Eunuchs Are Evil

""Why is it no one ever trusts the eunuch?""

- Lord Varys, Game of Thrones

So you've got a villain and you've got to give him a Right Red Hand, and your protagonist is the manliest of men. So, why not make your villain a Foil and remove his male organ? Especially prevalent in fantasy, the Evil Eunuch is simultaneously creepy and effeminate, which makes him an obvious villain. Eunuchs are also more snakelike. A subtrope of Sissy Villain. Eunuchs tend to be Evil Chancellor types. Comes out of Confucian historians' bias against Eunuchs in Chinese Culture.

Anime & Manga

 * The High Eunuchs from Code Geass, Evil Chancellors who betray the Chinese Federation for personal gain.

Card Games

 * The Magic the Gathering expansion Portal Three Kingdoms has a card called Corrupt Eunuchs.

Film

 * Donnie Yen plays one in Dragon Inn.
 * Evil Eunuchs are a Hong Kong cinematic tradition. If the movie has a fantasy bent, expect the eunuch to be some flavor of Evil Sorcerer.
 * Butterfly Sword
 * A Touch Of Zen
 * Amber Sweet's psychologically-neutered valets from Repo. They've still got their... ahem... parts, and are traditionally masculine-looking beefcakes, but have had their sex drives obliterated to the point of incapability.
 * Heroic Trio plays on the Chinese myth of eunuchs being evil, mystical beings.
 * Jonah King from Drive Angry was literally emasculated before the film begins, and he heads a Satanic cult. The heroes spend the whole movie calling him "Dickless."
 * The villain in Orgazmo is blasted with the orgazmo ray so many times in the "climax" of the film that he returns in the epilogue for a Sequel Hook, proclaiming himself to be eunuch, and thus immune to Orgazmo's weapon (just like the villainious character they created in the movie-within-a-movie to bump off Orgazmo's character).
 * Possibly averted in Curse of the Golden Flower, where the court eunuchs and servants side with the Empress and the coup against the Big Bad.
 * 14 Blades features a particularly powerful Court Eunuch, Jia, as one half of a Big Bad Duumvirate.

Literature

 * Varys, the eunuch spymaster from A Song of Ice and Fire, has traits of this, but it's unclear if he's really evil. While he'll gladly stab anyone in the back, he tells Ned that he'll do anything to keep the realm relatively stable, as the last thing he wants is a repeat of the last war and all its casualties.
 * In The Belgariad, the kingdom of Nyissa seems to have a lot of evil eunuchs. However, in the sequel, The Mallorean, one such eunuch is a good guy anti-hero who joins the protagonists.
 * While perhaps not fitting the spirit of the trope, The Elenium contains perhaps the ultimate literal example: the Elder God Azash, a eunuch who is essentially the personification of evil.
 * Not quite a eunuch, but Darken Rahl from The Sword of Truth series is implied to have a serious scarred, nearly burnt-off penis. But it's damn close.
 * In the first chapter of The Years of Rice and Salt, a character is made a eunuch and eventually becomes one of the high ranking ones in ancient China. He wasn't out-and-out evil, but pretty close.
 * Evil Eunuchs have been a staple villain in China for centuries--the trouble started in the Latter Han period, where the Emperor would end up in a power struggle between his relatives and the imperial court, and the eunuchs who served him would be trusted with state secrets. (Romance of the Three Kingdoms chronicles such a power struggle that sees Dong Zhuo rise to power.)
 * Inversion. In The Emperor's Winding Sheet by Jill Paton Walsh the most admirable character was a Byzantine Eunuch.
 * Another inversion. In The Janissary Tree by Jason Goodwin(and sequels), The Hero is a nineteenth century Ottoman Eunuch who solves crimes.
 * This is a given in the world of the Judge Dee novels; 'The necessary but horribly dangerous source of evil in every palace!' And yet he clearly feels a certain respect for the Chief Eunuch in Necklace and Calabash. It's mutual.
 * The Alexandrian palace cabal in the Masters of Rome series.
 * Biblical Inversion; the first Christian convert from Ethiopia was a Eunuch.
 * Narses is an Anti-Villain in the Belisarius Series. While a traitor and an assassin he is not particularly sadistic and has some claims to being an Only Sane Man. Interestingly he is not shown as effeminate; he is certainly more traditionally manly then the Vile One except in the strictly biological sense that the later has slave-girls as his favorite entertainment, while residing in his mobile palace so far to the rear of the battlefield as not to be in any danger. An entertainment which Narses is incapable of should he have been inclined to stoop to it.
 * Narses is a good-guy and the protagonist's mentor in Gillian Bradshaw's The Bearkeeper's Daughter. He himself says, 'When men curse eunuchs they make an exception for me.'
 * Mary Renault's The Persian Boy is a definite subversion. The narrator and protagonist is Bagoas, who was forcibly castrated at a young age and became the lover of both King Darius of III of Persia and, later, Alexander the Great. From the outside he might seem like a scheming eunuch, but because we see everything from his perspective and are privy to his train of thought, he becomes a very sympathetic character.
 * Renault took his story right out of the history books. To complicate matters, King Darius had had a Grand Vizier also called Bagoas, who was this trope to the hilt.
 * So very very inverted with Sazed in the Mistborn series, who is probably the nicest character among all the main characters of the series, and then.
 * Played With in Everworld; Hel's harem-city is guarded by eunuchs, but one of them purposefully slips Jalil a hint that, which helps them escape.
 * Somewhat subverted by Count Hasimir Fenring in Dune, he's a scheming member of the imperial court who may have poisoned Emperor Shaddam's father. But when ordered to kill Paul he refuses

Tabletop Games

 * The 3rd Edition Dungeons and Dragons: Oriental Adventures book had a Prestige Class based entirely around this trope called the Eunuch Warlock. Being evil is a requirement.
 * The Eaters of the Lotus from Feng Shui, an entire cabal of evil eunuch sorcerers.
 * Evil eunuchs (sorcerous and otherwise) also show up with some frequency in Martial Arts adventures in Hong Kong Action Theatre.

Theater

 * While it's nearly impossible to figure out what they're really thinking, Koby and Loby probably count as this in The Visit, since it was those two who decided it would be hilarious to set a vicious panther on the town of Guellen.

Video Games

 * Near the ending of Quest for Glory II, the hero must sneak past several eunuchs to get into the palace at Raseir - while not explicitly stated to be evil, they're Mooks of the very evil dictator who you're trying to overthrow, and if they see you it's game over.
 * Suwonkas from Utawarerumono not only a VERY creepy Sissy Villain of the highest order, he also

Strangely, even given the above, he gets an in-universe Alas, Poor Villain from the woman that he went Yandere level Love Makes You Crazy for, as she says, despite what she did to him in the above spoiler "she never really hated him."
 * Salazar from Resident Evil 4.

Real Life

 * Real Eunuchs were as good and evil as any other courtiers and no more inclined to plot than anyone else in a Deadly Decadent Court. Some were trusted and loyal servants. Byzantine Eunuchs were not slaves, but were often commoners who had been given The Procedure at their parents' request in the hope that they would have a good career. The Real Life Narses(not the fictional one), was a Four-Star Badass who conquered large parts of Italy for the Emperor Justinian.
 * On the other hand, Poul Anderson lists a Byzantine saying in one of his historical novels about Harald Hardrada to the effect of, "If you own a eunuch, kill him; if not, buy one, and then kill him." Though another character immediately responds that, were such a thing done to him, "I might make of my life one long revenge."
 * The Ottoman Turkish sultans frequently used eunuchs as assassins and executioners. Likewise, the harem women often plotted with eunuchs to kill the rival harem women's sons in order to enhance their own sons' chances on becoming the next Sultan. Unfortunately, those women themselves very often ended up stuffed in bag and thrown in the Strait of Bosphorus by those same eunuchs...
 * The usual method of execution in Ottoman Turkey was strangling the convict by a bowstring.
 * While Eunuchs are generally associated with oriental courts they were known in Europe as well under the term castrati. In this case they were valued for their boyish voices rather then their inability to breed and made part of classical orchestras that would play before several monarchs including the Pope. Several noted opera singers were this.
 * Here's some sound recordings of the last castrato, Alexander Moreschi. Not exactly his best work, but you can get some idea. Castrato voices are often described in contemporary accounts as eerie, unreal, bizarre, but beautiful. They had Michael Jackson-like fandoms. A choir of these gentlemen were part of the orchestra at Napoleon's coronation; their voices were so powerful as to drown out a nearby harp orchestra and three-hundred member choir of "normal" voices.
 * China has its share of evil eunuchs; and the Ming Dynasty is practically full of these. This was because the system gave the emperor dictatorial powers, but the later emperors may not be competent enough to use these powers himself and often uses eunuchs as their proxy. Wei Zhongxian, the most infamous of them all, even tried to deify himself.
 * Ming Dynasty subversion: Admiral Zheng He, loyalist, explorer, and commander of a gigantic treasure fleet.