So your ship runs on {{Unobtainium}} crystals, or your body is maintained by {{Nanomachines}}, or your magic relies on GreenRocks. Surprise! That's ''exactly'' what the MonsterOfTheWeek likes to eat most. Better keep it away from your WarpDrive, [[OverdrawnAtTheBloodBank bloodstream]], or BagOfHolding...

This trope is when a creature likes to consume whatever AppliedPhlebotinum is being used in the story -- maybe it even needs to do so to survive, often developing an insatiable HorrorHunger for the stuff. This can vary from a creature that snacks on GreenRocks, to a monster called into being by the protagonists' use of {{Aesoptinum}}. It overlaps with PhlebotinumDependence when the creature ''has'' to consume the Phlebotinum, although Phlebotinum's main plot purpose must be something ''other'' than keeping the Phlebotinum Muncher alive.

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!Examples:

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[[folder:{{Anime}} and {{Manga}}]]
* ''LightNovel/DirtyPair: [[TheMovie Project EDEN]]'' had this as a major plot point; the Sadinga monsters fed on Vizorium ore (warp drive fuel), and the fossils they were revived from were being mined for said ore until the EvilutionaryBiologist came along.
* Homunculi in ''Anime/FullmetalAlchemist'' are addicted to the Red Stone and munch on the stuff for extra 'lives'. Red Stones are created by sacrificing human lives and are needed to create the phlebotinous Philosopher Stone, which basically enhances the magical powers of alchemy. In the original manga, the Red Stones simply don't exist. The Homunculi rely directly on Philosopher's Stones (yes, ''plural'') to provide their limited immortality.
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[[folder:Comic Books]]
* There was one {{Superman}} story where he arrived at a moon of Krypton (long story short, it drifted away hundreds of years ago) and had to use kryptonite to prevent its Uranium core from exploding. On his search for enough kryptonite he came across a (space)monster that fed on it. He managed to save the planet, but since it was now made of kryptonite, he could never go there again.
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[[folder:Literature]]
* Creator/LarryNiven's ''Literature/TheMagicGoesAway'':
** The stories had dragons, mermaids, were-creatures, gods and such that metabolized {{Mana}}. This was a kind of [[GreenAesop environmental metaphor]]; when human wizards started using up the mana faster than it could regenerate, all the fantastic creatures went *poof*.
** The [[DoomsdayDevice ultimate weapon]] of the setting was a magic disk. Powered by a simple propulsion spell with no speed limiters (and a [[RequiredSecondaryPowers secondary spell]] to keep it from tearing itself apart), it simply spun around uselessly and thus wasted ''all'' the Mana in the area. Wizards were left powerless, werewolves lost their "were-", and ageless beings suddenly began feeling their age. This is the origin of the ''MagicTheGathering'' card "[[SdrawkcabName Nevinyrral's]] Disk", which does pretty much the same thing.
* Something similar happened in ''Literature/{{Xanth}}'' when the Demon of the same name temporarily absented himself from the realm.
** In addition, when Demoness Metria traveled to Mundania, she had to be accompanied by a guy whose talent was to project an 'aisle' of magic around him whenever he was in Mundania, because a minor demon's Mundane form is a dust devil. How the minor demons survived the Time of No Magic (when Demon Xanth left) is a FridgeLogic question.
*** Because they hadn't been introduced to the series yet? Alternately, possibly Hell isn't part of Xanth.
*** It was noted at the Time that the deep region of rock where Xanth abided had soaked up so much magic from his long stay to function as a battery. (There's a village which falsely believes ''they'' act as the source of the realm's magic by creating storms to spread magic-charged dust which comes up from the rock nearby - they have no idea of its ultimate source.) Demons were established at the time as already living deep underground where magic was already more powerful due to this, and their personal power somewhat dependent on how deep their society permitted them to reside. Taking in refugees from above would probably let most of them survive during Xanth's absence, or at least not sustained irreversible damage.
* Ungoliant in ''TheSilmarillion'' pretty much subsists on shiny elf artifacts.
** Ungoliant will eat pretty much anything. Shiny elf artifacts just happen to be delicious.
* ''Literature/{{Discworld}}''. Dragons eat magic, and salamanders absorb the magical [[FictionalColor octarine frequency of light]].
* In one of the interludes for ''Literature/WordsOfRadiance'', second book of ''Literature/TheStormlightArchive'', we encounter the larkin, creatures that seem able to suck the titular light out of a person's body.
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[[folder:Tabletop Games]]
* The [[http://ww2.wizards.com/gatherer/CardDetails.aspx?&id=1280 atog]] from ''MagicTheGathering'' eats magical artifacts, and its various relatives eat other magic-related things: the [[http://ww2.wizards.com/gatherer/CardDetails.aspx?&id=4862 auratog]] eats enchantments, the [[http://ww2.wizards.com/gatherer/CardDetails.aspx?&id=3635 chronatog]] eats time (you can give it a big stat boost by skipping your next turn), and the [[http://ww2.wizards.com/gatherer/CardDetails.aspx?&id=31834 atogatog]] eats [[ImAHumanitarian other atogs]].
** ''Magic'' also had a reference to "The Magic Goes Away" in the form of [[http://ww2.wizards.com/gatherer/CardDetails.aspx?id=3803 Nevinyrral's Disk]]--they were more willing to pull SdrawkcabName tricks in the earlier days of the game.
* Most creatures in {{GURPS}} that use magic naturally have a dependency on background {{Mana}} and will rapidly die if totally deprived of it.
* ''DungeonsAndDragons'' has had a number of creatures that feed on magic, such as the Disenchanter.
* ''TabletopGame/{{Shadowrun}}''. Strain III bacteria eats magic and lives in astral space. It can drain magic out of an Awakened creature, causing it to weaken and die.
* [[RodentsOfUnusualSize Skaven]] [[EvilAlbino Grey Seers]] or Warlocks from Clan Skyre can munch down [[GreenRocks Warpstone]] in order to fuel their spells. Can turn them into [[BodyHorror Chaos Spawn]] though.
** ''All'' Skaven eat Warpstone - it's what made them giant sentient rats as opposed to just rats, and it's a large part of what ''keeps'' them that way.
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[[folder:Video Games]]
* The Worm/Metroid Prime/Dark Samus from ''MetroidPrime'' (and other [[GreenRocks Phazon]] [[PsychoSerum enhanced]] [[TheVirus creatures]]) needs Phazon to live.
* The black mages and many other monsters in ''VideoGame/FinalFantasyIX'' are spawned from concentrated Mist, which is a decidedly evil fog composed of [[spoiler: souls of the dead that have been blocked from going to the afterlife]].
* Rock/Ice/Lava Monsters in ''LegoRockRaiders'' eat energy crystals, and will destroy your buildings to get at them. If destroyed the crystals they have eaten can be recovered. Slimy slugs are similar, except they suck the energy out of them instead.
* ''WorldOfWarcraft'' has mana wyrms and arcane elementals that feed on {{mana}}, often appearring in locations with large amounts of loose mana.
* The Adephagos of ''VideoGame/TalesOfVesperia'' gets summoned into the world by an overflow of Aer, [[GreenAesop a magical substance that all the machines in the world consume to function.]]
* The Zerg in ''StarCraft'' use minerals and vespene gas as resources by metabolizing them.
* The main character, splicers and little sisters in ''Franchise/{{Bioshock}}''.
** Although this is borderline, since they need it to make themselves powerful enough to survive rather than to live.
*** Only at first: long term use (enough to drive you mad, possibly [[BodyHorror semi-randomly mutate you]] and get you to the point you're referred to as a "splicer") gets you psychologically dependent on it; keep going, and you need fresh intake of Adam and the occasional plasmid just to keep your body from completely breaking down into a puddle of goo. Fortunately, THAT pleasant experience doesn't show up anywhere in the games.
* The Scrin in the ''CommandAndConquerTiberianSeries'' are the aliens who created [[GreenRocks Tiberium]], and their entire race is completely and hopelessly [[DrugsAreBad addicted to it.]]
* The Corruptor demon from [[NexusWar Nexus Clash]] has the power to devour spells and enchantments in a world that is chock full of them. It eventually gets so bad that even shooting at one with a magical gun and ''missing'' is enough to forfeit the weapon's magical-ness to the demon.
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[[folder:Web Comics]]
* ''TheInexplicableAdventuresOfBob:'' Thanks to a botched scheme by her clone Golly, Molly the [[CuteMonsterGirl monster]] now has a second clone named Jolly who is [[OurGiantsAreBigger the size of a small mountain.]] Considering what [[BigEater Big Eaters]] Molly and Golly are, Jolly's potential food intake beggars the imagination. This is HandWaved with the explanation that, among her various bionic implants to help her [[SquareCubeLaw move and respirate at such a huge size,]] she has a "[[AppliedPhlebotinum Phlebotinomatic]] Food Synthotron."
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[[folder:Web Original]]
* The Elders in ''{{lonelygirl15}}'' need to receive trait positive blood transfusions on a semi-regular basis to survive.
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[[folder:Western Animation]]
* Inverted in ''{{Futurama}}'': Nibblonians ''excrete'' Dark Matter, which is used as starship fuel.
** At least it was, until it was rendered inert in the third movie. Now interstellar travel is powered by whale oil. It's debatable whether this or Nibblonian poo is the more ludicrous fuel source.
* The energon in all incarnations of ''{{Transformers}}''. It powers their weapons and ships and is also their currency and food. This means Transformers ''eat'' money and starship fuel. And in every series except for G1 and RiD, it's a natural resource that the ForeverWar has made quite scarce, and making substitutes either is impossible or what you get comes with ''nasty'' side effects. DrugsAreBad, [[SouthPark mmmkay]]?
** In ''those'' series, though, it was possible to create energon from other energy sources. For ''them'' that makes it easy: oil, gas, etc. is a handy source of food and fuel. It makes them Phlebotinum Munchers to ''us'' instead. Many a G1 episode and comic revolves around raids on everything from oil wells to hydroelectric dams to ''concerts'' (the music is somehow made into energon, causing it to sound just horrible to the listeners.) for energon.
* In ''WesternAnimation/AladdinTheSeries'', the resident Phlebotinum Muncher is a one-eyed creature called the thirdak, which eats magic. It tried to eat Genie and managed to eat half of Carpet.
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[[folder:Real Life]]
* What would you need with a ''complex organic molecule'', ''acidic hydroxide'' and an ''oxidiser''? Why, you must eat ''sugar'', drink ''water'' and breathe ''oxygen'' to live.
* Long term alcohol addicts might find that withdrawing cold turkey can kill them through shock. A theoretical possibility of death also exists with benzodiazepines and barbiturates, because withdrawal from them can cause seizures, but alcohol withdrawal is the only withdrawal syndrome known to have actually killed anyone.
* A common [[ConspiracyTheorist accusation]] is that drug companies will never cure cancer/AIDS/etc. because cures would eliminate demand for expensive treatments. A [[UpToEleven related accusation]] is that drug companies are in fact ''spreading'' those same diseases to make [[TakeOverTheWorld the entire world dependent on treatments.]] They technically come about because of unrealistic expectations. For example; Cancer is in fact not ''a'' disease, but ''many'', and a cure for one type would not likely have an effect on any other type. Quite a lot of research is also done by non-profit organisations who can only really "make" money in the form of further funding (although this isn't their goal anyway) by coming up with results and would have very little reason to keep it to themselves. Similarly, even a "for profit" company would have to sell a cure or risk their competitors discovering it and doing so anyway. And any researcher who discovered a cure for any form of these diseases would have no reason to hide the cure, because ''revealing'' it would make them one of the most famous and wealthy people in the history of the planet.
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