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 MoralEventHorizon, 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.

Not to be confused with DeadUnicornTrope.

See also: MoralEventHorizon.
* In ''Film/{{Legend}}'', 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 BigBad shows just how evil he is by ordering a unicorn's horn to be cut off, which causes the world to freeze over.

* Killing a unicorn is seen as a particularly heinous thing to do in ''Literature/HarryPotter''; Firenze refers to it as a "monstrous thing". The only person known to have done it in the series is [[spoiler: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".
* King Haggard from ''Literature/TheLastUnicorn'' 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.
* Somewhat subverted in ''The Siege of Wonder'' by Mark S. Geston, where the Scientists only see the unicorn's destruction as a bad thing because of all the knowledge and power that are destroyed with it.
* In ''Literature/VoyageOfTheBasset'', among the many nasty things the trolls do is attempting to strangle a unicorn.
* Averted in ''Discworld/LordsAndLadies'', where a unicorn is a crazed horse (even more crazed than usual) with a huge horn on its head. Not helping its temper is its mistress trying to mind-control it from another dimension, but it turns out it can still be controlled by a [[spoiler:virgin]].

[[AC: {{Live Action TV}}]]
* ''Series/{{Merlin}}'' had The Labyrinth of Gedref. Arthur killed a unicorn despite Merlin warning him against it, and Camelot was cursed. Arthur had to succeed at three tests to prove his worth in order to lift the curse. He almost failed, but passed when he attempted to drink the allegedly poisoned potion to save Merlin. In the end, he buried the unicorn horn and the unicorn came back to life.
* ''Series/MightyMorphinPowerRangers'' Inverted the Trope ''completely'' with a MonsterOfTheWeek called the Polluticorn, an evil unicorn that was trying to destroy the world by despoiling it with pollution. (You'd think Rita had taken a page from a ''WesternAnimation/CaptainPlanet'' villain's playbook.) Ironically, this was a complete 180 from the monster's ''Series/SuperSentai'' equivalent, which was a WellIntentionedExtremist who hated humans [[GaiasVengeance for polluting the Earth and making mythical creatures such as unicorns extinct.]]

* in the ''ComicStrip/{{Dilbert}}'' strip, when he is assignrd to the Marketing department as a punishment, Dilbert discovers a group of otherworldly Elf-like types who boast every Friday as unicorn barbecue day. (Naturally, the eternal loser Dilbert gets the bun with the horn in). But elsewhere in the Dilbert universe, we are told Marketing is a place of great and terrible primal evil... (in other strips, Marketing and Sales conspire to make life Hell for engineers by selling things they haven't designed yet. Hell: Marketing sell things that haven't been invented yet and which are generally scientifically impossible...).
** When Dilbert's company starts drilling for oil in Elbonia this leads to the extinction of the Elbonian unicorn.

* In ''TabletopGame/MagicTheGathering'', the [[http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=16625 Feast of the Unicorn]] card 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 [[OurVampiresAreDifferent the baron]] knows of one."
* ''TabletopGame/DungeonsAndDragons'' TabletopGame/ForgottenRealms setting: In order to create the Tome of the Unicorn (which was made of metal plates), a wizard named Shoon killed 12 unicorns and bathed the plates in their blood. This was considered an especially evil act in a world where evil deeds are quite common.
** The same setting also gave us demonically tainted Black Unicorns, created by magically corrupting unicorns to the cause of evil.
* ''TabletopGame/{{Ravenloft}}'' includes Addar, a unicorn whose pride and hostility to the traditional act of being ridden by a virginal elven maiden led to his seduction by a female [[HellishHorse 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.

* Killing a unicorn of your alignment in ''VideoGame/NetHack'' incurs a sizable penalty to your LuckStat. ''Sacrificing'' a unicorn of your alignment (whether or not you killed it) will [[BoltOfDivineRetribution 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).
* Justified in ''VideoGame/{{Overlord}}''. The whole forest is tainted by evil, to the point the unicorns have become crazed [[AscendedToCarnivorism flesh-eating]] killers, and you can (and should) mercy-kill them.
* Averted in ''VideoGame/TalesOfSymphonia'', where, even though you have to kill a Unicorn to get its horn to heal someone, the unicorn 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.
* In ''VideoGame/PokemonBlack2AndWhite2'' the Legendary Pokemon Keldeo is more or less a unicorn, and the backstory behind it certainly suggests that some disaster occured when it was hurt.

* Inverted in ''Webcomic/TheAdventuresOfDrMcNinja'': The doctor's motorcycle is a transformed EvilOverlord unicorn.
* In "TheAdventuresOfGynoStar" 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 ''ChasingTheSunset'', one character is under the Forest Spirit's eternal disapproval because he put a curse on a unicorn, in ignorance.

* The [[http://www.thinkgeek.com/product/e5a7/ canned unicorn meat]] as sold by ''Think Geek'' is clearly playing with this trope.

* In [[http://www.youtube.com/watch?v=ixzhgsY6lQY this]] ''[[TheSimpsons Simpsons]]'' couch gag, the workers manufacturing the Simpsons merchandise are depicted as miserable slaves made to work for cruel masters at Fox. There is a unicorn chained up in the underground sweatshop, looking malnourished and unhappy.
** In another episode spoofing Adam and Eve, God is '''not''' pleased when he sees that his Unicorn has ventured outside the Garden of Eden and died as a result.