the stolen documents.
* In ''Film/FlightOfTheNavigator'', the boy was abducted by an alien spacecraft and had a bunch of star charts stuffed into the other NinetyPercentOfYourBrain. When he was returned, he was taken in by government scientists first to figure out why he hadn't aged in several years, and they discovered all the maps/charts stored inside his brain.
* In the 2002 film of ''Film/{{The Time Machine|2002}}'', a holographic AI librarian/computer called Vox works at the New York Public Library. Vox looks like a human and can answer any question you ask it.

* In ''Literature/{{Fahrenheit 451}}'', all of the rebels become these, each committing one entire book to memory so they can recite it if all copies of it are destroyed.
* The Archive from ''Literature/TheDresdenFiles'' has perfect recall of anything any human has ever written, whether on paper or digitally.
* The organization of Keepers in ''Literature/MistbornTheOriginalTrilogy'' have learned to store memories in copper, which they can use to store centuries of history, so that when the [[EvilOverlord Lord Ruler]] is killed, they can share what was lost.
* Captain Phantastic in ''[[Literature/ThursdayNext One of Our Thursdays Is Missing]]''. Granted, he's an elephant and not a human being, but he's a CivilizedAnimal working as the filing system for Jurisfiction and JAID in the [=BookWorld=].
* Appears (in UnbuiltTrope form) in the Creator/JorgeLuisBorges story "Literature/FunesTheMemorious". The title character's absolute, perfect memory -- the result of a head injury -- is useless, since every sensation or minuscule change in an object registers as a separate memory, requiring a specific name, to the point of near-sensory overload.
* In the ''Literature/CiaphasCain'' novels, Amberley's savant, Caractacus Mott, is portrayed as a GibberingGenius and has a habit of giving more exposition than Amberley would like Cain to receive.
* Simon Illyan in ''Literature/VorkosiganSaga'' has an implanted organic chip that records everything he sees and hears, and which he can recall later. Most people who got the implant went crazy. Subverted in that only he has access to the memories, and that most of the memories stored are near useless.
* In the Creator/CordwainerSmith story "Golden the Ship Was - Oh, Oh, Oh!", one member of a four-man crew recorded the actions of the ship's Captain.
* The plot of the novel ''Literature/{{Hammerjack}}'' begins when a courier of this type dies and the message he was carrying preserves itself by turning the next closest human -- who happens to be the main character -- into its new carrier.
* There's the Karma Catechist from the [[Literature/SecretHistories Eddie Drood books]] by Simon R. Green. He's a human storehouse of magical knowledge -- ALL the magical knowledge.
* In ''Discworld/SmallGods'', Brutha has a PhotographicMemory, so when a library is burning down, people make him read the books so they can still have the information. Unfortunately, he's also illiterate. [[spoiler:But it works out okay]].
* Brian Henrickson of ''Literature/TimeScout'' has a PhotographicMemory and works as a librarian. He might not have read '''every''' book important to the work of scouting and guiding, but you'll never prove it.
* The Mnemonic Service in Creator/IsaacAsimov's ''Sucker Bait''.
* Creator/HGWells' "The First Men on the Moon" has some moon-aliens with ridiculously large heads, whose sole purpose is to remember things. They are brought in so they can learn English vocabulary from the humans.
* In Creator/MichaelKurland's novel ''Literature/TheUnicornGirl'', the protagonists encounter a traveling band of hippies, which include a young woman who read an entire encyclopedia while under the influence of powerful drugs. She is able to answer an astounding array of technical or historical questions, but nothing about herself or her own feelings.
* ''Literature/ProfessorMmaasLecture'': In the termite hive, whose technology is based almost completely on (mostly genetically engineered) living termites, libraries are simply assemblies of termites whose purpose in life is to remember specific texts and recite them verbatim when requested.

[[folder:Live-Action TV]]
* ''Series/BabylonFive'' featured a "Vicker", as in "VCR", in one episode. This is someone whose brain has been re-purposed as a recording device, which can preserve information without contaminating it with personal opinions. If scanned by a telepath, they have no detectable thoughts of their own.
* The early 80s TV series ''ZorroAndSon'' featured Corporal Cassette, who could recite back any conversation that took place in his presence -- a {{Namesake Gag}} on cassette tapes. (Played by John Moschitta, the fast-talk guy.)
* The title character of ''Series/{{Chuck}}'' (a.k.a. "The Intersect"). He gets CIA and NSA information embedded in his head, necessitating one agent from each to protect him. Of course, he can use the combined intelligence to figure out scenarios that each agency wouldn't on its own.
* ''Series/StargateSG1'':
** SG-1 encounters a world where specialist children called "Urrone" learn a subject for ten years, and then "graduate", sharing their knowledge with the rest of their people. That's pretty much their whole purpose in society [[spoiler:because they have nanites in their brains that are removed and distributed upon "graduation", leaving the children in an infant-like state for the rest of their lives]]. (At the end, we discover that [[spoiler:the Urrone can, in fact, learn the old-fashioned way, maybe even have a normal life but for those ten years lost]].)
** Played with in another episode. The library computer in [[Series/StargateAtlantis Atlantis]] has a holographic person as an interface. When SG-1 visits looking for information, [[spoiler:they find that the "hologram" is actually an Ancient (or perhaps was replaced by one just on that occasion) who was trying to get the information to them]].
* In ''Series/{{Eureka}}'', an InstantAIJustAddWater creates a human body nearly from scratch and backups all information into the person's cells.
* The ''[[Series/TheAvengers New Avengers]]'' episode "The Three-Handed Game" features three agents with perfect memory. Each of them was shown one-third of a secret message and was sent to deliver it via a different route, so that in theory nobody could intercept the entire message. (Come to think of it, kinda like the way data packets work on the internet.) Of course the bad guy figures out a way.
* ''Series/{{Angel}}'': Wolfram and Hart have a worker in "Files and Records" who appears to have memorised the entirety of their resources. How does she know about the demon hunter who appeared and is fulfilling the ancient prophecy? "I'm Files and Records. It's my job"
* As an Emergency Medical Hologram (EMH), the Doctor from ''Series/StarTrekVoyager'' was made specifically to contain all the knowledge of Starfleet medical officers (the reason he is a hologram instead of just keeping the knowledge on a databank is in the name -- the EMH is intended to act as a doctor in emergency situations where a real Starfleet medical officer is not available). The EMH also appears in ''Series/StarTrekDeepSpaceNine'' and ''Film/StarTrekFirstContact'', but on ''Voyager'' he becomes a necessary part of the crew and comes to be treated as a person. An interesting reversal of the usual process: "hard drive" first, "human" later.

[[folder:Tabletop Games]]
* ''TabletopGame/{{Warhammer 400000}}'':
** Savants/Sages serve as these to inquisitors in the ''40k'' universe. They're cybernetically enhanced to allow them to better store data and live long enough to gather it.
** Some servitors (crude, single-purpose cyborgs) are made for this. Some people also have databanks attached to their brains for this purpose.

[[folder:Video Games]]
* ''VideoGame/TheElderScrollsIVOblivion'': Dyus from Shivering Isles is implied to be a library or a book, before he is encountered.
* Hieda no Akyuu from ''Videogame/{{Touhou}}'' holds memories of the human village from before she was born.
* Isabella in ''[[Vidoegame/NintendoWars Advance Wars: Days of Ruin]]''.
* ''Videogame/MegamanZero'':
** Maha Ganeshariff was designed as a data server... who also works as an armored LightningBruiser. He was sent to Zero's original resting place to gather information, and after you defeat him, you gain access to two new weapons for Zero (or, if [[AllThereInTheManual you go with the manual's explanation]], [[SwissArmyWeapon more variations of the Z-Saber]]).
** Protectos the Goreroid has a similar role, a weaponized living storage server. However, unlike his counterpart, he's more of a traditional MightyGlacier.

[[folder:Real Life]]
* Oral historians may serve this purpose for unwritten cultural legacies, with lifelong practice replacing magical or technological modification.
* In ancient Greece, musicians and storytellers, and sometimes the educated elite, were supposed to be able to recite the most famous epics (usually ''Literature/TheIliad'' or ''Literature/TheOdyssey'') by heart. As reported by his disciple Creator/{{Plato}}, Creator/{{Socrates}} was against writing itself: "It destroys memory and weakens the mind, relieving it of work that makes it strong. It is an inhuman thing."