Since the dawn of storytelling, many fictional works have dealt with sex and sexuality, whether as a way to titillate or a way to introduce drama or comedy. It has also been used as a normative trope to highlight or reinforce sexual morality: a good character or protagonist adheres to the sexual mores of their society, while an evil character or antagonist is a sexual deviant. The relationship between evil and perversion can go both ways: their sexual proclivities can merely be a reflection of how twisted their psyche is, or it can be the motivation for them to do evil.
Historically, "good" sexuality usually meant a monogamous, religiously-sanctioned relationship between two heterosexual cisgender adults. Anyone whose sexual activities venture beyond this are seen as morally reprehensible, if not a physical danger to themselves and others. This has often been an Enforced Trope — whether due to actual laws, industry standards like The Hays Code, or a simple chilling effect from the culture, it would be impossible for media creators to depict things outside the sexual norm as anything but negative.
This is also an Evolving Trope, as sexual mores shift throughout history and the Values Dissonance grows with time. For instance, the legal and social taboos regarding child marriage and first cousins marrying have become far stricter in the past few centuries, while those regarding premarital sex, homosexuality and polyamory have become far more relaxed. The DSM's definition of paraphilia
included homosexuality and masturbation for much of the 20th century, classifying them as unhealthy psychological aberrations instead of normal expressions of sexuality; the definition of paraphilia has since been narrowed to sexual habits that are debilitating or directly harmful to themselves or others around them. Even kinks well outside the mainstream, such as bondage and BDSM, are more likely to be portrayed in modern times as a Casual Kink instead of evil and demented — as long as it's Safe, Sane, and Consensual, that is.
Compare Heteronormative Crusader. Compare and contrast Sexual Karma, where heroes are depicted having pleasant sexual encounters and villains have unpleasant ones, and Sex Is Evil, where any and all depictions of sex in a work are portrayed negatively. Contrast Chivalrous Pervert, Lovable Sex Maniac, Ethical Slut, Hooker with a Heart of Gold, and Good Bad Girl. See also Bastard Bastard and Inbred and Evil for how breaking sexual taboos can have negative consequences in fiction.
Related to These Tropes Are Evil and Sexy, wherein villains themselves are sexualized.
Tropes:
- All Gays Are Pedophiles: Homosexuality is depicted as inherently pedophilic and predatory.
- Bestiality Is Depraved: Having sex with animals is taboo.
- Bondage Is Bad: Bondage and BDSM participants are depicted as evil.
- Corrupting Pornography: Porn is morally corrupting to people who create or consume it.
- Creepy Crossdresser: An evil or disturbing character who crossdresses.
- Defiled Forever: A person is permanently tainted by the sin of extramarital sex.
- Depraved Bisexual: An insane or unhinged character's sexuality has no bounds.
- Depraved Homosexual: A villain who is openly homoerotic and flirtatious.
- Eunuchs Are Evil: Eunuchs (castrated men) are portrayed as villainous plotters.
- Fetishes Are Weird: Characters with kinks are viewed as wrong in the head.
- Flaming Devil: Devils and demons are depicted as effeminate, if not outright gay.
- Gayngster: A gay criminal or member of a criminal organization.
- Gorgeous George: A pro wrestling heel whose theme is being effete and Ambiguously Gay.
- I Have You Now, My Pretty: A villain intends to rape or molest their captives.
- I Love the Dead: Having sex with a corpse is taboo.
- Jailbait Taboo: Having sex or sexualizing teenagers is scandalous or evil.
- Lesbian Vampire: Evil, corrupting vampires are also lesbian temptresses.
- Literal Maneater: A sinful seductress who murders and devours her partners.
- Lousy Lovers Are Losers: An unlikeable or flawed character is also bad in bed.
- Madonna-Whore Complex: Chaste women are associated with virtue, while promiscuous women are associated with sin and vice.
- Murderers Are Rapists: A murderer is also a sexual predator to underscore how evil or depraved they are.
- My Girl Is Not a Slut: Female promiscuity is seen as an evil and shameful act (not male promiscuity, though).
- No Love for the Wicked: An evil character defined by their lack of romance or sexuality.
- Pædo Hunt: A villain is a pedophile or child molester.
- The Peeping Tom: A voyeur who enjoys spying on sexual situations without victims' knowledge.
- Predatory Prostitute: A villain or evil character who works as a prostitute.
- Psycho Lesbian: An evil or insane character defined by her homosexuality.
- Rape Is a Special Kind of Evil: Rapists are portrayed as far more evil and abhorrent than other kinds of criminals.
- Robosexuals Are Creeps: Attraction to robots and machines is taboo.
- Royal Inbreeding: Brother–Sister Incest and/or Parental Incest within a noble or royal family, often resulting in The Caligula or other forms of Royally Screwed Up.
- Self-Abuse: Masturbation is portrayed as physically or psychologically harmful.
- Sissy Villain: A G-rated version of the Depraved Homosexual.
- Succubi and Incubi: Demons associated with excessive sexual desire.
- Unsexy Sadist: A sadist who comes off as creepy or disturbing.
- Villainous Incest: A villain who is sexually attracted toward their own family members.
