History Main / PerpetualMotionMonster

** The Watcher in the Water is a massive squid-like beast living in a lake just outside Moria. It had been driven from the deeps of Moria into the flooded valley as a guardian and to trap the dwarves inside Moria. A creature that big just hanging around in caves needs to have SOME of this going on though.

** The Animunculi, robots created by the Dwemer that guard their ancient ruins for thousands of years since the disappearance of their creators.

--> -- ''Film/HellboyIITheGoldenArmy''

* [[OurVampiresAreDifferent Chiropterans]] in ''Anime/BloodPlus'' won't die from starvation, as happened to one imprisoned in a concrete block in Russia. It was emaciated but still awake and capable of killing.
* The [[InSeriesNickname eponymous]] warriors in ''Manga/{{Claymore}}'' do not need to eat or drink except in small doses. Though, when they awaken, they eat human flesh regularly, but can go without for a long time (several years), but it does weaken them...
* The Angels in ''Anime/NeonGenesisEvangelion'' are explicitly stated to have an infinite power source in their bodies: the S2 Organ. Therefore, while alive, they have no need for sustenance, rest, etc. and are effectively immortal, though they can still be killed if damaged enough.
* The [[OurGiantsAreDifferent Titans]] from ''Manga/AttackOnTitan''. While lack of sunlight and fatigue can slow them down, they do not age, sleep, or thirst and do not need the human flesh they eat.[[note]]They lack digestive tracts beyond their stomachs and just regurgitate when full.[[/note]] They even regenerate biomass instantly and out of nowhere while thriving.

* A rare heroic example appears in the Laurel and Hardy film ''Film/BabesInToyland''. Towards the end of the movie, [[BigBad Barnaby the Crooked Man]] invades Toyland with an army of bogeymen. Stannie Dum and Ollie Dee try to fight off the monsters, but fail until they get the idea to activate the life-sized wooden soldier toys they constructed earlier. The wooden soldiers proceed to march out and absolutely ''devastate'' the monsters, and it's shown that, as automatons, they cannot be stopped, impeded, or harmed in any way. One of the soldiers even loses his head and just keeps going.

* The cauldron-born from ''Literature/TheChroniclesOfPrydain'' are deathless zombies animated by the Black Cauldron. They do not eat, sleep, breathe, or get tired, and they feel no pain. They do get weaker the farther they are from the Cauldron, however.

* Not "monsters" per se, but ''Literature/{{Discworld}}'' {{Golem}}s just keep going and going and going and going. They're used for menial, tedious labor typically, since they don't have to sleep and, for the most part, enjoy it as much as they can enjoy anything. They even use this as a form of passive-aggressive protest via LiteralGenie; they're smart enough to take initiative and can read the intent behind orders, but if you mistreat them, they're liable to fight back by doing ''exactly'' what you say, constantly, until someone figures it out and tells them to stop. This can mean that the golem you asked to "pump some water" doesn't stop until your shop's street is partly underwater. A more traditional version, also a golem, is Mr. Pump in ''Literature/GoingPostal''. As Moist's parole officer, it's explained that even though he can only walk while Moist can run, get a horse, a cart, or even a boat, he will never tire, and never stop until he catches up to him. After one demonstration of this, Moist gives up on trying to run away.
-->'''Mr. Pump:''' You can hide, but you can't run!
* In Brandon Sanderson's ''Literature/{{Warbreaker}}'', there are two. The first and most well-known are the Lifeless, an army of ImplacableMan zombies who do not need to rest or eat or drink or breathe. They obey any command given to them by anyone with the proper code-words. Whoever controls the army of Lifeless has control, more or less, over the kingdom.
** Much worse, as it turned out, were the Phantoms of Kalad -- like the Lifeless, but ''made of stone'' and thus damn near impossible to kill.
* In ''[[Literature/JohnCarterOfMars The Synthetic Men of Mars]]'', a malfunction at an already imperfectly working cloning facility produces a constantly growing mutant entity that consists of a huge blob of human flesh and random body parts. It's stated that [[ItsTheOnlyWayToBeSure if it hadn't been]] [[KillItWithFire fire-bombed]] from above until there was nothing left, it could have grown forever by ''eating itself''. Just think of the potential applications of something like that on a starving planet.
* The zombies in ''Literature/DiarioDeUnZombi'', minus some very gradual wear and tear.
* In ''Literature/MortalEngines'', the cyborg zombie Stalkers are explicitly stated to draw energy from the environment somehow, and are otherwise capable of functioning without needing to eat or recharge or refuel for an indefinite amount of time. And the oldest Stalkers, the ones made with LostTechnology, can't even ''die''. They just go dormant, ready to fight again as soon as they're repaired and reactivated.
** Lampshaded at one point; when a stalker expert is asked by Fever Crumb (who is rather confused about how Stalkers are possible) how they work, she responds with "molecular clockwork". Fever instantly identifies it as an In-Universe HandWave.
* ''"That is not dead which can eternal lie..."'' '''Lots''' of examples in the works of Creator/HPLovecraft.
* In ''Literature/FirebirdLackey'', the dragon and the "dolls" in the Katschei's palace are implied to be mechanical in nature, possibly even robots that obey short logical orders. More than that, neither need sleep or fuel, though the dolls do seem to "tire" and need a day to recharge.
* In the ''Literature/LeftBehind'' series, one of the perks Nicolae Carpathia gets from being possessed by Satan is that he no longer needs to sleep, drink or eat; the evil power of Satan providing all of his needs. When Satan leaves his body, all of this is immediately canceled and Nicolae becomes a shriveled, emaciated barely-living cadaver.
* The undead (both [[OurLichesAreDifferent lazar]] and [[OurZombiesAreDifferent regular ones]]) from ''Literature/TheDeathGateCycle'' don't get tired, don't need to eat, drink, or breathe, can ignore most injuries that don't directly impair their functioning and can repair even those with a necromancer's help (lazar who were necromancers can repair ''themselves'' almost instantaneously, making them [[ImplacableMan all but unstoppable]]). As such, if they want you dead, they can and will keep coming until you ''are''. The lazar are also an unusually literal example of this trope, as their soul wants to escape into the afterlife but cannot, and its attempts to do so compel the body to wander or, if prevented from doing so (such as by being trapped in a small room) to incessantly pace. These creatures are ''literally'' in perpetual motion.
* ''Literature/FamilySkeletonMysteries'': Sid the ambulatory skeleton doesn't need to eat or sleep to keep going, though being depressed does make it harder for him to hold himself together.
* ''Literature/{{Worm}}'': the Endbringers do not require any sustenance, and generate immense amounts of energy without apparent need to rest or refuel themselves. They do "hibernate" in hard-to-reach locations in between attacks, but analysis by various capes indicates they don't ''have'' to: the hibernation is not done for the purpose of conserving or recharging energy. [[spoiler:Scenes from the Simurgh's perspective reveal they do have limits, and if nothing changes they'd run out of power in around 300 years. But, the Simurgh knows methods to recharge their reserves (what those are is not explained), and doesn't seem to think keeping itself operational for over 4 ''billion'' years would be a problem.]]

* ''Series/GameOfThrones'': The White Walkers, and their Wight minions. Being magically create beings, the White Walkers have no need to eat or sleep, and Wight's under their control are mindless undead that can remain mobile as long as they have a White Walker to keep them animate.

* The [[ImplacableMan Dahaka]] from ''VideoGame/PrinceOfPersiaWarriorWithin'' fits the role.

* In ''Webcomic/ElGoonishShive'', Nanase and Sarah [[http://egscomics.com/egsnp/nanasecraft-07 discuss]] encountering [[SavageWolves wolves]] living in a sealed crypt and waiting by the door to eat someone despite there being nothing to eat or drink in such a place.
* ''Webcomic/TheOrderOfTheStick'': As one of TheUndead, the SorcerousOverlord lich Xykon doesn't need food, drink, air, or rest. The latter means he gets pretty bored [[OrcusOnHisThrone lounging around in his conquered territories]], because he's not interested in ruling and the RPGMechanicsVerse only lets him spend eight hours a day ItemCrafting.

* In the ''Podcast/FriendsAtTheTable'' series ''PARTIZAN'', one of the antagonists is Motion, a machine god (or "Divine") with the power to drive movement. It heads the Black Century, an elite unit of 100 soldiers and HumongousMecha who serve 100-year terms, during which Motion keeps them alive and fighting no matter how much damage they take or how low they are on supplies. Troops nearing the end of their century tend to be just a few steps removed from corpses, but are not allowed to die until Motion releases them.

* [[LivingShip Reapers]] in ''Franchise/MassEffect'' can operate a seemingly infinite amount of time without the resupplying other ships need constantly. This gives them a rather considerable advantage against everyone else. It's generally assumed that whatever it is they're using for fuel, it's based in [[SufficientlyAdvancedTechnology technology beyond the understanding of their targets]].

* The [[ImplacableMan Dahaka]] from ''VideoGame/PrinceOfPersiaWarriorWithin'' fits the role.

* Corprus infectees in ''[[VideoGame/TheElderScrollsIIIMorrowind Morrowind]]'' suffer massive, [[BodyHorror uncontrolled muscle growth]], to the point where they can apparently survive by cutting off their own tumors and eating them.

* Alex Mercer and James Heller in the ''{{VideoGame/Prototype}}'' games are stated to have no need for food or rest and only [[IAmAHumanitarian absorb]] people to heal major wounds.
* [[LivingShip Reapers]] in ''Franchise/MassEffect'' can operate a seemingly infinite amount of time without the resupplying other ships need constantly. This gives them a rather considerable advantage against everyone else. It's generally assumed that whatever it is they're using for fuel, it's based in [[SufficientlyAdvancedTechnology technology beyond the understanding of their targets]].

--> ''They don't eat, they don't sleep, WHAT KEEPS THEM GOING?''
* Robots in the ''VideoGame/{{Fallout}}'' games. By ''VideoGame/Fallout4'' it's been more than 200 years since the war that destroyed civilization, but you'll still find plenty of Mr Handies and Securitrons operating at full power despite a lack of access to any apparent fuel sources. Ghouls, despite being alive, are occasionally treated this way as well: there are multiple instances in the game where you'll encounter feral ghouls that have been trapped inside a room without a food source since the bombs fell, and they're still very active.
* Doomguy in ''VideoGame/Doom2016'' and onward is a player equivalent of this. Canonically he does not need food, drink, or rest, thanks to the enhancements in his body allowing him to subsist off of the essence he absorbs from the demons he slays. The result is a OneManArmy running on a perpetual RoaringRampageOfRevenge to slaughter Hell and its forces whenever they arise. He's so unstoppable and unceasing in his crusade that ''[[TheDreaded Hell itself fears his brutality.]]''

* Robots in ''VideoGame/{{Kenshi}}'', unlike every animal and sentient species in the world, don't need any food. This being a SurvivalSandbox game, not needing any food and therefore not having to devote money, manpower and resources to feeding yourself is a ''major'' advantage.
* ''VideoGame/WarcraftIII'': [=RTS=] [[GameplayAndStorySegregation mechanics aside]], the Scourge is so dreaded across Azeroth precisely because it's mainly comprised of the undead, who require no rest or sustenance, and who can replenish their lost numbers with those they kill.

* ''Manga/DemonSlayerKimetsuNoYaiba'': Demons have infinite stamina, and will endlessly keep regenerating unless they die. This makes a prolonged battle against them to be disadvantageous for the human Demon Slayers, since it's only a matter of time before they get tired and the demon has a {{VictoryByEndurance}}.

* ''Manga/DemonSlayerKimetsuNoYaiba'': Demons have infinite stamina, and will endlessly keep regenerating unless they die. This makes a prolonged battle against them to be disadvantageous for the human Demon Slayers, since it's only a matter of time before they get tired and the demon has a Victory by Endurance.

* The "politician" Vermin Supreme [[https://www.youtube.com/watch?v=4d_FvgQ1csE&=&t=3m34s proposed using zombies]] as a ''power source'' in his 2012 campaign to reduce America's dependency on foreign oil; by placing zombies in a giant turbine and dangling some brains in front of them to make them push the blades, they can become a PerpetualMotionMachine.

* Not "monsters" per se, but ''Literature/{{Discworld}}'' {{Golem}}s just keep going and going and going and going. They're used for menial, tedious labor typically, since they don't have to sleep and, for the most part, enjoy it as much as they can enjoy anything. They even use this as a form of passive-aggressive protest via LiteralGenie; they're smart enough to take initiative and can read the intent behind orders, but if you mistreat them, they're liable to fight back by doing ''exactly'' what you say, constantly, until someone figures it out and tells them to stop. This can mean that the golem you asked to "pump some water" doesn't stop until your shop's street is partly underwater.
** A more traditional version, also a golem, is Mr. Pump in ''Literature/GoingPostal''. As Moist's parole officer, it's explained that even though he can only walk while Moist can run, get a horse, a cart, or even a boat, he will never tire, and never stop until he catches up to him. After one demonstration of this, Moist gives up on trying to run away.
-->You can hide, but you can't run!

[[folder:Film]]

Science savvy characters may [[DiscussedTrope discuss]] how implausible it is that the walking dead in a ZombieApocalypse, despite craving brains, can keep walking 24/7 for years or longer without any kind of sustenance. Compounded by that fact that though decayed they [[SlidingScaleOfUndeadRegeneration never actually rot enough to stop posing a threat.]] Frequently, TheProfessor / MadScientist will fear (or marvel) at [[JustThinkOfThePotential the potential]] these thermodynamic law-breaking monsters represent. This is the whole idea behind undead armies in any setting-- they are weak but fearless and while slow, they can march 24/7 with no supply lines, all while [[TheVirus assimilating the enemies' fallen]].

[[folder:Anime and Manga]]

[[folder:Real life]]