Rarity also suffers from this when Fluttershy becomes a famous model. In an interesting handling of this trope, Rarity is actually very disappointed in herself for being jealous of her friend's success.
Spike gets this towards Owlowiscious.
Everyone thought Twilight was this in the second season finale, "A Canterlot Wedding" thus causing them to nearly disown her. If she wasn't Right for the Wrong Reasons that is.
Sweetie Belle gets a bad case of this in "For Whom the Sweetie Belle Tolls". Her resentment over Rarity "stealing" the spotlight is serious enough that Princess Luna feels compelled to help her get over it. Luna even mentions that she's been where Sweetie Belle is.
Jem is loaded with this. The Misfits want to destroy the Holograms because they're jealous of their success, Eric Raymond wants to destroy Jerrica Benton because he's jealous of her ability to run a music company better than him, and Jerrica is actually jealous of her own alter-ego because of of the attention Jem receives that Jerrica can't get for her own accomplishments.
Alexandra's reason for wanting to be the lead singer of Josie And The Pussy Cats was jealousy of Josie, and the fact that Alan paid her no attention.
An episode of Tiny Toon Adventures had this as its Aesop, but the characters don't realize that the warning about a Green-Eyed Monster isn't talking about a literal monster until the very end.
The two main characters in Kim Possible encounter this in the third season and The Movie, due to a Romantic False Lead and a new friend with a kickass wheelchair and video games. There was also Kim "jelling" over how close Yori seemed to Ron. It's kind of a coincidence considering Kim really does have green eyes.
Kim gets jealous over Ron at almost the drop of a hat: she also gets jealous when he becomes good friends with Felix in "Steal Wheels," and gets very angry over the time he and Bonnie spend together in "Homecoming Upset" - a lot more justified that time, however, as they were dating at that point and Bonnie was doing everything in her power to rub it in. To her credit, she manages to direct almost all her anger at Bonnie and not Ron.
"What You Want" showed Tucker envious of Danny's ghost powers. It's a kick in the teeth to him especially because Danny was once on equal terms with him before he got his powers, making him (in Tucker's perspective) more "superior".
Code Lyoko has Sissi Delmas who loves Ulrich and is jealous of the relationship between Yumi and Ulrich — so she tries to make Yumi jealous in turn (sometimes successfully). Also, when William Dunbar enters the scene in Season 2, Ulrich shows serious envy of William's easy flirting with Yumi, while he himself Cannot Spit It Out.
In "Date With Destiny'', Starfire becomes something of a Yandere once she finds out that Robin is taking a bratty Daddy's Girl to her prom (as part of the Big Bad's blackmail).
Robin also becomes rather green-eyed over Starfire when she's getting married in "Betrothed". Cyborg explicitly teases the boy about it, saying, "You sure you're not just, y'know... jealous?"
Princess of The Powerpuff Girls became a supervillain because she was envious of the Powerpuff Girls ("If I can't be a Powerpuff Girl, then there won't be any Powerpuff Girls!"). In "Superfriends", she becomes jealous of Robyn, who has become the Girls' best friend, the only thing theSpoiled Brat has ever wanted but could never have. ("Why would the Powerpuff Girls want to hang out with you when they could be friends with me?!!...")
An episode of Disney's Hercules (called, appropiately enough, "Hercules and the Green-Eyed Monster") has Icarus being jealous that his drama teacher is marrying his father, and thus getting most of his attention, and disrupting the wedding with Pandora's box. He is then consumed by Jealousy, as in swallowed whole by an Anthropomorphic Personification who has been feeding on his envy.
Thrust, one of Starscream's clones in Transformers Animated, embodies his creator's envy. This is appropriate, as he's the only clone who doesn't appear in the cartoon or the toyline - he only showed up for the second Allspark Almanac.
Heloise on Jimmy Two-Shoes gets extremly hostile over Beezy's friendship with Jimmy, which often results in episodes of her doing terrible things. For that matter, any supposed instance of Jimmy showing attention to anyone but her can lead to trouble. There was even a role reversal in one episode where Heloise managed to make Jimmy jealous, despite being Oblivious to Love.
Often a major reason for Bluto going after Popeye the sailor usually does a better job fixing/building something than his big rival. Occasionally inverted, but a dose of spinach always lets Popeye win the final round.
An episode of 3-2-1 Penguins! is actually titled "The Green Eyed Monster", and it involves a planet where a pack of sheep is jealous at another because of their pastures.
Tygra from Thundercats 2011 seems to have been suffering this for a long time, in regards to his little brother Lion-O and the girl they both have feelings for.
In the interquel comic series of Avatar: The Last Airbender called The Promise, Katara shows a mild case of this. She feels a bit upset that Aang hangs out with the Air Nomad fan club more than her, making her feel left out. But this is resolved (somewhat) when Aang explains that the fan club reminds him of his old home. That, and he loves her.
She's shown a bigger case of this in The Waterbending Scroll, though. This is due to not getting Waterbending right instantly while Aang, being an Airbending Avatar, did. This causes her to yell at him about it only to feel guilty and apologize, and she also put the others in danger due to stealing a pirate's scroll. She gets over all this, though.
In the Sequel SeriesThe Legend of Korra, it becomes clear that Unalaq, Korra's uncle, chief of the Northern Water Tribe, and apparent Big Bad of season two, is deeply jealous of his older brother Tonraq, Korra's father. He was so envious of his brother's position that he engineered his banishment so he could become chief. Korra also suggests that Unalaq's desire to train her stems from his envy of the fact that Tonraq sired the Avatar.
Ben 10 has multiple exemples of this. Considering the protagonists gains Famed in Story starting with the third installment of the show, that's kinda understandable:
Captain Nemesis, despite being himself a famous superhero as well as possessing his own company, developped a jealousy when Ben starts becoming more popular than him (ironically, Ben himself admired him then). He first attempted to get back credit in a so-called friendly competition with him, but ends up humiliated (the only round he is able to win is only thanks to part him cheating and part Ben's Omnitrix malfunctionning). Unable to stand this, he turns evil as a result. By his second appearance, he has gone as far as becoming a murderer.
A more light-hearted exemple than the two previous ones, minor villain Billy Billion from Omniverse has his whole motivation running around the fact he was jealous of Ben for getting more attention at school than him.
Prince Tritannus in Winx Club is jealous of his twin brother's popularity and lock on the throne. As such, he attempts to assassinate Nereus. When this fails, he retaliates by trying to conquer the whole Magic Dimension, brainwashing Nereus in the process.
Gumball becomes literally possessed by his jealousy of Leslie in "The Flower".