Sometimes works of fiction are so astoundingly dark that they Break the Cutie, Break the Haughty, Break the Badass, and they even go so far as to use their fictional universe to kick the heart's ass of even the most sympathetic characters. These are those characters.
Break the Cutie and Break The Woobie are not the same. Break the Cutie is essentially a Woobifictation process. Break The Woobie essentially requires that a character being some sort of Woobie is already in their backstory. Basically, a Trauma Conga Line has to happen before the work actually starts for the character to qualify.
Note also that Break the Haughty or Break the Badass can be a parallel process to this if the characters undergoing that process, again, have the woobiness in their backstory.
Note: These characters are not necessarilly killed, though many of them do die. (See Draft Note below.)
SPOILERS AHEAD!!!Examples: Manga and Anime
The entire Metal Gear series since Metal Gear Solid does this to almost every single character, and then most of those end up dead by the end of MGS4 anyway. The entire series is already Worldof Woobie, so you could've seen this coming. All examples here are contained to the specific game and it's specific backstory reveals, for further breakage, see later games.
Solid Snake: In one of gamings famous occurences of Break the Badass, Metal Gear 2: Solid Snake had him [[spoiler: see the death of countless people, kill his best friend Frank Jaegar (AKA Grey Fox), and kill his "father" (Big Boss). In this game, he's betrayed by Mission Control constantly, kills even more relatives, and in one of the possible endings his Love Interest dies.
Naomi Hunter: In her backstory, that isn't even her real name. She bought her identity, she doesn't know her own backstory. She did, however, have a brother in Frank Jaegar/Grey Fox, ( who, it turns out, is the one who killed her parents, as part of the Rhodesian independence effort.) who Snake killed in MG2. As revenge, she injects him with the Fox-Die virus, altered so that it also eventually kills him. That wouldn't exactly be a Happy Ending anyway, but as the game progresses, Snake becomes more sympathetic to her, and she has to live with the regret of eventually killing the world's greatest hero.
Hal Emmerich (Otacon): Less of an example than in latergames. Still, his backstory is that his entire family has worked in nuclear weapons research. He tried to avoid this, but got sucked into it anyway, lied into it really. Then, he falls in love with Sniper Wolf (See below) and she gets killed.
Raiden/Jack: Over the course of the game, despite Raiden's best efforts, his objectives are not completed, explained beautifully in this essay. Then, after Big Shell finall collapses and Arsenal Gear is launched, we learn he was a child soldier in the Albanian Civil War. Then it turns out Solidus Snake (see below) was not only his CO who made him do those horrific things, but is also his godfather,and killed his parents. His story doesn't have a Downer Ending in game, but it is later subverted through a retcon to allow his appearance in MGS4.
Emma Emmerich: As a child her father either died or left her mother (both suck, though the latter is obviously prefferable), and her mother married Hal Emmerich's father (See below.) Hal's father commited suicide by throwing himself into their family pool and drowning, carrying Emma into the water and trapping her. Hal saved her, but she was injured and would have massive aquaphobia for the rest of her life. When the game starts, she is captured and held hostage. Later when Raiden saves her,but then she dies.
Hal Emmerich (Otacon): This is when he really starts to set in to his official Butt Monkey status. Keep in mind what we already know from MGS1. Add on to this that he was seduced by his step-mother, which is why his dad killed himself. In game, his sister (See Emma Emmerich above) ends up dying because of her pressence on the Big Shell which, to make a long story short, was a result of trying to impress Hal to get him to "see her as a woman."
Olga Gurlukovich/( Cyborg Ninja): She was almost definitely a child soldier. She's preganant when the game starts, and her child was born and captured by the Patriots sometime between the Tanker and Plant chapters. As a result, she has to betray the troops under her command to assist Raiden to keep her child alive. She's dead by the end of the game.
Dead Cell (as a whole): Before the game starts, they were a group that helped mostly VR trained soldiers to respond to real attacks, but their the Patriots start framing them for much more deadly incidents that they themselves have no part in, and their original commander (Fortune's husband, see below) dies in prison after being arrested on corruption charges. Over the course of the game, they are manipulated into acting the way FOXHOUND did in Metal Gear Solid, and they all die except Vamp (see below).
Helena Dolph Jackson/Fortune: The commander of Dead Cell made their activities become more radical after the death of her husband. (See Dead Cell above.) In addition, her father died during the Tanker chapter. In her appearance here, she is a Death Seeker who Cannot Self Terminate, and she is the last of her team mates to die. She is also led to believe that her lover, Vamp (see below) dies, but, he's Vamp.
Solidus Snake: He was the third, supposedly perfect result of the Les Enfants Terrible project, which means he's already straddled with the baggage of that. In Metal Gear Solid, he was President, however it seems that he was not at all involved with the dirty stuff the government was trying to do in Metal Gear Solid, and was even trying to negotiate the (in-game universe) START 3 treaty. As part of the terrorists plans to make the Big Shell incident reflect Shadow Moses, they conspired to bring down his presidency and bend his ideology to something reflecting right-anarchism or radical libertarianism, which is how he ends up on Big Shell, and why he ends up dead at the beggining of the game. YMMV applies heavily to this example due to his commanding of child soldiers in the First Liberian Civil War.
Hal Emmerich/Otacon: Keeping in mind everything else in hisbackstory, this game has him watch the death of yet another love interest.
Jack/Raiden: He started drinking too much, had believed his child was miscarried, and left his wife after the end of MGS 2, and then he's turned into a cyborg with only a human heart and upper head (even his jaw is cybernetic.) Observing his role in the game, it's half him kicking more ass than any single character ever had, and then getting tortured. He gets a Happy Ending though.
Draft Note: Perhaps an aditional YKTTW could be created for Kill The Woobie, and this could be it's super-trope?
Five hats means that five tropers think it is ready to publish.
You are saying that you think this draft is ready to be published. That means the description is not ambiguous,
it doesn't duplicate an existing trope, there are at least three examples, and the title makes sense.