Hate Plague

""This spell allows me to exploit the petty prejudices of man. Minor grievance would escalate to murderous rage and oh, the sweet terror when the spell wore off and they saw their hands covered with their neighbor's blood.""

- Kain, Blood Omen, Legacy of Kain

A plot wherein the characters are affected by a force unknown to them and become increasingly snappish and disagreeable to each other, sometimes escalating to outright murderousness. This is often a subtle plan by the Villain of the show who figures it's easier to let the heroes kill off each other. Naturally, the heroes realize it just in time. This is sometimes a way for characters to vent hitherto unmentioned grievances. Ironically, despite the use of Applied Phlebotinum, this is a more believable version of Toilet Seat Divorce and Conflict Ball, since everyone is Not Himself.

The Trope Namer is the plot of the Transformers Generation 1 cartoon storyline "The Return of Optimus Prime", a red glowy virus transmitted by touch that affects human and robot alike. Contrast with Love Is in the Air. Subtrope of Emotion Bomb. See also Mind Virus and Artifact of Attraction. In video games with Standard Status Effects, this can show up as an actual game mechanic, usually "Confusion" or "Berserk."

Anime and Manga

 * Higurashi no Naku Koro ni arguably deconstructs this trope.
 * Higurashi no Naku Koro Ni Kai turns it straight again when
 * Further, one character does have it figured out in every arc (and a few more know about it but don't find out about specific instances until too late).
 * It's actually more of a Plague than a Hate Plague, with a side order of, but it gets the job done.
 * In Read or Die The Television Series, one Villain of the Week uses two kinds of sounds to protect his base as the heroines try to infiltrate it, both of them out of the range of normal hearing: one is a subsonic hum that enhances depression and melancholy in people who are already disposed to it, and the other is a supersonic hum that makes more excitable people angrier and more irritable.
 * Yubel uses this in duels to great effect in Yu-Gi-Oh! GX. While she's on the field as a monster, she can force monsters to attack her; she takes no battle damage, and inflicts the same damage to her opponent in retribution. She calls this effect "Nightmare Pain." Shortly after Yubel reveals herself in Season 3, Judai's cloest friends are also infected with a Hate Plague against him, which was quite effective in bringing out his Super-Powered Evil Side, especially when followed by their apparent deaths.
 * In the first Star Trek manga, a man and a woman who were once lovers (and who had a bit of a falling out) come on board the ship. They end up making all the men and women on board turn against each other merely from their presence.

Comics

 * Also Transformers-related, one issue of Marvel's Generation2 comics featured black energy goo beings that induced and lived on other creatures' aggression.
 * Inverted in the Hellblazer arc "The Red Right Hand", in which the plague makes its victims incredibly empathic. Unfortunately it takes hold in Glasgow and so everyone begins to share one another's guilt and misery, culminating in mass suicides.
 * An alternate version of the New X-Men, set in the House of M universe, dealt with Wallflower, a mutant with pheromone powers, causing Sooraya to engulf her best friend Jubilee in a sandstorm that likely would have shredded her body to its bones if given time.
 * In The Savage Dragon #55, a massively powerful mind-controller unintentionally sends everyone in Chicago into a murderous rage the moment he steps out of his bunker.
 * In a Star Trek the Original Series comic a long time ago (it came with a vinyl record to read along with) wherein an alien Catgirl's pet, a Waul, gets loose on the Enterprise. It's agitated yowling makes everyone on the crew start sniping at each other, and the closer they got to the critter the worse it got. Once it was reunited with its mistress, it was happy and purring again.
 * During the Blackest Night, Psycho-Pirate used these on Smallville. Nightmare Fuel ensued as his mask's abilities to influence any nearby target to near-suicidal hatred, uncontrollable fear or demented avarice ensued, heightening minor feelings to killing urges.
 * The main shtick of the villain Hate-Monger from the Marvel Universe. (Who is actually Adolf Hitler. )
 * And Psycho-Man, a Fantastic Four villain.
 * A new (non-Hitler) Hate Monger appears in a Punisher story as the leader of a racist organization. The Punisher infiltrates the group, but discovers that his final initiation is to beat a Hispanic reporter investigating the group to death. Unfortunately, by then he's succumbed to the Hate Monger's Hate Plague and he goes through with it. Doubly unfortunately she was the girlfriend of the Punisher's current tech guy. Needless to say, there was a falling out and a rare bout of guilt for Frank Castle.
 * In Asterix and the Roman Agent, Tortuous Convolvulus has the ability to sow mistrust (indicated by Speech Bubbles gaining a green background) that quickly escalates into shouting and fistfights.
 * He complemented the power of causing mistrust and discord by his presence alone (he didn't have to say or do a thing to start a fight between Caesar's advisers) with a good amount of mundane skill in psychological warfare and sowing mistrust and fear. He also had been sentenced to death at the Colosseum, and was alive at the beginning of the book due to making the beasts attack one another.
 * In Judge Dredd East Meg One used a literal Rage Virus as a precursor to invading Mega City One.
 * In Archie Comics, a flower putting off purple "bad vibe lines" caused nearby people to start acting meanly and selfishly. It, naturally, got passed around town for a while during the course of the story, making as many people as possible get into shouting matches. Probably not the only time such a story happened in that series.
 * The eponymous Black Gas of Warren Ellis' Zombie Apocalypse -style comic operates via progressive brain damage, eating away at the parts of the brain responsible for people's inhibitions.
 * The Wonder Woman villainess Genocide has powerful energy blasts. Anyone lucky enough to survive the explosion gets consumed by rage and paranoia.
 * Ares tends to incite rage in order to start wars.
 * Batman: Jekyll and Hyde had a drug that was described as unifying the conflicting halves of a person's identity. Apparently everyone secretly wants to murder, torture, and/or cannibalize the nearest primate. Huh.
 * Les Schtroumpfs Noirs (The Black Smurfs), the first Smurf comic book story, involved a Smurf being bit by a blackfly. As a result of the bite, the Smurf turned solid black and became insane, spreading the plague by biting his fellow Smurfs' tails. Fortunately Papa Smurf was able to cure the plague before it was too late. This story was made into an episode of the Smurfs cartoon, although in the cartoon, the evil Smurfs were purple, not black.
 * In Astro City, when Black Velvet is mortally wounded by Jitterjack, her body releases black energy that infects the populace and starts a riot.
 * In the earlier Sonic the Hedgehog comics, evil wizard Ixis Naugus can amplify peoples' emotions. This is hinted to be the driving point for the Great War between the Mobians and human-esque Overlanders, and then the Mobian/Robian civil war.
 * More recently, he used that same magic on the citizens of New Mobotropolis, magnifying their mistrust of NICOLE - following her stint being brainwashed by the Iron Dominion - into full-blown paranoia, so that they will view her as a threat, and him as their "savior".
 * The plot of Crossed is centered on a virus that causes its victims to turn into predatory psychopaths.
 * In Darkwing Duck, the Phantom Blot has created an inky mind-altering substance to create new rogues in St. Canard which is also used to control the populace briefly.

Films -- Live-Action

 * 28 Days Later and its sequel revolve around a sort of Zombie Apocalypse caused by a literal Hate Plague, the Rage Virus.
 * Ditto The Crazies and REC. The Crazies is a somewhat different variant, as the infected often retain coherence and elements of their personality, unlike the mindless fury of the 28 movies and REC.
 * In the movie Return in Red, a government agency uses sound waves to induce insanity and homicidal urges in the people of a small town.
 * In the movie Ghostbusters II, the sewers of New York City become filled with an ectoplasmic sludge that absorbs emotions. The Ghostbusters discover it while it's been negatively charged, and after they end up covered in it, they briefly end up going at each other's throats. Egon discovers the malleable nature of the slime, however, and in order to break through a barrier of negatively-charged slime, the Ghostbusters positively charge some of it through a combination of the song "Higher and Higher", and the most inspiring thing they can find in Manhattan: The Statue of Liberty.
 * One of the "non-lethal" weapons employed by the good guys at the end of Mystery Men is a ray (the Blame Thrower) that can cause angry arguments amongst whomever gets hit with it. A rare case of the protagonists employing such a tactic as psychological warfare.
 * Serenity: The Reavers (murdering, raping madmen who terrorize the fringes of the universe small star cluster/ solar system) are revealed to be
 * This is the alien threat in the film Alien Cargo.
 * Utilized by Loki through his scepter in The Avengers to make the already volatile team turn on each other so as to distract them from his assault and unleash the Hulk upon S.H.I.E.L.D.'s helicarrier.

Literature

 * The Cunning Man from I Shall Wear Midnight is an embodiment of this. He's the ghost of a witch hunter whose hatred for witches is so great, wherever he goes people become more suspicious and angry with witches.
 * In David Moody's Hater and its sequel Dog Blood, a virus causes people to murder their loved ones and anyone else in their path. The local media even calls the infected people "haters."
 * Played with in Star Trek: A Time to.... It sort of happens on the planet Delta Sigma IV, in A Time to Love and A Time to Hate, only with a twist.
 * Used in David Eddings' Elenium arc--the negative influence of the MacGuffin / Sealed Evil in a Can, the Bhelliom, causes the heroic Five-Man Band to start getting mutinous...
 * The Bhelliom got far nicer in the Tamuli, though.
 * Harry Potter, in Deathly Hallows.
 * The Chronicles of Ancient Darkness have a few hate plague-inducing things, including the Fire Opal and soul-sickness.
 * In James Tiptree Jr.'s short story "The Screwfly Solution", a mysterious plague spreads outward from the equator, turning male sexual urges into murderous violence against women.
 * In Cell (the 2006 horror novel by Stephen King) a signal (possibly sent by terrorists) broadcast over cell phones strips away the higher functions of the brain, leaving just a state of murderous rage.
 * Another Stephen King example, 1987 novel The Tommyknockers. A crashed spaceship begins to effect the area around it, causing the inhabitants of the nearby town of Haven to start changing, mentally and physically. During the mid-point of their transformation, they begin seeking out and killing those who have done them wrong, regardless of whether that wrong was real or simply perceived.
 * Steven King also used the idea in Needful Things, where the Big Bad, Mr Gaunt (a demon, if not the devil himself) manipulates the town into destroying itself through a series of escalating "pranks". Evidently Mr King likes this trope.
 * The novel One Rainy Night by Richard Laymon is about a bizarre black rain that causes Ax Craziness in everyone who gets wet.
 * Similarly, the Brian Keene short story "Purple Reign" features purple rain that does the same, though this Hate Plague affects animals as well as humans.
 * In The Long Last Call by John Skipp, the Devil goes to a strip club, where his tainted fifty dollar bills inspire murderous rage in the employees. Yes, even the girls. Especially the girls.
 * The One Ring in The Lord of the Rings has this effect, turning people against one another by playing on their lust to use its power, particularly on Bilbo and Boromir. Was shown well in the film adaptation in a shot which showed the arguing Council of Elrond reflected in the Ring as fire blazed within.
 * Also the flashback to Deágol and Sméagol finding the Ring while fishing. Within minutes Sméagol (Gollum) has killed his relative in order to possess the Ring.
 * Sam proved resistant when he used it to rescue Frodo, since he had no desire for power whatsoever.
 * was also resistant. Well, in the original text, anyway.
 * Even in their cases it still took a fair bit of willpower.
 * was exposed to the ring far longer than his brother; Tolkien may portray one as a "better" man, but the younger brother had been exposed for only hours, not days and days.
 * Morgoth in The Silmarillion was capable of sending these off with his will eventually, although he was just as good at using rumor and misdirection to accomplish the same end without sorcery.
 * Able Team #8: Army of Devils. A drug capable of creating instant rage in the user is smuggled into Los Angeles, in an attempt to create a race war in the United States.
 * One of the Dinotopia companion novels (The Maze) includes a heavier-than-air Hate Plague-inducing gas as one of the obstacles en route to the center of the titular maze.
 * In The Wheel of Time, the dagger from Shadar Logoth is so tainted with evil that his carrier becomes paranoid and hateful, and then starts to infect other people.
 * Padan Fain, a recurring villain partially possessed by the spirit who created Shadar Logoth, also has this effect- people who spend too much time in his company become increasingly paranoid, ill-tempered, and generally corrupt. When he gets the dagger back (another character carries it for a good chunk of the early books) his powers are increased dramatically.
 * Kyr Bulychev's book The Purple Sphere is about an artificial virus (stored in the titular container) which causes unnatural hatred in anyone infected. The developers got infected. They killed each other off, the rest of their planet's biosphere evolved into a Death World.
 * James Herberts the Fog is about the titular mist--it's a bio-weapon that turns half of England insane and depraved in a manner very reminiscent of The Crazies.
 * The Dark by the same author uses a more supernatural version of the same trope, with similar results.
 * The god of war Ares in Percy Jackson and The Olympians radiates an aura that makes people around him more susceptible to violent impulses. It's not quite a weapon, but it means the characters have to be more careful around him since he is always looking for an excuse to start a fight.
 * Brian Keene's Jack's Magic Beans takes place in the same universe as the aforementioned "Purple Reign", but this time, the Hate Plague has no detectable cause and doesn't appear to affect animals or people who take Prozac.
 * The god of war Ares in Percy Jackson and The Olympians radiates an aura that makes people around him more susceptible to violent impulses. It's not quite a weapon, but it means the characters have to be more careful around him since he is always looking for an excuse to start a fight.
 * Brian Keene's Jack's Magic Beans takes place in the same universe as the aforementioned "Purple Reign", but this time, the Hate Plague has no detectable cause and doesn't appear to affect animals or people who take Prozac.

Live-Action TV

 * Star Trek: The Original Series, "Day of the Dove": An Energy Beings that feeds on hate brings the Federation and the Klingons, who are trying to abide by the peace treaty, into conflict. It goes as far as implanting False Memories so that the manipulated will have an extra source of conflict. An interesting part of this trope in Star Trek is that those who are killed are somehow brought back to life with their fatal wounds healed to fight again. Once they all figure it out the creature is repelled from the ship by laughter. Lots and lots of laughter.
 * In "The Tholian Web," a Negative Space Wedgie drove the crew of one starship to kill each other, and then begins to drive the Enterprise crew to outbursts of anger.
 * In "This Side Of Paradise", an anger-inducing sonic broadcast is used to counteract the effects of tranquility-inducing spores.
 * Star Trek: The Next Generation also had such an episode, which was caused by an aging Vulcan telepathically "leaking" his suppressed emotions into the minds of the crew.
 * Star Trek: Enterprise had an episode where the closer the ship got to an undetected singularity, the more the crew started to freak out, basically giving them a nuclear version of Super OCD.
 * This is also one of the possible effects of Orion pheromones on other women.
 * Crusade, the sequel to Babylon 5, had an episode where the crew visited a planet that was boobytrapped with a means of driving visitors into murderous rages.
 * It was much more devious. The people would not only perform violent acts. Afterwards, they would have no memory of the event and instead remember seeing a shadowy figure performing the act. Of course, it wasn't really a plague but.
 * The Croatoan virus from Supernatural, which was later part of Pestilence's plan to release it nationwide as part of Lucifer's endgame.
 * Not quite a hate plague but a spiritual sister to the trope would be the depression toxin from the Red Dwarf episode "Back To Reality".
 * Used for humorous effect in the "Syzygy" episode of The X-Files, in which a rare planetary alignment causes strange behavior in a small town, and even Mulder and Scully begin to snipe at each other.
 * More serious versions appear in "Ice" in which an extraterrestrial parasite causes an Arctic research team, and later the investigating team, to turn on each other by increasing their paranoia; and in "Red Museum" as part of a Government Conspiracy the children of a town are infected with alien DNA which causes an increase in violent behaviour.
 * Angel had a variant: the touch of a particular vicious misogynist caused any man he touched to hate and attack any woman they came near.
 * In another episode, the bizarreness of the week causes people to bleed from their eyes and go into a murderous rage about whatever they feel.
 * One episode of The 4400 concerned an attack by a 4400 who was able to stimulate aggression in men, resulting in a breakdown of discipline at NTAC headquarters.
 * The Hate Master, one of the many Monsters of the Week that the Power Rangers had to deal with, has this as its primary ability.
 * An early episode of Stargate SG-1 subjected the team to hypersonic frequencies that made some of them very irritable, resulting in a shouting match and a delightfully awkward non-apology apology afterward.
 * A minor one was caused by withdrawal symptoms from some creepy Goa'uld light in the episode with the same name. Similarly, Daniel's withdrawal from the sarcophagus in Need had him almost shooting Jack in one scene.
 * The Sarah Jane Adventures had a single-target variation, where anyone who heard or read the name "Clyde Langer" turned against Clyde.
 * An episode ('Sense and Antisense") of Millennium (the TV series produced by Chris Carter) has Frank Black tracking down a man supposedly infected by a hate virus. At the end we see a photograph of the man posing with military personnel marked "Kigali, Rwanda, 1994".
 * An episode of The Man from U.N.C.L.E. ('The Suburbia Affair') centered around a plot like this-- the electric lights in a suburban neighborhood vibrated on a frequency that caused the people living there, including our undercover heroes, to become irritable, suffer headaches, and fight amongst themselves. A mob scene was narrowly averted at the town meeting.
 * The Farscape episode "Crackers Don't Matter" has a highly amusing Hate Plague, causing several characters to become obsessed with ensuring their fair share of crackers, to the point of barricades and gun battles.
 * One of the Gelliant Gutfright sketches from A Bit of Fry and Laurie features the "Fighting Buttercup," a flower which causes anger and aggression
 * Eureka - "All the Rage": A device designed to calm people down instead turns GD into "a Romero movie".
 * Ultra Seven episode 8 had aliens lace cigarettes with a toxic seed that made humans violent. It was all a plan to repopulate the Earth after humans wiped each other out.
 * In Alphas, one of the Villains Of The Week Matthew Hurly has the ability to release pheromones that causes the people around him explode in homicidal rage.
 * The "Hound of Baskerville", in the Sherlock episode of that name, turns out to have been a hallucinogenic drug that also functioned as this, giving those it was forced upon images of horrible monsters... and then making them want to murder them.

Tabletop Games

 * Dracorage in Forgotten Realms was murderous madness periodically magically induced in dragons world-wide. Designed by ancient elves to break dragons' control over the world, later magical device was hijacked and used
 * Mindflayers are given magical stones that could potentially have this result in the D&D 3.5 supplement Lords of Madness.
 * Promethean: The Created has Disquiet, an instinctual reaction by all living things towards the titular creatures that makes them gradually desire to destroy them-even if that isn't normally in a person's nature (several times, the book features humans going into jerk-mode towards Prometheans, then wondering exactly why they were doing that a moment later). Is it any wonder that a Prommie's quest To Become Human makes perfect sense?

There are two things that don't instinctively hate Prometheans -- Vampires and Werewolves. Instead, they find Prometheans so unsettling that it actually becomes harder for them to resist their Unstoppable Rage -- meaning that they'll quite likely end up killing the Promethean anyway, along with any other allies or innocents that are unfortunate enough to be there at the time.
 * One of the horrors described in the GURPS sourcebook Creatures of the Night is the Dread Blossom, a flower that makes people exposed to its scent paranoid and xenophobic.
 * Wraiths in Shadowrun can cause uncontrollable aggression in those near them.
 * Skarbrand in Warhammer Fantasy Battle and Warhammer 40000 has a special rule which causes EVERYONE around him to reroll misses in close combat due to amplifies hate.
 * Some Apostates in Black Crusade can 'Inspire Wrath' in people against specific targets, with just a few words. It makes Player Characters more determined, and so more likely to, hit the subjects. NPCs are a little less predictable.
 * Classic Traveller Adventure 6 Leviathan. When the PC's explore the world Pa'an, the natives will use their psionic powers to inflict telepathically induced aggression toward other party members. The crew will begin by feeling antagonistic and short-tempered with each other, and within one to six hours will be actively engaged in trying to finish each other off.
 * Villains and Vigilantes adventure Devil's Domain. When the PC's are fighting at the Stonehenge tower, killing a demon will cause it to explode in a cloud of demon ichor, which becomes a toxic brown smoke. After the battle is over, if the PC's didn't destroy the smoke when it was created it will cause inhabitants of the nearby town to converge on Stonehenge in a killing frenzy directed at anyone who isn't infected.

Toys

 * In Bionicle, the Dreaming Plague's first symptoms included irritability, which then grew to hatred and violent behaviour, finally leading to complete insanity followed by death.
 * This is one way Kurahk can use its power.

Video Games

 * Video game example (sort of): in Nethack, there is a "ring of conflict" that, when worn, makes every creature (including peaceful creatures and the player's own pets) start attacking the player and each other.
 * In Postal 2,
 * In Blood Omen: Legacy of Kain, the player can generate this effect with the 'Inspire Hate' spell, causing all nearby Mooks to ignore the player and attack each other. The description of the spell specifically states Kain's sadistic amusement with the effect this has on the survivors...
 * Kain gains the same ability in Defiance. In both cases it's related to the pillar of conflict.
 * This is the main goal of Dr. Regal in Mega Man Battle Network 5: Combine the Soul Net (unifying all hearts) with the power of the Dark Chip (makes people evil). We see a little bit of the effects during the cutscene before the Final Boss.
 * Gemini Spark's chapter's evil plan in Mega Man Star Force is to attach a virtual plus or minus to each person, invariably attaching the same sign to two friends, lovers, spouses, etc. so that they'd argue with each other. The game never explored the effect of two people with opposite signs...
 * It's pulled again at the end of the second game. The villain gets away with it for a while, too, and this time without the awkward positive/negative questions.
 * The Bonus Dungeon of the same game is a twisted Bad Future in which the villan's plan actually succeeded and humanity was completely wiped out. The result is a rather depressing dungeon where you wander around a world without life or hope, and kill insane versions of your allies from the normal time line and eventually confront a Bonus Boss who's sole intention is to escape to your world and wreak havoc on it as well.
 * The infectious "kombat rage" spreading from Dark Kahn's mere existence in Mortal Kombat vs. DC Universe is a straight example, though this is also subverted when Superman and Raiden eventually realize that they can focus their rage towards what they see as the invaders rather than each other. During gameplay, it also serves as a literally Unstoppable Rage.
 * In the video game Majesty: The Fantasy Kingdom Sim, one temple provides the spell "Rage of Krolm" which promptly fills your heroes with an unstoppable rage that gives them bonuses to fighting ability.
 * The violence of Condemned centers on this.
 * Used in spell form in Suikoden III, during the attack on . Naturally, the bad guys did this to sour relations between the Grasslanders and the Zexens, so as to be able to conquer them both later on without any troubles.
 * Used in Command & Conquer 3: Kane's Wrath. The Brotherhood of Nod's Humongous Mecha the Redeemer can cause enemy units to go into a rage; attacking anything within sight (including their allies); but only after they finish off their current target first.
 * Black Hand Confessors in the same game can throw hallucinogenic grenades, which cause any infantry caught in their area of effect (including friendlies) to attack their own allies. Unfortunately, it doesn't affect vehicles.
 * Similarly, in Red Alert 2: Yuri's Revenge, Yuri's faction has the Chaos Drone, which emits a psychedelic gas with a similar effect. Or to be more exact, the gas causes units affected by it to prioritize targeting friendlies over targeting foes, with an extra helping of doubled rate of fire.
 * Fallout 3 has Vault 108, a social experiment where the interior was pumped full of hallucinogenic gases to see how the inhabitants would react. Result: everyone had gone insane and killed each other.
 * Vault 92 as well. Using the internal PA system, everyone was subjected to low-frequency white noise with combat suggestions hidden in it. After a while, everyone who heard it gone berserk and brutally killed the nearest person.
 * Left 4 Dead doesn't actually feature the undead, but rather "infected" humans, in the vein of 28 Days Later, which the developers cite as an inspiration.
 * Resident Evil has this introduced instead of the zombie plague in all the other games in the form of Las Plagas, which (in their normal form) are only able to make their victims more aggressive, albeit controlled. Experiments show how much worse this can actually be for its victims.
 * In Trauma Team, almost all of the murders solved by Naomi was caused by the murderer being infected with the virus.
 * In BioShock (series), the Enrage plasmid causes splicers to go crazy (well, crazier than usual) and attack anyone-- you, their fellow splicers, or even Big Daddies.
 * This happens in Pokémon Colosseum and its sequel Pokémon XD. Pokemon's hearts are closed, so that they have no sense of compassion, and only their primal bloodlust. They'll attack anything, and they sometimes go into uncontrollable rage fits.
 * The Pox of LeChuck in Tales of Monkey Island.
 * The Delphinius Parasite in Shin Megami Tensei: Strange Journey is effectively this, though they have difficulty even finding out a physical vector for the disease.
 * Because it does not have one.
 * Features in Deadly Premonition.
 * And it happens again
 * Kingdom of Loathing: Almost everything that increases monster leveling has a description to that effect. The Annoy-o-Tron, the badly tuned radio, the Canadian Mind Control Device which takes it Up to Eleven... even, as a Shout-Out to Nethack, a ring of conflict. Most infamous is the hockey stick of furious angry rage, which is imbued with everything that makes hockey hockey.
 * One of Omega's powers in Mega Man Zero is his ability to turn normally sane reploids into murderous psychopaths. This power combined with his bloodthirsty desire to kill is ultimately what caused the deaths of 90% of reploids and 60% of humans in the Elf Wars. Imagine a robotic Skarbrand and you have Omega in a nutshell.
 * The Spice from Sly Cooper 2 causes insanity and unbound hatred, the Big Bad  intends to use this worldwide hatred to fuel   immortality.
 * According to most Touhou fanon, this is how Parsee's "power of jealousy" works. Well, that and Bullet Hell...

Western Animation

 * The Trope Namer is the Hate Plague in Transformers Generation 1. Also occurred as one of a small handful of Shout Outs in Beast Machines.
 * Despite the name, it doesn't really fit. The infected often initially become violent, but will then begin to work together with other infected. In the second of the two-parter that introduced the plague, Cyclonus commands the other Decepticons to retreat after coming under fire from the Autobots, and they follow his orders unquestioningly. It's more of a "Lack of inhibitions" plague than a "hate" plague.
 * One example of the afflicted cooperating are the combiners. In spite of fighting amongst themselves minutes earlier, the Aerialbots re-combine into Superion. They later infect Defensor. Defensor immediately collapses into the 5 Protectobots; the five fight amongst themselves. The same happens when Galvatron raids the lab containing the plague. Menasor and Bruticus are touched immediately by afflicted Autobots and immediately collapse into 10 brawling Transformers.
 * The Decepticons' cooperation could be Fridge Brilliance at work, as hatred had already been a part of their driving motivation, so wouldn't necessarily alter their behavior as much as it does, the non-villainous characters'. Doubly so for Menasor and the Stunticons, whose bios indicate that they operate on a level that barely makes it up to Teeth-Clenched Teamwork.
 * In Justice League, supervillain Gorilla Grodd uses his mental abilities to give the team's minor issues with each other a little push, much to their embarrassment.
 * Both the first and second Care Bears movies show the villains having a dark influence on surrounding people - the kids at the amusement park where Nicholas and the evil book are become rotten little monsters, and so do the kids at the camp where Dark Heart sets up shop.
 * One episode of the animated series featured a mysterious meteorite infecting a small town, making the surroundings dull and gray and the citizens depressed and apathetic. Rather creepy, in retrospect, when it started affecting the Care Bears as well.
 * The So Bad It's Good Batfink program featured main recurring villain Hugo A-Go-Go creating "hoke", a combination of hate and smoke. After it was released, the eponymous hero and his sidekick began arguing, including placing a lampshade on the overuse of the hero's "My wings of steel will protect me" catchphrase, with the henchman replying, "Yeah, yeah, why don't you get some new dialogue?"
 * An episode of Powerpuff Girls had Him replace everyone's love with hate, causing them to turn against the girls - even the Narrator was affected.
 * Really hit home when the girls went to see the Professor. Imagine all the love a parent has for their children magically swapped with hate.
 * A more family friendly version is see in Theodore Tugboat, in the debut episode of Guysborough the Garbage barge. His grumpiness gets Theodore in a bad mood, which puts Emily & George in a bad mood and so on until the entire harbour becomes snappy with each other.
 * One episode of Dungeons and Dragons, featuring the usual "get to the one-chance exit back home" set-up, forced the kids to go through a maze to reach a portal. One part of the maze made all the kids become very aggressive, tetchy and downright bloodthirsty, which almost resulted in a nasty fight. Fortunately, Hank was able to snap everyone out of it.
 * The My Little Pony movie had the Smooze, which, in addition to making everything putrid and covering the land in a thick layer of concrete-like substance, made characters touched by it aggressive, spiteful and pessimistic.
 * My Little Pony Friendship Is Magic: In "The Return of Harmony", Discord inflicts most of the main characters with the opposite emotions from their respective Elements of Harmony. Honest Applejack becomes a liar, merry Pinkie Pie becomes broody, generous Rarity becomes greedy, kind Fluttershy becomes cruel and loyal Rainbow Dash deserts her friends.
 * The little pink dog Courage once faced a literal sweeping Hate Plague called the "Cruelty Curtain". This energy barrier caused anyone it touched to become ridiculously rude to the point where benevolence was considered a crime. Courage managed to re-wire the Curtain so that it turned people nice--even its evil creator, who was later elected mayor.

Alternate Reality Games

 * The Red Horse virus in the Year Zero ARG is a weaponised haemorrhagic virus that causes violent psychosis, encouraging the spread of a disease that would otherwise be self-limiting given its extreme virulence.

Real Life

 * Mob mentality can often resemble this.
 * Historically, the Mob mentality revolving around Witch Trials seen in Salem, Massachusetts are said to have been amplified by a disease caused by a certain type of mold that worked its way into the people's grain, making this example a little more literal.
 * In the right doses, the right drugs can induce a psychotic episode, which can lead to explosively violent outbursts. However, the victim is just as likely to pass out, have a heart attack, or go on a bad acid trip instead, so the effect can't be used reliably as a weapon.
 * Many illnesses, such as rabies or brain tumors, often result in mood swings and sometimes increased aggressiveness.
 * Dogs (particularly in Springer Spaniels) can have something called "Rage Syndrome" which does resemble Hate Plague. Fortunately, it's rare and it only lasts a few minutes.