When souls become Hollows in Bleach, they are driven by an eternal and insatiable hunger to devour other souls, living or dead. However, when the void within an ordinary hollow's heart becomes so much that human souls are incapable of sustaining it, the hollows are driven to cannibalize other fellow hollows. This usually results in the evolution of a bigger, larger hollow.
In Fullmetal Alchemist, while Philosopher's Stones, the Homunculi's power source, are easy for them to get, they tend to take heavy damage to the point where Pride devours Gluttony in order to stave off Ed and Greed.
A similar case occurs in the 2003 anime version; when Homunculi are injured, they start losing human appearance and power and develop a ravenous hunger for red stones. It doesn't seem to actually be necessary, and before they've had any they don't even want it. This is perhaps played most horrifyingly straight with Wrath, who is given some red stones by Envy to eat like candy, and is horrified when Envy tells him that the stones are made of human lives, but can't resist chowing down on them again immediately after.
Worthy of note is that, after his initial frenzy of devouring his family/servants, Papillion never needs to eat again. Eventually another homunculus determines that the hunger is out of a desire to become human again - which Papillion (who made himself into a homunculus) doesn't have.
In Claymore, Youma and Awakened being can only eat pure human entrails. The most powerful ones are also the most hungry.
In Trinity Blood, the Methuselah can normally keep their thirst for human blood under control using an artificial substitute. However, sadistic enemy Dietrich once got Ion to go horrifically bloodthirsty while locked in a cell with good friend Esther.
Used to devastating effect in Shiki, where vampires who were harmless, or even good, people when they were alive frequently find themselves killing their own friends and family owing to their hunger.
In Sankarea a drug allows for dead bodies to be brought back to life as intelligent zombies, but rot and decay causes these zombies to slowly lose their humanity, until they find the act of eating the people and things they love as the ultimate and most romantic pleasure. All of them eventually degrade until they reach a point where they bcome completely mindless and become a standard zombie, slow, mindless and rotting corpses that want nothing more than to eat flesh.
The main concept of Tokyo Ghoul, where ghouls start to crave human meat if they haven't eaten enough. It's also the only thing they can digest besides coffee. All the major conflicts are due to this hunger, and it especially haunts Kaneki, who was turned half-ghoul by accident.
The medical condition that drives Clayface III to reduce people to pools of protoplasm in the Batman comics.
Dead High: Yearbook - An anthology of horror stories about typical teenagers thrown into not-so-typical situations. In one story a limp-noodle of a man and a fat, ostracized girl take experimental drugs that end up giving the man muscles and make the girl lose weight rapidly. However, with each passing day, the drugs work too well: the girl keeps getting thinner and thinner no matter how much she eats and is constantly hungry, and the man's muscles keep growing to the point he is hardly able to move and unable to control his anger. In the end, unable to control her hunger anymore, the now anorexic girl transforms (via body horror) into a giant, tape-worm like creature that proceeds to eat the guy before his muscles make him explode.
The zombie superheroes in Marvel Zombies often refer to the Hunger as something that controls them.
Marvel vigilante Cloak has this for a vaguely defined kind of human Life Energy, represented as light. It's generally not an issue because his partner Dagger naturally generates an excess of the stuff, but on one occasion when she'd abandoned him he came near to killing several innocent people.
The now-deceased alien member of New MutantsWarlock was a member of an alien race who had to consume Life Energy to survive. Unlike most members of his species, he was morally averse to feeding on senntient beings, so only fed on nonsentient beings (like plants). Another exiled member of his species named Douglock was the same.
An early Hellblazer story featured a "famine demon" who would cause people to develop an insane hunger— not just for food and drugs but things they desired like clothing and jewelry. One memorable moment has a bodybuilder suddenly sink his teeth into the biceps he was just admiring. The source of the demon was eventually discovered to be one of John's old bandmates, who was a drug addict. In order to contain the demon, John and Papa Midnite had to seal him into a wall — alive.
This is referenced in the film Constantine when John's ally, the alcoholic priest, is desperately thirsty but no liquids can pass his lips. He wrecks an entire convenience store's worth of booze, unaware that he's actually drowning himself in alcohol.
This condition afflicts Ultimate Venom. He swallows people whole. He once did this to a horse, complete with rider. One issue used this for the weirdest Forrest GumpShout-Out ever: the people he's talking to on the bench are different every time because he keeps eating them. There's also a bit of Hammerspace, or maybe just ridiculously rapid digestion, going on, as immediately after eating them there's no visible difference.
Less so with main Marvelverse Venom. While main Venom does require a chemical compound found in few locations outside of the human brain to survive, and he begins getting cravings if he goes too long without it, one of the few other locations the compound can be found is chocolate. Yes, a Horror Hunger for either brains... or chocolate. Either one works.
Ultimate Carnage is even worse: he assimilates people's DNA to try to complete himself, the process of which leaves them drained, skeletal husks. Because a writer got the two mixed up, the main universe Carnage also displayed this trait once—or so we're told; it mostly just served to make Luke Cage look tough by easily resisting it.
Since she actually cares about the lives of other lifeforms, Galactus' daughter Galacta considers the hunger for Life Energy that comes with being an embodiment of the Power Cosmic to be this. To ease her conscience, she limits herself to eating the alien microbes and bioweapons that appear with alarming frequency on Earth since they don't belong there anyway. However, this isn't nearly enough to satisfy her hunger pangs which are almost as strong as her father's (who has to eat entire planets to briefly satisfy his hunger). She spends every moment of every day on Earth searching for more alien food while resisting the temptation to gorge herself on the literal tons of food surrounding her. Then she discovers a "Tapeworm Cosmic" parasite inside her feeding off of her power and exacerbating her hunger. She gets so desperate she briefly considers creating a planet to eat from scratch using Wolverine's DNA as a template to give it a regeneration factor. Galacta doesn't go through with it; reasoning that it would be way too immoral to create an entire world just to use it as a buffet. In the end, she is driven to use the Ultimate Nullifier on herself in an attempt to destroy the Tapeworm, knowing and not caring in the least that this could destroy her as well (the Nullifier is one of the few things in existence that can kill beings like Galactus and Galacta). Galactus saves both Galli and the Tapeworm because the "Tapeworm" isn't really a parasite: it's the larval form of beings such as Galactus and Galacta. In other words, it's Galli's unborn baby. That's why she's so hungry — she's eating for two!
According to Sage, vampires in Marvel comics can't stop feeding on people even if they want to. "Oh I do, Blade. You have no idea what the hunger's like. It controls you... makes a puppet of you. There's no way to fight it." Most don't have enough sense of morality or even former human personality to care, but those that do hang on to their former selves experience this trope in full.
That said, a certain mystical pool, the 'Penance Pool', allows those vampires who seek it to overcome the bloodlust and be cleansed of their guilt, as did the group of vampires known as the Forgiven.
Morbius the Living Vampire as well. He is more sympathetic than other vampires, as he was transformed into a pseudo-vampire by a scientific accident, and has retained his humanity (vowing to feed only on criminals). He is shown fighting the impulse to drain people of their blood several times over his own series, only to finally give in and attack.
Vampirella struggles with the need to take blood, which each dose of the substitute serum only holds off for 24 hours, and every story manages to contrive a way for her to not have enough serum, leaving her eternally fighting against her literally bloodthirsty desire.
An interesting case- in Downfall the "villain's" troops are largely composed of a race of cannibalistic predators who hear voices urging them to 'Kill/Devour/Destroy'. Due to the nature of the villains, most of the named characters of that faction are of the sort who strive to overcome this instinct. The Heroes, on the other hand, would wipe out their opponents if given the chance; and, following one of the early battles, are actually shown executing the wounded that were left behind following a desperate retreat. What the Hell, Hero??
The The Seven Hunters is a The Land Before Time fanfiction where the main protagonists are all suddenly turned into sharpteeth. They begin to suffer from this when they are forced to leave the valley and must either begin to feed upon their former kinds or turn on one another in the resulting hunger madness.
Uetora ("Hungry Tiger") is a Touhoudoujinshi by Zounose, starring Toramaru Shou. Okay, hands up - who else thought that a vegetariantigeryoukai sounded like a bit of a stretch? Basically, Shou went feral one full moon and started eating Nazrin, and now Mamizou is standing in for Nazrin while the real one recovers from the savaging Shou gave her. The rest of the temple youkai are mixing recently-deceased babies into the soil in the garden to try to take the edge off Shou's hunger. Shou herself doesn't realize any of this; all she knows is that the vegetables have been especially tasty lately.
Films — Live-Action
Lifeforce. When a human was drained of Life Energy by a space vampire, it would awaken 2 hours later and have an overwhelming need to drain Life Energy from another human once every two hours thereafter. This also occurred with the humans drained by other humans, leading to an epidemic of Life Energy draining zombies wandering around.
Slither has the parasite hosts (and the leader of the Hive Mind) suffer from massive hunger for meat, to the point where they'll eat ANYTHING, be it dog, cat, horse, sheep, cow, human...
In Return Of The Living Dead III, the hero's (undead) girlfriend loves her boyfriend so very much, but she's so hungry all the time, and the kibble at the local Circle K isn't cutting it. She feels much better after going berserk and tearing into some street toughs, though.
Vampires in Daybreakers get increasingly deranged and mutated (into the kind of giant man-bat that Dracula is famous for) the longer they go without human blood. Starve them for long enough, and they'll not only start trying to feed on other vampires, but even themselves.
Modern Vampires (aka The Revenant) explores the vampire side of this trope. It ends with the vampires - the good guys - turning Van Helsing and leaving him to contemplate the horror of his new bloodlust.
The Deaths of Ian Stone approaches this as a literal addiction—Harvesters can survive just fine on ordinary fear, but the rush from slowly murdering someone is quite an amazing experience, and hard to wean oneself off of.
Rapper Brotha Lynch Hung, known for Humanitarian-themed lyrics, made a movie called Now Eat in which he plays a gangbanger who is cursed by a witch to eat everything he kills... I.E., other gangbangers.
The Silicate in Island of Terror only eat human skeletons. While the victim is still alive.
In Stefano Benni's novel La Compagnia dei Celestini, an urban legend said that, as the result of a curse cast upon him by a worker that he fired for no good reason, Count Feroce Maria suffered from an eternal hunger that he could not sate, which drove him to sack Banessa's food reserves. Later, we discover that the curse never existed: it was only a legend, and the truth was that the Count had drained Banessa's food reserves only out of greed and stupidity.
Gerald Tarrant in C. S. Friedman's Coldfire Trilogy can function as a kind of vampire if he really needs to, but his true needs are more complex: nightmares, coldness, darkness, and everything humans fear. To survive an ocean crossing in which he is deprived of his usual sustenance, he inflicts terrible nightmares on his stalwart companion Damien Vryce — with the latter's agreement, because they've teamed up to fight a worse evil.
Shelob from The Lord of the Rings is described as only desiring "death for all others, mind and body, and for herself a glut of life, alone, swollen till the mountains could no longer hold her up and the darkness could not contain her."
Worse than Shelob was her mom, Ungoliant, from The Silmarillion. She literally ate the life of the two Trees of which the sun and moon are but fruits, and was still so hungry for gemstones that it scared Morgoth. She would have eaten the Source of All Evil had he not been rescued by an army of balrogs. She must have either died of starvation or old age some time afterward.
The centipede-like Taxxons from Animorphs are a chilling example. They're constantly plagued by a hunger so fierce that even the Yeerks apparently controlling the Taxxons can barely restrain it. Such is its severity that they'll even eat each other to satisfy it. Part of it is driven by an irrational fear of starvation, and the worst part is that it can never be satisfied. At point a Taxxon ate too much and nearly dies from the bloating, yet in its head is still convinced that it's starving and needs to eat more. Averted somewhat with the rebel Taxxons who refused to ally with the Yeerks. In fact, they willinglyShapeshifter Mode Lock themselves into anacondas in the epilogue to rid themselves of their eternal hunger.
In fact, some Andalites commented that Taxxons will even eat parts of themselves if they're wounded and there's no other viable option.
Ax: <I think we are in trouble, Prince Jake.>
Jake: <Is it dead?>
Ax: <In a matter of speaking. One half of it is consuming the other half.>
In Twilight, it's a metaphor for sex and lust. Not a very convincing one though, as the happily married couples seem to get it on regularly.
Premarital sex, that is.
In the Spaceforce series of books, Jez's species is a kind of non-supernatural space vampire, evolved to drink the blood of another sentient species. Unfortunately the species on the receiving end of this arrangement rebelled and rose up against the 'vampires', massacring most of them and exiling the surviving remnant from their world. Jez hates having the driving need to ingest blood regularly or die, as she feels it makes the remaining Mixitors social outcasts.
Mercedes Lackey's Children of the Night has an Unwillingly Evil character (Lackey's major characters come in three flavors: absolutely Good, absolutely Evil, and about-to-pull-a-Heel-Face Turn) who has been converted into a psivamp; he can only survive by empathically causing and feeding on strong negative emotions, rage and fear etc, in people. He can't control it very well, so they either die or "burn out", which is implied to be worse. The hunger is described as being ravenous and directly connected to his empathic ability, and even when he feeds it it's never really quiet. He tries to feed only on the attack junkies and rapists of New York, preying on the predators, but the hunger doesn't distinguish between these people and their victims, and he knows he won't be able to do this for long before he loses control. At the end of the book, after helping the heroes take out the Big Bad whose side he started on, he commits suicide.
Vampires in the Laura Caxton series can survive without blood, albeit as rotting corpses, but the rush it gives them is addictive beyond anything humans have created. If someone nearby is bleeding, they're almost incapable of resisting the urge to attack, a fact that can be used against them.
In The Dresden Files, Harry Dresden's incubus half-brother, Thomas, once gave a vivid demonstration of what resisting his own inborn Horror Hunger (desire/life force) is like. After racing Harry along the beach long enough that both were sweaty and overheated, and very thirsty, he knocked Harry's water bottle out of his hand the second a drop of water touched his lips.
In the Night Huntress series, newly turned vampires can think of nothing but their hunger and will shred anything with a heartbeat to sate their thirst. As they age, they gain self-control, but a starved vampire may revert to this condition. Throughout the series, several characters are shown just starved enough to lose control, but aware enough to be horrified by themselves as their friends try to restrain them.
The hunger itself is described in excruciating detail on several occasions in Oleg Divov's Night Watcher (it's a vampire novel, so that's par for course of course). Every vampire eventually either manages to beat the addiction and transcend to a new evolutionary level or become a hideous degenerated mindless monster that hunts in packs (it's both more and less Anvilicious than it sounds, and is pretty self-conscious about it).
Obscure example or not, it must be mentioned due to the very unusual handling of this trope: Curse of the Transhumans gives us the titular transhumans. They're extraordinarily smart, deliberately Uncanny Valley in appearance, and they eat humans. Psychologically speaking they are all also by and large sadists who enjoy eating humans while they're alive for fun and think children are the most wonderful food because they freak out so beautifully (even though they aren't big and thus yield little food). The interesting thing is that there's no attempt to humanize them or play this as a metaphor for addiction, they're just straight up evil, unrepentantly and happily so. It's VERY effective.
While it's not actually necessary for their survival, the carnivorous impulses of werewolves in the Mercy Thompson series can get out of control if they're in the presence of blood or fresh meat. It's considered remarkable that one of the lead characters manages to work as a physician, because other surgeons or veterinarians who become werewolves don't dare interact with injured humans or animals, lest their appetites get the better of them.
Most Eldritch Abominations from The Laundry Series find humans - primarily their minds and souls - crunchy and good with ketchup. In fact, that's generally why the Earth is interesting to them in the first place. However, their insatiable hunger tends to make them less dangerous, as they tend to ignore anything past immediate feeding. And if a lesser predatory spirit is bound to a human, its host must periodically kill to feed it.
Poem from a Monty Python book: "Much to his Mum and Dad's dismay, Horace ate himself one day..."
An intriguing variation occurs in the Zenna Henderson short story "Food to All Flesh": a Catholic priest in a rural parish witnesses a landing spaceship which contains a single, utterly alien occupant which is quickly revealed to be both peaceful and extremely hungry. When the priest deduces that the alien is in the process of giving birth and desperately needs to feed its young, he endeavors to find something the creature can eat, but nothing is palatable. Until one of the newborn aliens takes a bite out of his arm... and contentedly swallows. The priest says a prayer, closes his eyes and offers himself to the alien, but it in turn packs up its babies, returns to its ship and flies away, presumably to inevitable starvation.
The creature of The Relic must eat the human hypothalamus to survive.
One of the things Ben Mason from Sacreya's Legacy hates the most about being a zombie is his craving for flesh. He keeps it in check by eating raw meat, but whenever he's gone for a while without eating or just is starting to lose focus, he starts feeling predatory.
The title of the novel The Hunger (and its film adaptation) refers to this as it applies to vampirism. Even if a turned human was good before, it's virtually impossible not to give into their newfound hunger for blood.
Sylar from Heroes has "the Hunger" for supernatural abilities. It's either a side effect of his own ability or a psychological addiction. Either way, he regularly goes on killing sprees to steal the powers of others.
It would appear that this hunger isn't always confined to gaining new abilities and it could be a combination of a side-effect of Sylar's ability and a psychological addiction. Peter copied Sylar's ability for a few episodes at the beginning of season three. Peter is normally a sweet person who just wants to help others, but upon gaining Sylar's ability, he goes completely apeshit and starts trying to rip people's heads open, just like Sylar. It should be noted that Peter isn't really doing it to understand how abilities work. Peter tries to saw open Future Nathan's skull to better understand his thought process and attempts to do the same thing to Angela when he gets back to the present so he will know her secrets. It was more about learning how someone's thought process worked for Peter than acquiring abilities, especially because Peter had already copied Nathan and Angela's abilities.)
During the second half of season 3 (volume 4) Sylar meets his biological father, Samson and it turns out that he has the same ability as Sylar and that back in the day Samson used to go on killing sprees to collect abilities. Samson says that The Hunger went away after a while. That is, until Sylar revealed his cool regeneration power to Samson, who just happened to be dying a slow and painful death from lung cancer.
"Craving" had a meteor freak overweight girl who tried smoothies made from kryptonite fertilized home-grown vegetables. It made her slim down all right... and crave calories, especially fat. She sucked all the fat out of a roadkill deer and tried to do the same to a classmate. For some reason whenever she did this her mouth stretches a couple of feet down (is this Body Horror ?). She realized what was happening to her and spectacularly destroyed her greenhouse. They said she was taken to "a hospital", where God only knows how they will find a way to contain and cure her.
The local cosmetic surgeon might just have a new way to dispose of certain medical waste.
Two episodes before that, we had a guy who received heat draining powers, with a strong craving for body heat. A much less sympathetic blend of this trope and a Walking Wasteland.
In Season 6, Phantom Zone escapee Aldar was a cannibal who devoured people's bones. He doesn't seem capable of stopping and goes through numerous victims every day.
The X-Files went through just about every horror hunger in the book, as well as some not in the book. The Monster of the Week might be out to consume a victim's flesh, blood, bones, melanin, brains, liver, cancerous tissue, fat or anything else you might think of that can possibly exist within the human body.
In the Torchwood 5-part series Children of Earth, an alien species demand that they be given human children. They use them as drugs.
The big bads of Stargate Atlantis, an alien race called the Wraith, feed on human life force and have subjugated an entire galaxy of human colonies to use as their own livestock. Curiously, the one time the heroes find a child Wraith, they discover she was capable of eating normally until she hit puberty. In the Alternate Reality episode "Vegas", the early effects of starving them can be seen on the captured Wraith leader Todd, who's become delirious and philosophical as a result.
The Wendigo and Rugaru are former humans who transformed into man-eating creatures (although for different reasons.
The Crocotta, Wraiths, Rhakshasa and probably others are monsters who eat humans or part of them (like their soul).
Sam Winchester in season 4 becomes addicted to demon blood
Famine can push people's desires Up to Eleven, and he himself eat souls.
The implication in the last two episodes of season 4 that Lilith eatsbabies is suggested in season seven to be something demons equate with rank. Whether this is necessary or just overkill isn't specified.
The kitsune who show up eat human brain material. It's specifically stated to be mandatory, and Amy normally gets by with material scavenged from the mortuary but her son becomes ill without fresher brain matter. (Amy gets it for him, so we don't actually see a kitsune overwhelmed with hunger at any point)
The "zombies" created by the resurrection power in episode 3.7 of Misfits crave blood (of any kind, it seems)
Several of the cryptids in Lost Tapes are shown/stated to have eaten some of the unfortunate people who encounter them, but the Wendigo from the third season takes the cake: it is literally an evil spirit of cannibalism and no one who went into those woods during the episode got out alive, and two of them were never even found. Other monsters in the show which have done so include the "megaconda", the lizardman, and the strigoi.
In Candorville, this is even more like a drug addiction than in most works. Now that Roxanne has fulfilled a prophecy and lost the standard vampiric weaknesses, she no longer needs blood, but still feels a desire for it that she has to resist through Villainous Willpower.
In Vampire: The Masquerade (and the GURPS adaptation thereof), vampires with low levels of blood were at risk of going into Frenzy and uncontrollably trying to drain the blood of any creature available.
Furthermore, some books mention the risk of developing the "Elder's Thirst," under which no blood will sustain an elder vampire — well, save for that of younger vampires...
Played with in Vampire: The Requiem. As vampires get older, their Blood Potency (or BP) goes up, thickening their blood and (among other things) limiting their feeding options. At BP 3, animal blood stops sating their thirst, and the vampire has to start hunting humans. Then, at BP 7, human blood loses its effectiveness. The vampire then has a choice: he can start hunting other vampires, join the Ordo Dracul to learn a Coil that lets them hunt whoever they want, or go into Torpor to try to drive their BP back down to more manageable levels.
In the New World of Darkness sourcebook Antagonists there is a supernatural disease called "The Hunger." Over a period of weeks it transforms the carrier into an inhuman monster with an uncontrollable desire for human flesh.
The same sourcebook also has the Aswang (an even nastier array of which showed up in the "Wicked Dead" splatbook for Vampire: The Requiem), who crave human blood, and a supernatural entity called The Thief, which hungers to devour key organs (such as hearts from vampires) of any supernatural creature it encounters.
Cannibalistic urges can also appear in Changeling: The Lost, most often among those of the Ogre and Beast seemings.
Sentient Pandorans in Promethean: The Created have a bottomless hunger for Promethean flesh. This is generally just played as part of their antagonist status, but in the last book, Saturnine Night, a Sublimatus (sentient Pandoran) is introduced who manages to snap into lucidity on occasion, and outright weeps at how the Prometheans he feeds on have the chance to redeem themselves and become human... and he never will. He's damned to be hungry for the rest of time.
Dungeons & Dragons example: mind flayers. Minimum survival diet: one human, elf, drow, or svirfneblin brain per month. Optimal diet: one human, elf, drow, or svirfneblin brain per week.
Ghouls in Shadowrun (humans suffering from a magical virus) must eat human flesh to survive.
Any flesh will do, and they prefer it pre-rotten. Human cemeteries just happen to be easy pickings, but they prefer giant Gugs from the Dreamlands' Underworld, if they can get away with it.
Every other monster in Deadlands has a Horror Hunger, which even led to eventual lampshading: "Oh, and it has a taste for human flesh. But what doesn't these days?"
Harrowed have a drawback unique to them, Unnatural Appetite, that afflicts them with this in varying severities. At first level, it's gross but harmless; stuff like rotten food and mold. At fifth level, you need stuff like raw human organs (either one specific kind or in general). Harrowed also need to eat raw meat (human or animal) on a fairly regular basis anyway, to be able to heal themselves.
In the D&D Dark Sun setting, thri-kreen really love elves. They exude a pheromone which thri-kreen find hard to resist... especially if the elf is frightened or running! (In that setting, elves are fast, but thri-kreen are usually faster.) As a result, slavers know to never put a thri-kreen and elf in the same cage. Shame when a PC thri-kreen and elf have to work together. Not surprisingly, there was a kit called Thri-kreen Slayer.
The Fair Folk of Exalted can only stay within Creation when powered by virtue, in the sense that they can consume it, often permanently, to stave away Creation's attempt to define their fundamentally false and chaotic natures into stasis. They can get around this requirement by staying in areas soaking with the Wyld or with natural motes, by wearing pendants created by such places converted to their cause, or by only 'gently' feeding on the breadcrumbs of emotions spent in minor squabbles and keeping their power consumption down. The vast majority, however, just nom human minds away until their victims have less personality than the average Exalted robot.
Taken slightly more straight by the Erymanthoi, better known as blood apes, who are summoned by and for the explicit purpose of draining the last drop of blood from a mortal being. They don't have to literally drink blood after every fight, but they'll complain if they're stopped from doing so.
The Yozi Metagaos is chiefly motivated by an eternal hunger that can never be sated no matter how much he devours. We can perhaps consider the lack of official Metagaos charms released so far to be a good thing, since Infernals become more like their patrons as they learn their powers...
Dark Eldar in Warhammer 40,000 are cursed to have their soul slowly drained by the Chaos God Slaanesh, and must replenish it by feeding on pain and suffering. Doing so rejuvenates them, so a Dark Eldar could theoretically live forever, provided they have access to a steady supply of victims. However, the hunger grows with age, so the oldest Dark Eldar Archons have thousands of slaves sacrificed for them every day, and even that isn't enough to rejuvenate them, but merely keep them alive. Presumably eventually they'll hit the point where they will metaphysically starve faster than they can feed.
This is less a curse and more a side-effect of living in their Crapsack City. Dark Eldar who leave Commorragh to go live with their less evil cousins no longer need pain to survive. This is extremely rare.
It's not so much living in Comorragh (indeed, staying in the Webway actually decreases the speed at which their souls drain), as it is the lifestyle. Dark Eldar adopting the way of life of their Craftworld of Exodite cousins (which involves denying themselves of excessive emotion through a strict and regimentalized way of life) don't seem to suffer from the Thirst, while Craftworld outcasts that adopt the Dark Eldar way of life eventually develop it.
The various lycanthropes, werewolf or otherwise, of The Elder Scrolls universe are magically cursed to hunt down man or mer monthly, if not nightly, or be at the edge of death when the transformation ends in the morning. Unusual for this trope, there's no actual eating involved in the game's canon; this particular form of Horror Hunger is due to the lycanthropy being a "gift" provided by the Daedra Hircine, whose sphere is the hunt.
Zombies in Resident Evil only have their muscles and mid-brain reactivated by T-virus. The Midbrain governs motor control and the need to breathe, pump blood, and eat. Being that they're also viral carriers, T itself might have something to do with why they're such personal space invaders.
True to its name, zombies from the Half-Life mod They Hunger are stricken with an unsatiable hunger, moaning and scrawling (in blood, of course) "why do we hunger?".
In World of Warcraft, hunter pets once had a Happiness status relating to hunger. You could make pets Happy by feeding them, if you didn't feed them they got Unhappy, etc. (This feature was removed in one of the expansion packs.) This was played with in the web original fanfic/ parody Text Adventure GameYou Awaken In Razor Hill, in which the protagonist hunter tames an Amphibious Shark, whose happiness status is described as A Pit Of Endless Ravening. The shark's hunger is so intense that his happiness goes down rapidly and constantly unless he is eating at all times, and even if his happiness is raised to 100% he is still described as A Pit Of Endless Ravening.
According to the storyline, death knights experience the constant need to inflict agony on other creatures. This is described by the game as an endless hunger and, if not sated, death knights experience terrible pain that can drive them into a mindless, blood-seeking hysteria (which is not reflected in game mechanics).
While the main character in Aquaria learns that though the originally-horrified god Mithala succumbed to mindless hunger after being fed his own children for a sufficient period of time, the translatable message in his chamber indicates it was meant to be inflicted upon him as punishment by the Creator.
The Neverwinter Nights 2 add-on mask of the betrayer has you stuck with/as a gaping void creature that needs to feed on spirits to survive, unfortunately feeding increases your hunger..
In Digital Devil Saga, you are explicitly eating your enemies. Every one of them is a human who can shapeshift into a demon form, like you. Eating them is how you get stronger and there are many attacks specifically designed to allow this. Fortunately, most of the time, devouring is a stylized "the enemy is vaporized and sucked into your mouth" style attack. Trying to curb this never-ending hunger is one of the main goals for the protagonists of the game. The ones who represent this trope the most are Lupa and Jinana. While their attempt to resist the hunger is somewhat heartwarming, both cases end badly; Jinana is driven to a hopeless frenzy after a brutal beating by Mick the Slug, and Lupa ultimately succumbs to the hunger after traversing the Svadhisthana Waterways.
Darth Nihilus of Knights of the Old Republic II is this trope. And, as it turns out, the player character is something like this, too - Nihilus straight-up drains the Force from people, while the player character instead forms Force bonds with people and draws strength from them. When the two meet, it's essentially a Force vampire versus a Force black hole, which ends up weakening Nihilus enough to be killed in combat.
Wizard Needs Food Badly is the practice of imposing a time limit in video games based on the insatiable need to consume food and/or health items or else death is imminent.
Sauron from Primal Rage is this. Being the "God Of Hunger" he must constantly dine on flesh to sustain himself. His own followers flee for their lives due to this.
To make things more horrifying, he's one of the good characters in the game. He can be pretty reasonable, when he's not feasting on everyone in sight.
Kingdom of Loathing has the Zombie Slayer path. The name is a trick - you're a zombie. You feed solely on brains, and you're constantly ravenous - every food you can consume has a fullness of 1 to reflect your constant need for it. Mostly this is played for laughs, but the strongest skill of the Path of Hunger (which focuses on eating your horde and more efficient brain consumption), Ravenous Pounce - an attack that's stronger the less you've eaten that day - plays it frighteningly straight. The skill description is as follows:
Hungry! So hungry! SO HUNGRY! GRAAAAAGH!
Also, this is how you find out you are a zombie, and not just somebody who was buried alive, courtesy of the poor old guy who came over to see if you were all right.
In Saya no Uta, Fuminori discovers that his screwed-up perspective of the world makes human flesh delicious. Depending on the player's choice, he can either be disgusted by this enough to want his brain fixed, or indulge his newfound hunger for his fellow man.
Ran Ru / Li'l Ronnie from Fate/EXTRA has a compulsive disorder forcing her to eat whatever or whoever she loves, and nothing else.
It's easy to forget in the semi-Sugar Bowl that is Touhou that most of its cast are, in fact, man-eating monsters... Really, really Cute Monster Girls wearing Pimped Out Dresses, sure, but man-eating monsters none the less. It's a Downplayed Trope since there's an agreement between the youkai and humans of Gensoukyou not to kill each other but, guess what? Humans from the outside world that happen to stumble into Gensoukyou are fair game. It's even more-or-less outright stated that people who go "missing" in the outside world are actually abducted by YukariYakumo in order for her to feed the inhuman inhabitants of Gensoukyou with.
In Fallout 3 cannibalism can become a compulsive disorder that can overwhelm the afflicted's ability to resist it. Ian West was able to cope with his sister's counseling, but after she left for a job in Megaton he eventually broke down and killed his parents. He fled to join the Family, which treats the cravings with the less lethal substitute of blood.
Dining with devils in Fallen London may cause you to acquire the quality "Unaccountably Peckish", which is a constant hunger you can't seem to sate. In its earliest stages, you can settle the matter by eating some roasted chestnuts, although the hunger is always on the edge of your mind. As it grows, however, you can only get rid of it by devouring living animals (like your pets). And if you want to Seek Mr. Eaten's Name, you have to let it grow and grow...
The eponymous character of Charby the Vampirate can turn into a ravenous monster at the sight of blood. It cost him a girlfriend, and almost caused him to eat his only "normal" friend's grandmother.
Parodied in TwoKinds, Flora has stated (twice, and both times as a joke) that she wants to try eating human. There's also a joke on a bonus comic that if the group runs out of food, they can eat Keith.
In Homestuck Vriska's Lusus eats young trolls. And if she doesn't feed her regularly, it may eat her instead...
Then there's what happens to those eaten trolls' lusii: They're fed to Feferi's lusus, whose starvation could kill an increasing number of trolls, up to and including all of them in the whole galaxy except for Feferi herself and the current Empress who are immune because of their extremely rare blood caste.
From Kubera we have anybody related to Clan Taraka, including Yuta. He's not the only one constantly hungering to eat anything that moves and isn't from the same Clan— alive. He has to fight that instinct every second of the day, and only lets it loose on sura that attack him. Others from the Clan? Not so picky.
The Sun from Nebula feels this for the planets. Its implied that the result of succumbing to it would be him becoming a Red Giant. That, or its a sign that he is already starting to become one.
Duane in Unsounded suffers from a craving to devour people, although as far as can be told he doesn't gain any direct benefit from doing so. Other non-sentient plods are permanently muzzled because they have the same drive.
Liches in Angel Of Death must devour the souls of the living to survive. If they fail to do daily for too long, they will go into a frenzy and devour hundreds of people. Even when they're not in their frenzy state, they still crave human souls, it's just not as overpowering.
Carmilla of the Whateley Universe. She needs to eat live things in order to live, and she sucks out the life force, turning her prey into blue dust. She doesn't usually eat humans, she usually settles for other mammals.
In the online browser game Fallen London, seekers of a certain name will find themselves experiencing this.
Back at the Barnyard - comic example: Freddy the ferret is obsessed with eating his best friend, Peck the rooster.
One of the episodes of Extreme Ghostbusters involved the team battling Ravana, a gluttonous ghost who feeds by infecting people with a virus that gives them an extreme metabolism and makes them eat constantly, which is converted into ectoplasmic energy which it absorbs.
Spoofed in an episode of South Park where Butters' parents think he's come back from the dead. They think he has this and needs to eat people, when really his friends just faked his death so he could infiltrate the girls' slumber parties and find out the secret of their mysterious fortune-telling powers. The episode ends with Butters' parents killing a random woman and offering her corpse to him in an attempt to sate his bloodlust.
"Can't I just have some Spaghetti-Os?"
In the pre-show cold open of the aptly-named "Curses" episode of Space Ghost Coast to Coast, Future Man inflicts a curse on Space Ghost such that he will be driven to feed off the flesh of humanoids to survive. Sure enough, during the show proper, SG is utterly consumed by the desire to eat two of his guests, Moby and Emo Philips, midway through their respective interviews (plus, apparently before the show, Richard Crenna). Shirley Manson was spared (Space Ghost merely asked if Moltar had anyone thicker), but the curse said "humanoids", and Zorak and Moltar are both pretty humanoid in appearance...
The mental disease known as Pica causes people to uncontrollably eat things that are not conventionally considered edible. Dirt, sand, paper, wood, stones, rusty nails, hair... Depending on the severity of the disorder and developmental level of the afflicted individual, they may be completely aware that their behaviour is insane but unable to stop themselves, sometimes to the point of requiring physical restraints. An even more severe form of Pica is Autophagia, which is all of the above except with the compulsion to bite off and consume chunks of your own flesh.
Anything that needs food, really. People on the extreme edge of starvation have been known to eat almost anything from trash to feces, including cutting of pieces of their own limbs to devour them.
Also, malnutrition can distort a person's usual dietary preferences, causing them to crave parts of animals that they'd normally reject as disgusting (guts, eyes, bones, brains) because of the precious fats, vitamins, and minerals that these tissues contain.
Serial Killer Richard Chase was delusional enough to believe that if he didn't eat people's organs and drink their blood, he would die.
An actual real life version of this trope occurs for those who suffer from the genetic disorder, Prader-Willi syndrome, where the defining behavioral symptom after the first year of life is an insatiable and endless hunger that can never be satisfied no matter how much the person eats due to a defect in their genes that disables the areas in the brain responsible for feelings of fullness. Left unsupervised, people with Prader-Willi syndrome may eat until their stomachs tear.
Wendigo psychosis is a culture-bound syndrome that manifests as an intense craving for human flesh and constant fear that the sufferer will turn into a cannibal.
On a more mild note, people who become vegetarians or vegans for moral reasons but absolutely love meat could view their cravings as this trope.
There is a man who for some reason developed a nasty reaction to pretty much all normal foodstuffs until he found out that raw meat was the only thing he could keep down.