[[quoteright:314:[[PiratesOfTheCaribbean http://static.tvtropes.org/pmwiki/pub/images/Pirat_6627.jpg]]]]
[[caption-width-right:314:Nobody expects the [[NinjaPirateZombieRobot skeletal pirate]] [[SuperNotDrowningSkills SEAL team]].]]

->''"My lord,"'' it was the master of the goblin blacksmiths, offering to build the king a new army, a mechanical army ''"seventy times seventy soldiers that can never tire, never know hunger or pain, and never be stopped."''
--> -- ''Film/{{Hellboy}} II: The Golden Army''

This is a type of monster that is immune to starvation and dehydration, it may not even [[TheSleepless have to sleep]] or breathe. Much like the Energizer Bunny, it just keeps going and going and going. Perpetual Motion Monsters are either explicitly supernatural (e.g. TheUndead), a set of super advanced MechaMooks, or [[{{Magitek}} both.]]

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]].

This is usually a JustifiedTrope for [[OurGhostsAreDifferent Ghosts]], DemBones, and {{Elemental Embodiment}}s since they aren't really biologically based, so they don't need traditional food sources. Although, they may need some ''other'' form of energy or material as a PowerSource [[GodsNeedPrayerBadly (like prayers]] or lighter fluid), thus [[AvertedTrope averting this trope.]] For MechaMooks and other technology based creatures they usually incorporate some near infinite PowerSource (or a means to tap into an external one) and some form of {{Regeneration}}.

It's worth noting that a character with the right type of {{Immortality}} who eats and drinks can still be a Perpetual Motion Monster -- or rather, a Perpetual Motion '''''Man''''' -- their form of immortality specifically preventing them from dying due to starvation and dehydration ([[ImmortalityHurts though they probably won't enjoy it]]). Such a character can make for a truly ImplacableMan -- nothing can keep him from his goal, not even the ravages of time!

For extra threat, the Perpetual Motion Monster is also usually unaffected by dismemberment (except for the "annoyance" of a lost limb, though a [[AppendageAssimilation needle and thread can solve that]]). For extra ''extra'' threat, it's also a SuperPersistentPredator; since being a Perpetual Motion Monster means it doesn't actually need to eat [[EatingOptional except for the pleasure of it]], it can afford to go to the ends of the Earth in pursuit of that one tasty hero-sized morsel.

Compare AutomatonHorses (not the [[MechanicalHorse mechanical variety]]), where this is noted as one of the features that make fictional horses unusual. Compare ForgotToFeedTheMonster when this is averted.

Related to TheInsomniac type 4 (doesn't need to sleep).

A SubTrope of TheNeedless.

----
!!Examples:

[[foldercontrol]]

[[folder:Anime and Manga]]
* The [[ArtificialHuman synthetic humans]] in ''{{Biomega}}'' come pretty darn close. They can live for months without food and for weeks without water and not lose efficiency.
* Androids 17 and 18 in ''DragonballZ'' are "infinite energy models" according to their creator, Dr. Gero. Androids 19 and 20 must absorb energy from people instead.
** Super-17 from ''DragonballGT'' [[MasterOfAll had the best of both worlds:]] He had the "infinite energy" power source, but could ''also'' drain power through his hands to increase his power level. Unsurprisingly it takes [[spoiler:a combination of FightingFromTheInside from 17 and [[IKnowYoureInThereSomewhereFight 18 pressuring him]] to even bring him down to the same level as the Z fighters.]]
* Alucard, a vampire, in ''{{Hellsing}}'' was sealed in the Hellsing estate for decades without blood and was still "alive". Granted, greatly weakened, and dessicated into a husk, but he still woke up when exposed to blood.
* [[OurVampiresAreDifferent Chiropterans]] in ''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 ''{{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.
[[/folder]]

[[folder:Comicbooks]]
* ''{{Superman}}'' foe Doomsday.
* TheIncredibleHulk cannot be stopped except by being calmed down by a close friend or loved one. Trying to subdue him by physical means only makes him angrier and his strength is proportional to his anger and has no upper limit.
* [[ComicBook/FantasticFour Reed Richards]] in ''MarvelZombies'' cites this trope as his justification for believing the zombie plague is the next step in evolution. He then proceeds to [[spoiler:infect the rest of the Fantastic Four.]] In this case, [[ReedRichardsIsUseless Reed Richards is]] [[EvilutionaryBiologist Genocidal]].
* [[ComicBook/DisneyDucksComicUniverse Scrooge McDuck]] once had an immortal zombie ([[PunnyName called Bombie]]) go after him for very long time, often walking nonstop across oceans, being frozen in ice for long time, and so on.
* The zombies in ''ComicBook/TheWalkingDead'' are Perpetual Motion Monsters, like most zombies. They technically don't last forever, as the characters have started to notice that more and more [[NotUsingTheZWord Walkers]] are extremely rotted, and on the verge of falling apart.
* For ''ComicBook/{{X-Men}}'' foe Juggernaut, this is basically his power (mystical power in the comics, mutant power in the movie).
** Taken to an interesting new height in ''ComicBook/FearItself''. While possessed, he truly becomes unstoppable. At some point in the event, he calmly walks to San Francisco from a dozen miles away, while the X-men try a [[CrazyPrepared bajillion]] plans to stop him. Teleporting him away does nothing, he just reappears instantly. Digging a giant trench in front of him does nothing, somehow he strolls calmly across thin air!
* Willy Pete from ''Comicbook/{{Empowered}}'' is an incredibly powerful fire elemental that eats superhuman flesh because he likes the taste, and because super-strong flesh is the only food that his mouth won't instantly incinerate. Being a fire elemental, he doesn't actually need to eat.
[[/folder]]

[[folder:Film]]
* The eponymous army in ''Film/{{Hellboy}} II: The Golden Army'' is a positively inhuman combination of perpetual motion monster, TheJuggernaut, and ''[[PullingThemselvesTogether regenerating]].'' It was an ancient weapon GoneHorriblyRight to the point the elf king who commissioned it sued for peace after it massacred a human army.
* The monster from the movie version of ''PeterBenchleysCreature'' survived locked in a cage on the sea floor without any food or room to move for decades without any debilitating effects. The book version averts this by having it stalk out of its cage in a deep sea trench ever so occasionally.
* The original ''{{Terminator}}'' movie made the eponymous cyborg sound like this trope, until the second film subverted it by revealing that his power cell would eventually run out....after 120 years.
* In the ''Film/{{Underworld}}'' film series, the first Lycan William Corvus was sealed in a tomb for 600 years. Once he's out of his coffin, he's at full strength. He clearly wasn't in suspended animation.
* Referenced in ''Film/PiratesOfTheCaribbean: Curse of the Black Pearl'', when undead Barbossa banters with an equally-undead Jack that they could keep fighting their duel for eternity.

[[/folder]]

[[folder:Literature]]
* In Creator/RobertEHoward's ''ConanTheBarbarian'' story ''Literature/BlackColossus'' there's a giant venomous python which slithers out of a ''3000 years old tomb'' and is still lively and in top shape.
* Similarly, the basilisk in ''Literature/HarryPotterAndTheChamberOfSecrets'' had apparently been stuck there since the founding of the school, waiting for its master's heir to come and release it.
* In ''TheLordOfTheRings'' there's the Watcher in the Water, a massive squid-like beast living in the pool of water 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.
* In ''TheZombieSurvivalGuide'' zombies are explained by the virus which creates them replacing their mitochondria and taking over respiratory functions so they no longer need to eat or breathe ([[HandWave ...somehow]]) and slightly more plausibly, delaying decomposition by protecting the body from rotting as the immune system would have. The later part of the trope is also averted, since zombies do rot away after a few years, unless they're in arid environments or end up being frozen.
* 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 ''Discworld/GoingPostal''. As Moist's parole officer, it's explained that even though he can only walk while Moist can run, get a horse, or a cart, 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!
* In ''[[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 ''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 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.
[[/folder]]

[[folder:Live-Action TV]]
* ''Series/BuffyTheVampireSlayer'': Adam is one, thanks to his Uranium-235 core.
* The Jem Hadar in ''Series/StarTrekDeepSpaceNine'' are genetically engineered so that the only source of nourishment they need is [[{{Phlebotinum}} Ketracel White]], a narcotic which keeps them loyal and without which they die after going violently insane. On top of that, they are conditioned to be unwaveringly loyal (though this has proven to be slightly unreliable, hence the White as a secondary measure).
[[/folder]]

[[folder:Mythology]]
* The serpent that guarded the GoldenFleece, which never slept or left the tree except when drugged.
[[/folder]]

[[folder:Tabletop Games]]
* Constructs in ''DungeonsAndDragons'', such as golems.
** While similar, living constructs, the Warforged in particular are this as well, though it was changed to needing down time similar to sleep, though less of it than other races.
** Also, undead.
* Artifacts in ''MagicTheGathering'' usually have this quality, as do a lot of undead. Phyrexians in particular are prone to combining the two.
* ''TabletopGame/RoleMaster'' has the Black Reaper, an extremely powerful demon that is commonly used to guard items or places. Once disturbed, it will never stop pursuing the offender until he or she is dead. It is immortal and doesn't need food or air, and is never bored. When it follows it's soon-to-be victim, it will just walk underwater through oceans or use it's magic axe to tunnel through all but the hardest material.
* Vampires in ''TabletopGame/VampireTheRequiem'' need blood to awaken in the evening but not to function normally. In theory, one could be perfectly happy in a sun-proof room for as long as it can force itself to stay awake at dawn.
** One particular covenant of vampires, the Ordo Dracul, have a way to increase the amount of sustenance from the blood they drink, increasing to 1.5X what they get when they drink from humans and ''doubling'' blood drunk from vampires. Two such vampires can (canonically!) make infinite blood by feeding off of each other, becoming this trope. The downside is it leads to blood addiction and/or MoreThanMindControl and/or FoodChainOfEvil kicking in. So to keep its members from trying this the elders in the covenant seal all such vampires in steel boxes which they dump into the ocean, whereupon said vampires spend ''eternity'' feeding from each other [[note]](unless one eats the other, at which point it's an eternity of starvation)[[/note]].
[[/folder]]

[[folder:Videogames]]
* Necromorphs in ''Franchise/DeadSpace'' don't need to eat, drink, sleep, or breathe. Have fun! The Hunter has the added benefit of infinite biomass to regrow lost limbs, making it almost unstoppable.
* The [[ImplacableMan Dahaka]] from ''VideoGame/PrinceOfPersiaWarriorWithin'' fits the role.
* ''VideoGame/DwarfFortress'' actually has tags for these including [NOEXERT], [NO_EAT], [NO_DRINK], and [NO_SLEEP]. In-organic creatures like bronze colossi and iron men don't need any, while Goblins just don't need to eat or drink (due to the idea that all of them should die a violent death).
* 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.
* ''VideoGame/Left4Dead'' hangs a dramatic lampshade regarding the [[TechnicallyLivingZombie Infected]]. One of the pieces of graffiti on a safe room reads:
--> ''They don't eat, they don't sleep, WHAT KEEPS THEM GOING?''
[[/folder]]

[[folder:Webcomics]]
* The Uncroaked/decrypted in ''{{Erfworld}}'' have zero upkeep.
** Interestingly, the latter still eat and drink, and are provided with what they need as if they had their usual upkeep cost (in the textual interludes, Parson tried Decrypted archon rations). ''Something'' outside the known forces of the world is evidently picking up the tab.
* The God Tiers in ''Webcomic/{{Homestuck}}'' are likely this. A player who reaches god tier can only die a heroic or just death. Death by starvation/thirst probably doesn't count.
** They could go on a hunger strike, or be executed by starvation.
[[/folder]]

[[folder:Web Originals]]
* The wooden soldiers from ''Doraleous and Associates''. Though they can be disabled with enough damage, their master need only command them to rise again and they will.
[[/folder]]

----