Psycho Lesbian

""Oh! You can pile-drive me next Miss Kirie!""

For years an unfortunate cocktail of censorship and bigotry made lesbian characters on screen psychotic and villainous. Hays Code-era requirements that villainous and controversial characters be suitably punished meant that such characters would almost inevitably be toast before the credits rolled - and this convention has persisted long after the demise of the Code itself.

This trope can sometimes carry uncomfortable subtext: go straight or go crazy. Or at least have the decency of being bisexual so you can be of proper use for men.

The Psycho Lesbian will often be a villainess for a Hide Your Lesbians couple; two women who care for each other but don't actually say it out loud.

See Depraved Homosexual for the male equivalent. See Heteronormative Crusader for when another character consider a lesbian to be psycho simply for being lesbian. See also Love Makes You Evil, Love Makes You Crazy, and Yandere for more general tropes that are closely related.

Anime & Manga

 * Kagari from Black★Rock Shooter.
 * Semmerling from Riding Bean. Add to that the fact that she's a shameless pedophile and a Manipulative Bastard (maybe even a Magnificent Bastard; she also displays elements of The Chessmaster and may be a sociopathic example of The Trickster), and she's well on her way to fitting every negative stereotype of the screen lesbian.
 * Shirai Kuroko from To Aru Majutsu no Index and To Aru Kagaku no Railgun. However unlike most examples, Kuroko is a heroic use of this character type, who spends half her time stalking/fondling/trying to seduce her Mikoto-Onee-Sama and the other half being a Reasonable Authority Figure / Little Miss Badass.
 * From Mahou Sensei Negima, we have secondary villain Tsukuyomi. She starts as a mere Punch Clock Villain with shades of Psychopathic Manchild and a crush on her ex-sempai Setsuna Sakurazaki, but as time passes, she becomes really, *really*, creepily obsessed with Setsuna. And also seems to derive sexual pleasure from murder. And... well, just LOOK.
 * The previous chapter has a more obvious example here (where her left hand is halfway down the page doesn't help her case).
 * More to the point, she's also probably the only villain in the series who's totally evil with no Anti-Villain tendencies or Freudian Excuse for her actions, which just makes her even creepier than most other bad guys.
 * The series also uniquely avoids any Unfortunate Implications about homosexuality because her target Setsuna has been in the Transparent Closet all along, and is one of the most popular, competent and genuinely kind characters.
 * It's been hinted recently in Ch. 290 that she may have "interest" in Negi and Fate in addition to her well-known taste for Setsuna (and, to a lesser extent, Konoka and Asuna), making her a Depraved Bisexual instead of, or in addition to, this trope..
 * Played for laughs with Anna from He Is My Master.
 * Dark Action Girl Rimelda Jorg from Madlax. Again, contrast with Madlax's other potential love interest, Vanessa.
 * The results of My-HiME's Wham! Episode altered many characterizations, including the kind and serene Shizuru who went a bit nuts near the end.
 * Mai-Otome itself had one in Tomoe. While most of the Coral Otomes loved Shizuru and looked up to her as a heroic figure, Tomoe was actually in love with her, and at one point attempted to kidnap and seduce her (in a decidedly creepy fashion). This, coupled with her mean-spirited attitude toward some of the other characters had turned fan support against her, though an attempt at a comedic makeover of her character in Zwei (similar to the one Shiho received in her transition from My-HiME) tried to soften the blow somewhat.
 * Ryofu Housen from Ikki Tousen skirts this trope, though she can also be seen as a female Depraved Bisexual. Slightly subverted, as her girlfriend Chinkyuu is the one who brings up her Pet the Dog moments.
 * Kan'u Unchou almost ended up as one of these, what with her devotion to Ryuubi being taken to extremes in the third series. She did not, fortunately, as it only happened because she was kind of Brainwashed and Crazy due to an amulet that goes to extract her deepest desire that thus far she managed to hide. After the hijinx, her relationship returned normal.
 * Mylanda Arker Walder from Battle Athletes.
 * From GaoGaiGar FINAL we have one of the 11 Soul Masters, Pillnus. She takes a special...interest in Renais/Renee, loving beating her in combat and putting her into...compromising positions. It's even implied she raped her.
 * Ran Asuka from Devilman Lady, who discovers and largely manipulates the lead character Jun Fudou, seems to be attracted to her, or at least her superpowers.
 * Goldie Musou from Gunsmith Cats.
 * Yoko from Hana no Asuka-gumi.
 * Mika from Kyoshiro to Towa no Sora.
 * Ophelia from Claymore.
 * Nina Einstein of Code Geass, the cast's resident Meganekko and racist who instantly falls head over heels in love with Eupehemia after her life is saved by the princess, so much so that she masturbates to pictures of Euphie using the edge of a table. After, the girl really becomes unhinged, enough to let Prince Schneizel recruit and manipulate her into becoming a part of a research project that creates a nuclear weapon to wipe the Japanese race from existence.
 * Part of the reason is she makes some of the most disturbing facial expressions ever...of all time
 * B-Ko Daitokuji from Project A-ko is a textbook example. While she is never explicitly called a lesbian, her affection for C-Ko clearly goes way beyond "pure affection," and sends her into increasingly over-the-top jealous rages against A-Ko, eventually involving military-grade weaponry and an invading alien armada (even though A-Ko and C-Ko's friendship is clearly only platonic, a point which is utterly lost on B-Ko.) For their part, A-Ko and C-Ko's relentless failure to acknowledge or even notice B-Ko's crush is probably a contributing factor in B-Ko's rage spiral. By the last two movies in the original setting, though, she could be called a "Psycho Bisexual", as she immediately "falls in love" with the same handsome biker that A-ko has her heart set on. Of course, that could just be her taking rivalry to the extreme, and/or reflect her intense envy of A-ko. Ironically, her dimensional counterpart in the "Vs." OAVs is nothing like her, and is even on fairly good terms with her dimension's version of A-ko.
 * Magic Knight Rayearth II has the delightfully bipolar (dementedly schizo might be a better descriptor) and certifiably psychotic Nova, whose switch every few moments from sweet and childish declarations of affection to a raving engine of powerful magical destruction can be a bit jarring. Although the circumstances of her consuming longing for Hikaru and the origin of both her and her madness are rather unique and in her own case most likely constitute use of this trope as a justified one.
 * Asami Hoshino from Myself Yourself, who was so in love with Shuri that she ended up causing the very object of her affection to leave. Though not before defending her from an Ax Crazy old lady.
 * Shiori in Witchblade, although her Phlebotinum Breakdown may have helped. Then again, she was a bit messed up to begin with.
 * Chikane Himemiya in the Kannazuki no Miko manga.  Though it can be argued that   Not to mention the Unfortunate Implications about how she's so Easily Forgiven and even idolized by fandom for such actions... likely just because she's a woman and Girl-On-Girl Is Hot.
 * Subverted to a point in Cynthia the Mission. Big Bad Cybele is a cruel, evil sociopath who will has a tendency for cutesyness and being generally cheery and nice when she's not killing. She's also a lesbian, but there's nothing psycho about it.
 * Also a subversion from the same manga, Takaya Kanae is a sweet, kind, gentle schoolgirl who has kissed more then a few girls in her day. Not psycho at all by any means... until you get to her alternate personality, Shii, who is a psychotic, evil man who will do anything to protect the innocent Takaya, while leaving her mostly unaware of his protection.
 * In Suzumiya Haruhi, fourth book,  seems to have somewhat Psycho Lesbian tendencies towards
 * She even waits for her at the school at 4:00 AM!
 * And in the anime she seems even worse, sprinkling  with blood from her knife as she dances around in front of her...
 * Kasumi Kisaragi, the vice-president in the 2006 version of Kujibiki Unbalance, especially in the manga adaptation, where she tries to kill Chihiro when a love potion causes her to be attracted to him.
 * Rio in Gamerz Heaven ...she doesn't seem to have any sanity whatsoever when it comes to Kyouko.
 * from Fushigi Yuugi is speculated to be one of these for . "I couldn't find a place between you and  ", indeed!
 * Played for laughs with Chizuru Honshou of Bleach. Two words: "Karakura Raizer!" She is very disturbed in many ways which is best depicted when she asks what a little girls cup size is.
 * Sui-Feng is often accused of being one. Specially by the most rabid Urahara/Youichi shippers.
 * Rukia's younger sister Homura from the third movie. She wanted to kill all the Shinigami to keep them from coming between her and Rukia.
 * Possibly Yoshi from the Bount arc in the anime as well. She's Ax Crazy, seductively calls Rukia cute and says that Rukia's cuteness is making her excited, invades Rukia's personal space when trying to kill her, and appears to try to slash Rukia's robe/take off Rukia's robe with her sword.
 * Dark Action Girl Drei  with a gun.
 * Liang Qi in Canaan.
 * Kosame in Girls Bravo. Her actions towards Kirie are played up as comedy.
 * There is also Hijiri the kids teacher who turns out to be working for the series Big Bad and after fighting Kirie develops a similar attitude towards her. Before that it's mentioned that Hijiri had been obsessed with Miharu since childhood.
 * Nami in Aki Sora. She starts out with a Matchmaker Crush involving her best friend Kana and her brother Sora, but after the date she set them up on went far beyond her expectations, she.
 * Sousou from Koihime Musou is a borderline case. Sure, she gets presented relatively sympathetically as the series progresses, but not before forcing one of her subordinates into sex with her and trying to do the same with Kannu.
 * Never mind that her subordinate is more than happy to comply with the "forcing...", though Kan'u only accepts a Sousou's proposal under duress.
 * The second season of Darker than Black has Mina Hazuki, a.k.a. "Japanese Lesbian Catwoman". She's a Contractor who Does Not Like Men and shows absolutely no respect for the personal space of her female teammates, who she constantly hits on. The "psycho" comes from a combination of the usual Contractor Lack of Empathy and a Stalker with a Crush attitude towards Kirihara.
 * Actually, even though she's extremely forward at first, she takes being rejected by Kirihara fairly well, all things considered.
 * In Kämpfer, the Big Bad,
 * Mnemosyne has Sayara and Laura.
 * Miharu from Baka to Test to Shoukanjuu is crazily in love with Minami. Her solution to anyone who happens to get between her and Minami is to try to Murder the Hypotenuse.
 * Kokoa from Rosario + Vampire is utterly obsessed with the vampire side of her half-sister Moka.
 * Akuha of manga season II is revealed to be one of these for Moka.
 * Double subverted with Suruga from Bakemonogatari who is dangerously in love with Hitagi. She is actually a perfectly pleasant person, even to Koyomi, her crush's boyfriend. But she unconsciously wishes that Koyomi would disappear, and when the sun goes down her demonic hand takes control over her and tries to grant her wish, which means trying to beat Koyomi to death twice. There's also the fact that she starts stalking Koyomi after he hooks up with Hitagi.
 * from Bondage Fairies Extreme. There's more to her than that, though.
 * Zombie Loan: The school nurse from the first two episodes, also Koyomi's "other" personality Yomi has a definite fondness for groping Michiru's breasts and attempting to molest her. Though the Ass Pull-ed its way out of this one by saying that
 * Pretty Face: Nozomi would go to great lengths to get Rando (as Yuna) into her bed.
 * Venus Versus Virus: Sumire, in Berserker mode! It's a little bit subtle as she is violent with the Viruses and more sexual (in a rape sort of way) with Lucia, as at one point she says they should "become one."
 * Also, Lucia appears to be this in the anime, when she stakes Sumire's boyfriend.
 * from Umineko no Naku Koro ni. An odd example because they're a couple.
 * W Juliet: Nomura Tsugumi, Ito's senpai by one year, doesn't make it a secret that she wants "Ito-kun" for herself and can sometimes behave as a Psycho Lesbian for comedy relief.
 * Mao Nonosaka from Mirai Nikki.
 * Nagasarete Airantou: Mikoto.
 * Uruka from Steel Angel Kurumi 2 for Nako. Uruka sees Kurumi as an obstacle to Nako and will try anything to remove Kurumi, even if it means asking her father to call upon the family's private army to take her down.
 * Chloe of Noir fits this, but only in her final appearance. She met the lesbian criteria the entire time, but she doesn't turn psycho until after Kirika rejects (or more accurately, fails to even notice) her advances, and then acts to protect Mireille from her, causing her to snap.
 * Reimi from Bamboo Blade has stalked Miyako from the shadows ever since the latter had brutally rebuffed the advances of the former's crush in middle school (though the two attend different high schools). It soon emerges that, rather than wanting revenge on the boy's behalf, Reimi had become enamoured with how cool Miyako looked; she even has nosebleeds when she recalls the incident. However, she's not exactly the most subtle of stalkers; during a kendo sparring session between the two schools, Reimi walks right into the dojo, claiming to be in the photography club, and spends the whole time taking pictures of the weary Miyako.
 * Rin "Clone" Yatagai towards Nao in episode 11 of Oniichan no Koto Nanka Zenzen Suki Janain Dakara ne!!!! She ends up kissing Iroha and falls in love with her instead much to Iroha's horror.
 * Kaguyahime: Although a bondage-wearer perv, Maggey is nice enough to be mostly harmless (beyond groping of strangers), and Chun-Lan is funny more than anything... but Mayu can get seriously scary.
 * Hellsing: In the first anime, a Lesbian Vampire character named Boobanshee/Bubbancy (actually a corruption of a Baobhan sith, pronounced roughly the same way in Japanese) tricks the entire Hellsing organization, save Seras and Alucard, into thinking that she is Integra's sister, Laura (a reference to Carmilla). Later, she attempts to drink Integra's blood, and even bites and licks her chest after partially undressing her, after which Integra realizes that she has no sister; shortly after Bubbancy is dispatched and Integra refers to her as Countess Karnstein (another Carmilla reference). She also licks Integra's blood from her hand after stabbing her.
 * Saki: Touka has a rather unhealthy obssession on Nodoka Nodocchi. "I'm going to lick you all over and savor this delectable favor" anyone?
 * Tactics: The yuki-onna in the first episode (When she's possessed by an aradama, anyway.)
 * Zero no Tsukaima: A Love Potion in season 3 episode 6 turns most of the girls into one of these. Also, Janette based on subtext. In the opening for the fourth season there's a part where Janette hugs a struggling Louise close and licks her face. And in episode 2 of the fourth season Janette licks Louise on the face again and practically flirts with her calling her "cute and innocent" after slashing her with a poisoned knife.

Comic Books

 * Purgatori, the lesbian vampire demon originally created by Brian Pulido as an antagonist for his main Stripperiffic heroine, Lady Death. She may actually be a Depraved Bisexual, having once been Satan's concubine, but all of the (semi-)consensual relationships we've seen have had her with women.
 * Roxy Richter from the Scott Pilgrim books. May well still be in love with Ramona and wants to cut Scott's head off. Although she's not noticeably more psycho than any of Ramona's other six evil exes, all of whom are men.
 * The Daughters of the Amazon in Y: The Last Man are frequently branded psycho lesbians by other women (they're certainly psycho, and have little use for men). Subverted in that a) we never see any lesbian behavior among the Amazons and b) discreet lesbianism (especially with male impersonators) quickly becomes the norm in a world deprived of men. One of the few openly lesbian characters simply describes the Amazons as "nutters who cut off their norks".
 * They're likely "political lesbians" - heterosexual radical feminists who "became lesbians" for ideological reasons. Many real lesbians don't like them because their stance reinforces the fallacy pushed by homophobes that homosexuality is a choice. Another complaint from quite a few real lesbians who have been in relationships with political lesbians are that political lesbians are often unenthusiastic about gay sex, which the comic is probably pointing out.
 * Inverted in the case of Victoria Hand in Dark Reign. She is a lesbian (or perhaps bisexual) and easily the most sane of all of Norman Osborn's subordinates (Osborn himself included), but that might not be saying too much when everyone else is a Psycho for Hire at best and Eldritch Abomination at worse.
 * This is the subtext to Ursula Imada's obsession with Sundra Peale in Nexus. By the time of Ursula's, it was only just barely subtext.
 * Harley Quinn and Poison Ivy in DC Comics. Mind you, their relationship with each other is probably the sanest either of them has.

Film

 * Eve Harrington from All About Eve (1950). Not outright stated, but quite explicit for the era, including a one-scene Spear Carrier whose presence is all but impossible to explain any other way.
 * In the Spanish horror film The Blood Spattered Bride (1972), a young bride, uneasy about sex with her husband, encounters Lesbian Vampire Carmilla and is seduced, and together they unleash murderous enmity toward men.
 * The Maids (1975) is all about this. Well, it has just three main characters: two are psycho lesbian Meido sisters, and the third is their mistress who doesn't look very straight or very sane.
 * Andrea Glassen from Windows (1980).
 * The evil Queen Gedren from Red Sonja (1985) seemed visibly attracted to the titular character, before said character disfigured her.
 * Serial Killer Catherine in Black Widow (1987). Though she seduces, marries and murders wealthy men (ostensibly for their money, but long past the point where she would already be rich) there's a definite lesbian subtext with the female Justice agent pursuing her.
 * Roxy from Basic Instinct (1992).
 * Hedy Carlson from Single White Female (1992).
 * Rebecca (played by Leighton Meester) from The Roommate, which is essentially a remake of Single White Female.
 * The main characters from Michael Winterbottom's Butterfly Kiss (1996).
 * from Mulholland Drive (2001) is a lesbian, and definitely doesn't have both oars in the water. Interestingly,
 * In Lost and Delirious (2001), the main character learns that her boarding school roommates are in love. Of course, one girl's family pitches a fit, and of course she goes to sleep with the first guy she sees, and of COURSE the other girl goes completely insane, chasing eagles in the woods and
 * Paulie's much less palatable in the book: She not only, but she worships King Kong and she strings (the much less naive) Mouse along much further. Her own sexuality is never mentioned, although there's a brief scene with Tori, who professes a crush on "Lewis". The older teacher is still in a forbidden romance (here explicitly stated when Paulie and Mouse find letters from the teachers), but this is better justified by deliberate Values Dissonance (the book's set in the 50's).
 * Make a Wish (2002). A group of lesbians go camping in the woods. Is the killer one of the male red herrings?
 * An alternate title for it is even Lesbian Psycho.
 * from High Tension (2003).
 * Parodied in D.E.B.S. (2003).
 * The villainess Lucy Diamond is more than willing to sink the entire continent of Australia in frustration over not being able to form an emotionally satisfying lesbian relationship. Fortunately she is redeemed by the love of an incredibly hot secret agent in a plaid skirt.
 * Lucy's blind date Ninotchka, who was clearly not all there and completely lost it when Lucy tried to back out of their date.
 * Barbara from Notes On a Scandal (2006).
 * Jennifer from Jennifer's Body (2009) can be interpreted as being romantically attracted to her best friend Needy. When she becomes possessed by a demon and starts eating people, she specifically targets boys who Needy likes or loves.
 * The sadistic Nazi Ingrid in Roberto Rossellini's seminal classic Rome, Open City. Ingrid plies her targets with luxuries like narcotics and fine clothes in order to gather information on the Italian resistance in Rome; eventually disposing of them when they outlive their usefulness. The young woman she seduces doesn't come off too well either, but she's desperate, bitter, and impoverished in war-torn Rome and is somewhat easier to sympathize with.
 * Kate's Addiction (1999) follows Kate's obsessive pursuit of former friend Sara up to and including killing anyone who gets in her way.
 * The Great Tyrant in Barbarella, even hooking the titular character up to an Orgasmmachine, planning to kill her through death by orgasm.
 * There's a downright aggressive and vicious woman at the stereotypical lesbian bar in Foxy Brown.
 * The animal liberation group/diamond thieves from Jay and Silent Bob Strike Back, according to a deleted scene and Kevin Smith.
 * Sister George from The Killing of Sister George is pretty unstable, and very possessive of her lover. There's also her predatory boss Mercy Croft.
 * Eunice from Butterfly Kiss is very much this trope; the only twist is that the girl she's obsessed with reciprocates her feelings, and they turn into an Outlaw Couple that wreak havoc in their wake.
 * Harris from Camp Blood went insane and became a serial killer after catching her girlfriend cheating on her with a man.
 * Syl and Madie from Maskhead are a sick lesbian couple who make fetish porn that always ends with the participants being slaughtered by their pet killer, the eponymous Maskhead.

Literature

 * An early example, from 1895, is Mary Wilkins Freeman's story "The Long Arm" (probably inspired by the sensationalistic media coverage of the Mitchell/Ward murder case in 1892). Here, Phoebe Dole, a terrifying, powerful, manipulative woman, has been maintaining another woman in subjection for years, and when this woman finally takes steps to leave her for a man, Phoebe bloodily murders the hypotenuse, pinning the crime with diabolical cleverness on an innocent party. She attempts to justify her crime (in a Villainous Breakdown) by saying that she's defending her domestic happiness, but this "happiness" is presented as perverted. She's described as physically monstrous as well as morally — she's the one with the abnormally "long arm" of the title — as one critic put it, "a desperate figure of lesbian evil, a hypocritical, sick, self-absorbed carnivorous flower."
 * Mary Whitaker from the Lord Peter Wimsey mystery Unnatural Death (1927); though Sayers also presents a lesbian couple in an earlier generation, Agatha Dawson and Clare Whitaker, as not psycho and as having a successful relationship.
 * In Junichiro Tanizaki's novel Quicksand (1928), Sonoko Kakiuchi, a bored, wealthy housewife, is seduced by Mitsuko Tokumitsu, who proceeds to insinuate herself into Sonoko's life and utterly wreck it.
 * Subtext in Nella Larsen's Passing (1929). The egotistical, needy, manipulative Clare, a practiced seducer, uses her beauty and charm to fascinate Irene before setting out to take over Irene's life and husband.
 * Mrs. Danvers from Daphne du Maurier's Rebecca (1938).
 * Kathryn Hulme's The Nun's Story (1956) strongly implies that the Archangel Gabriel (an inmate in an insane asylum) is one of these, not least because
 * One of these features as a villainess in the Judge Dee novel The Chinese Maze Murders (1957).
 * The first book in The Beebo Brinker Chronicles, Odd Girl Out (1957), stars Laura, who transitions from a self-loathing neurotic mess into a full-blown Stalker with a Crush who manipulates the pseudo-butch Beth into continuing a borderline Masochism Tango romance.
 * The third book has Beebo.
 * Agatha Christie had one of these as the murderer in Nemesis (1971). The lady couldn't accept her 'protege' leaving her for a man.
 * In Daemon in Lithuania (1973), some characters put on a play that contains half of all the old-fashioned clichés ever invented. Kinga is found to be pregnant, and: "Enter the Lady-in-Black. She nourished a tragic passion for Kinga, and heaped the most terrible reproaches on her head, striding up and down the stage and drawing on her long cigarette holder. Finally, she tossed it on to the ground, stamped on it, and flung herself on to her frivolous friend's couch, intending to strangle her..."
 * Andrea from The Zone series (1980 - 2007) of World War III novels by James Rouch, is certainly (psychopathic if not psychotic) and is widely assumed to be a lesbian by the other soldiers because of her contempt for men. Eventually however she forms a sexual relationship with Major Revell.
 * One of the more uncomfortable subplots of Tom Clancy's The Cardinal of the Kremlin (1988) features a American female rocket scientist who essentially hands her male co-worker over to the KGB in order to (clumsily) attempt to seduce the guy's wife. Nice job bringing up the old "all gays are potential traitors" trope, Tom.
 * in Affinity (1999) by Sarah Waters.  Perhaps an attempt at deconstructing this trope, by putting it in a social context. The protagonist of the book, whose lesbian impulses are tightly repressed, is mentally disturbed in other ways.
 * It's also worth remembering that . She only seems less culpable because , and neither is exactly an unbiased observer.
 * in Val Mc Dermid's The Torment of Others is a particularly nasty example who
 * in Beyond Varallan, the second book in S.L. Viehl's Stardoc series, not only exemplifies the trope but manages to be the first person in her planet's known history to have homosexual tendencies at all.
 * Lisbeth Salander is portrayed as this by the Conspiracy attempting to discredit her in The Girl Who Played With Fire.
 * Robert Westall's Futuretrack Five has a mild parody; Dronfield Biological Warfare Research Centre is staffed entirely by female Techs. All of the male Techs believe them to be Psycho Lesbians.

Live Action TV

 * An episode of Law and Order SVU had an "aggressive" (it's a subculture) lesbian accused of killing her girlfriend
 * Subverted in Heroes
 * "Daddy" from Prison Break: The Final Break.
 * Mickie James from WWE started out as Trish Stratus' psychotic lesbian stalker.
 * It's interesting to note, that unlike many of the other examples, Mickie James was embraced by the fans. It helped that along with being a genuinely talented woman, she was funny in the role and likable.
 * In the episode "Good Night, Dear Heart" of Quantum Leap, Sam tries to determine the cause of death of a young woman who was apparently drowned.
 * In the NCIS second season episode Conspiracy Theory the killers turned out to be two women who had been committed to a mental hospital and where they now have sex with each other. In other words they were literally Psycho Lesbians.
 * The show actually had a few other cases with Psycho Lesbians during the first 2 seasons; Un SEA Led involved a man who was falsely convicting of murdering his wife. The real killer who turned out to be her lesbian lover, who was married to another SEAL.
 * The other was Lt. Jane Doe, where a lesbian petty officer killed and raped her lover and then implanted semen from a old cold case into her so they would think the rapist had struck again. It probably would have worked if they hadn’t figured out the original rapist's identity. (In a bit a Contrived Coincidence he had just gotten out of a Canadian prison a month before and moved back to Virginia). It turns out he had died a few weeks before the murder. Since the second season ended, their problem with Psycho Lesbians seems to have disappeared.
 * Legend of the Seeker has one in
 * Lydia Hart on Hollyoaks. After being dumped by Sarah, she sent dead flowers to herself pretending they were from her ex-girlfriend Charlotte, making Sarah get back together with her out of pity. Not long after that she tried to murder her love rival Zoe during a skydiving holiday by sabotaging her parachute, but the parachutes were handed out in a random order and Sarah was killed instead.
 * Several characters of Cutie Honey The Live. The title character, Honey, is lusted after by another female main character, Yuki. Yuki gets extremely jealous and posessive although they never develop a romance, her insanity builds up to the point where she becomes the main villain. Additionally, another main character, Miki, initially appears to be somewhat insane (introduced in a prison, then slaughters a bunch of men attacking the prisoners; proceding to become a hero until her death, only to be brought back to life, only to be merged (in the midst of a lot of lesbian subtext) with Honey to help her defeat the Psycho Lesbian villain Yuki. That's not all, however; Mayumi, a sadist teacher who likes to perform an ambiguous lesbian sex act involving raw eggs on her students, develops a passionate attraction towards Miki, whilst fighting the heroes throughout the series. In the end, in Miki's last moments, she finally shares a kiss with her.
 * Smallville: Tina Greer, Lana's only lesbian Stalker with a Crush of the Week.
 * "Somebody's Watching," an early episode of Criminal Minds had  She confronts Lila and Spencer at gunpoint in the end, furious because Lila and Spencer are attracted to each other.
 * The murderer in one of the season 5 Psych episodes.
 * Which is also a case of Nobody Over 50 Is Gay.
 * The Dresden Files a couple of times.
 * Admiral Cain from the new Battlestar Galactica is implied to be in a romantic relationship with Gina Inviere, the Number Six assigned to the Battlestar Pegasus. Which does not help Gina one iota when she is revealed as a Cylon.
 * In Buffy the Vampire Slayer, Willow's paramour Tara is murdered by Warren and she goes APESHIT!!!, sucking magic power from a variety of sources until she is the most powerful witch on the planet which, after flaying Warren, she then takes steps to destroy, thanks to a Combined Energy Attack from Giles. Cue Buffy to avert another apocalypse.
 * Her vampire doppleganger fits this trope like a glove. Psycho? She treats burning Angel alive as a form of sex. Lesbian? She's on both guys and girls, so hell yeah this fits.
 * The ITV Miss Marple adaptation of The Body in the Library actually changed the identity of the killer from Christie's original plot in order to cater to this trope.
 * Carmen on South of Nowhere is supposed to be portrayed as this but the worst thing she does is push Spencer into a wall by accident when fighting over the fact Spencer still has feelings for Ashley and immediately apologizes for it. She is popular in the fandon, not with Spencer but many people prefer her with Ashley's sister Kyla
 * Penelope Taynt of The Amanda Show.
 * On iCarly, Missy is believed to be this and some people also view Sam as one as well.

Music

 * One possible interpretation of PJ Harvey's "Catherine", where a woman is singing about her envy and anger towards the titular character, and even plans to murder her current lover.
 * The unnamed narrator in Sound Horizon's "Baroque" seems to have been a fairly nice girl (if shy and socially awkward) until she fell in love with another girl and proceeded to push said girl down a flight of stairs for rejecting her.
 * The video for Amanda Palmer's "What's the Use in Won'drin?" seems to be setting up a story of a battered wife who's secretly in love with a female friend until the last thirty seconds or so, when it makes a distinct turn for the darker.

Theatre

 * The Miracle Worker alludes to Psycho Lesbians existing in the asylum : "The asylum? [...] There were [...] some of the kind that keep after other girls, especially the young ones."
 * Inez in No Exit is a lesbian, and she's open about living for the pain of others, but her orientation seems fairly incidental to her character.

Video Games

 * A really good example of this is the antagonist  from Rule of Rose. It turns out that she was the mastermind behind all the tormenting and torture of Jennifer, including the execution of  . All of this was apparently   Unfortunately, the last one was what brought Jennifer over the edge. However, it's hard to call foul when pretty much everyone in that orphanage was nuts.
 * Amongst the Ax Crazy bosses of Dead Rising, Jo Slade stands out. A sadistic police officer who brutalizes young women, she was one of the creepiest enemies in the game.
 * Hirasaka Hatsune from Atlach=Nacha absorbs energy by having sexual intercourse with people or eating them. She prefers females for sex and males for eating. If you piss her off, she will tear you apart before devouring you...all with a smile, too.
 * Claudia Wolf of Silent Hill 3, possibly. She seems to be obsessed with Heather, or rather with Alessa, in more ways than one.
 * Played for Squick in Haunting Ground, the (technically) asexual Homunculus  could qualify. Insanely jealous of Fiona's , she gropes her in her sleep before breaking a window with her own forehead to get a piece of glass sharp enough to dismember the girl.
 * The Interactive Fiction game The Blind House has heavy subtextual hints at an attraction between its two main characters, Helena and Marissa, and both of them are clearly pretty unstable in different ways—but especially Helena, who has just killed a woman who is implied to have been her lover. What really takes it into this trope's territory, though, is The Reveal that, and the fact that in one possible ending,.
 * Inverted in A Dance With Rogues, in which the lesbian characters tend to be nicer.

Web Animation

 * Yukari and Yuyuko from Touhou Project are like this in the 18+ version of the IOSYS fan video Border Of Extacy. For general safe for work principles and even sanity, a link shall not be provided. (A search on YouTube will not reveal this video but will reveal the other version of the video)

Webcomic

 * Gail Swanson, the Villain Protagonist of When She was Bad.
 * In A Day of Lucy, It is likely from this strip that Natalie is one.
 * In YU+ME: dream Sadako is a pretty perfect example. That being said, other characters provide more positive depictions of homosexuality and bisexuality.
 * Lemon and Lime from Evil Plan. The inseparable supervillainesses refer to each other as their "wives," and while they seem to be happy and perky, the right conditions are all that needed to let the unsettling mania show...
 * One of Vanessa's exes in Something*Positive, whom she left for casting aspersions on her bisexuality once too often, apparently still calls her, begging to get back together while calling her "whore."
 * Yuki, from "Ménage à 3", both figuratively and literally. Not only does she have a brain disorder where she sees all male sex organs as "Naughty Tentacles", but she has repeatedly attacked said "Naughty Tentacles" with the intent of utterly destroying them. She constantly turns the protagonist Gary's life into a living hell, forcing him to make out with his gay roommate and blackmailing him into helping her illustrate a manga. Yuki seems to be inching toward bi in recent strips, though, and has become somewhat friendlier.

Web Original

 * Diamanda Hagan. Played for Laughs.
 * Lyn "Laeil" Burbank of Survival of the Fittest's third version. After confessing her love to a female friend, she gets bullied by her classmates for being a "dyke". Once she gets on the island, she kills her cousin (who was one of her major bullies) by stabbing him in the groin repeatedly. Afterwards, she decides that she was going to die anyways, and that she was going to get revenge on everyone who ever bullied her.
 * Reiko Ishida in version 4 likely qualifies as well, rather quickly abandoning any pretense of possessing a conscience. Her sexuality and sociopathy seem largely unrelated, however. In fact, in a way it's subverted; she seems to genuinely care for her girlfriend Sarah Xu, and after a bit of Character Development starts to be concerned about what she thinks of her actions.
 * Missy from The War Comms. At first she was just a lesbian who happened to be a psycho, then a psycho who happened to be a lesbian. Then she started making some suggestive comments about Esmeralda and Trisha, whom she claims to despise and, well.