Drama Bomb Finale

Many shows are tempted to do big finales, but the nature of the story is just too low-key for a Grand Finale.

More common is an otherwise comedic story trying its hand at a dramatic moment near the show's last episode or two, totally out of left field. This usually involves the separation of one character from the others, the realization that the isolated character was important to the group, and the co-star (and his friends) having to chase him down and get him back.

Bishoujo series seem particularly fond of this formula, even though it seems like a really obvious attempt to install pathos after having Filler pad the story.

It becomes even weaker in British shows, where a season might be six episodes, and a series might be three seasons. Some Britcoms fall entirely flat, trying to have something momentous happen after a grand total of five and a half hours worth of fluff. Blackadder Goes Forth got away with it, which is all the more remarkable since it came from a series which had played the deaths of all the characters at the end for comedy in the first two seasons.

Compare Sudden Downer Ending.

As an Ending Trope, Spoilers ahead may be unmarked. Beware.

Examples of Drama Bomb Finale include:

Anime and Manga

881 (Papaya). A comedy show, ends with one of the main characters (Who is terminally ill) succumbing to her disease.
Ojamajo Doremi has this as its series finale, and is pulled off quite well, considering it's Doremi herself that gets the Heroic BSOD...
Doki Doki School Hours ends with the realization that Mika might not be teaching anymore due to marriage...though falls on its face after the meeting.
Mahou Tsukai ni Taisetsu na Koto ~Natsu no Sora~ is for the largest part a fairly lighthearted Slice of Life affair—until it is announced out of left field that Sora has a terminal heart condition, to which she succumbs after fulfilling her late father's wish.
Excel Saga. The drama properly starts a few episodes before the finale. Of course, with the show's trademark genre-hopping, a few serious emotional episodes were to be expected.
- And then it spirals into utter insanity in the very last episode.
School Rumble Yakumo & Karasuma in particular.
The second season of Hanaukyo Maid Tai was particularly a victim of this. The maids and slice-of-life were abruptly destroyed by ACTION, FIGHTING, and other such things in the last couple episodes.
The Rozen Maiden anime is a huge culprit of this. After spending the majority of the show switching between lighthearted comedy and action-filled drama, Souseiseki decides to stop playing around and to win the Alice Game, but instead gets killed off by Suigintou in the process. This in turn triggers Hinaichigo's death in the following episode, clearly cementing that playtime is over in the anime, and the remaining dolls spend the final two episodes duking out in an extremely drama-filled Battle Royale With Cheese. And the worst part is that the ending leaves a lot of openings for another season.
Ouran High School Host Club ends this way. It's a comedic series, though a few episodes near the end had a more serious tone, but the second to last episode ends with a huge bomb being dropped on the audience(and the main characters!) and the last episode is full of drama.
Tatsunoko's 1969-70 anime Hakushon Daimao, a very cartoony Gag Series, ended on a downer note with the genie being forced to leave Earth for 100 years.
Potemayo attempts to do this by revealing the back story of Sunao's mother in the second to last episode, as well as aming it seem that Potemayo and guchuko were dead in the final episode, although they turned out to be merely unconscious and recovered by the end of the last episode.
Soredemo Machi wa Mawatteiru Does this by having hotori write a story, and then be hit by a truck while she is reading of her failure to get the story published. While there is still some humor in this episode, it still ultimately gets played in this way.
Dokkoida?! did this with its final two episodes. The show had been an episodic Status Quo Is God comedy, but the last two episodes were substantially more serious than the rest of the show, and included some truly epic action.

Live Action TV

The final episode of Seinfeld shows a little of this, at least when the plane malfunctions.
Coupling does a slightly different version of this. It's not a death, but a birth, the culmination of the pregnancy that's formed the basis for a lot of the comedy in the fourth and final series. But the final few minutes are played completely serious.
Subverted on Everybody Loves Raymond. A doctor announces that they are having trouble resuscitating Raymond after a very minor surgery, but seconds later he is completely fine. Debra then made everyone swear not to let Raymond's mother know about the near-death experience, since it would bring out the worst in her motherly overprotectiveness. The episode did have a little more emotion than usual, but otherwise it had the same tone as any other episode of the series.
Dinosaurs. It's a comedy series about dinosaurs that suddenly ends with a Green Aesop in which they all go extinct.
Season Six of Buffy the Vampire Slayer (otherwise not a low-key show) went along somewhat slowly. Then Willow went insane in the last four episodes.
Most of the light hearted Super Sentai series such as Goonger follow this trope. The darker ones however such as Changeman or Liveman are serious already so the finale episodes generally are of the same tone as the rest of the series.
Lexx, which had for the most part had been humor of the WTF variety, turned quite dramatic in the final episode, most notably the death of the Lexx, Kai's return to life only to die, and the destruction of Earth. (Although to be fair, some of the show's subplots and backstories were kind of tragic to begin with.)
- The destruction of Earth was actually a very clever part of it; Lexx being the show it is, very few viewers doubted that it would happen as soon as it was shown on-screen, but as season four progresses, it seems to become increasingly unlikely, to the point where the audience is seriously questioning whether or not it will happen with many close-calls ultimately prevented by the crew instead of caused by them like usual. The finale seems to take this further, with the crew trying to save it from a different threat until 790 pulls the trigger. By the time it finally happens, the audience has essentially been fooled into thinking Like You Would Really Do It applies, and it's genuinely dramatic instead of a gag like it's been for the entire rest of the show.
Every season of The Big Bang Theory ends with a Drama Bomb Finale.
The last episode of the fifth season of Curb Your Enthusiasm ends with Larry's death. It doesn't last, though.
Red Dwarf ended Series 6 with "Out of Time", a typical funny episode. However, they are attacked by their evil corrupt future selves right at the end (literally within the last 3 minutes), and one by one fall, until only Rimmer is left to do a Last Stand, and it ends on a cliffhanger.
The first series of Downton Abbey ended with the announcement of World War 1; the second series ended with the arrest of Bates on the charge of murdering his obnoxious wife. The war itself was pretty anti-climactic and had little serious impact on the family that wasn't somehow reversed.
Blackadder finished with everybody dying in series one, two, and four. Series four did not play it for laughs.

Video Games

The Visual Novel Heart De Roommate is for the most a fluffy slice of life comedy with the odd burst of drama for flavour, generally kept upbeat even through the more serious second half of the game by the cheerful, quirky characters. Then you get to the downright dark finale, featuring an honestly suicidal new character with a very dark backstory and a nasty Nonstandard Game Over for the incautious. The epilogue on the other hand is a straight Bittersweet Ending, actually made all the more effective by the previous happiness.
EarthBound spends most of the game being a quirky, silly, absurdist take on RPGs with a generally idealistic tone, but in the final area of the game, the game drops all humour, transfers the party's conciousnesses into robots, and sends you into a cavern in the past to destroy a Cosmic Horror before it can destroy the world.
Sonic Heroes can be summed up as: "Alright guys, let's PARTY!" WHEN SUDDENLY, MECHANICAL ABOMINATION THAT CAN FREEZE TIME
The season finales of the Sam and Max Freelance Police games tend to be somewhat Darker and Edgier than the rest of the episodes, like Hugh Bliss putting Sam through magic-themed torture devices as Max watches in Season One or Sam & Max having to visit Hell and stop Armageddon in Season Two or Max becoming an Eldritch Abomination and being Killed Off for Real in Season Three.
The first installment of Wasted Youth is basically Bully as a Flash Game with absurd situations, crude humor, and outlandish characters. Then after the main plot wraps up in rather shaggy fashion, you discover the missing girl's corpse buried in a shallow grave on the sports field. Cue Cliff Hanger, credits, and some major Mood Whiplash.

Web Original

The last act of Dr. Horrible's Sing-Along Blog has aspects of this, but it didn't come out of nowhere; the setup for the sudden attack of tragedy had clearly been building since the beginning. However, it was significantly aided by the usually Joss Whedon cruelty.

Western Animation

The finale of Ed, Edd 'n' Eddy has one of Eddy's scams backfire and seriously injure the neighborhood kids. It also shows Eddy's older brother to be a Complete Monster to Eddy, who routinely abuses his little brother, and the movie ends with the Eds finally being accepted by the other kids, with no Snap Back or Reset Button or anything.
The finale of each Total Drama Island season tends to drop an actual Drama bomb rather than the parody ones the series makes use of.
- Total Drama Drama Drama Island: Courtney crosses the Moral Event Horizon by actually threatening to let fellow campers die if they don't hand her the money, an angry Izzy leads Noah and Eva in a tirade against their Arch Enemy Justin, Courtney betrays Duncan for the money leading to some bitterness between them, Heather has a breakdown and Harold of all people helps her through it and alot of the characters show how incredibly determined they are to win the competition, making the fact that only fourteen of them qualify for season two quite depressing to the fans.
- Celebrity Manhunts Total Drama Reunion Special: After Total Drama Action ends the campers find themselves lost without their celebrity status. So when they find out that Chris is premiering a new show called, "Total Drama Dirtbags" with an all-new cast, the original campers, feeling bitter and wanting their fame back set off together to sabotage the new cast. In a bus war in the middle of a desert. Let's just say there's a reason this entire episode's listed as a Crowning Moment of Awesome.
Season Two of My Little Pony Friendship Is Magic ends with a two-parter "A Canterlot Wedding", which involves an army of shapeshifting creatures invading Canterlot, easily defeating Physical God Celestia and attempting to take over Equestria.