Unicorns are mythical animals which often represent things such as grace, purity and light in works of fiction. Given this, anybody killing or otherwise harming a unicorn can be taken to be an utterly repugnant character. This can often mean that they have crossed the Moral Event Horizon, but it doesn't have to. Often, the act of killing the unicorn will cause some curse to be placed upon the perpetrator.
This is a common trope in works that feature unicorns, due to the fact that the symbolic significance of unicorns is widely understood, making it useful in establishing or reinforcing villainy in a character.
Unicorns' purity may be reflected in a high resistance, if not outright immunity, to all or evil magic, as well as the ability to undo magic and/or being strong against evil or undead opponents. Evil or corrupted unicorns may also exist, but will generally be noted to be explicitly tainted, desecrated or otherwise "wrong" in some manner even where other evil creatures aren't.
Not to be confused with Dead Unicorn Trope.
See also: Moral Event Horizon, Unicorn, Nature Adores a Virgin (for when virgins are believed to be sacred, and the two are heavily associated with each other). Often leads to the Broken Angel trope. A similar role is sometimes filled by The Marvelous Deer. Contrast Hellish Horse.
- In Rivers of London: The Fae and the Furious, a fey lord who's been compelling humans to participate obsessively in street races is discovered to also be rearing unicorns to be butchered, their horns and meat sold on the demimonde black market. The Faerie Queen whom Peter lures into the fey lord's slaughterhouse is so horrified that she unleashes her army on the lord and his vassals. (Note that the Queen in question is a pretty harsh figure herself, with little evident compassion for either mortals or her fey underlings: she just has a soft spot for unicorns.)
- When he's assigned to the Marketing department as a punishment, Dilbert discovers a group of otherworldly elf-like types who boast that every Friday is unicorn barbecue day. (Naturally, the eternal loser Dilbert gets the bun with the horn in.) Elsewhere in the Dilbert universe, however, we're told Marketing is a place of great and terrible primal evil who lives to make life Hell for engineers...
- When Dilbert's company starts drilling for oil in Elbonia, this leads to the extinction of the Elbonian unicorn.
- In Legend (1985), unicorns are treated as ethereal beings so holy it would upset the order of the universe for a mortal to touch one. Killing the last two unicorns that guard the power of light would allow the demon lord to roam the world freely in darkness. Also, the Big Bad shows just how evil he is by ordering a unicorn's horn to be cut off, which causes the world to freeze over.
- Chronicles of Amber: Even the royal family of Amber, with literally god-like powers, regard the unicorn as special. Oberon made the creature their crest after glimpsing one in a sacred grove.
- Harry Potter: Killing a unicorn is seen as a particularly heinous thing; Firenze refers to it as a "monstrous thing". The only person known to have done it in the series is Voldemort/Quirrel, further emphasising this. Drinking unicorn blood can prolong one's life, but the drinker will be cursed from the moment the blood touches his lips for having slain "something so pure and defenceless", although the nature of the curse is never elaborated upon.
- The Last Unicorn:
- King Haggard captured all the unicorns (except one) with the Red Bull and drove them all into the sea, so he could always watch them. His explanation for his actions was that the sight of a unicorn was the only thing that could make him happy.
- A similar situation is going on in the nearby town of Hagsgate, which is cursed to "share [Haggard's] feast and share his fall." It is strongly implied that they never interfered with Haggard's capture of the unicorns because the Red Bull always drove them past the town so they could see them too.
- Magic Kingdom of Landover: Meeks and the wizards who came before before him enslaving the black unicorn is used to show how corrupt and wicked human magic users were before Questor came along, although the act is repugnant enough it would likely still be an In-Universe Moral Event Horizon even were unicorns not involved.
- In The Siege Of Wonder, by Mark S. Geston, the Scientists see the unicorn's destruction as a bad thing, but only because of all the knowledge and power that are destroyed with it.
- Villains by Necessity: This is cited as a reason not to kill a unicorn by Valerie (who's otherwise ruthless and cruel) as it would inspire dire vengeance on the killer by Good folk.
- In Voyage of the Basset, among the many nasty things the trolls do is attempting to strangle a unicorn.
- Merlin (2008): In "The Labyrinth of Gedref", Arthur kills a unicorn despite Merlin warning him against it, and Camelot is cursed. Arthur has to succeed at three tests to prove his worth in order to lift the curse. He almost fails, but passes when he attempts to drink an allegedly poisoned potion to save Merlin. In the end, he buries the unicorn horn and the unicorn comes back to life.
- Mighty Morphin' Power Rangers Inverted with a Monster of the Week called the Polluticorn, an evil unicorn that's trying to destroy the world by despoiling it with pollution. (You'd think Rita had taken a page from a Captain Planet villain's playbook.) Ironically, this is a complete 180 from the monster's Kyōryū Sentai Zyuranger equivalent, which was a Well-Intentioned Extremist who hates humans for polluting the Earth and making mythical creatures such as unicorns extinct.
- The Barbarian and the Troll: Kristoff the Unicorn is known as the finest cartographer in the land of Gothmoria, but only offers his services once every 100 blue moons to whoever deems themselves worthy. This generally takes the form of offering a lavish feast in his honor, with the protagonists's attempt going off the rails when a hired comedian accidentally dies and the dessert turns into a Blob Monster.
- Blue Rose: Unicorns are holy creatures, and murdering one is one of the most heinous sins possible. They're also explicitly listed as incorruptible — just as players will never find a good demon, they will never find an evil unicorn.
- Dungeons & Dragons: Unicorns are Chaotic Good as a rule, benevolent protectors of woodlands, and generally considered to be beautiful and near-holy beings — some bards are said to spend their lives searching for them, as one glimpse can inspire a lifetime's worth of songs. 5E changes them to Lawful Good and classifies them as Celestials, the same creature type as angels, instead of Monstrosities, as would be the case if they were simply horses with horns.
- Forgotten Realms: In order to create the Tome of the Unicorn (which is made of metal plates), a wizard named Shoon killed twelve unicorns and bathed the plates in their blood. This was considered an especially evil act in a world where evil deeds are quite common.
- Ravenloft includes Addar, a unicorn whose pride and hostility to the traditional act of becoming the Sapient Steed of a virginal elven maiden led to his seduction by a female nightmare in disguise. This eventually led to his murdering a would-be rider, a crime for which he was sentenced to the Demiplane of Dread. There, he become a foul, corrupted creature, and also gave rise to his own race of defiled unicorns, the shadow unicorns, by coupling with the nightmare who had led him down the path of evil.
- Magic: The Gathering: Unicorns are as a creature type very strongly aligned with White, the color of light, purity, moral law and angelic forces, but certain cards are especially notable as examples:
- Feast of the Unicorn depicts the head of a unicorn roasted with an apple in its mouth, with the flavour text "Could there be a fouler act? No doubt the baron knows of one."
- Mesa Unicorns of Sursi are considered to be living incarnations of the godlike Serra's joy and compassion, and offer blessings to all they encounter.
- The Revered Unicorn's flavor text notes that some people feel unworthy to even dream of them.
- Pathfinder: Unicorns are Chaotic Good creatures and implacable foes of evil, and often become steeds of especially valorous or pure-hearted humanoid women.
- Dungeons: In Dungeons II, unicorns are encountered on the Overworld, and slaying them will net you a large amount of evilness to upgrade your Throne Room and Dungeon, a vile act that can only be topped by things like razing a whole Pixie Village to the ground. You have to do this twice in the campaign.
- NetHack: Killing a unicorn of your alignment incurs a sizable penalty to your Luck Stat. Sacrificing a unicorn of your alignment (whether or not you killed it) will invoke your god's wrath. Possibly a Zig-Zag example, in that you incur no penalty for killing cross-aligned unicorns (and are, in fact, rewarded).
- Overlord: Inverted. The whole forest is tainted by evil, to the point the unicorns have become crazed flesh-eating killers and you can (and should) mercy-kill them.
- Tales of Symphonia: Averted. Even though you have to kill a unicorn to get its horn to heal someone, it reveals that its death just means a new unicorn will be born elsewhere, so there is no "curse," nor is it an evil act, to kill a unicorn for a greater good.
- World of Warcraft: While it is not specifically stated that Wild Dreamrunners (unicorn-like beasts from the Emerald Dream) are sacred, gaining one as a mount is a clear indication that the rider is a heroic Friend to All Living Things. (to specify, the mount is a possible reward from a Dreamweaver Cache, which is a weekly award you can gain if you first gain Paragon Reputation with the Dreamweavers, something that requires Exalted reputation with all the original factions of the Broken Isles.)
- The Adventures of Dr. McNinja: Inverted: the doctor's motorcycle is a transformed Evil Overlord unicorn.
- In The Adventures of Gyno-Star, the heroes discover that unicorns are being slaughtered at a factory farm (to grind their horns into powder which is used to make iPads so magical). They then proceed to brutally dismember the slaughterhouse workers and boycott the corporation.
- In Chasing the Sunset, one character is under the Forest Spirit's eternal disapproval because he put a curse on a unicorn, in ignorance.
- In El Goonish Shive, during the "Parable" storyline, Arthur orders his minions to "kill the horse!" (referring to the unicorn) cementing himself as the actual main villain just before he's poofed out of existence.
- The Junk Hyenas Diner: Subverted. Unicorns are among Growl's deadly fauna as they use psychic illusions to put a person's guard down so they can stab them to death. They are suprisingly close to the original myth in both behavior and design.
- Skin Deep: Unicorns were driven to extinction by human hunters during the Middle Ages, something generally treated as a great tragedy and which was one of the deciding factors that convinced other mythical creatures to go into hiding. On the other hand, Ravi, who was alive back when unicorns were still a thing, remembers them as just having been essentially weird-looking goats and isn't really clear on why people make such a fuss about them.
- Archer: Implied. When Cyril ends up shooting the last few people who can fly the space shuttle back to Earth, he gets chewed out by Lana and Sterling, who cared more that he shot a black astronaut than that he got them stuck in space.
Sterling Archer: A black astronaut, Cyril, that's like killing a unicorn!
- Gravity Falls: Played with in "The Last Mabelcorn". Ford's research indicates that only the pure of heart can get unicorn hair because they themselves are so pure. Mabel bends over backwards to become worthy and stops Wendy, Greta, and Candy from taking the hair by force under this belief. Then it turns out that the whole thing is a scam because the unicorns simply don't want to share their hair (even though, in their own words, they have more than they know what to do with), and the one unicorn seen on-screen is an abrasive, holier-than-thou jerk. We don't actually SEE the fight that ensues, but the girls arrive home disheveled with not only hair, but unicorn tears and eye lashes. This is not portrayed as especially heinous.
- My Little Pony: Friendship Is Magic surprisingly averts this quite a bit, as all major pony villains are either regular or Winged Unicorns, and unicorns generally aren't any better than other types of ponies. However, the Winged Unicorn Princesses are practically gods and represent positive forces, although not immune to evil influences.
- The Simpsons:
- In this couch gag, the workers manufacturing the Simpsons merchandise are depicted as miserable slaves made to work for cruel masters at Fox. There's a unicorn chained up in the underground sweatshop, looking malnourished and unhappy.
- In an episode spoofing Adam and Eve, God is not pleased when he sees that the unicorn has ventured outside the Garden of Eden and died as a result.
- Star vs. the Forces of Evil: Zig-zagged. The unicorn-like Flying Princess Pony Head is a rowdy, self-centered party girl who often gets Star and herself in trouble, and the unicorns usually seen in the series are wild, hot-tempered "warnicorns". However, in "Deep Dive", Star's magical sleep-walking takes her to the Realm of Magic, which she purified way back in "Toffee", and the place is populated with all sorts of adorable unicorns.