Belarus from Axis Powers Hetalia has an unreturned Yandere crush on brother Russia. She doesn't react very well when Russia tries to get her to leave him alone. Meaning she tears out his doorknob and stands in the doorway with an insane look on her face telling him that they need to get "married"...
One Piece: Vander Drecken responds very badly to Princess Shirahoshi rejecting his marriage proposals, leading to a very bad case of If I Can't Have You. Subverted when it's revealed he only wanted her for her ability to control Sea Kings.
Goshuushou-sama Ninomiya-kun: Inner Reika (who's Yandere for Shungo) tries to rape Shungo to help get her feelings across, is willing to pull a Murder the Hypotenuse on Mayu her rival for Shungo's love, and completely loses it in the last episode upon seeing him try to kiss Mayu, screaming at her subordinate Hosaka to kill Shungo. She gets over it though.
In the SHUFFLE! anime Kaede goes Yandere when Rin rejects her in favor of Asa. She gets better.
Sailor Moon has a few characters that fall under this, namely the first anime's Ali and En (for Usagi and Mamoru respectively), Prince Diamond (for Usagi), and Emerald (for Prince Diamond). And the R movie's Fiore for Mamoru. And Queen Beryl's unrequited love for Endymion/Mamoru. Most of them get over the rejections though, more or less.
Usagi in the first anime falls into a depression after Mamoru breaks up with her and tries to tearfully eat her troubles away
Tokyo Mew Mew features Quiche who attempts to murder Ichigo's boyfriend Masaya or Ichigo herself when she rejects him. It certainly doesn't help that he's a Stalker with a Crush and Ichigo's primary foe throughout the series, which only adds more fuel to the fire.
In Outlaw Star Harry beats up Melfina and tries to kidnap her when she refuses him. He also tries to kill Gene the guy he thinks she's interested in and tries to Mind Rape her twice. He gets over the rejection though eventually.
Sakura Gari: Katsuragi towards Souma. Also, Sakurako towards Souma. Generally, a lot of people towards Souma. Also Souma towards Masataka.
Also, when female Ranma discovers that Ryoga (that had accidentally hit Ranma with a love rod) doesn't love him back, he transforms himself into a guy and starts to beat the crap out of Ryoga. Normally Ryoga is as equally skilled in Martial Arts as Ranma, but this time Ranma was in such a rage that Ryoga was forced to surrender...
A few people in Ai no Kusabi didn't take rejection by Riki well but Iason and Guy really took it to extremes since they are both Yandere for Riki.
In Black Cat the protagonist's enemy, Creed Diskenth has an obsessive fixation on him, and when Train leaves the Chronos Numbers, he kills his closest friend and doesn't hesitate later on to kidnap his friends and hold them hostage.
In Elfen Lied, when Lucy learns Kouta lied to her about the gender of the cousin he was taking to the festival, she murders his father and sister in a fit of jealousy and tries to murder his cousin.
In Monster Eva Heinemann tries to win over Tenma several times after they break up, each time becoming angrier and angrier until she threatens to turn in his tie and use it against him.
Perfect Blue: Me-Mania (real name Uchida) has a thing for Mima that she doesn't even notice. When she publicly announces that she's quitting her singing job and moving to something else, Me-Mania takes this as rejection. Being the crazed fan that he is, he sends her a fax message simply saying "TRAITOR" over and over again. Then he stalks her, murders people connected to her, and attempts to rape and kill her.
Both of the main female characters on School Days fit this trope to a T. And it's not pretty.
Mizore from Rosario + Vampire towards Tsukune though she does get better about this and becomes nicer after being added to Tsukune's harem.
Akuha of the second manga season is an even worse offender towards Moka. She freaks out and goes even more Yandere when she sees Moka choose Tsukune over her.
In The End Of Evangelion the violence between Shinji and Asuka reaches a crescendo as Shinji eventually strangles her. This happens shortly after Asuka kicks him, gives him a nasty "The Reason You Suck" Speech which includes her rejecting him after he confesses his feelings to her, and shoves him to the ground causing a pot of painfully hot coffee to spill on him.
In episode 22 Asuka flirts with Kaji and when he rejects her she screams "I'm an adult! So look at me!" while pulling her blouse apart and shoving her breasts in his face.
Ritsuko deludes herself that Gendo genuinely loves her instead of just having her as a mistress. When she's proven wrong, she incinerates the Rei clones and in End of Evangelion, she hacks the MAGI to remotely self-destruct it as a final 'up yours'... only to have Naoko's woman personality in Casper-3 veto the order. Gendo instantly pulls a gun and kills her.
Nodame Cantabile: In the Paris Chapter, when Chiaki wanted to break up with Nodame, she beat the crap out of him (on a bridge overlooking the Seine) until he changed his mind.
Chiri in Sayonara, Zetsubou-Sensei towards Nozomu. One such case is when Nozomu (and guest commentators) immediately and bluntly rejected her suggestion that they could be a successful match (proper love) in the "Maybe Maybe" episode, despite considering and conceding the possibility of success of romantic relationships with Abiru (puppy love), Nami (normal love), Manami (unfaithful love), Kaere (violent love), Chie (adult relationship), Maria (acquaintanceship) and even Ikkyu (Ho Yay), upon their suggestions. Chiri's reaction to the rejection is frighteningly hilarious.
In Wolf's Rain during a confrontation between the two, Jagara stabs Darcia with a poisoned dagger when he refuses her.
In Fruits Basket Kagura Sohma is usually a cute, sweet girl with a cheerful disposition, but she actually shows her love for Kyo by beating him to a pulp on sight, especially if he refuses her advances. This frequently leads to Shigure's house being broken. When they were both little kids, apparently she got Kyo to propose to her by threatening him with a knife (or a big rock in the anime). Subverted at the end when she grows to accept his affection for Tohru.
Haruna Niekawa of Durarara!!. Professor Nasujima at Mikado's school clearly has a thing for Anri, which naturally Squicks the hell out of her. The same guy is also dating Haruna Niekawa (one of his former students). Or was. Haruna doesn't like that he's changed his preferences, so she gave Anri a visit and tried to kill her...
Tabool in Now and Then, Here and There is unhealthily obsessed with garnering any attention whatsoever from his best-friend-turned-rival, Nabuca, to the point that he gets jealous of a freaking six-year-old. Long story short: Nabuca continues to reject Tabool and it does not end well.
Saitama Chainsaw Shoujo: After being dumped by her boyfriend Fumio Kirisaki declares "Alright, I'll kill him...Then I'll die."
In the anime Speed Grapher Ginza has a one-sided, desperate love for Saiga and ultimately rapes him.
Ryoki of Hot Gimmick in regards to Hatsumi his girlfriend. At one point in the manga Hatsumi tells Ryoki that she can't be with him anymore when he orders her to make the impossible decision of choosing between him or her family. When she leaves him he's shown thinking to himself "That stupid woman...If she can't be mine she should just die."
Aoshima of Ah! My Goddess is a playboy that can have any woman he wants except for Belldandy and Skuld. When they reject him he doesn't take it well and attempts to rape them. Thankfully, they both escape him before he can.
Togainu no Chi: Keisuke becomes Yandere as a result of not having his feelings toward Akira being acknowledged and being rejected as well as the effects of Line making him insane. Whether he snaps out of it or not depends on the route (in the game). In the anime though, he snaps out of it and reverts back to his normal self.
Mai-HiME: Shizuru out of her love for Natsuki, goes insane when she believes Natsuki has rejected her (Natsuki, however, also considers Shizuru her most important person) and kills those she sees as Natsuki's enemies. And even better, her CHILD is named Kiyohime, see the Myth and Legend section of this page for more.
In Full Metal Panic! we have Leonard Testarossa. He has a crush on Kaname, once forced a kiss on her, and kidnapped her after besting Sousuke (in a gentlemen's duel), and personally assured him that despite his attraction to her, he wouldn't force anything, and will see to that nothing untoward should happen. Later on, however, he becomes so enraged with Kaname not giving in to him, and sort of "betraying" him by finally declaring to Sousuke that she loves him, that he slaps her hard enough to make her fall to the ground, speaks to her very rudely, and generally tortures her (more mentally than physically) in order to weaken her mind so that she won't be able to resist his plans of world-domination.
In Lovely Complex Mimi briefly acts this way but Koizumi punches her and tells her to deal with it. She gets better.
The subtext of Yurimaru's death via Zakuro's Action Bomb trap in Ninja Scroll is blatant. Yurimaru is an an electrokinetic Bishōnen who uses Razor Floss- Zakuro is a viciously inventive explosives expert with at the least a prominent facial scar and at most is so covered in scars she looks like Frankenstein's Monster. Zakuro has a major crush on Yurimaru, but Yurimaru is a Depraved Homosexual in love with (and sleeping with) their leader, Himuro Gemma, and so he rejects her advances rather bluntly. Yurimaru promptly stumbles into an explosives-rigged shed near the climax of the movie, and is blatantly blown to pieces when a detonating rat triggers the whole place going up in flames.
Happens at least twice in Detective Conan. The first time, the guy not only killed himself... but he made it look as if the Idol Singer who rejected him actually murdered him.
Inverted in another case. Miyuki wanted to marry Hideomi, but he was still feeling the guilt over the incident in which he caused the house fire that killed her parents, and as a result Hideomi crossed the Despair Event Horizon and later killed himself.
Gunslinger Girl: First, we have Elsa, who shot her handler Lauro and then put a bullet through her eye because Lauro did not return her feelings. Many chapters later, Henrietta, who as of late had been ignored by Jose, frags him during a rampage against Dante's men brought about by Ski Mask Guy. Jose has her finish the job. As Henrietta puts one more through Jose, Jose shoots her through the eye, killing her instantly.
Masaru "Chaplin" Sukegawa was imprisoned after murdering a woman his lover was caught with.
One of the creepiest examples comes from Minoru Murao's Knights manga. Of all people, Nina, the cute little girl of the cast goes nuts when she assumes that the object of her affection Mist is physically involved with his Ms. Fanservice companion Euphemia. Her response is to lead a supernatural agent of the Corrupt Church (the same Church that nearly burned her at the stake after accusing her of being a witch) to kill him. She even shoots him in the leg with a crossbow. Her motivation? To send his soul to Hell, where it will be "purified", then join him in death so they can be together for all eternity. Keep in mind that this guy saved her life in the first few chapters, which is why she's so hung up on him in the first place. This is borderline Love Makes You Evil. To her credit, she does eventually realize just how utterly screwed up she was, and works to undo her actions.
Hitagi Senjougahara from Bakemonogatari makes it clear that she won't tolerate her boyfriend Koyomi Araragi showing interest in any other woman. At one point, she nearly stabs him in the eye with a mechanical pencil after he so much as talks about another female using her first name without an honorific. And only stops once he screams, "Stop it! There's nothing guilty about it! I didn't mean it like I knew her well! I'm only devoted to you, Senjougahara!"
Faina Shinozaki from Infinite Ryvius. When her boyfriend breaks up with her, she tries to kill him. When her previous boyfriend broke up with her, she did kill him. She also killed an old friend just for mentioning his name.
Manami Anzai from Life, who first appears as a cute and childish clique leader who snaps utterly when she suspects Ayumu is trying to steal away her boyfriend. She goes so insane that she then dates a gang leader on the side to use him to get back at both Ayumu and her boyfriend, and then promptly screws her boyfriend and the gang leader both over. Not to mention her vow to kill Ayumu with her bare hands. Then she crosses into Cute and Psycho territory.
Chloe of Noir She turns psycho 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).
Ringo of Mawaru-Penguindrum for Tabuki. She drugs and attempts to rape him when she learns he doesn't love her back. Tabuki also falls into this in episode 11 for Ringo after she gives him a Love Potion.
Dai of Let Dai for Jaehee. He ties Jaehee down to train tracks when he considers him to have spurned his love.
Karl Fei-Ong of Blood+. The fact that Diva didn't love him is what drove him insane.
Ritsu in Lovelesssexually abuses a young Soubi and generally acts like a Jerk Ass because Soubi's mother married another man over him.
Threads Of Time: Sali Tayi. He explicitly tells Atan Hadas that if she runs away with Moon-Bin and doesn't marry him, he'll kill them both.
Haru To Natsu has protagonist Makoto caught between twin sisters who both want him,. He prefers Haruna, the stable and sweet model student, while also being chased by Natsuki, who wants him because Haruna wants him. Oh, and did I mention Haruna's quite Yandere for Makoto? To the point that their first kiss is while she's holding a very large butcher knife, and later promises (while wielding that same knife) that if he ever cheats, he wouldn't like what happens.
Shuichi Shindou from Gravitation qualifies for this when the stress of Yuki being outed puts him into the hospital, and Shuichi talks at length about how he would rather Yuki die than leave him.
Sengoku Otome has Akechi Mitsuhide, who is so yandere for her master, Oda Nobunaga, that after catching her "kissing" supposed-rival Hideyoshi (but she was just giving her medicine), she torches the temple that Nobunaga's passed out drunk in, then goes in after her "so they can always be together." Fortunately, the plan is thwarted, everyone survives, and although Mitsuhide passed out from smoke inhalation, she wakes up in the middle of getting mouth-to-mouth from Nobunaga.
What specifically pushes Claudine into shooting himself dead is how Sirene, his third and last love, leaves him for his older brother Andre.
Similarly, what pushes Louis Lacques into killing Claudine's dad and his own sister Cecilia is finding out that they were involved... since Louis himself was Monsieur de Montesse's former lover..
Girls Bravo: Lisa Fukuyama is an insane user of black magic who develops an intense infatuation for Yukinari after his appearance matches a description in her horoscope for her soul mate and often employs her magic to get closer to him-which often fails spectacularly. She often has her attendant Kosame stand nearby with her loaded gun trained on Yukinari, making a not so subtle threat to shoot Yukinari if he refuses her.
Warau Hyouteki: When Azusia and Yuzura were mere children, they were betrothed to each other by their parents. Many years later, after Azusia's mother mysteriously dies, Azusia returns to Yuzura with the intent of marrying him. Of course, Yuzura has a girlfriend, Satomi, and this doesn't sit to well with Azusia. Add to the fact that Azusia is anything but "normal", and she has no problem eliminating the competition by any means possible.
Maki in Darker Than Black, (despite being a cute little kid), right down to trying to murder the guy his crush is in love with.
Tony Stark broke up with Kathleen Dare because she was being too clingy. So, she shot and crippled him.
The Venom Symbiote is this to Spider-Man. Venom believes in the concept of having a permanent bond with its host so Peter's rejection was especially painful to the symbiote. Its thought process can best be summed up as "That bastard! How dare he kick me out! Didn't he realize how awesome I was?! Well screw him! I hate him, I hate him, I want him to die! He deserves to suffer for hurting me! But then... I won't have him! I know, I'll kill off everything he loves and then force him to take me back! Then it will just be us together forever..."
Superman once had Maxima, Queen of the planet Almerac after him. Maxima learned about Superman after viewing a transmission of outer-space gladiator games that Superman was forced to take part in, and set out to make the Man of Steel her mate. Since Superman rejected her advances, Max periodically attempted to wreak revenge, including an alliance with his nemesis Brainiac.
The second was an Earth woman named Dana Dearden. She always fascinated by the legends of ancient gods. Since the Man of Steel is more-or-less a modern-day god, she transferred her interest to him, filling her room with various news clippings and other memorabilia of him. After stealing some ancient coins at the local museum, she gained superpowers and donned a hero costume of her own, insisting that she was Kal-El's Super-Woman. But not only did Superman deny her the love she sought, she was quickly given the somewhat irritating name "Obsession". In her fury, she destroyed an oil tanker, and disappeared for awhile. And when Obsession resurfaced during Superman's split into Red and Blue versions, she ran up against Maxima, who wasn't interested in Dana's suggestion that there was now one Supes for each of them. In the end, though, Obsession's love for Superman proved 100% true, when she sacrificed herself to save him from a magical attack.
Takada and Mikami in Ragnarok. When Light began dating Takada in college they agreed it would be nothing serious since they both wanted to focus on their careers. But when Light broke up with her, Takada did not take it well and has held a grudge for four years and seems to be out to ruin Light's career. Also Light went on a date with Mikami once and Mikami has been stalking him ever since.
Both Light and L in Seigikan. Results may vary - Light goes on a mass murder spree and L bashes Light's head against a bathroom sink.
Sasuke in Slash Fic "Purple" by kodak-85 to Naruto. Naruto tells Sasuke he's not gay and doesn't even like him. Sasuke's response is to punch him, tell him "You led me on", rape him and then carve his trademark whiskers on his face with a knife. As well as telling him he belongs to him.
Admiral Xen of the Mass Effect fic Project Gethinator, who is Yandere in a big way for Commander Shepard, utterly loses it in the final chapter when he decisively turns her down and calls her on her mad scheme to control geth with the brains of kidnapped and murdered humans, going as far as to make the star of Eta Carinae go hyper-nova in a mad bid to destroy him, Tali and the crew of the Normandy.
Films — Animated
Hal/Titan in Megamind. He goes absolutely bonkers when Roxanne turns him down. He even decides to destroy Metro City just because one girl didn't return his feelings.
A deleted scene from the first The Lion King film that is mostly restored in the play as "The Madness of King Scar" is downright creepy. Scar starts hitting on Nala, wanting her to be his queen. She refuses. In front of the pride, he banishes her.
Mark Wahlberg's character David McCall in the 1996 movie Fear.
My Super Ex-Girlfriend: On one side there is Matt, a normal guy. On the other side there is Jenny Johnson AKA G-Girl, a SupergirlExpy. They were an item at first, but then Jenny became more neurotic, aggressive and controlling. So Matt breaks off the relationship and...she does not take the rejection well.
She only terrorizes his life, sends his car into orbit, and throws a shark at him.
In Titanic Cal (Rose's fiance) shoots at Jack and Rose after he sees them reuniting. He later tries to keep Rose from going to Jack after she rejects him with "I'd rather be his (Jack's) whore than your (Cal's) wife!" but Rose spits at him.
Rat Race: Tracy goes into psycho mode when she finds her boyfriend cheating on her with his ex. Upon seeing him and his ex in a steamy pool in the backyard, she attempts to nose dive at them in her helicopter and in their haste to avoid it they break the pool and the water sends them crashing into the side of his house. After that, she proceeds to drop things, including a can of pink paint, onto his truck, and chase him down in the chopper, while using the landing skids to destroy his truck. After running him off the road, she steals the truck upon finding her helicopter's engine is shot. She then yells and punches him in the face after he breaks up with her, almost strangles him with the truck window, puts a bra in his mouth and throws him out of the already running truck.
In Swimfan Madison initially doesn't seem all that upset that her one time lover Ben has a girlfriend Amy already but then she becomes more unhinged and tries to murder Amy...
In Villain, when the Villain Protagonist Shimizu's girlfriend stands him up to go off with another guy, Shimizu follows them and kills her.
Back to the Future Biff frequently makes unwanted advances on Lorraine and becomes very angry when she rejects him, tries to rape her in 1955, and wants to marry her (he eventually succeeds in marrying her and treats her horribly).
Bad Education: Father Berenguer tries to blackmail Juan when he refuses to see him.
Horrible Bosses: The Maneater boss regularly sexually harasses Dale. When he rejects her advances, she drugs him and takes sexually explicit photos of him to blackmail him with.
Play Misty for Me: Dave (Eastwood) is a womanizing DJ who constantly gets calls from a woman asking him to play the song "Misty". He eventually meets the woman, named Evelyn, and has a one-night-stand with her. Evelyn insists on making herself part of Dave's life and, at first, Dave likes the attention. However, his ex-girlfriend, Tobie, moves back to town and Dave decides to patch things up. After he attempts to tell Evelyn that he's not interested, she responds by attempting suicide. Dave and Tobie get closer, but Evelyn isn't going to take it and tries any way she can to keep Dave to herself, even if it means getting rid of Tobie for good...
Spider-Man: Occurs in the third film when Mary Jane breaks up with Peter. Also, in the first film Green Goblin has much Foe Yay towards Spiderman and doesn't react well when he rejects his offer to join him. "NO ONE SAYS NO TO ME!"
Sandy Burrow (Joely Fisher) from Seduction in a Small Town is a great example of a Lifetime-like Yandere: when she throws herself at local dad Paul Jenks (Dennis Weaver) and is rebuffed because he's Happily Married to Sarah (Melissa Gilbert), among other things, she gets so pissed that she falsely accuses them both of being horrible abusive parents to their two kids and gets them thrown in jail. Twice.
Dark Shadows: After Barnabas rejects her love, Angelique goes on to Murder the Hypotenuse, curse Barnabas to be a vampire, lock him in a coffin for almost 200 years, and spend those consequent 200 years sabotaging his family for revenge.
In Scream 4, we hear a lot about a Noodle Incident in which Trevor declared his love for Jill, they had sex and then he "just goes out with someone else". Jill absolutely refuses to forgive him, no matter how much he tries to apologize. And right after she reveals herself as the killer, she shoots Trevor in the groin as retaliation.
In P2, Thomas is of the Stalker with a Crush variety, veering into Ax-Crazy. He chooses to kidnap the heroine when she refuses to stay after work and have dinner with him on Christmas Eve.
Batman & Robin: Dr. Jason Woodrue tries to kill Pamela Isley after she rejects him. He even admits that he doesn't take rejection well.
Kill Bill: Bill doesn't take being rejected by The Bride well.
Nish from The Three Worlds Cycle books by Ian Irvine is eventually this for Tiaan after she rejects him numerous times.
In Death series: Indulgence In Death has a guy who killed a girl he was interested in a drunken fit of rage because she was not interested in him.
In the Warrior Cats series, Ashfur. He reacts to rejection by deciding that Squirrelflight needs to feel as much pain as he had. He tries to set up her father's death, framing her current mate as a murderer in the process. When that fails, he decides to try killing her kits in front of her.
Raggedstar wasn't good with this either. When Yellowfang (the she-cat he loved) decides to be a medicine cat, he gets angry and refuses to talk with her...and it causes him to demean and insult her a lot.
The Princess Bride: When Buttercup gives Prince Humperdink "The Reason You Suck" Speech, he throws her into her room. Then he races down to where her true love Wesley is being tortured, and sets the torture device on maximum, killing him. Clearly, the Prince did not take to being rejected by Buttercup well.
Lydia in Peter Moore's Caught In The Act towards Ethan.
The Odyssey has Calypso who, after offering her lover Odysseus a chance to stay with her on her island forever, tries to force him to stay on her island with her after he rejects her and tries to get back to his wife at Ithica. She eventually lets him leave because Hermes told Calypso that Zeus said she had to let Odysseus go back to Ithica.
Tess of the d'Urbervilles Tess, beginning when Angel initially rejects her and she offers to kill herself, among other things, if it restores his good name.
The Sorrows of Young Werther is about an emotional young man named Werther who falls madly in love with an young woman named Lotte, who is engaged to someone else. Werther gradually becomes more emotional and less mentally stable as a result of the rejection and ultimately kills himself.
Lord Arlington in the Louisa May Alcott book The Inheritance tries to seduce Edith many times but each time she rejects him. The final time she rejects him he reacts very angrily and it's implied that he means to rape her but Lord Percy shows up and Arlington departs.
In Ellen Hopkins book "Crank" Kristina hooks up with Brendan who drives them both out into the woods, where they get high together, and he starts to take off her clothes. When she says no, he becomes violent, claiming that he has “waited weeks,” so she should “put up and shut up”. He then starts ripping her clothes off and rapes her.
In Twilight, werewolves' pack leader Sam snaps, when his imprintee Emily keeps rejecting his advances. She makes it clear that she isn’t interested and sends him back to his old fiancée, Leah (her cousin). However, because San imprinted on her and is thus forced to love her even against his will, he keeps pushing her. Finally Emily calls him out on being just like his father (who left his family), unknowingly pressing Sam’s Berserk Button. Thanks to a mix of frustration over her rejection and his daddy issues he attacks her in his wolf form, scarring her for life.
It's also hinted that Edward, due to how controlling he is over Bella, would not take it well if she ever rejected him or left him.
Bella herself effectively went catatonic when Edward broke up with her. The infamous blank pages showed that well enough. She proceeded to spend most of the book finding various self-destructive ways to hallucinate Edwards voice.
In Fifty Shades of Grey, neither Christian or Ana can handle rejection. Ana breaks down sobbing over the fact that Christian wouldn't kiss her, then later when she attempts to break up with him he breaks into her apartment and rapes her.
The Mortal Instruments: Really, it gets to the point where should-be True Companions are abandoning each other to vampires and demons for slights like "I can't believe you like her/him more than me!" and "It wasn't my fault!" Kind of sends the underlying message that this is all teens are capable of.
In Best Served Cold, Caul Shivers risks his life to save Monzcarro's many times, even being permanently disfigured on her behalf. After the last such attempt, she has a tryst with the Grand Duke Rogont...and Shivers decides that he's now ready to kill the woman he's saved half a dozen times.
Live Action TV
Star Trek: The Original Series: There was one episode called "Charlie X" where a boy with god-like powers ends up in the hands of Captain Kirk and Spock. The boy takes an interest in one of the crew members, and she is old enough to be his mother. He rejects a female crew member his age rather bluntly and rudely. He slaps the crew member he is interested in in her rear. She is appropriately turned off by his advances. Kirk tries to explain to the boy that what he is doing is inappropriate, but it doesn't work. It culiminates in him making moves, she in turn bluntly rejecting him, and he angrily uses his powers to teleport her somewhere and he refuses to say where he put her. Fortunately, she gets teleported back safely by the end and the boy is taken by entities that will be able to handle him properly!
Adebisi goes into a depression after Shirley rejects him.
Unit Manager Tim McManus forms a brief liaison with prison guard Claire Howell. When he tries to break off the relationship she assaults him in his office (to the delight of watching inmates), then charges him with sexual harassment when he tries to fire her. Howell's later actions definitely cast her in the role of a villain — she assaults (and in one case murders) inmates, as well as using them for her own sexual gratification whether they want it or not. Also, when Ryan said they should stop their sexual relationship she threatened him telling him "It's not over till I say it's over!" Also, when Chris rejected her sexual advances she beat him up.
Beecher got quite pissed off when he learned that Keller, the man he fell in love with, was working for Schillinger his enemy and told him he never loved him to begin with. It got worse for him following that, meaning Schillinger and Keller break his arms and legs.
Rose of Two and a Half Men. It's implied that she even kills Charlie when she spotted him cheating on her on her honeymoon.
Bertha: Never cross a psycho woman.
Also Bridget, Walden's ex-wife. She screams at Walden when he rejects her for another woman and drives her car through his wall deliberately with an angry look on her face.
When his wife left him, Walden tried to drown himself in the ocean. Apparently he didn't realize that the water would be really cold.
In the TV movie No One Would Tell we have Bobby (played by Fred Savage) towards his girlfriend Stacy.
Flashpoint: The very first episode had a Croatian man murder his estranged wife, apparently because she rejected him. There are indications that he may have been mentally ill. The 50th episode had this one employee who was carefully fired because he was more interested in his boss than was proper. Unfortunately, he ends up coming back with a gun and shoots at least one person he comes across. He tries to propose marriage to his former boss, ring and all. She ends up rejecting him, which results in him getting violent and Ed having to shoot him dead. The interesting part was that the team had warned her that he is mentally ill and dangerous and yet she went and put herself in danger (at least to save an employee) anyway.
Then there's Tucker Wells, who trains hell-beasts to kill everyone at the Senior Prom, because he asked one girl to go with him and she turned him down.
Anya was cheated on by her boyfriend (possibly husband) Olaf. So she turned him into a troll and became a vengeance demon, dedicating the next thousand years to punishing men who wrong their female love interests. Eventually she is forcefully turned human again, but three years later she is left at the altar and becomes a demon again for a few months.
"Creepy Connie" takes Luke's lack of interest very poorly on Jessie.
In an episode of Supernatural, Sam and Dean have to protect a girl from a spirit who kills people who have been involved in other's deaths. The girl's past includes a boyfriend who threatened to commit suicide when she tried to break up with him. When she left anyway, he did go through with it and she's felt guilty ever since.
Dollhouse: Sierra's rejection of Nolan causes her to get institutionalized, drugged, and involuntarily conscripted into the Dollhouse. Where she's booked on regular engagements with Nolan.
Cheers episode "A Ditch in Time". Sam Malone gets involved with Amanda Boyer (Carol Kane), who becomes obsessed with and possessive of men she goes out with. When he tries to break up with her she implies that she'll commit suicide if he does.
Lila from Dexter. She had Dexter ambushed in a parking lot by a man who wanted to kill him because she thought it would bring them closer. When Dexter dumped her, she obsessively tried to win him back with methods including arson and framing one of his friends for sexual assault. She also burned down her ex-boyfriend's house with him still inside. Not to mention that said arson methods weren't just used on Dexter - she put Rita's kids, essentially her competition, in serious danger as well.
Desperate Housewives: George, a pharmacist, lusted after Bree once she ended their affair together and became jealous of her husband Rex. So he tampered with Rex's prescription drugs by replacing his heart medication with placebos which led to Rex's death. He also beats up and attempts to kill other people who look like they are trying to come in between him and Bree. He also drugged Bree at one point and was seriously considering taking advantage of her. He eventually proposed to Bree and pressured her into marrying him. After the engagement he became increasingly possessive of her, and increasingly violent.
Carlos towards Gabrielle in the first season. She was cheating on him, but he ended up physically assaulting the wrong man twice (both of them turning out to be gay) and getting a prison sentence for it.
The Nanny: C.C. shows shades of this towards Maxwell (as early as Season One, her therapist has diagnosed C.C. with being clinically obsessed with him). It gets much more severe after Fran and Maxwell announce their engagement. Upon hearing the news, C.C. immediately starts twitching, attacks the messengers who brought her the news (she's holding one of their hats, torn to shreds, in the next scene), and actually ends up spending a few episodes in a mental asylum (in Real Life actress Lauren Lane was taking time off because she was about to give birth). She gets better by the end of the series though.
Fran gets her own stalker in the form of Jeffrey Needleman, an old classmate from middle and high school. He threatens to fling himself out a window if Fran doesn't start a relationship with him. At one point before this, he gives her an old makeup kit, explaining that it's the same one their fifth grade teacher confiscated from Fran. Cue Fran's response: "And you saved it...all these years. How sweet...and yet disturbing!"
When Blair dumps Chuck on Gossip Girl he puts a dating fatwa on her.
Queer as Folk: A mild version in the case of Brian and Brandon. Brian is used to getting whomever he wants, whenever he wants. When Brandon rejects him in the backroom of Babylon, Brian has issues letting it go.
Dancing on the Edge: It is implied that Jessie's refusal of Julian's sexual advances is what causes him to attack her.
Q from Star Trek: The Next Generation has on occasion not handled Captain Picard's rejection very well. Word of God has stated that Q's obsession with Picard was intended to be romantic, so when read that way Q's reactions to Picard's rejections come off as that of a scorned lover. However even if not read that way Q is clearly not good with taking no for an answer and is very insistent on getting Picard to be interested in playing his games.
In Q Who Q requests that he become part of Picard's crew and serve aboard the Enterprise, to prove to Picard that Q's powers are useful in helping humanity explore the universe, and that he's an indispensable asset to the Captain. When Q is rejected he throws Picard and his crew to the Borg, to show them how truly weak they are without him. As this was their first encounter with the Borg Picard's crew was unable to fight them off, and Picard is forced to ask Q to rescue them, reluctantly admitting to the entity "I need you!", and having gleefully proven his point Q rescues their ship.
In Q Pid Q tries to grant any wish that Picard wants as a reward for saving his life when he lost his powers. When Picard rejects Q's offer Q disappears in a huff, "You are simply the most impossible person to buy a gift for!" That same day Picard's old girlfriend Vash shows up who Picard is much more responsive to when it comes to accepting favors, but is blinded by her feminine charms into making a few embarrassing mistakes. Q comes back later to commentate on how Vash made Picard look like a romantic fool, citing that love has made him weak and offers to get rid of her. This leads up to Picard being thrown into a fantasy world by Q where he must rescue Vash in a classic damsel in distress scenario to prove his love is truly genuine.
P!nk slowly goes insane when her boyfriend attempts to leave her in the music video "Please Don't Leave Me".
Kesha sings to "Stephen" that she "can't take rejection".
The Beatles: "Run For Your Life," despite its pleasant jangly sound, is about a man threatening to murder his girlfriend if she gets with another man.
The girl from "Baroque" in Sound Horizon is a Psycho Lesbian yandere nun (going by her costume in the live version, anyway) who kills the girl she loves for rejecting her.
And in "Stardust", Stella, an actress who's implied to be a White Dwarf Starlet, shoots her lover after catching him with another girl. "The bouquet in my left hand can't stop the impulse [read: gun] in my right..."
There's also the song "Yield", which is more or less about a girl living at a farm who is in love with her father, and when he doesn't return these feelings, she murders both him and her mother.
Played for laughs in Napoleon XIV's "They're Coming To Take Me Away Ha-Haa".
Inside Out makes a parody of "Happy Together" and transform it into a song about a guy who was rejected by his girlfriend and stalks her. At one point does he take her cat and threat to hurt it unless she talks to him. He's arrested at the end of the song.
A now infamous series of strips in the Mickey Mouse newspaper comic had Mickey attempting to commit suicide after being rejected by Minnie.
Stanley in A Streetcar Named Desire hints that he absolutely will not tolerate it if his wife Stella ever rejects or leaves him.
Blanche, when Mitch rejects her, starts to exhibit even more Sanity Slippage.
Medea: The original Woman Scorned, she killed her husband Jason's new fiancée after being dumped for her. This wasn't an attempt to win him back, however, but pure and simple revenge, particularly when she also put her children by Jason to the sword just to make him suffer all the more.
F.E.A.R. 2: Alma in regards to Becket. She develops romantic feelings for him and frequently does Attempted Rape on him. However he fights her off each time and this angers her. At the end of the game she does eventually manage to rape him and is pregnant with his child.
A mild example in inFAMOUS, which has the homicidal character Sasha, leader of the Reapers and briefly the Dragon to the Big Bad prior to the game. Throughout the game, she develops a one-sided crush on Cole. The Player can pursue this by following the Evil Side mission path, or ignore it by playing Good side missions, or ignoring this mission set entirely. Playing Good will see a developing hostility towards Cole as his Karma increases.(Though there are scripted story scenes in which she reveals her true nature, regardless of Karma) While the player must fight her regardless of Karmic path, it has a bigger impact if the love is unrequited. Not Good with Rejection comes into effect once the players learns that Cole is a younger version of Kessler whose timeline is irreparably altered due to Kessler's interference. This means that Sasha is in love with Cole, but is also flirting with him as payback towards Kessler, who tossed her aside.
Played with in Chapter 4 of Unchained Blades: Hector works up the courage to declare his love to Mari, but she tells him that she will never love him. He then goes mad (marked with Red Eyes, Take Warning) and schemes to use the wish of the Titan that they are in to force her to love her. However, it turns out that Mari said that she would not ever love him because she CAN'T: she is a doll-turned-girl who did not have emotions, and wants to make the wish to get them. And Hector; he was so overcome with the desire of his wish that he ended up having to be Unchained by Fang, after which he is very apologetic over what he tried to do.
The bosses in Gingiva will immediately attempt to kill you when you refuse their marriage proposals.
Lucan from (P)lanets is a Nice Guy, but he has a crippling fear of rejection. If Marin rejects him after he reveals that he unintentionally brainwashed his Unwanted Harem of fangirls into loving him, Lucan responds by intentionally brainwashing Marin into loving him.
Fate/stay night has Shinji Matou. Despite his extremely off-putting personality, he is (somehow) noted to be rather popular with the girls at his school. Except for Rin Tohsaka, who repeatedly turns him down whenever he flirts with her, eventually giving up all subtlety and saying "I have zero interest in you whatsoever". In "Unlimited Blade Works", when he eventually gets Rin at his mercy, he decides to punish her for rejecting him by raping her. Fortunately, he is stopped before he's able to do much.
Of course, the reason the "witch" rejected Kinzo in the first place was because she was Kinzo's daughter that he had with his secret mistress, Beatrice Castiglioni, who died in childbirth. She grew to look so much like her mother that Kinzo deluded himself into thinking she was her mother's reincarnation, leading to him raping her and making her pregnant.
The Swordmaster from Oglaf tries to use this as a means to make his pupil more badass in combat. It doesn't work the way he intended.
Diego from Gunnerkrigg Court towards Jeanne. It's heavily implied that he sent Jeanne on a mission he knew would result in her death when he realized that she would never love him like she loved her forest-bound boyfriend.
Ping from Megatokyo becomes violent when rejected, because her programmers forgot to test how she handles it in QA.
The Word Weary: Grace is visibly angry after Poor Trotmann rejects her offer for a date.
Eridan from Homestuck does not take Feferi, with whom he's in love, breaking off their moirallegiance, well at all. To the point that later in the story he actually kills her when she tries to stop him from joining forces with Jack. This is also his Despair Event Horizon as, ironically, he's known as the Prince of Hope.
Subverted in Something Positive. Davan's late friend Scotty committed suicide after Donna broke up with him. But a later flashback reveals that Scotty had been suffering from depression for a while before that, and the breakup, along with Davan not calling him back, was just the last straw.
In Orange Marmalade, when a girl named Yoo Chae Rin is dumped by the vampire she considered to be her boyfriend, she declares the wish to see the entire vampire race wiped out. Of course, there is not much chance of a high school girl pulling genocide off, but she is able to reveal the main character's vampire heritage to the entire school during a huge vampire scare, putting her and her families' lives at risk.
It only takes about five episodes of firm (but reasonably kind) rejection from Todd in the Shadows for The Nostalgia Chick to lose her marbles and start kidnapping him, trying to get him to love her.
Paul in Website/Chatoyant College followed Corrie to Chatoyant College because he's Not Good with Rejection. Some acquaintances of Corrie try to help by subjecting Paul to a magical restraining order. However, Corrie feels that magic should not be used to subvert someone's will so rescinds the order in Book 9. See If I Can't Have You.
Family Guy: Meg goes Yandere sometimes when she gets rejected by a guy, namely Brian. Also, Stewie acts like this sometimes as well, most notably in regards to his babysitter Liddane and to Olivia when he was married to her. When he found her with another guy he burned down the house when she and the other guy were still inside.
Also, there's Joan the maid in the episode "I Take Thee Quagmire" who marries Quagmire. When Quagmire tries to bring up divorce following becoming aroused by seeing Lois's breasts Joan goes into Yandere mode and threatens to cut both herself and him with a kitchen knife, right before saying "I love you Glen." When Quagmire says "I love you too insane woman I'm having second thoughts about" Joan goes into Freak Out mode again and screams "WHAT?!"
And when Stewie falls in love with the babysitter, he breaks her boyfriends legs, ties him up and locks him in his trunk leading to his death.
This is part of Mad Hatter's origin in Batman: The Animated Series. He had a crush on his secretary, who actually was named Alice, but she didn't reciprocate.
In the Pepe Le Pew short "Really Scent" Pepé removes his odor by locking himself in a deodorant plant so Penelope (Or known as "Fabrette", in this instance a black cat with an unfortunate birthmark and thus an arguably different character) would no longer be afraid of him. However, Penelope had decided to make her odor match her appearance and had locked herself in a Limburger cheese factory. Now more forceful and demanding, Penelope quickly corners the terrified Pepé, who, after smelling her new stench, wants nothing more than to escape the amorous female cat. Unfortunately, she will not take "no" for an answer, gets an angry look on her face when Pepe repulses her advances and proceeds to chase Pepé off into the distance, with no intention of letting him escape.
Flame Princess on Adventure Time goes on a rampage when Jake disguised as Finn tells her he doesn't like her after Jake found out she was evil.
An episode of Regular Show has Starla, Muscle Man's old girlfriend. She falls in love with Mordecai, and he starts dating her just so he can get her and Muscle Man back together. But when Mordecai can't take it anymore and breaks up with her... well...
Tiny Toon Adventures: Fifi LaFume but only in How I Spent My Vacation. In other episodes she takes being rejected quite well. After Johnny, who Fifi has a crush on, gives the autograph that was meant for Fifi to Bimbette, Johnny suffers the wrath of one very, very angry Fifi.
It's more of Fifi finally realizing Johnny is a jerk after she's tried desperately to get his autograph. Fifi's had a very bad day, even by her standards, and that was the final straw. She's upset that Johnny broke his word and gave away something he promised would be her present, she has nothing against the other girl specifically. Fifi might very well have accepted that Johnny liked someone else better IF he had been less obnoxious about it.
In the Tom and Jerry cartoon "Blue Cat Blues", Tom is sitting on a railroad track, waiting to be run over, after his girlfriend leaves him for another. At the end, Jerry joins him after his own girlfriend does the same.
The Planet Express Ship from Futurama. She tries to kill herself and the rest of the crew after Bender breaks up with her.
Mai from Avatar: The Last Airbender is not happy when Zuko, not wanting to drag her into a life of treason, breaks up with her to go join the Avatar. She does end up saving his life and getting thrown in prison for betraying Azula, and they're later reunited in one of the series' greatest Crowning Moments of Heartwarming. Mai later warns Zuko to never break up with her again.
In The Legend of Korra, several offhand remarks reveal that this trope once applied to ChiefLin Beifong, of all people. When Tenzin left her for Pema, she not only attempted to have Pema arrested, but also caused considerable - though unspecified - damage on Air Temple Island.
The Martian Queen in the Duck Dodgers episode "The Queen Is Wild", who seeks revenge on Dodgers for rejecting her in "To Love A Duck". Dodgers, being Dodgers, has completely forgotten the entire incident.
Berry from the Foster's Home for Imaginary Friends totally fits this trope, acting sweet and kind, but being homicidally jealous of anyone who she perceives as a threat to her relationship with Bloo, which is even more imaginary than she is. She didn't react well when Bloo rejected her and went into a rage.
Pinkie Pie also has a mental breakdown when she thinks her friends don't like her parties and don't want to be her friends anymore in "Party of One", complete with her temporarily talking to inanimate objects and sporting a Slasher Smile.
Twilight Sparkle has a freak out in "Feeling Pinkie Keen" when her normal approach of methodical research doesn't yield an answer to how Pinkie Pie can apparently predict the future with "Pinkie Sense". Essentially, it's the universe rejecting her entire life's philosophy that nothing is unexplainable by giving her something that is that drives her batty.
In "Plane Crazy" Mickey Mouse gets angry when Minnie rejects him when they're in a plane together and deliberately flies so that she falls out of the plane. When he again tries to kiss her she refuses him again and he angrily forces kisses on her.
Both of them fall under this category. They somehow get back together, and a few seasons later, they mistakenly believe that the other broke up with them. Lola becomes a monk and takes a year-long vow of silence, while Bugs leaves everything behind and becomes a fisherman. They work things out, though.
Sadira in Disney's Aladdin: The Series is a "street rat" like Aladdin was, and falls for Aladdin the way he did for Jasmine, but, since he's in love with Jasmine he refuses her. Then she stumbles onto an ancient library of forgotten magic, and the end result is increasingly dangerous plots to get rid of Jasmine and take Aladdin for herself, including rewriting reality at one point and altering his mind. Eventually she gets over her crush and befriends the gang, but almost has a brief relapse when she believes they don't trust her.
Cookie BaBoom, Mayor Tilton's ex-girlfriend on The Mask episode "Flight as a Feather." Uses a variant of the Stock Phrase, "If I can't have you, then no one can" (on the episode, it was, "If I can't have Mortimer, then no one can!" Standard. Is still bitter over being dumped by Mayor Tilton? Okay. Uses two strategically placed explosive belts strapped around her body to kill herself, the mayor, and everyone else around her because of the deep-seated resentment she has over being dumped.
The Problem Solverz: Katrina Rad is obsessed with Roba and stalks him in "Magic Clock". She then steals a time-freezing clock so the two of them can be together for eternity and tries to marry him against his will. When Roba refuses to kiss her at their wedding, she threatens to rip a hole in the fabric of the space-time continuum.
Amora the Enchantress in The Avengers: Earth's Mightiest Heroes is this to Thor. She takes out her anger from being rejected by him in battle with Thor and his allies frequently. This follows along with her comic book character.
In DuckTales, Gyro invents a robotic maid to help take the strain off Scrooge's housekeepers. His first attempt is so emotionless, it creeps everyone else out. So he dials up the emotions, creating a robo-Yandere who instantly falls in love with Gizmoduck, who unbeknownst to her is just a normal duck in Powered Armor. When he tries to let her down gently by explaining, she interprets it as him having another lover, and literally explodes in a rage.