Most {{Magitech}} and machines require some kind of PowerSource. Common sources are coal, steam, electricity, or even {{Phlebotinum}}. But sometimes, that source is something which is biological and alive, sometimes even sentient. It's a LivingBattery, which the machine or device takes the LifeEnergy from almost parasitically.

We generally don't feel too bad if such living batteries are plants or insects, but the more intelligent, humanoid and sentient the creature, the more likely this will be PlayedForDrama. The story may reveal the battery is being taken advantage of, if not outright enslaved, and the extraction of the LivingBattery's energy is harmful, traumatizing, or even lethal. Often the justification for why it is necessary is some form of Higher-Species-Rights, FantasticRacism, the fact that the parasitic species created the LivingBattery in the first place, or simple desperation and need on the part of the extracting species. Or the extractors might just be {{Villain}}s who don't care who they hurt in the name of gaining power.

A SubTrope of PowerSource. PoweredByAForsakenChild is itself a subtrope. Compare LifeEnergy, SentientPhlebotinum, HumanResources and CastFromHitPoints. HamsterWheelPower is the family-friendly comedy equivalent.
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!!Examples:

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%% This trope is about using the energy contained or given off by something alive as a pure
%% power source. Power generated by living things through mechanical means, such as pedaling
%% devices or cranking, '''does not count''', the energy must be extracted directly from
%% the creature's body to apply.
%%
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[[foldercontrol]]

[[folder:Anime And Manga]]
* In ''{{Trigun}}'', the people couldn't survive on Gunsmoke without the plants, [[spoiler: giant humanoid alien things that were placed in equally giant bulbs from which energy was extracted, which powered just about everything.]]
* The machines in ''{{Kakurenbo}}'' use the children they captured for this.
* The [[http://yugioh.wikia.com/wiki/Batteryman Batteryman]] and [[http://yugioh.wikia.com/wiki/Gadget Gadget]] cards from the ''TabletopGame/YuGiOh'' Trading Card game. They also appear in the series finale of ''[[Anime/YuGiOh Duel Monsters]]'', as well as ''Anime/YuGiOh5Ds''.
** Everyone at Duel Academy during part of season 3 of YuGiOhGX. They were forced to wear wristbands which sucked out their energy as they dueled, all to [[spoiler: give yubel the energy to regenerate from her arm.]]
* ''Anime/SailorMoon'' villains, especially Ail and Ann, quite often extract some sort of energy directly from human victims to supply to awakening some evil BigBad.
* ''BlackBird'' has this, with a twist. The living battery (the heroine) isn't harmed by having her energy used. She just gives it off like a fire gives off heat. Though the ''other'' things that she can provide aren't nearly as non-invasive to harvest...
* ''Manga/NurseAngelRirikaSOS'' has the Flower of Life. The flowers are used to make both the Green Vaccine (the heroine's power source) and the Black Vaccine (the power source for her enemies) through a process that [[LawOfConservationOfDetail isn't discussed]], but seems to use the flowers up. Even though the flowers are supposed to grow wherever living things exist, quantities are [[{{Unobtainium}} severely limited]] and mostly in the hands of the bad guys.
* In ''Manga/{{Bokurano}}'', [[HumongousMecha Zearth]] is moved by this. [[spoiler:It sucks the LifeEnergy of the pilot after the fight is over, meaning that everyone who [[HeroicSacrifice pilots it dies.]]]]
[[/folder]]

[[folder:Comics]]
* ''[[ComicBook/{{X-Men}} The Uncanny X-Men]]'': When the group first discovered the island of Genosha, they discovered that mutants had been enslaved to increase the quality of life for the human citizens. One mutant was used as a living power source for the monorail-like mass transit vehicle that he piloted.
* In ''ComicBook/{{BPRD}}: Hollow Earth'', The King of Fear has Liz Sherman kidnapped so he can use her life force to power his war mechas.
* In ''ComicBook/AllFallDown'', the Order of Despots kidnaps the superhero Isotope to use him for this very purpose.
* In the story "Fountains of Youth", in issue #22 of ''The Vault of Horror'', an elderly woman that went through a series of young female companions turned out to be a centuries-old creature that was sucking the life force from them.
* The Powermasters from {{Transformers}} are this, though are more willing than usual for this trope. Though they usually use normal energon as a power source, the Marvel Comics versions were also capable of providing energy directly from their own body for a Transformer, though they had to eat absolutely ''enormous'' amounts of food to do this.
[[/folder]]

[[folder:Fanfiction]]
* In the WesternAnimation/DarkwingDuck fanfiction ''FanFic/NegaverseChronicles'', [[ShockAndAwe Megavolt]] of the [[MirrorUniverse Friendly Four]] is captured by [[MadScientist Gyro]] specifically to use as a power source to charge up his new invention. [[spoiler:And he's not very concerned about the survival of his power source...]]
[[/folder]]

[[folder:Film]]
* The machines in ''Franchise/TheMatrix'' were powered by a mixture of fusion and the energy produced by humans which they grew and harvested in fields like livestock or produce.
* ''Film/{{eXistenZ}}'': The biological game device runs on the energy of the user, since it plugs directly into a "bioport" (sort of an extra anus artificially installed in the lower back). It's suggested that all gaming devices operate the same way.
* In ''Anime/FinalFantasyTheSpiritsWithin'' some of the weapons and equipment used organic power cells containing bacteria from which "Bio-etheric energy" was extracted. [[spoiler: The power pack of some long dead RedShirt's weapon turns out to be one of the [[PlotCoupon spirits]].]]
* ''Film/XMen'':
** In ''Film/XMenFirstClass,'' Shaw ''was'' the main component of the weapon he was going to use to wipe out humans so mutants could inherit the Earth. [[spoiler: In ''his'' mind, "Mutation may have been helped along by nuclear power/weapons" equaled "mutants are nukeproof."]] His energy powers were what would fuel it.
** Magneto's mutating device in ''Film/XMen1'' also needed to be powered by Magneto's own magnetic abilities. Unfortunately, it would kill him. Fortunately (well, for him) there's a girl who takes on the powers of whoever she touches...
[[/folder]]

[[folder:Literature]]
* The best devices of ''TheTommyknockers'' were powered by lifeforce.
* "Lose Now, Pay Later" by Carol Farley has aliens who powered their tech with human fat from special slimming machines they invented--and to ensure an adequate supply, they also came out with some beverage that was irresistibly delicious but also super-fattening.
* One of the dark secrets of TadWilliams's ''TheWarOfTheFlowers'' is that, with Oberon and Titania gone, the world of Faerie is drawing its power from [[spoiler:living, working class fairies, draining and discarding them]]. It's only a secret to Theo and the audience, though. The world of Faerie knows and hates it.
* In the Literature/DoctorWhoNewAdventures novel ''Time's Crucible'', a prototype Gallifreyan time capsule is powered by the psychic energies of its crew. "Battery" is an official title of one of the crew.
* In the {{Ravenloft}} novel ''Dance of the Dead'', a magical riverboat turns out to be powered by magical creatures and benign spirits imprisoned in its hold.
* A generic high-school science textbook used the following example to describe a hypothesis: A car engine is considered a black box, but you can expect this car engine to contain alien creatures from another planet who feed off fuel and are then used to provide the power provided to propel the car. Note that the example doesn't meet the definition of a hypothesis given that there was no prior testing, examination or research of said engine.
* In the ''Literature/DresdenFiles'' novels, once Harry gains access to [[spoiler:Soulfire]], the obvious part of him is his own LivingBattery.
* In ''Literature/{{Coda}}'', Conduits power the city via energy extraction. [[spoiler: They also power President Z and the Board.]]
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[[folder:Live Action TV]]
* The titular "beast" from the ''Series/DoctorWho'' episode "The Beast Below". It was revealed that [[spoiler: the entire cityship was being powered entirely by its own energy.]]
* Also in ''Series/DoctorWho'', The Doctor explains that the 'pilot fish' in the Christmas Invasion wanted to carry him off because they could "run their batteries off [him] for a couple of years" with the energy from his regeneration.
* In the fourth season of ''Series/BuffyTheVampireSlayer'', there was an episode where Buffy and Riley were living batteries in a frat house via nonstop sex.
* In the ''Series/StarTrekVoyager'' episode "Equinox", the USS ''Equinox'', like ''Voyager'', had found herself trapped in the Delta Quadrant. Her crew had discovered a faster way to get home by torturing the alien of the week. Janeway was not pleased.
** The rest of the victims' race [[RoaringRampageOfRevenge were even less pleased]].
* Occurs accidentally in ''Series/{{Farscape}}'' when a Luxan priestess needs D'Argo's help to perform her death ritual, but chooses instead to make herself younger when she realizes how strong he is. Turns out she was actually sensing and stealing Moya's life energy.
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[[folder:Tabletop RPG]]
* ''TabletopGame/DungeonsAndDragons''. The Spelljammer campaign setting had Lifejammer and Death Helms, which powered their ship's flight by draining the LifeEnergy of the victim strapped into them (in game terms they drained HitPoints).
* In ''GeniusTheTransgression'', Geniuses can take the merit "Calculus Vampire" which allows them to drain [[MagicPoweredPseudoscience mania]] from living creatures (or other things). [[ArtificialHuman Manes]] also have the ability to do so automatically.
* ''Dark Conspiracy'' supplement ''Darktek''. A number of the Dark Minion items can only be recharged by draining the user's LifeForce.
* ''TabletopGame/{{Shadowrun}}''. Most cyberware is powered by the owner's bioelectric energy.
* The monster [[http://www.bogleech.com/mortasheen/abcoulix.htm Abcoulix]] from {{Mortasheen}} was designed for exactly this purpose, though it also works very well at dispensing ShockAndAwe in monster fights.
* ''TabletopGame/{{Rifts}}''. The Splugorth's bio-wizardry frequently makes use of this, ranging from lobotomized alien snakes on the end of staves, to guns that literally torture faeries into projecting their powers out of the barrel.
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[[folder:Web Comic]]
* The webcomic ''MachineGunAngel'' has the MegaCorp who took over the world AfterTheEnd running power plants on energy harvested from genetically manipulated humans (originally, they used sentient human clones, but they caved to public pressure and made clones that were {{Empty Shell}}s).
* The Ψiioniic from ''Webcomic/{{Homestuck}}'' was forced to CastFromHitPoints to fuel the Condense's intergalactic ship.
* In ''Webcomic/GirlGenius'', Agatha drinks water from the Dyne and is super-charged as a temporary power source.
* In ''BreakfastOfTheGods'', Cookie Jarvis the Wizard forsaw the coming of [[ItMakesSenseInContext Count Chocula and his forces]] and needed someone pure of heart to act as a battery to boost Cerelia's defenses. This turns out to be the reason [[spoiler:King Vitaman was missing for nearly the entire story]]: he volunteered to be the battery.
[[/folder]]

[[folder:Web Original]]
* Battery from ''Literature/{{Phaeton}}'' is this in every sense of the word, being a quadriplegic who produces more energy than he or anyone else knows what to do with it seemed like a good idea. It is no secret and no one, not even Battery himself has a problem with this. He is even nick named "The God of the Orphanage".
[[/folder]]

[[folder:Video Games]]
* The badniks of early ''Franchise/SonicTheHedgehog'' games were powered by little animals, making it Sonic's mission to destroy them, freeing his friends inside. This played a large ([[HeroicSacrifice and tragic]]) part in E-102 Gamma's story in ''VideoGame/SonicAdventure''.
** In ''ShadowTheHedgehog'', Black Doom wants to use ''humans'' as a power source instead.
** Eggman returns to form in ''VideoGame/SonicColors'', where his mind-control ray is powered from energy syphoned from an alien race called the Wisps.
* In the ''MegaManZero'' series, Cyber Elves are sentient beings of energy that will sacrifice themselves to the benefit of the player. The nurse types specifically are converted into usable energy. The Dark Elf is the only one that is used as a continuous power source without dying.
* In ''Metroid'', infant Metroids are used like this by Space Pirates in ''Metroid Prime 2: Echoes'', and in ''Super Metroid'' it is implied in the intro that this is what is meant by them being used to benefit mankind.
* In ''MarioAndLuigiPartnersInTime'', the Shroobs use Toads to power their flying saucers. A used-up Toad turns into a small purple (ordinary) mushroom.
* In ''Ecco: Defender of the Future'', there's a level in the evil version of the future where evil dolphins are using humpback whales as a living power source.
* In ''VideoGame/QuakeIV'', we discover just what produces the energy that the Strogg use: human corpses in various stages of mutilation [[note]]just the torso, torso and head, or sometimes the entire body. The ones with heads seem to be completely unaware of their surroundings[[/note]], attached to the machinery they power. Near the end of the game, the player himself has to activate the distribution of these to power up a certain facility.
* While they don't require one to ''operate'', [[spoiler:Lares and Lemures]] from ''{{Solatorobo}}'' will turn you into one in exchange for controlling them.
* Unfortunate humans captured by demons in ''ShinMegamiTensei'' games can look forward to this as their eventual fate. The Mantra facilities and the Nightmare System in ''Nocturne'' and the Ashura-Kai Red Pill creation process are good examples of this, some of them crossing with PeopleFarms.
* It provides power even without this trope, but Yuri's basic power generator in ''VideoGame/CommandAndConquerRedAlert2 Yuri's Revenge'' can have its output boosted by putting infantry in it. The good news is that this doesn't actually seem to do any damage to the people it uses, even if the reactor is destroyed (though that can be a bad thing if you put mind-controlled people inside it -- they get liberated from the mind control once inside. So long as they're inside, they can do nothing but provide power to you, but once released...).
* ''VideoGame/WildStar'' has a giant terraforming device powered by the local ice golems in the Northern Wilds. A nearby datacube has one of the Eldan researchers expressing dismay they had to use them, but concedes that things like ethics musn't get in the way of "The Project."
[[/folder]]

[[folder:Visual Novel]]

* The Synchronizers in ''{{Tsukihime}}'', e.g. [[spoiler:Hisui and Kohaku]], are living magical batteries that can accumulate and transfer life energy to other people, such as [[spoiler:Akiha, who has to live off a half of normal human life energy, and Shiki, after his EvilTwin starts parasitizing him]].
* Masters in ''VisualNovel/FateStayNight'' act as batteries for their Servants, empowering their abilities and allowing them to maintain a physical form. This is a dangerous prospect for some Masters, as a reckless Servant can use so much prana that it kills their Master [[spoiler:as with [[FateZero Berserker and Kariya in the Fourth War]]]].
[[/folder]]

[[folder:Western Animation]]
* In ''GeneratorRex'' there's a whole country that gets its electricity from a single EVO.
* TheSecretSaturdays once visited a small nation that got its power from two imprisoned cryptids. What's more, they're ''baby'' cryptids, [[MonsterIsAMommy and momma isn't happy about it.]]
* ''WesternAnimation/TheVentureBrothers'' has a [[Comicbook/FantasticFour Mr. Fantastic]] knockoff using the flames of their Human Torch knockoff to power his entire facility.
* In ''WesternAnimation/{{Ben 10}}'', Max met his future wife Verdona when a group of aliens meant to use her (an EnergyBeing) as a power source, which would be painful and eventually kill her.
** The Megawhatts were introduced as annoying electrical beings who play pranks on people. However, they once needed to ask Ben's help because some of them were being kept as a fuel source by the villain of the week.
* In the first episode of ''WesternAnimation/BatmanTheBraveAndTheBold'', Batman and the Blue Beetle face the villain Kanjar Ro, who is harvesting the Gribble aliens because apparently their bodies can be used as fuel. The process doesn't sound particularly pleasant.
* In ''Ultraforce'', it was revealed that Prototype's PoweredArmor was fueled by his latent ultra abilities rather than having a built in power source.
* At the end of ''WesternAnimation/JusticeLeagueUnlimited'' episode "Alive", Lex Luthor uses Tala as one of these to revive Brainiac after a failed revolt led by Tala and Gorilla Grodd. In a final act of revenge, Tala [[DyingCurse interferes with the ritual]], causing the resurrection of Darkseid instead.
[[/folder]]

[[folder:Real Life]]
* There are already quite a few types of devices that can be powered by human movement, body heat etc. but these tend to be novelties that are much simpler in function than counterparts with conventional power sources.
* [[http://www.popsci.com/technology/article/2012-06/rough-sketch-snail-could-be-used-battery This article]] tells how Evgeny Katz, a chemist at Clarkson University, has developed a way to use live snails to generate a small amount of electricity. The idea is to eventually make implanted medical devices such as pacemakers self-powered by applying similar principles to the human body.
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