During Selfie, this trope pops up a little between Henry and Eliza-despite not being in a relationship, the two have feelings for each other and this tends to come out when they talk about other people. Henry says Eliza's sex buddy Freddy is a tool, and Eliza gets a way bigger dose of this trope when Henry dates Julia, insulting her height, and trying to come between the couple so as to not lose out on spending time with Henry.
In Buffy the Vampire Slayer Faith envies Buffy for being the "main" slayer, having friends, family, love, acceptance, etc. So she envies Buffy's life in general — right until she has to lead the charge.
In both Buffy the Vampire Slayer and its spin-off Angel, Angel has been shown quite frequently, despite having left her for her sake, been openly jealous towards Buffy's love interests or suitors, especially to Riley and Spike. So has Spike; the episode "The Girl In Question" has them try to find her when they find out she was dating their former rival, their excuse being they were worried about her.
The brotherly relationship between Frasier and Niles Crane is dominated by this trope.
Farscape had an episode actually called Green-Eyed Monster, in which Crais' jealousy of Crichton (and vice-versa) nearly led to Crichton's death. It also led to John telling Aeryn about his feelings, again. To be fair, the near death was courtesy of Talyn, not Crais. He actually had him Thrown Out the Airlock.
Oh come on, Talyn gets all his ideas and feelings from Crais, pretty much. He's just a very powerful baby who wanted his Mummy and Daddy to stay together - though, admittedly, the fake sex tape of Crais and Aeryn isn't something most toddlers would come up with.
Chandler feels a lot of jealousy towards Richard, as he believes for a long time that he's still the love of Monica's life and is sophisticated, mature, an eye doctor, and and able to grow a moustache. After they're married, Monica points out how silly this is given she chose him over Richard several times. As an Insecure Love Interest, he has trouble acknowledging this. It's also worth remembering that all his previous girlfriends cheated on him, so his fears aren't exactly groundless.
Rachel and Phoebe are also this towards Monica and Chandler relationship, as they're depressed about not having anyone themselves. Lampshaded in Season 6 when Chandler's planning to propose and they say they're only 2% jealous...then 10%...then 20%...
Ross towards Paolo. Actually, Ross is this repeatedly. When they begin dating, he is extremely jealous of Rachel's colleague Mark, despite the fact that Rachel shows no romantic interest in him. He is also jealous of Emily's burgeoning friendship with Susan (Carol's lesbian lover), believing she will steal Emily from him. Monica points out that his divorce from Carol must have really done a number on Ross since in high school, Ross was not a jealous person despite the fact that ALL of his girlfriends were cheating on him.
In Desperate Housewives episode Back in Business, Mary Alice's ending narration focuses on the various types of envy, stating that if you look carefully at the people near you, you may spot a green-eyed monster.
iCarly: Freddie suffers this in iLike Jake and iDate A Bad Boy. Carly also gets this like whoa during the recut version of iSaved Your Life. When another girl comes up to Freddie and offers him weekend sex with her whilst her parents and brothers are away, Carly grabs Freddie by the shoulder, embraces him and starts kissing him so the girl will take the hint that Freddie is taken, much to his surprise (and approval).
In Robin Hood, Guy of Gisborne envied Robin his popularity and status as a national hero, and the love of Marian.
In the third season, Kate envied Isabella and Guy because of Robin's continual obsession with all things Gisborne-related.
An episode of Hercules: The Legendary Journeys had Cupid turn into a literal green-eyed monster when the woman he was in love with fell in love with Hercules (who reciprocated due to being struck with one of Cupid's arrows).
Prince Arthur a couple of times on Merlin. He responds to the sight of Lancelot and Guinevere holding hands by throwing a Big Sulk (and this is before he and Guinevere are in a relationship), and later gets riled at Gawaine for flirting with her. The fact that both knights have been reinstated at Camelot gives you the feeling that this is heading somewhere...
One of the longest running jokes in Everybody Loves Raymond is how much Robert envies his brother, Raymond. In his rants, he would talk about how "Everybody loves Raymond", how his mother favors Ray over him, how successful Ray is compared to him, and how he has a better life than him (at least in his eyes). It gets to the point that whenever Ray fails at something or doesn't get what he wants, Robert finds joy in this and openly mocks him for his shortcomings.
Mash has Margaret, who is jealous of Frank's wife. When she finds out Frank bought a set of expensive pearls for his wife and a second, cheaper set for her, Margaret devises a plan to get Frank to swap out the cheaper ones so she will have the more expensive necklace and Frank's wife will get the cheaper set.
The tables get turned when Margaret marries Donald Penobscot. Frank's own jealousy causes him to kind of lose his marbles and he ends up sent back to America on a Section 8.
Lex: You were always one step ahead of me. Clark: It wasn't a competition. Lex: Of course it wasn't; you're simply better than the rest of us. Clark: And that always killed you, didn't it? Lex: No. What killed me was that you didn't evenwantit. You rejected it. If I had your destiny, I would have embraced it.
More generally, Pierce frequently falls victim to this, being older and somewhat out of touch with the younger members of the study group. He is often left out, which leads him to become more of a jerk, which leads to him being left out even more.
In the Castle episode "Eye of the Beholder", Castle and Detective Beckett are joined on their investigation by Serena Kaye, a classy, attractive insurance investigator who is clearly attracted to Castle and whom Castle begins to find intriguing in return. Not entirely surprisingly, Beckett spends most of the episode seething with badly-concealed jealousy about this.
In general, Beckett seems prone to struggling with her inner-teenager-with-a-case-of-this whenever other women attract Castle's attention. Castle, of course, returns the favour whenever other men take an interest in Beckett.
In episodes since the characters have gotten married, however, this seems to be more Played for Laughs than anything on the occasions when it happens.
On Leverage, Parker is this during the episode "The Double Blind Job" with regard to Hardison being friendly with the client. She later breaks a beer bottle as she is watching them talk.
This comes up periodically in Supernatural; people who don't know the boys see that they're handsome, tall, competent, charming, good liars, etc., and conclude they have it easy. As the stars of one of the most depressing shows on television, this is emphatically not true.
The loser behind the problem in the wishing well episode says something to the effect of them having it easy with their great looks and cool car, and they assure him in deadpan that they are absolutely miserable. This is a little surreal, in that it's true, but they say it like they're remarking on the weather. On the other hand, Sam lies to the asthmatic warlock kid in 'Swap Meat' that he'd love to have his life without the demon bounty hunters and blood addiction problems and responsibility for the Apocalypse and all that. Actually, he'll take all that rather than be that kid with the collegiate future locked in stone by his asshole family, and a no-good body. Probably the most significant factor being that by Season 5 Sam has long since grown uncomfortable with restrictions on his ability to kill the fuck out of his problems, and is not actually fit to live in society anymore, even if he is wearing a white hat again.
Played for Laughs in order to alleviate the high levels of tension in an otherwise rather grim and humourless episode of Sherlock (which is known - and loved - for its dry wit): John spends the entirety of A Scandal in Belgravia reveling in barely-concealed jealousy over how much attention Sherlock awards Irene, to the point where his Girl of the Week breaks up with him for being a better boyfriend to Sherlock than he is to her. John becomes completely incensed after the first time Irene fakes her own death, threatening her in an attempt to convince her to tell Sherlock that she's still alive. This doesn't stop him from feeling sorry about her apparent death at the end of the episode. Sherlock himself suffers from the Green-Eyed Monster whenever something other than the case they're working on distracts John.
While playing a conceited version of himself in Extras, Orlando Bloom seethes with jealousy over Johnny Depp:
MythQuest: In one episode, Cleo visits a Swahili fairy tale. The brother of the fairy tale's protagonist refuses to let her have any success, always claiming that whatever she earns belongs to him, despite how much wealth he alread has.
Surgical Spirit has Sheila, who used to date a coworker, got engaged to him but they then split up. Both of them start dating other people, but when the coworker's new girlfriend joins the hospital as a nurse, Sheila… isn't particularly kind to her for the first few days. She gets better, though.
On Once Upon a Time, Zelena, the Wicked Witch of the West, physically turns green when she allows her envy get the better of her. Once she gets over the fact that Rumpelstiltskin chose Regina over her, she returns to normal. Then she gets envious when Dorothy Gale turns up in Oz and is prophesied to be The Chosen One, so she turns green again.
On The Paradise, Katherine Glendenning is jealous because Moray, her boyfriend and later fiance can't seem to forget his dead wife.She considers this this the reason they have not married yet. She tries to remove her painted portrait from his office without permission. Once Denise Lovett, the new shopgirl, catches the eye of Moray, Katherine changes targets. Her envy is greater because Denise was able to make John Moray forget Mrs. Moray while she couldn't. Katherine does not allow Moray to break up the engagement. She waits until the day of the wedding to do it herself. She exiles Moray and thanks to her rich banker dad, now she owns The Paradise, Moray's life's work.
On Star Trek: Voyager, Neelix refers to jealousy as "that green-eyed pus-hog." Typically, he does so in reference to his own jealousy of what he thinks is Tom Paris trying to get too close to Kes. This leads to a food fight in the mess hall before they get sent on an away mission, during which they finally patch things up.
One of the Monsters Of The Week on Sleepy Hollow was Ichabod's ex-betrothed, a woman who became an evil spirit after her death and targeted women that she considered romantic rivals.
In Ik Mik Loreland, this is Karbonkel's reason for turning everyone else in Loria illiterate.
In House of Anubis, all the girls do this at one point or another, except for KT and Willow.
Amber was very jealous over Mara and Mick during the time Mara was running for class representative, to where she ran against her former best friend and turned into a slight Alpha Bitch in order to both win Mick back and intimidate Mara. However, she soon got over this and encouraged Mara to get back with Mick after their breakup.
Patricia has a tendency to be possessive and insecure about her relationships in general, getting jealous when Fabian was spending more time with Nina (who Patricia was bullying at this time in the show). She got much more jealous over Eddie, when he spent time with people like Mara, KT or Sophia, as it was all she could really think about a lot of the time.
Nina was pretty possessive over Fabian, to where she was angry when he merely spent a little time talking to Joy. This caused her to get very temperamental and snappy with him, while he was doing his best to keep both girls happy.
Joy herself was pretty bad, taking her jealousy over Fabian and Nina to such extremes as to write a toxic article on Nina and publish it under Mara's blogging alias, Jack Jackal. Even Patricia, her best friend, found this disgusting. Joy eventually got over this and stepped down, agreeing to just be friends with him.
Finally, Mara got nasty during the end of season 3, when she bullied Joy over falling for Jerome. She had meant to just have her friend pretend to like him as revenge for him cheating on her with Willow, but instead the two of them actually fell for each other. Mara revealed she was jealous soon after, calling Jerome her boyfriend and getting mad at Joy for liking him. Eventually they reconciled, and like the other cases, she helped Jerome and Joy get back together.