Boardwalk Empire: Agent Van Alden towards Margaret Schroeder. He stole and sniffed her hair ribbon, specially ordered her immigration file for his own perusing, questioned her neighbor about her, and caressed, and later whipped himself to, a picture of her. Van Alden's boss even calls him out on his obsession with the Schroeders.
Glee: Rachel towards Will in episode 10. Also Suzy Pepper before her. Suzy's crush faded after she hospitalized herself, and she told Rachel to stop before she made the same mistakes.
Jacob Ben Israel. A stalker with a knickers fetish for Rachel.
Finn toward Rachel any time she's dating someone not him: in "Laryngitis" he accompanies Rachel to the doctor's surgery in order to instruct her to break up with Jesse because Jesse doesn't 'get her' as well as Finn does, then openly pervs on her as she gets changed behind a screen, and in "Prom Queen" he insults Jesse repeatedly and punches him in the face for slow-dancing with her at the junior prom - while he himself is supposed to be another girl's date.
Finn tried to punch Jesse but he has cat-like reflexes and dodged.
Also, Kurt's behavior towards Finn in the first season is a bit stalkerish. Kurt himself clearly doesn't see it though, as he thinks every attempt to call him out on it is due to homophobia.
Finn: The way you were all over me last year... if I did that to a girl, she'd take out a restraining order.
Kurt: You have issues with me being gay, I get it.
Finn: No, actually I don't. I have issues with the fact that you don't understand that no means no.
DaveKarofsky, anyone? He's way worse than any of the others. He's Kurt's homophobic bully and the crush comes out when Karofsky forcibly kisses a very terrified Kurt. Add to that the physical assault, constant insults and eventual death threat... it doesn't exactly go well.
True Blood: Lorena just can't accept that Bill has moved on.
Sam Merlotte, in Season One. Thankfully, he got better.
Monk: In "Mr. Monk and the TV Star," Monk ends up nailing actor Brad Terry for murdering his ex-wife with the help of an obsessed fan named Marci Maven, and accidentally transfers the stalker crush to himself. In "Mr. Monk and His Biggest Fan," we see Marci's new obsession with Monk has grown to extremes: she has a partially accurate diorama that is supposed to depict the carjacking scene of "Mr. Monk and the Three Pies", she has plastered the walls of her house with
In the earliest days of Smallville, every other Monster of the Week had a crush on Lana. For that matter, Clark does the same thing to Lana with his telescope when she still lives next door to him.
Lana:(looking through the telescope) Did you know you can see my house from here? Clark:(acting innocent) No... Really? (moves the telescope to point somewhere else)
There's Also Alicia Baker, a girl with teleporting powers who did this to Clark. She eventually got better and one season later the two dated for real until Alicia was killed by a man who was framing her for crimes that he committed. Clark was not happy about that.
In one episode of the short-lived Probe, Austin is pursued by a stalker who murders one woman and tries to murder another she sees as an obstacle to her obsession with Austin. The twist? The stalker is a mentally enhanced orangutan.
Fifth from Stargate SG-1 cranked up the creepiness factor by declaring his love for Carter. This love led him to inflict Replicarter on the galaxy.
Samantha Carter seems to attract these types. Orlin and McKay both nurtured (relatively creepy) obsessions with her. Several others, much creepiers, have died.
Arguably the Master and his obsession with the Doctor on Doctor Who: eventually the butt of jokes on the show itself "Are you asking me out on a date?" and the Tenth Doctor's quip about the Master's lavender marriage.
Sharaz Jek in "The Caves of Androzani" quite clearly has the creepy kind of hots for Peri, doing things like chloroforming her, stroking her face while she's unconscious, and carrying her around in his arms (again, unconscious) while whispering "so beautiful...so beautiful...". The fact that he also dresses entirely in black leather really doesn't help.
Used on Law & Order: Special Victims Unit with quite a twist: a cellist is attacked and continues to get threatening messages before being shot. The detectives find the man who's been stalking her, but he claims never to have attacked her. It turned out his landlady also insanely believed herself to be in a relationship with the stalker, and she threatened and shot the girl out of jealousy!
Sue White on Green Wing will do just about anything to get with Dr. Mac... witchcraft, attempted murder, slander...
Criminal Minds: in "Somebody's Watching", the profilers figure a male Loony Fan is the one killing people connected to a certain actress, but the unsub turns out to be the actress's Psycho Lesbian friend.
"Broken Mirror" had a rogue FBI agent who was obsessed with a pair of twin sisters, one of whom he abducted, while "The Crossing" had a fairly generic stalker going after a woman he met while fixing her computer (they accidentally touched hands and she smiled at him, it was good enough for him). The rapist in "Aftermath" also learned absolutely everything he possibly could about his victims before going after them.
Wire in the Blood: in "Nothing But the Night", Tony Hill has a brief conversation on a plane with a woman. Her erotomania over the course of the episode escalates to the point where by the end, he comes home to find her in his house cooking him dinner and acting as if they're already married.
Sketch (towards Maxxie) from the second season of Skins.
Emily is kind of this towards Naomi in the third season, but she's far too nice and likeable (her pursuit of Naomi is more lovestruck puppy than Psycho Lesbian) for it to be creepy. Naomi declares her to be "very annoying" when she manages to break into Naomi's bedroom (not hard, since Naomi's mum has turned their house into a hippy commune), rather than pulling the all-out freakout that might be associated with this trope. But even so.
The Chief of Police in Hill Street Blues had a really obvious crush on the police officer played by Mimi Kuzyk. He often made serious compliments to her, that were (in her opinion) too personal, such that it bothered her enough that she filed a Sexual Harassment complaint. Later, when she decided to leave the police force, the lack of the boss/subordinate power structure made her lose her fear of him, enough that they ended up Shipping and she moved in with him.
Steve Urkel on Family Matters found himself on both sides of this: for years he'd been Laura's stalker with a crush, then eventually found his own in Myra Monkhouse. Unfortunately for poor Myra, Steve was a more successful stalker than she was.
Harper has a huge crush on Justin, sometimes bordering on obsession. Alex even takes advantage of this fact, when she tries to break the temporary connection that formed between Harper and Justin, telling Justin that Harper watched him once, while he was sleeping.
A more serious and frightening example is Mason towards Alex.
Good Luck Charlie: Disney comes back to this trope time and time again. On Good Luck Charlie, another sitcom, there is Teddy, the main character. Her brother, has a friend named Emmett, who has a crush that's basically been built up by him into a full blown relationship with Teddy as his girlfriend. As usual per the Kid Com genre, it's played for laughs.
Booth on Bones gets saddled with a repeat offender of this. At the end of the episode, she accidentally shoots him while trying to kill Brennan.
Season one also has a stalker who fixates on Bones after his previous obsession dies.
They track him down later, still obsessed with Bones. They clear him of murder and he disappears after Bones punches in the face.
Hodgins is this to Angela in the early episodes.
Spike from Buffy. He became accustomed to following Buffy down the pavement or hanging around outside her house at night. He watched Buffy through her window, made a shrine to her, smelled one of her sweaters, and had a sex robot designed to look and act like her. Of course his little crush got a little less one sided in Season 6 and by Season 7 he became a little less evil.
Arguable in that Angel himself was one even before Angelus came about in S2. In Season 2's "Lie To Me" Angel shows up at The Bronze and even claims that he was hoping Buffy would show despite the fact that Buffy often attends with Xander and Willow. Also in Season 2's "What's My Line Part 1", Buffy climbs through her window back into her bedroom. Somewhat creepily, Angel's already standing in there holding her stuffed pig, Mr. Gordo. It's clear he's been waiting for her to arrive. In that same scene, Angel admits to knowing about Sunnydale High School having its Career Week and explains his knowing about it as, "I lurk."
Of course, it was essentially his job to stalk her, handed straight to him by the Powers That Be in order to keep her safe, even though she was unaware of it for a while. That being said, however, it's a little disconcerting that when Angel falls in love with Buffy, he's hiding in a run-down car and she's wearing pigtails and sucking on a lollipop.
Angelus was also this towards Drusilla, stalking her before eventually turning her into a vampire after making her insane.
Ryan O'Reily from Oz was this way with Dr. Nathan. After she helped him through cancer, he immediately divorces his wife. Later, he forced a kiss on her, paid a fellow inmate to steal her stethoscope, and when she started ignoring him, had his brother Cyril kill her husband. After she was raped, he very quickly murdered the man that did it. It was even said outright that his love for her was more of a stalker obsession. The weirdest part about it: Dr. Nathan actually falls for him in the end.
Chris Keller as well. Such was his obsession with wanting to remain in Beecher's life even though Beecher repeatedly told him that he didn't want anything to do with him anymore.
In the recent adaptation of Sarah Waters' Affinity, a brand new character called Theophilius was drafted in as the heroine's wannabe suitor. Despite Margaret being a lesbian and mourning the death of her father, Theophilius wouldn't give up and insisted on pursuing her. He's finally written out when he tries to rape her, ranting about his belief Margaret's hung up on her father and saying he'll 'erase his mark' from her. What a freak.
Bad Girls: Di Barker, one of the prison guards, is a serial stalker, obsessing on numerous unfortunate men who pass through Larkhall. She steals their possessions, builds shrines and does whatever she can to break up their relationships. She receives her comeuppance when she's wrongly convicted for her husband's murder.
Sylar's developed something similar with Claire as well. Which raises the disturbing question of how their relationship is going to be changed now that he's been brainwashed into thinking he's her biological father.
Especially since she doesn't actually know the real Nathan is dead yet. She'll probably find out as soon as Sylar's brainwashing wears off—which it has to, because eventually his healing ability will reject it.That ought to be an...interesting confrontation.
Claire is on the receiving end again in Volume Five, this time from Gretchen. However, Gretchen comes clean a lot sooner, and Claire seems to have forgiven her.
Rose on Two and a Half Men is a bit odd in that she's both quite self-aware of what she's doing, and is actually on friendly terms with Charlie and his family. This is justified as not only is she a nice, helpful person who happens to have some obsessive tendencies, she's also highly intelligent with a PhD in psychology.
Her father, Harvey, was known to show the same behavior. Harvey had a one night stand with Charlie and Alan's mother and began to stalk her in the exact same manner that Rose stalked Charlie.
Johnny Smith of The Dead Zone gets one of these, of the Loony Fan variety, in the episode "Misbegotten". She's played for laughs in The Teaser, breaking into his house so she can cook for him, while Johnny blinks at her in bemusement. She gets a good bit creepier after she helps kidnap him, duct-tapes him to a chair, and nearly rapes him.
After being hit on by an 82-year-old woman albeit with syphilis in Season 1, "Informed Consent" and "Lines in the Sand" showed what a staggering age range of women are sexually attracted to House. 17-year-old Ali shows up at the clinic just to expose herself to him, calls him 15 times a day, wears low-cut jeans in front of him to show her thong (justified by the resultingEureka Moment), straddles his motorcycle while waiting for him in the garage, ignores most of Cuddy's threats to call the police, and locks herself in House's office. Subverted in the end by House telling that her she has a brain spore that causes loss of inhibition. Although it is rather heavily implied that he exaggerates the effects of said spore in order to make her give up her obsession.
House himself, sort of. The crush part is up for debate. House hires a private investigator to spy on Wilson when Wilson cuts ties with House, quits his job, and moves away. The PI accuses House of wanting to see if Wilson is pining, and he's right. House is clearly upset to discover that, despite having the PI set up bugs and everything in Wilson's car and home, Wilson hasn't mentioned House at all.
Doctor Pilfrey spends most of the third episode of Fortysomething chasing after Estelle, acting on the e-mails that Edwin sent to him on her account, and turning his office into a love den complete with candles for when she showed up to see Paul. Similar tothe above, he turned out to be suffering from hypermania.
Leoben is Starbuck's Cylon Stalker with a Crush on Battlestar Galactica, keeping her trapped in an apartment with him for months and introducing a fake daughter. Starbuck keeps killing him, but he keeps coming back. She was understandably frakked in the head after being rescued.
ATF Agent Josh Kohn for Dr. Tara Knowles in Sons of Anarchy. It does not end well for him.
Freddie in iCarly. He and Carly are really good friends, and the stalker side of things is pretty much limited to him waiting for her to come home after school by looking through his peephole (they live in opposite apartments), but it weirds some people out. Pretty much limited to Played for Laughs.
Freddie's stalker-ish behavior drops off pretty quick. If you watched the rest of the series, then watched the pilot, you wouldn't recognize Freddie as the same character. Of course, post-pilot, Freddie is hanging out with his crush most of the time with her consent, so it would be a little difficult to stalk her at that point.
The Mandy character seems to be a better fit for this trope.
Nevel. Oh boy Nevel. He has a wall of monitors solely for the purpose of showing slow motion close ups of Carly. Creepy.
Jason Stickler from Cory in the House, who (mis)uses high-tech gadgets provided by his CIA Director father to spy on Meena.
David Platt from Coronation Street just doesn't get the fact that Tina does not want to be his girlfriend anymore.
In Dollhouse, Alpha is one of these towards Echo. Disturbingly, he's even shown to sit naked in a room of a house in which he killed two people, watching a video of Echo. And later on it is revealed that Nolan is one for Sierra's original personality, Priya.
Abby from NCIS once had to deal with a stalker ex-boyfriend. His walls are covered with pictures of her (all taken from outside restraining order's limits), and the team assumes he's the one hacking into all her records. Turns out he was, but, he could only do it because a professional killer/hacker had already done it.
Tully is arguably this for George in Being Human. He figures out George's general location by using newspaper articles, finds him in the woods post-transformation, and tracks him down to his home, where George finds him comfortably sitting in the living room. All because Tully is lonely and wants a friend (who he also bit himself).
Also Adrian has had behaviors bordering on this to Ricky in seasons 2 and 4. Tom to Adrian. Jack has shades of this in his behavior to Grace. Grant transfered schools to get closer to Ashley in season 3. Ashley to Ricky in Season 3. Dylan has behaviors like this to Ben in season 4.
Victorious: Robbie for Trina, after she kisses him whilst acting a scene.
He later becomes this for Cat.
He appeared more awestruck with her kiss than anything, they went back to normal next episode.
On Seinfeld Elaine was very prone to getting these.
Happy Days: Joanie had an early crush on Potsie, and later in the series Joanie was on the receiving end of an obsession from Fonzie's cousin Chachi. It was quite unwanted until even later when they became an item and eventually married in the series finale.
In The X-Files episode "Milagro", Mulder's loner neighbor turns out to have a scary infatuation with Scully. He moved next door to Mulder in an attempt to get closer to her, he knows everything about her...even the novel he's writing is about her falling in love with him. Of course, in addition to being a stalker, the book he's writing has a villain who lives outside the book and tries to kill Scully.
Dexter: Lila eventually becomes a version of one of these, going so far as to murder Doakes to protect Dexter's secret because she believes them to be soulmates, and eventually attempts to murder Dexter himself, as well as Cody and Astor.
Sherlock: Moriarty seems to be this where Sherlock is concerned from the very first episode onwards, as it turns out that the cabbie in "A Study In Pink" and The Black Lotus in "The Blind Banker" were sent to 'test' Sherlock's skills and to see just how good he is at his job as a consulting detective and Moriarty's arch-nemesis; his first words to Sherlock (albeit through another's mouth) are "Hello... Sexy".
Supernatural: Gordon Walker becomes this over the course of his first appearance for Dean Winchester, as he repeatedly tries to distance Dean from Sam. In each subsequent appearance on the show his obsession with Dean becomes more pronounced as he kidnaps Dean repeatedly and when he's turned into a vampirehis first instinct is to find Dean and Sam so that he can kill Sam and turn Dean so that they can hunt together. Forever.
And let's not forget Sam's own Stalker with a Crush Becky Rosen, who initially is not too bad since it's Played for Laughs, but in Season 7 she actually kidnaps him and drugs him with love potion, all while fooled into a deal with a demon.
Jenna Maroney has one on 30 Rock. Or rather, had one. She's terribly upset to find out that her stalker has moved on, treating it as if her actual boyfriend had left her. Kenneth cheers her up by stalking her instead.
Episode 6 of Kieślowski's Dekalog, "Thou Shalt Not Commit Adultery". A 19-year-old postal worker is the Stalker with a Crush of a woman in his apartment building. This is shown as odd and unhealthy, but nonetheless a manifestation of a pure impulse to love. He explains that he no longer watches her when she has sex, for instance...
In a Law and Order episode, one of these kills a woman's husband in what nearly everyone thinks is an accident, and then marries her. They even have a child together. But the late husband's mother wasn't fooled.
Hoyt of Rizzoli & Isles develops a peculiar fixation on Jane and preys on her. He also wants to kill her because he likes that he thinks she's equal to him in some ways.
Nathan/Lyndon from Pretty Little Liars develops an obsession for Maya, following her all the way back to Rosewood. When she notices this, she hides in the Khan cabin. It didn't help her, as she was later found, and killed, by him.
Lily's high school boyfriend Scooter from How I Met Your Mother cannot seem to grasp that Lily is happily married to her college boyfriend. He's mostly just a harmless, sad little puppy of a recurring character, but he seriously has revolved his entire life just around seeing Lily, and for some reason thinks he still has a chance.
In a non romantic variant, Patrice is kind of freakishly obsessed with Robin. Robin isn't precisely subtle about her abhorrance of her coworker, but Patrice is sort of obliviously half in love with her anyway.
"PS: I Love You" explores this and Stalking Is Love, and basically says the difference between being a stalker and being romantic is whether the stalkee is interested in the stalker.
Happens between a boss and an employee in Flashpoint where the employee became madly infatuated with his boss who did not return his affections. He repeatedly sent her emails and left gifts at her house. When she gently tried to tell him she wasn't interested and fired him as a result, he returned to the office with a gun so he could propose to her, believing he had a better chance with her, Completely Missing the Point of said firing.
C.C. Babcock from The Nanny has borderline Yandere tendencies towards Maxwell Sheffield. Throughout the series, she's unable to grasp that Maxwell's not romantically interested in her. She gets better towards the end as she finds herself falling for Niles.
Community Dean Pelton's interest in Jeff is generally considered harmless. He went way over the line at one point (reading Jeff's email and basically blackmailing him into going on a date with him) but after Jeff pummelled him for it, the inappropriate touching and closeness continues. This may be because Jeff is practically twice the Dean's size and quite capable of beating him up, making his approaches seem less threatening.
Scandal: Becky, Huck's girlfriend, certainly comes off as this with a secret room loaded with photos of him. Sure, she's an assassin, but that's still creepy.
Simon gets one of his very own in the second series of Misfits.
Homeland presents the Stalker with a Crush as the hero: Carrie plants hidden cameras and microphones in Brody's house, follows him, arranges to run into him when he goes to a support group for veterans, and otherwise stalks him. At some point in all this, she falls in love with him. Of course, she is a spy, so doing all these things does come with the territory, after all.
Craig to Lois in Malcolm in the Middle. He even bought a house that was situated where he could peer into Lois's backyard from his window through binoculars.
In the Only Fools and Horses 1993 Christmas special "Fatal Extraction", during a brief split from Raquel, Del sets up a date with Beverly, the receptionist of his local dentist, but calls it off after Rodney manages to talk him out of it. In the following days, Del sees Beverly wherever he goes, and starts to believe that she's stalking him. In a subversion, it turns out that their meetings were coincidental, and Beverly actually believes that Del is stalking her. She thought the date was a bad idea to begin with and didn't mind it being called off, but Del's threatening behaviour when he confronts her actually motivates Beverly into taking revenge by selling Raquel an answering machine which had Del's message about cancelling the date on it.
In Helix, After asking a series of increasingly personal questions in their various interactions, Dr. Hiroshi Hatake wistfully peruses an album of pictures of Dr. Julia Walker, both posed and taken from distances suggesting covert surveillance.
Season Four has Psycho!Derek, a guy who stalks Peyton and gets closer to her by pretending to be her half-brother. The situation comes to a head in You Call It Madness, But I Call It Love, where he abducts her on the night of prom and keeps her Bound and Gagged inside her own house. It gets out of control when Brooke shows up- he promptly strangles her to subdue her, ties her up too, and then decides that since Peyton and Brooke had gotten into a severe fight, the best way to win Peyton's affections would be to murder Brooke in front of her. The girls barely escape with their lives.
Another stalker shows up in Season 7/8: Katie Ryan, Identical Stranger to Clay's dead wife Sarah. When she can't convince Clay to leave his current girlfriend Quinn to date Katie, she proceeds to invoke Murder the Hypotenuse and If I Can't Have You by shooting both Quinn and Clay. They barely survive, and Katie isn't dealt with until the S8 midseason finale, where she comes back to try to murder Quinn again, and fails.
The show Stalker of course contains these, though it also has plenty of the other kind as well.