Excel♥Saga parodies this, like everything else, in one late-run episode, which is very dark and humorless compared to the other episodes and ends with Excel being shot and left to die. It's actually around episode 23 of 25; the actual final episode (#26) was unaired due to crossing the lineway too many times.
Though this itself was a parody of a Sequel Hooks, since immediately afterwards Brief is told that he must embark on a quest to revive Panty and stop the villains, setting the stage for a second season that was never in the works to begin with.
Master of Martial Hearts: The first 4 out of 5 episodes will make you think that this OVA is just a silly, goofy, mushy comedy with some brutal fights between the main character Aya and her opponents in a tournament. Then the 5th episode comes in. To wit: Aya ends up killing her opponent in a Berserker Rage. Then she finds out that every one of her friends was a Bitch in Sheep's Clothing who had manipulated her right from the beginning. They mentally broke all the losers of the tournament, making them into "perfect women" to be sold into sexual slavery. Aya's "friends" did this because her parents did the same thing to their parents, and they want to kill her to get back at her mother. Then Aya's mother shows up and kills them off, revealing to her that this is a Cycle of Revenge going back to their grandparents. So Kill 'em All ensues, with Aya limping away from the blown up building. Then her so-called best friend's mother gets a visit from someone that she is very scared to see.... There had been very few hints that something like this was going to happen. Yikes!
The 1975 anime adaptation of A Dog of Flanders, true to the original material, has the main character and his dog freeze to death in the last episode. The series is quite positive and upbeat (and looks like Heidi) otherwise, so to many children, this came as quite a shock.
Since a lot of people in Japan were familiar with the eponymous tale and how it ended, fans of the show sent tearful mails to the staff days before the final episode aired, pleading not to have Nello and Patrasche die at the end. Though the staff ignored the pleas, they at least softened the blow of the ending a little by having it presented on an uplifting note.
The first half of the first series of Magical Princess Minky Momo had this in episodes 45 and 46. In episode 45, Momo's main mode of transportation, the Gorumepopo looses energy and disappears, Momo looses her pendant and pets on a train, Momo encounters bad guys who wanted her pets, and when she tries to get her pendant in order to transform to save the man who helped her, her pendant shatters. In the next episode, Momo tries to go to school and can't pay attention, so she goes to the park where she tries to retrieve a baseball and gets run over by a truck. She then dies, but is reincarnated as the real child of her foster parents. The rest of the series is All Just a Dream in the mind of the human Momo about a new Minky Momo that came to earth.
Happens in-universe in episode 8 of season 1's Boku wa Tomodachi ga Sukunai. Sena is playing a Visual Novel where her character is having fun with friends at a swimming pool, and Yozora nonchalantly mentions that the game would be godly if a shark suddenly appeared out of nowhere and killed them. Sena berates her for suggesting such an awful thing, but then that's exactly what happens. Sena at first thinks its a joke and that her main character would easily vanquish it, only for the shark to kill him, and she suffers from a bad ending. Rika mentions that this game was particularly notorious in online forums for this ending if you failed to trigger a certain flag earlier in the game. Everyone in the clubroom, Yozora included, were completely shocked by it, and after she recollects herself, Yozora calls it a godly game, while Sena angrily snaps the disc in half.
In Guardian Fairy Michel, after 25 episodes of happy, lighthearted hijinks, Michel dies at the end to rejuvenate the Tree of Life, Kim leaves the island, and the villains still have their floating castle.
Transformers: Wings of Honor: Metalhawk's and Onslaught's teams (as well as the other Elite Guard teams who operate mostly offscreen) work well together, complete many missions with an unbroken victory streak, and beat back numerous Decepticons, in relatively light-hearted adventures. And then it all goes to hell. Onslaught's team defects to the Decepticons, and attacks the Autobot base. They also become a combiner, Bruticus, which ends up crushing Sentinel Major in its hand, Over-Run is crushed by one of his drones, and almost all of the other Elite Guard are also killed in various ways including Powerflash. While Bruticus is finally brought down by one of the heroes, Onslaught still kills his former friend Metalhawk on their way out. It finally ends with the last remaining Elite Guard team coming to the base and requesting permission to land, but finding no response. Even a side comic which is usually a bunch of humorous stories about goofy newscasters, ends with, not a funny punchline, but one of the reporters coming to the sight of the carnage and asking to go home in shock. Geez.
Though this was only the first story; the sequel ends with a bittersweet, but more upbeat note.
Graduation Day, the Grand Finale of Young Justice. After 56 issues of comedy, the mini-series sees the violent deaths of Omen and Donna Troy, and the dissolution of both Young Justice and the Titans. One of the last scenes is of Wonder Girl tearfully stating that the kids will never learn enough to be real heroes, and that the entirety of the series was essentially a massive waste of time.
Thanks to a combination of Running the Asylum (editor Nick Lowe's determination to see Gert Yorkes be resurrected at any cost) and Executive Meddling (Marvel's decision to cancel the series in mid-arc due to dropping sales), Runaways ended with Chase Stein abandoning the other Runaways and then getting hit by a car after somehow running into Gert Yorkes on the street.
Roller Boogie, a light-hearted roller-disco film, inexplicably ends on a downbeat note, with the main characters tearfully separating to pursue their futures in different cities.
Notoriously, the original ending to Clerks would have ended with this. A lighthearted comedy about two lazy store clerks wasting a day shift? The original version ended with a robber entering the store and shooting the main character, killing him instantly.
The silent film Exit Smiling is a zany comedy about a terrible actress in a traveling theater troupe trying to save the man she loves from going to jail. She succeeds. But he never finds out she was the one who saved him, and he's so happy about being able to stay in town with some other girl he likes that she simply doesn't tell him. The movie ends with her crying quietly as he steps off the train.
At the end of Boytown, the band dies in a plane crash, leaving behind wives, children, and an unrealised relationship for the recently outed Carl. It's extremely incongruous for a film that was quite light and farcical up to that point. It's uncomfortably played for laughs and drama.
The end of The Mole People: Adad and Bentley managed to escape the destruction of the Sumerian kingdom and had reached the surface... Only for Adad to suddenly and inexplicably turns back towards the cave entrance and be crushed by a falling pillar. Her death was mandated by the studio, who considered American Bentley and Sumerian Adad a "mixed-race couple" and feared having them live happily ever after would be seen as endorsing miscegenation. This◊ is Adad, by the way.
In Train Of Life, the Jewish villagers manage to smuggle their train across half of Europe, tricking the Germans along every step of the way, and eventually reach the safety of the Russian border. Everyone is celebrating, and Schlomo starts telling us what happened to the characters as the camera slowly zooms out from his face... revealing him standing behind the barbed wire of a concentration camp. The entire story was wishful thinking on his part.
Magic Mike starts out (and was marketed as) a comedy with male stripper Mike taking 19-year-old Adam under his wing at the strip club. It ends with Adam getting involved with drugs and owing $10,000 to drug dealers, and Mike having to bail him out.
The film Rue des plaisirs is the story of a handyman in love with a prostitute called Marion whose own boyfriend is in danger with mobsters. They've successfully managed to evade them and are living idyllically in the countryside. And then the gangsters arrive out of nowhere and kill her boyfriend, and then her, leaving the handyman alone to mourn. Cut to the two prostitutes who've spent the movie listening to a third one tell the story of how Marion managed to make something of herself, and cut to the credits. (Even the director later regretted sticking on the unhappy ending.)
Pay It Forward infamously ends with the hero being unceremoniously murdered by random bullies and all of his good deeds being undone in increasingly cruel ways.
Brazilian Z-movie "Zindy The Swamp Boy" set up a happy ending where Zindy kills the ever-present cougar and is taken back to civilization by the parents of the girl he rescued. Possibly even able to claim inheritance of his grandfather's estate. Then the film suddenly pulls the rug out from under the audience: Zindy gets mauled by the dying cougar and dies himself, leaving the girl lost in the rain forest to fend for herself, with no word on whether or not her parents find her.
In the final chapters of Tottie: The Story of a Doll's House, one of the dolls is burned to death.
Xinran's Miss Chopsticks is a fairly upbeat book about three sisters making their way in modern China and finally gaining their father's respect. The Author's Note at the end reveals that of the three real-life girls the characters were based on, one was then forced into an unwanted marriage, one lost her job when her employer was shut down for distributing banned books, and the third disappeared.
Played with in the Captain Underpants series. At the end of the ninth book, Tippy Tinkletrousers accidentally creates a post-apocalyptic timeline and apparently gets crushed to death, and the book appears to end with a textless two-page spread of Scenery Gorn... but then the following page reveals that the story will be continued. Doubly so when you realise that Tippy's disruption of George and Harold's arrest (seen at the end of Book 8 and the beginning of Book 9) had yet to happen.
The novel Breathers is a horror-comedy about a world where the recently dead randomly reanimate (but still retain their minds) and have no civil rights, are used as lab animals and are even destroyed for fun in the streets. The protagonist Andy eventually becomes a celebrity who fights for zombie rights and really seems to be making a difference despite that fact that he and several other zombies secretly eat people, since human flesh reverses zombie decomposition, makes their hearts beat again and even makes them able to have children). Then at the very end Andy, his pregnant zombie girlfriend Rita and his zombie best friend Jerry are attacked by fratboys who burn Rita and Jerry to (re)death. Knowing which fraternity is responsible, Andy then gathers their circle of zombie friends and attacks the frathouse in a Roaring Rampage of Revenge, slaughtering everyone inside despite knowing full well that this will utterly destroy the zombie rights movement. While some of their armed friends rescue them after their capture, they face a Bolivian Army Ending with the police closing in and nowhere to run. Andy's only comfort is that he'll at least die on his terms rather than as a lab rat. This all happens in the last twenty pages.
Live Action TV
In the final episode of Dinosaurs, the main character accidentally triggers an ice-age by over-industrializing the world. He then has to explain why they're all going to die to his youngest child. Cut to the outside of the house, where snow is piling over the entire house. In the final shot, a newscaster solemnly states that the snow is getting harsher, the days are getting darker, and there's no end in sight. He issues a formal "Good night". He reconsiders for a moment, then looks straight in to the camera with weary, uncertain eyes, and solidly states, "Goodbye."
Also because for anyone with any emotional investment in WW1 (read: everyone in Britain above a certain age), the ending is actually incredibly touching, respectful, and appropriate. Writer Ben Elton's uncle, an eminent historian specialising in the period, was outraged when he first saw Blackadder Goes Forth and practically disowned him for what he saw as trivialisation of the war. After seeing the final episode, he wrote his nephew a letter apologizing and praising him for the way it was handled.
The finale of Roseanne, where it's revealed that the entire last season was part of a book Roseanne had written after Dan died of a heart attack.
In the last episode of Alf our wise-cracking alien protagonist is captured by the Alien Task Force, presumably never to be seen again by the Tanners. The producers were told they'd get a TV Movie to Wrap It Up, but it wasn't until years later that it actually happened, and the tone of it was distinctly darker than the series.
This trope began a season early in the BBC's version of Robin Hood. At the end of season two, Maid Marian was brutally murdered at Guy of Gisborne's hands, changing an upbeat family show into something unimaginably bleak, and without any hope for a happy ending. Bizarrely, season three tried to regain its reputation as a family show, but the fed-up actors left for greener pastures, ensuring that the show ended with the deaths of Robin Hood, Allan-a-Dale, Guy of Gisborne, and the Sheriff of Nottingham. Despite the gutted cast, there was an attempt to introduce a Legacy Character for Robin Hood, but the show was not commissioned for a fourth series. The show ended with the remaining outlaws vowing to continue the fight against Prince John, but anyone with a rudimentary knowledge of English history knows how well thatwould have turned out.
Publicity for the last ever episode of largely light-hearted series Lovejoy focused on the return of Will They or Won't They? love interest Lady Jane and Lovejoy's wedding to Replacement Love Interest Charlotte. Instead, the Villain of the Week kidnaps Lovejoy on the way to the wedding as revenge for foiling his plot and Charlotte refuses to believe it, thinks she's been jilted, and takes a job away from the area. What's more, Lovejoy's other two friends also take jobs away from the area and he's effectively evicted from his home/shop. The final scene of him packing his things into the back of his truck and driving off alone is actually quite depressing.
Seinfeld's two-part series finale. The show itself was about selfish, peoplecoasting through life, and the finale showed them finally getting their comeuppance. Still, it divided fans of the show, some thought that it was a very dark and uncharacteristically serious way to send off a sitcom, especially one that had prided itself on being a "show about nothing".
Although Medium dealt with many bad things, its overall ethos was generally that the bad guys always got caught and everything turned out well in the end. Which made the series finale in which Alison's husband Joe is killed in a plane crash, most of the episode is taken up with a bizarre soap opera tale of it all being a ghastly mistake and an amnesiastic Joe is living in Mexico which turns out to be a dream, and then Alison spending the next 40+ years of her life without the one person who has kept her sane throughout her psychic travails and who she has repeatedly been shown to depend on utterly and all alone because she never finds someone else or remarries all the more difficult to take.
The True Life episode "I Don't Trust My Partner" had two couples talking about their trust issues. The audience sees Nikki and Shawny, the second couple interviewed, fighting for the extent of the episode, thanks to Shawny flirting with girls behind his girlfriend's back, and eventually going to couple's therapy to see whether they should move in together. Fast forward some months later, the show pans over to the new apartment the couple talked about renting, with their stuff inside. Problem is, shortly after they moved in together, Shawny suddenly died after complications from a hernia, and Nikki went through a period of overwhelming grief. For a show that usually goes no further than a Bittersweet Ending, this depressing conclusion came out of nowhere.
The last episode of 3rd Rock from the Sun: all of the main characters are forced to return home. Mary doesn't want to leave Earth, and she is given a Mind Wipe so she won't remember Dick. An alternate ending has Mary being abducted by Dick after the Mind Wipe, but it still ends on a depressing note.
In Glee's third season finale, Kurt was rejected from the prestigious performing arts college he spent the whole season trying to get into. The whole thing felt extremely out of the blue since his audition made him out to be a shoo-in several episodes prior, being praised by the recruiter and all.
The final episode of Xena: Warrior Princess. Things looked dark, darker than usual, but there was a clear path to victory set up that was going to make everything better. Except right before reaching it, the protagonist suddenly decided that Redemption Equals Death (despite the entire show up to that point being explicitly about redemption via living a better life) and chose to just stay dead, leaving her soulmate alone. It wasn't even a heroic sacrifice, as nothing was gained by it. This ending was quickly disavowed by the comic book continuation.
Titus did this for every season finale — but especially in the final three episodes of the series. In the first, Christopher's mother Juanita shows up suddenly in Christopher's house, apparently having broken out of the mental hospital she was in. The episode is mostly lighthearted as usual, focusing on Christopher and his family trying to catch/find Juanita... until they finally have her cornered, in a closet, when Erin comes in with a message from the mental hospital, that Juanita had committed suicide four hours prior; meaning Christopher had been hallucinating her the entire time. And THEN, there is the two parter finale that continues the story, 'Insanity Genetic', in which the cast is on an airplane coming back from Juanita's funeral, Christopher has a mental breakdown, and they all cause a panic and get arrested under suspicion of being terrorists. They are all thoroughly interviewed, the authorities become convinced Christopher is mentally ill, and the rest of the cast end up admitting him to a mental hospital, where he reassures Erin that he'll be okay as she tearfully says goodbye, and we're left with a last, lingering shot of Christopher sitting alone in his cell.
The series finale of How I Met Your Mother had earned the scorn of most fans for this. The mother dies, Barney and Robin divorce, and the gang split apart and become shells of their former selves. For a show that was mostly light hearted and fun the ending came as a shock to many fans. The season 9 DVD is said to contain a more "happy" ending to the series.
BBC's Merlin suffers deeply of this - for all that the first 4 years were mostly light, and even for all the Darker and Edgier vibes on the 5th season, it reaches new heights by the series finale. Considering the legends it comes from, though, it is a Foregone Conclusion.
The infamous ending of Choujin Sentai Jetman. The Vyram have been defeated and all is well. We flash forwards two years to Ryo and Kaori's wedding and then Gai gets murdered by a random street thug.
The last track of The Dark Side of the Moon, "Eclipse", is a lively song explaining that everything under the sun is in harmony... and ends with "but the sun is eclipsed by the moon".
In the true ending of Persona 3The Hero defeats Nyx but suddenly dies in the game's last second. The mini-sequel, Persona 3 The Answer explores the reason behind this sudden downer ending.
The true ending of Braid. Open to interpretation, but it would appear that the princess was trying to escape from the protagonist to the antagonist, not the other way around. Or she's the atomic bomb. Either way, or both ways, she appears to explode, which is sort of hard to think of as a positive ending.
Drawn to Life: The Next Chapter for the DS. Basically, all of the adorable animal characters in the village are killed, G-Rated style (they fade away). One of the characters, named Mike, fades away last. The voice of Mike's sister Heather is heard asking the Creator, the god-like figure in the game, to bring her brother back, which at first seems like a Heartwarming Moment. Then, her message changes and she was really trying to say, "God, just bring back my little brother to me." It is now revealed that Mike and Heather are actually humans, and the whole story with the village of cute animal things was all just a dream that Mike was having. It wasn't a regular dream, either; it turns out that Mike and his family were in a car crash, which killed his parents, injured his sister, and put him in a coma.
Harvest Moon: A Wonderful Life. You die. Admittedly, the game is one of the darkest in the franchise (if not the darkest), but it's typically quite happy. To make matters worse you die suddenly and rather young (likely in your 50s or 60s).
The Narrator's clear and unmistakeable announcement that it would happen should have removed the 'suddenly' qualifier, but that was taken with a hearty dose of Like You Would Really Do It, leaving the shock when it actually did happen.
There was also a last-minute, post-credits inversion of this trope didn't so much negate the Downer Ending as even it out to Bittersweet Ending. The Max that died was still the same one who had been with Sam since "Chariot of the Gods", when time travel copies of Sam and Max was created. And if the Max who joined with Sam at the end was the "real" one, then that would mean the real Sam had died during his adventures elsewhere.
These events are mentioned in Poker Night 2. Strangely, Max confirms Sam's version of the events instead of his own.
Conkers Bad Fur Day. After a humorous South Park styled adventure, Conker becomes King Of All The Lands.... but at a price: the people in his kingdom are all morons, and to make matters worse, his girlfriend, Berri, is dead. As for Conker himself, it's highly implied that he's spiraling towards a booze-filled self-destruction.
In the original ending, things were a bit less... subtle. In the bar scene at the end, Conker was supposed to shoot himself in the head. The only reason this was changed was because the creators were planning on a sequel.
DeathSpank is a comedic hack and slash RPG that prides itself in its wacky, lighthearted Monkey Island-esque humor. Then, at the end of the sequel, DeathSpank's closest ally and possible love interest goes batshit insane due to the Thongs of Power's corrupting power, and he must either let himself be killed to fuel her delusions of godhood or cut her down himself, which greatly troubles him as he mourns and buries her. Unlike literally the entire rest of the series, this is all treated as somber and tragic as possible. And the canonical choice? He kills her.
This isn't the ending of The Reconstruction as a whole, but it is the ending of chapter 3, "Life and Debt". Up until that point, the story reads like a fairly typical Heroic Fantasy adventure story, with a few hints of a greater, overarching plot and only a few very serious moments. You'll probably think that it'll maintain the fairly carefree, happy-go-lucky vibe the heroes have going on. Well, at least, until Metzinogets thrown off the Faithall Tower, you fight your first boss fight with a human character (who dies bloodily), and at the end of the day, it's revealing that the characters were Unwitting Pawns the whole chapter and their efforts were meaningless. It's also immediately followed by interlude 3, which is filled to the brim with Tear Jerker.
The Bad Ending to the 8-bit version of Sonic the Hedgehog 2, in which Sonic fails to get all the Chaos Emeralds before fighting Silver Sonic, and is punished for it by not completing his adventure, and instead showing a montage of him running from the middle of the day into the dead of night while the credits roll. The bad part? When he stops running, he looks up into the sky and sees Tails' face in the sky, implying that he died.
The ending to Blade Dancer: Lineage of Light, which had up to that point been a fairly normal, relatively upbeat (no major betrayals, no major massacres, nobody dies, etc) RPG, can only be summarized by this trope.
You could argue that Sly 2: Band Of Thieves ends this way. Granted, the Big Bad is finally gone for good (both of them) and Sly gets away in the end, but the gang disbands due to Bentley getting crippled for good during the fight and Murray blaming himself for it. Sly 3: Honor Among Thieves' first chapter is the three coming back together and confronting their lingering feelings from that disaster.
Also, the fourth game becomes a Downer Ending when Penelope betrays the Cooper Gang for her own selfish gain (but escapes prison and continues sending postcards to her now-ex Bentley), Sly disappears without a trace and the Bad Guy nearly wins. The secret ending reveals that Sly is alive in Ancient Egypt, setting up a sequel which has yet to be announced.
The Conquest ending to the otherwise giggles-and-rainbows game Hyperdimension Neptunia mk2 has Nepgear taking the lives of the 7 other CP Us, including her own sister, in the most heartwrenchingly depressing death scenes you can imagine.
Fire Emblem 7 talks about what happened to all the characters after the ending. All of them turned out pretty okay getting married and whatnot...oh except for Canas who died along with his wife in a snowstorm. Nino also disappears and leave two children behind since either she or her husband is wanted by soldiers.
Fire Emblem 3 and 12, where certain characters get bad endings for little reasons. Est, for example, feels guilty over her uselessness that caused her husband Abel to commit Face-Heel Turn to protect her, and leaves him without saying a word.
Ultima 5 ends this way; the Avatar returns to Earth to discover that his house has been robbed while he was away saving Lord British. This was apparently done to drive home the moral that the path of virtue is its own reward.
Possible in Maniac Mansion if you contact the Meteor Police before showing the Meteor the publishing contract. While the Meteor is on the talk show in the ending, a policeman will beam down and arrest him. "I don't care if you're reformed, I'm still arresting you."
Mass Effect 3 had this problem, amongst other issues (such as a Gainax Ending, Railroading, multiple inferred holocausts, plot holes large enough to drive a truck through). The endings contain a combination of Shepard dying, the Citadel exploding, and a guarantee in all endings that the mass relay network is destroyed. This effectively ends galactic society as we know it and dooms all the ravaged worlds to a slim recovery at best. At worst, it outright obliterates every system with a mass relay (of which most Homeworld systems are) due to the established precedent of exploding mass relays = supernova-grade explosion. Retconned in the free Extended Cut DLC, where the relays and Citadel are merely lightly damaged. Also, Word of God confirms that Shepard lived in the destroy ending.
Ratchet & Clank Future: Tools Of Destruction appears to end on a happy note. Tachyon and Slag are defeated, the Cragmites are permanently banished again, and Polaris is now free from the former's tyranny. But then the Zoni reappear and kidnap Clank, taking him back to their home where he is put into a coma.
The various books in Odin Sphere give each of the playable characters relatively happy endings, with Velvet making progress in trying to avert Armageddon. Then Armageddon happens anyway, and everyone dies except for four of the five main characters. Things get better after that, but the sudden swerve towards the sadistically cruel can be surprising.
The 'Flower Knight' sidestory in Drowtales. A Knight quested and struggled for years to find the world's most beautiful flower for his queen. He finds it, brings it to his queen and the two live Happily Ever After alongside Babies Ever After. Then the flowers reveal themselves to be parasitic in nature and drain the life out of every single person in the Knight's city. His wife, his children, his servants, the commonfolk... Everyone,leaving him the sole survivor in a city of bodies. He sets out of the city to kill the creature that gave him the flower and ruined his life. That is when the story ends. No resolution and to make it worse The flowers are still around.
Doobl. What appears to be a normal family-friendly webcomic for a fair number of strips, then has the protagonist go crazy and slaughter the cast before killing himself. Meanwhile, in the news posts, the author's mother dies. He spends the remaining posts increasingly lashing out against the world. It ends with a newspaper clipping covering the author's suicide. It turned out to be a hoax.
Concerned, the Half-Life and Death of Gordon Frohman, is mostly a gag strip that ends with... oh, guess. Of course, it's still funny while doing so.
The Last Days Of FOXHOUND has everyone Doomed by Canon. As such, the last chapter is just a montage of their bodies. It's emphasized by how sudden it is — cutting straight from the "preparing for battle" montage to the death montage. At least the ghosts of the dead characters show up to joke about their ineptitude, providing a relieving comical note.
It's All Been Done ended with the main character and his wacky group of talking toys about to have an adventure when he realizes the entire thing was an attempt to avoid dealing with his wife's death.
In the last episode of Nyan~ Neko Sugar Girls, Raku dies of a broken heart after she confesses her love for Hitoshi, only to find out that he has entered a romantic relationship with his kidnapper.
The flash series "My Little Pony: Thinking With Portals, is a lighthearted comedy crossover between MLP and Portal, and features each of the Mane Cast (and the Princesses) having lighthearted hijinks with portal guns. The final episode, which will involve Twilight getting her revenge for being the Butt Monkey for the entire series, is stated to be much more serious than the rest of the series, the author admitting some of it may end up veering into Grim Dark territory. However, the author has personally leaked that in the end, everyone lives.
The finale of GuavaMovement's Let's Play of X-COM Apocalypse. Humanity won. They defeated the aliens. Then, in the final chapter, Soup Bot, an android who has been protagonist Otto Zander's closest friend and ally throughout the story, reveals that he was manipulating and using Zander from the beginning as part of his plan to commit genocide on humanity in retribution for their mistreatment of Androids. Soup Bot also reveals that he was responsible for several of the story's major events (the attack on the Evening Star, the attack on the Senate that X-Com was framed for, etc). The story ends with Otto, alone and dejected in his base, unable to do anything but watch as Soup Bot's army takes over the world. Oh, and The Stinger has a member of the Cult of Sirius forming an alliance with the Alien Hive Mind to destroy both the Androids and humanity.
Demo Reel was never very happy to begin with, but The Review Must Go On ended with the death and Ret Gone of all of the characters except Donnie, who regressed back into The Nostalgia Critic, who seems to be even more unhappy and suicidal these days than he was before To Boldly Flee.
At least until the Stinger: "[Father] bought it. Oh, and Numbah One? Welcome back."
Camp Lazlo - Lumpus was never really the scoutmaster, he was a literally insane man who had locked the real scoutmaster away, presumably for the duration of the entire show, to steal his life. He is sent to an asylum. This twist is so dark and downright shocking that the entire cast except Lazlo can do nothing but stand in silence for a moment. Word of God claims that Jane Doe busted him out afterward and married him, but it's still a Shocking Swerve.
The classic Disney short "Chicken Little" plays like a normal Cat-and-Mouse cartoon... until the end, where despite the Narrator's assurance to the audience that everything turns out alright, Foxy Loxy catches and eats all the chickens, turkeys, and ducks, smiling smugly all the while. "Hey, wait a minute!" the Narrator exclaims. "This isn't right! That's not the way it ends in my book!" Foxy, leaning against his "Psychology" book, responds, "Oh, yeah? Don't believe everything ya read, brother!" Yeah.
The Snowman, which remains upbeat Sweet Dreams Fuel until the final moments, which reveals first that the Snowman has melted and died, then that it definitely wasn't a dream. The main character breaks down and cries. Cue credits.
"Well what did ya expect in an opera— a happy ending?"
The infamous (within its fandom, at least) "Holly Jolly Secrets" Christmas Special of Adventure Time. It is about the heroes Finn and Jake watching a bunch of videotapes made by their arch-enemy and Ineffectual Sympathetic Villain, the Ice King. The whole time, Finn and Jake continue because they believe the Ice King has hidden "evil secrets" in the tapes. Once the Ice King finds out that they are watching his tapes, he tries to stop them, but fails to prevent them from putting the last tape in their VCR. At that point, all he can do is watch in horror as Finn and Jake discover that he used to wear glasses, but more importantly, that he used to be a normal human being who was driven insane and transformed by a supernatural artifact that he'd bought. They watch the young Ice King lose his mind and the woman he loved (who he called his "princess" before she left him). Before this, the Ice King had almost always been a funny character, and plenty of things that were Played for Laughs in the past were made tragic by this revelation. The writers seem to understand this and have given the character a break so far. Or possibly they don't know what to do with him. In addition, the other tapes before the last one are usually the Ice King saying or doing hilarious things, but some of them show him sitting around his house, crying, although that still seems to be Played For Laughs. Ice King's past comes up again in "I Remember You", when it's revealed that Simon took care of Marceline when she was a child in the aftermath of the Mushroom War. The crown's magic was the only thing that kept him alive, but was also slowly driving him insane; at present, he doesn't remember her very well. It's later subverted when he temporarily becomes normal again and brings Betty (his "princess") to the future. She swears that she'll find a way to reverse what the crown did to him, and the fact that he never lost her makes the revelation less tragic.
If any episode of The Simpsons has any character change in a positive way or gain something nice, and they keep it near the end of the episode — expect it be suddenly yanked away soon afterward. The Status Quomust be preserved. That being said, there were only a few notable exceptions: Barney recovering from his alcoholism (although the writers eventually undid this), Lisa telling Homer that she'll never be happy with her body image (though the whole thing about Lisa being insecure with her body hasn't been mentioned since that episode), and Milhouse's parents staying divorced (though they did get remarried in "Little Orphan Millie,").
Drawn Together ends with one of the main characters dying a brutal, tragic death, and then reality itself being Retgoned due to Spanky's idiocy.