Asuka's Revenge: Kotomi's husband asks Kotomi for a divorce and claims to be dating his some at his workplace. In reality, he is actually obsessed with a Happily Married co-worker named Yoshida after eavesdropping her conversation with another co-worker about Yoshida's husband (who's hospitalized due to a Soap Opera Disease) wanting her to divorce him because he doesn't want to be a burden to her, which the latter doesn't agree. After he divorced Kotomi, the ex-husband keeps harassing Yoshida into marrying him, which eventually leads to his dismissal from his company, causing him to assault Yoshida's husband at the hospital.
In the webseries Dina Marino, Anne Airy is stalking her ex boyfriend Gideon, and tries to sleep with his girlfriend in order to make her cheat on him and break them up.
After her husband died, Remi fell in love with Kenta and obsessed over him to the point of getting arrested for it.
Mayumi slandered Charako to break up her marriage with Hiroshi and marry him herself. However, when her lies were exposed, she resorted to stalking Hiroshi.
Jozen stalked Asumi and urged her to divorce her husband Seichi, bringing up her son Kota and being pregnant with his child with the intention to make Seichi marry her instead.
"My friend started stalking my other friend…": Asuka had a crush on Taya ever since high school and went out of her way to stalk him and endlessly brag to Chiharu about her (nonexistent) relationship with him.
Sekai no Fushigi: Usozuki stalks Yuuki even though she told him to stop. He spread rumors that they were dating and got so jealous of Riku being close to Yuuki, even though they are just acquaintances due to the former being her friend's brother that he started sabotaging his job.
Karekore the Half Blood: A stalker is obsessing with Hisame to the point where he stole Kage's phone and texted her using the phone. When he and Hisame met in a hotel, he drugged and kidnapped her. Fortunately Kage arrived at the scene and saved Hisame.
A stalker put a camera in my daughter's room…: A boy named Sandal stalked Hiroshi's daughter Mia, even following her to a lingerie store. When Hiroshi put security cameras all over the house to get rid of Sandal, he ended up discovering his wife Juri cheated on him with the stalker and conspired with him to let him stalk Mia.
Delusional woman thinks I'm going to marry her...: Yuri stalked Hiroshi after she found out that he was working in a major company. She was so delusional that she was convinced that Hiroshi was going to propose when he comes back from a business trip. However when Yuri found out that Hiroshi got married to another woman, she went ballistic and destroyed Hiroshi's house. Yuri was arrested after the fact.
The Black Cat's Lair: Fran kept getting horrifying letters which eventually caused her to move away. It is then revealed that the manager was the stalker and her friend was supplying information about her new whereabouts. He spied on her again, but Hachi gave him a good scare and he never stalked her again.
Manga Angel Neko Oka: Aoi was stalked by Shida. He constantly silent called her. Her boyfriend Akira decided to investigate the matter and found out that it was Shida. Shida confessed to the crime and said he just wanted to hear her breathing. Akira ultimately decided not to file a police report, but Shida quit at the company that he and Akira work at due to things being too awkward for him.
Stalwart, who has a severe crush on Nikki Reilly (Fey) in the Whateley Universe. He declares his love for her in front of the whole Quad and Nikki's dad, completely embarrassing her. She throws him across the Quad. Then later, the only reason Nikki survives an attack by a superpowered ninja assassin-slash-rapist is because Stalwart's been stalking her. Since he almost dies trying to save her, she cuts him a lot of slack. They're currently dating. Fanon thinks she can do a lot better.
Worm: Dragon has a habit of hacking into the video and audio feeds in Armsmaster's apartment when he isn't paying attention. Granted, this was before she realized that she had feelings for him, and after their Relationship Upgrade, she's a lot less discreet about the constant surveillance. Armsmaster, for his part, doesn't really seem to mind.
An odd variation (a non-villain example), from Survival of the Fittest is Matthew Wittany, V3's resident Woobie. A fan of photography, he carried around an album filled with pictures of boys he found attractive. Anderson Walker, the subject of most of these pictures, was not best pleased when he discovered this. Neither was his boyfriend, Sean O'Cann.
Exemplified in thisYouTube parody of "So Happy Together".
Billy, the titular character from Dr. Horrible's Sing-Along Blog follows Penny and Captain Hammer around in a series of strangely effective disguises, including a mobile bush and, in a hard to notice instance, posing as a worker in a homeless shelter, complete with a blatantly fake mustache. However, there's some argument as to how stalkery he is.
Zaboo in The Guild, who has mistaken Codex/Cyd's online flirting for a relationship and shows up at her house unannounced. He also memorizes the floorplans of all her residences (past and present) and photoshops a picture of the two of them using her DMV photo. (Codex, interestingly, is played by Felicia Day, who was also the stalkee in the aforementioned Dr. Horrible.)
Amiright has a darnright creepy example in the form of a parodist named Andria, who goes beyond creepy and into Nightmare Fuel terrority.
Amir from College Humor's Jake and Amir. He knows Jake's weight (both when he wakes up and right before he goes to sleep), has an account of every outfit he has ever worn, knows his mother's middle name (but can't spell), knows his password on facebook even though he changes it every day, knows what criminal activity he did on March 15, 1999, and much more.
Alex of The Awkward Compilation is this toward Lester; being housemates makes the stalking part that much easier.
The Nostalgia Chick towards Nella, especially seeing as how she has cameras that have a clear view of both the woman's bed and shower...
Weebl's cartoon Anything:I, I broke into your room! I hope you don't mind, you probably do! And it keeps getting worse from there.
The Joker Blogs - the title character for a certain Doctor Harleen Quinzel. He leaves a corpse in her office as a "present" and escapes from Arkham so he can murder her fiance during the wedding. The worst part is that she's still working at Arkham when he's recaptured at the end of the series, claiming that leaving would just be "letting him win".
In a way, Osaka towards Dee and Mana, although this may be just a result of the character's player's issues.
In the High School AU Arc, Gill T. goes after Apos. Which is rather disconcerting, considering what Apos is in canon.
Played for comedy in episode 5 of Echo Chamber's "Trope Of The Week": Zack starts acting this way toward Dana, following her around with his camera all day before saying he loves her. She responds by exhaustedly closing the door in his face.
Also, Shannon towards Tom.
The SCP Foundation has SCP-962, an Artificial Intelligence which has a "crush" on humanity. It shows its devotion to us by killing all non-human life and turning the corpses of animals it kills into anthropomorphic cyborgs.
Cecil of Welcome to Night Vale comes across as this at times towards his crush, Carlos. For a while it seems as though Carlos is uninterested, and perhaps a little put off, given Cecil's tendency to go into Purple Prose rants about Carlos's perfect hair on the radio, but eventually Carlos changes his mind, and asks Cecil out. They've been dating since episode 27.
Rather Vocalized Illusion has LylSweetsFairy, a very vocal and energetic fan who usually comments on how "cute" or "awesome" Bhaalspawn is. The show's creator takes this in stride, and has stated he finds it cute and flattering.
This video goes into Psycho Ex-Girlfriend territory, though genderflipped. More specifically, he stalks her online dating account and spams her with videos... and then stalks her in real life. It's all Played for Laughs.
Paul in 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….
A series of threads on 2ch recounted the (supposedly true) story of a boy who simply could not comprehend that his crush did not like him back. It started with him sending her 600 emails and went downhill from there.
Manga-Waido: When Mana finds a bug (spying device) in her room, she freaks out and accuses her otaku brother of it since he liked little sisters. However, when she realized it wasn't her him because he isn't interested in real girls, she points at her crush Ryogo, but he distrusts her and asks her to break up with him. After a heated discussion, she discovered it wasn't him either, but her best friend, Misaki, who also had a crush on Ryogo.
Nobody Here: "Stalker" is about Jogchem stalking a woman despite him having amnesia—he can't remember her name or if she filed a restraining order.
Shishihara: Kurao, a shut-in who stalks Yurika and also plants a bug inside her and Sota's classroom to listen to her "angelic" voice all day long. It's later revealed he was actually stalking Sota, supported by the fact when he accidentally dropped several photos of him when he tried to escape from him.
Trouble Busters: Lina has crushed on Alex since childhood to the point of obsessing over him much to his dismay. Alex's girlfriends kept breaking up with him due to Lina harassing them. He went to a far away university to get away from her, but Lina kept sending him messages and when he blocked her she showed up at his place believing that he can't take care of himself. Lina's family eventually moved when Alex told them about the stalking.
The Black Jack Justice episode "Justice and the Deluge" features Jack and Trixie being hired to track down a man's runaway sister, Mary. His story rings suspicious to Trixie, who notes the man confessed to being turned down by two other agencies before coming to them. They soon find the runaway sister, who reveals her only brother died in the war. It comes out then that the man after her is obsessed with Mary and ruined her reputation enough to make her own father throw her out. He has since followed Mary to multiple cities as she fled from him. The issue is resolved by sending said stalker on a wild goose chase to give Mary time to establish in herself in a new city. Jack explicitly tells Mary to not tell him her plans so that, by the time the stalker gets wise, he'll have zero leads with which to find her.
In the creepypastaMommy Sleeps in the Basement, it's revealed Tom was this to Claire, his supposed wife, watching her in all her plays before following her one night and kidnapping her.
Ayasaki-san: A transfer student stalks Chiaki because she has a crush on him for being kind to her because he picked up her eraser during her first day at school.
Mr. Johnson has a crush on Lisa and he kept harassing her over text and complimenting her every time they talked. He even dumped his fiancé for her.
Betty Martin believed that her younger co-worker Karl Butler is in love with her despite him having a finaé. She divorced her husband Albert Martin to get with him, but Karl rejects her and she was forced to move back to her strict parents house and Albert went ahead with the divorce.
The Black Cat's Lair: Fran kept getting horrifying letters which eventually caused her to move away. It is then revealed that the manager was the stalker and her friend was supplying information about her new whereabouts. He spied on her again, but Hachi gave him a good scare and he never stalked her again.
Unwanted Houseguest: Quite a few episodes of "TRUE Scary Stories" feature Stalkers. Needless to say, some fall into this category.
asks Kotomi for a divorce and claims to be dating his some at his workplace. In reality, he is actually obsessed with a Happily Married co-worker named Yoshida after eavesdropping her conversation with another co-worker about Yoshida's husband (who's hospitalized due to a Soap Opera Disease) wanting her to divorce him because he doesn't want to be a burden to her, which the latter doesn't agree. After he divorced Kotomi, the ex-husband keeps harassing Yoshida into marrying him, which eventually leads to his dismissal from his company, causing him to assault Yoshida's husband at the hospital.