Dragon Ball Z, with Vegeta having his home planet destroyed at around age 5, and being a forced underling of the creature who massacred his people for most of his life.
In Delicious in Dungeon, hinted at about Kabru in Chapters 32 and 38. Later confirmed in Chapter 45: he was a survivor of a village that was destroyed by a dungeon. Which explains why he has such severe opinions of anyone who wants to use the dungeon to make a living rather than destroy it outright.
Kenshin Himura from Rurouni Kenshin and Samurai X: Trust and Betrayal. After the death of his parents, Kenshin (a child at the time) is taken by slavers, who are later violently killed in front of him by bandits. After burying the mutilated victims alone, Kenshin is resolute to create a peaceful world where people could live without fear. To accomplish his ideal, Kenshin trains with the master of the Hiten Mitsurugi-ryū (a fighting style so deadly that, to truly master, it means death to the teacher) and, at 14, became the legendary assassin "Hitokiri Battōsai. Kenshin goes into hiding years later and marries a mysterious woman named Tomoe for appearance only, but they later fall in love. After a series of events, Kenshin kills Tomoe unintentionally in battle. As Tomoe died, she gave Kenshin half of the X shaped scar on his cheek. Kenshin later finds out, after reading Tomoes diaries that he had killed Tomoes fiancé (a man who years earlier, gave Kenshin the other half of the X shaped scar) before he met her and she only married Kenshin out of revenge, but, after living together, fell in love with him. Broken and filled with remorse for killing countless people, Kenshin wanders off wielding a sakabatō or reverse blade sword. He is determined to never kill again and to aid those in need, as atonement for the murders he committed.
Hiei from Yu Yu Hakusho. Being tossed away by your clan, brought up by bloodthirsty thieves who later abanndon you, and going through torture just to find your homeland only to learn that your mother committed suicide and your twin sister has been kidnapped by a sadistic psycho will make you be just a little bit dark.
Alice In Sexland
Protagonist Alice was poor, but worked alongside her mother as housekeepers. As soon as she was considered even remotely sexually mature, she was forced into the life of a Sex Slave.
The Queen of Hearts is revealed to have had one, too. She was poor and homeless, then decided to sell her body as a prostitute as soon as she 'became a woman'. However, she seemed rather happy with that life, seeing it as a good way to give herself a decent life, compared to the nothing she used to have.
Vash the Stampede from Trigun. He was born as an Artificial Human on a space cruiser transporting most of humanity to a distant world, where the crew was paranoid of him. Thanks to his brother, he got to watch the cruiser destroyed, killing millions, including his mother figure. Years later, after the discovery of his destructive powers, he unwittingly caused the annihilation of an entire city.
Wolfwood in the manga as well. Raised in an orphanage, "adopted" by a church to go around doing general labor, physically modified, artificially aged, and trained to become a killer. He spends a lot of time conflicted about life.
Black Lagoon has quite a few characters with these kinds of pasts:
Revy is a Chinese-American who was abused by her alcoholic father (whom she later murdered) and brutalized by the police for laughs. She sometimes loses control of her bloodlust, slips into a scary-calm state of Ax-CrazyTranquil Fury nicknamed "Whitman Fever" by Dutch, and starts shooting everyone she comes across whenever something gets too close to her past. She either has to run out of steam or be physically restrained whenever that happens.
Balalaika is for the most part far more calm and controlled as befitting a mob boss, but her feelings of being rejected by her country (the former Soviet Union) despite her years of service, as well as the collapse of said country, have left her with nothing else but the enjoyment of planning and winning wars. Balalaika enjoys playing at war so much that she even gives Revy pause, and good luck trying to stop her once she decides to unleash her army.
Roberta, meanwhile, is a former soldier and assassin renowned for her animalistic ruthlessness, earning her the nickname of "The Bloodhound of Florencia", who tried to find solace working as a housemaid for the Lovelace family. She nearly went permanently insane because of the guilt she felt as a former assassin and because of the loss of her patriarch.
Hansel and Gretel were war orphans in Ceauscescu's Romania who fell into the hands of the mob after the orphanages closed down. They were put through absolute hell, culminating in them being forced to murder other kids in snuff films and getting a real taste for blood.
The entire main crew of Cowboy Bebop has this to some degree. Spike Spiegel used to be an enforcer for the Red Dragon crime syndicate, essentially Space Triads, only to fall out with them and his former best friend and fellow assassin Vicious over a girl named Julia, resulting in him faking his death. Jet Black used to be a cop until his own corrupt partner and best friend set him up and tried to kill him, though he got off with merely losing his left arm and needing a cybernetic replacement — this, after the love of his life dumped him for, basically, being too controlling. Faye Valentine lost her family, her memories, and her past after she was placed in cryogenic suspension after a space shuttle accident, and after she was revived, the one man who seemed to care for her "died"...and left her stuck with a debt reaching into the millions. Radical Edward's father was so absent minded that he was barely aware of her existence, so she spent her entire childhood wandering aimlessly in and out of orphanages and possibly over most of the planet. Even Ein, the "Data dog," was subjected to experimentation to make him a Data dog by people with questionable ethics.
The first segment of Memories "Magnetic Rose" had Heinz, a space salvage specialist who had some really weird reactions to such harmless things as a falling china doll. The haunted space ship, of course, uses his trauma over his daughter having died after falling off the roof while wearing a toy spacesuit he gave her to try and convince him to stay...forever.
In Baccano!, there's Czeslaw Meyer, a young boy who, when his grandfather and caretaker died, was taken in by his grandfather's alchemy student, Fermet. A few years later, they become passengers on the ship the Advene Avis. Cue both of them becoming immortal. Fermet's true nature begins to shine through, and he starts experimenting on Czes, claiming it's for science. This torture continued for the next two hundred years. The torture and abuse is only ended when Czes finally manages to kill Fermet, in a way that causes Czes to gain all of Fermet's memories. This means that Czes now has both his own memories of being tortured and memories of sadistically enjoying torturing himself. Because of all this, the kid now has intense trust issues.
Neon Genesis Evangelion: Notable since this trope applies to virtually every character with any significance in the story, not simply the protagonist.
Guts' childhood is singularly horrific. His mother was hanged from a tree outside a town while she was pregnant with him, causing him to be born prematurely and likely only surviving due to the soft mud from the rain. He was found by Gambino's wife Sys when his mercenary company was passing by the town and she took him in only to die of plague a year or two afterward. Gambino continued to keep him around but brutally trained him as a child soldier to earn his keep. Gambino's believed that Guts was a bad omen due to the way he was born and that he was the reason Sys died, which led to young Guts being raped when Gambino sold him for a night to a pederast soldier in his band (whom Guts later killed in the chaos of a battlefield at age 9) in addition to the horrific violence of war and constant risks to his life. It all came to a head when Gambino, his leg having been blown off by a cannonball and thus making him unfit for combat, got drunk one night and tried to kill Guts despite Guts trying his best to use his mercenary earnings to take care of Gambino. Guts was forced to kill his adoptive father in confused self-defense, but only after Gambino told him how he sold Guts to the soldier that raped him and had always resented him. Guts was almost immediately spotted by the rest of the company who proceeded to attack Guts and he only barely escaped alive. And that's just peaches compared to the stuff that comes afterwards.
Casca's past isn't much better — she lost her village at an early age and was sold to a noble who wanted a new serving girl, only for it to transpire that he wanted her for sex. Just as he's about to rape her, though, Griffith shows up. Instead of killing her would-be rapist, however, he makes her do it instead ("If you have something you wish to protect, take up that sword."). She has a relatively easy life afterward, until the Eclipse goes down and she suffers a horrific ordeal — the worst of it at the hands of her original savior, no less — that ends with her being driven insane.
Griffith's past wasn't much of a walk in the park either, as revealed in the second to last episode of the anime, just before he crosses the Moral Event Horizon. It involved selling his body to a creepy nobleman in exchange for the funds he needed for his army among other things.
Sword Art Online: Shino Asada was a happy child, until a trip to the post office with her mother took a turn for the murderous when a robber held up the office. When the robber turned his gun to Shino's mother, the eleven-year-old girl wrested the gun away and killed him in self defense. Sadly, this lead to Shino being ostracized by her classmates and her own mother, plus PTSD so severe that she can't hold a toy gun or even have someone point at her without suffering a severe panic attack. She tries using the VRMMO shooter Gun Gale Online as a form of self-help, but with minimal success.
Many of the main characters in Hellsing have some pretty dark childhoods: Seras Victoria witnessed her parents being murdered by burglars while hiding in a closet,Her mother's corpse was then violated as she watched. and Integra's uncle tried to kill her to take control of the Hellsing family. Even Alucard counts: back when he was just an Ottoman kid named Vlad III Dracula, he had been sold over to the Turks, whose ruler raped him.
This seems to be the case with a number of characters in Elfen Lied, most particularly, Lucy, who had to deal with abuse from asshole kids at her orphanage who beat her dog to death in front of her, and her horrible experimentation at the research facility that she escapes from at the very beginning of the series.
While a majority of Axis Powers Hetalia is silly and cute, the characters are still countries, thus, all of them have some negative points in their history. Nevertheless, Russia takes the cake for troubled pasts; the best example would be the "Bloody Sunday" strip, in which he finally snaps and starts gunning down his own people as they're rioting in the streets ("If they hate me, they're not Russian.") before turning to Lithuania and stating "We don't want children who can't play nice, do we?".
This trope is probably why certain countries, such as Israel, will never show up in this series, as it would quickly destroy the very comedic nature of the series itself.
Then there's Asuna. We don't really know the details, but she underwent Laser-Guided Amnesia so that she could forget all that she had been through. What we do know is that it includes being imprisoned in a tower and used as a human weapon, and the destruction of a Floating Continent.
Setsuna. During her fight with Evangeline, is revealed that she has no parents, and because of her white white wings, she was chased out of the Crow village and picked up by Eishun.
Kaoru in Ai Yori Aoshi (physical abuse, betrayal, abandonment), to the point of not even remembering his childhood friend when he meets her again.
Digimon Adventure 02: Ken Ichijoji. Just...Ken Ichijoji. What started out as The Un-Favourite Syndrome developed into a death in the family. Then he ended up being infected with the Dark Spore, which started playing on his huge inferiority complex and guilt over his brother's death, which was one reason he became the Digimon Kaiser, at which point he was convinced that the Digital World was makebelieve and he was just expressing his anger in a fictional world. He was bluntly shown otherwise by watching his Digimon die right in front of him, and never mind the better part of the hell the rest of the season puts him through while he's trying to make up for his misdeeds.
Chichiri in Fushigi Yuugi has a Trauma Conga Line in his past. His childhood best friend, Hikou, betrays him by stealing a kiss from his fiancee, who immediately calls off the engagement in shame. Chichiri goes berserk and attacks Hikou, but as they are fighting, a massive flood sweeps through the village. Chichiri's fiancee and family are killed in the flood, and although Chichiri attempts to save his former best friend's life, Hikou is lost in the flood before they can make amends. Chichiri also lost his eye in this incident, and, in fact, it was getting hit by the driftwood that caused him to let go of Hikou's hand. This all comes back to haunt him near the end of the manga and the OVA, when Hikou reappears as one of Tenkou's demon underlings...
While Chichiri is the most notable example among the protagonists, lots of other characters follow this trope, particularly from the Seiryuu and Genbu sides. Nakago has a particularly nasty one as his Freudian Excuse, though the fact that he's a horribly Manipulative Bastard who infamously winds up being a Karma Houdini means that few fans want to pity him for it.
One Piece: To say the Author Eiichiro Oda is fond of tragic backstory and quite good at writing them would be an understatement. The man is an absolute master, every canonical story arcs has several Dark and Troubled Past to tell. Not only are they informative and emotional but also filled to the brim with Chekhov's Gun. He also has a knack for taking otherwise mundane backstory mold and drawing them into originality.
Romance Dawn arc:
Luffy's backstory part 1, the climax of which provided the current Tear Jerkers picture of the manga.
Coby's. Though short and mostly played for laughs, it provided the starting point for his Character Development much later.
Zoro's past, following the otherwise generic "my best friend/rival died" past but adding in the mix that his friend didn't die honorably; she died falling down the stairs. No epic sword fight, no sacrifice, she was just tired and slipped down some stairs. First "recruitment backstory".
Orange Town arc:
Buggys "tragic" past was mostly played for laughs. But the crew that he and Shanks started their careers with would be important hundreds of chapters later.
Also Captain Morgan (a minor antagonist of previous arc)'s backstory was revealed, retroactively adding depth to his character.
Sanji's backstory took the standard "stranded on an island with an enemy" story and turn them into something unique. Everyone knows being stranded on an island sucks, but this is hardly an island: it's a mushroom rock that's too far above sea water to fish and incapable of sustaining any life...because it's a ROCK. Not to mention, he realizes that the only other person on this island has a big ol' bag of, what he thinks is, food, much bigger than the one he gave to Sanji. However, it turns out that other guy just had a bunch of money and absolutely NO food, and that instead of keeping any for himself, gave all the food he recovered to Sanji and broke off and ate his own leg to survive. And on top of all that, the food that Sanji got was barely enought to last 20 days (though it lasted 25 days). It took eight-five days for a ship to find them. One can only imagine how hellish the last 60 days (two months) must have been. No wonder Sanji considers wasting food to be a horrible offense.
Arlong Park arc:
Nami's past was told here. Her backstory arguably set the formula for "recruitment backstory" which almost all of the Straw Hats later followed: Tragic backstory was caused by the current arc villain, after which Luffy was so pumped up and delivered a well-deserved beatdown to the Arc Villain.
Rogers execution, which is the backstory of the whole series was revealed in depth here. Notable in that though this is an execution, its hardly portrayed as "tragic". In fact the one detail were meant to take away as Rogers smile before his death and how Luffy mirrors him in that regard.
Reverse Mountain arc:
Laboon the Whale's story was told. It will be important much later.
Little Garden arc:
Dorry and Brogys past was told. Though not particularly tragic, it did break his crew and led to two of his men tricked into servitude later.
There's one for Vivi, Kohza and the entire Alabasta Kingdom. In short: Crocodile needed a beatdown.
Also Robin provided a very brief, very neutral version of her backstory to the Straw Hat when they snuck abroad their ship. Some tantalizing hints to her full backstory were dropped during the conversation with Cobra as well.
Montblanc Cricket's backstory revealed that he was the descendant of "Noland the Liar" and he was locked into a battle with his own ancestors legacy ever since. A "fictional" version of Noland's Tragic Past was also told.
Nolands "real" tragic past was told. Also the backstory of the Shandoran and Skypeans Forever War, and Sky Knight Gan Falls personal history were told.
Long Ring Long Island arc:
Aokiji dropped some vague hints about Robin's past. Namely, every organization associated with her was eventually destroyed.
Water 7 arc:
Franky, Iceburg, Kokoro and Tom's mutual history was told. It is simultaneously awesome, tearjerking and heartwarming.
Enies Lobby arc:
Robin's long Mysterious Past was revealed in detail. It's arguably the most tragic backstory revealed thus far and is the most important to the entire series Myth Arc bar none.
Thriller Bark arc:
Moria and Dr. Hogback had one. It only make them more disgusting and despicable.
On the other hand, Brook's story was so good that it brought Franky and Brook himself to tears. It also fired off the Chekhov's Gun set hundreds of chapter earlier.
Sabaody Archipelago Arc:
The Roger Pirates' story was told by none other than the Pirate King's first mate himself. Like a good story teller, he encouraged the Straw Hats to seek out their own answers and adventures.
In what could only be described as the dark and troubled Past of an entire species, the history of racism against Fishman and Merfolk was revealed. It retroactively provided a backstory for Arlong and every villainous Fishmen the Straw Hats encountered.
Amazon Lily Arc:
One without a twist, but still absolutely horrible. Hancock and her sisters. Slavery is never a pretty story.
Impel Down Arc: There's no new backstory here but there's one humorous example that deserved special mention. And that is:
Buggy the Clown's history with the Pirate King's Crew comes back to bite him as the Marine labels him the mastermind. To Buggy this is tragic but to every prisoner he rescues, this is the ultimate badass confirmation of their savior and they pledge their life to him immediately. Buggy decided to go with the flow and led them all to Marineford.
Ace's past isn't very heartwarming either, putting aside all the time he spent with Luffy and Sabo. Ace's father was none other than Gold Roger, the Pirate King. Now normally, being related to such a powerful and important figure would be a cause for joy, right? Not. In the eyes of many who actually met Roger (and didn't antagonize him), he was a great man. But the truth of the matter is that hiding his identity as Ace's father was imperative, seeing as his enemies basically amounted to the entire world. For years, Ace was tortured with the fact that in the eyes of the world, he wasn't supposed to exist, that the world would be better off without him, making him far more jaded than a child should and causing him to despise his father for the rest of his life. Most of all, the only reason he bothered to continue living was to find out whether or not he deserved to be born, just because the blood of a Pirate King ran through his veins. Living only stopped being so painful when Luffy and Sabo, and eventually the Whitebeard Pirates, came into his life.
This arc devotes entirely to the story of a young Ace, Luffy and Sabo, especially. This will be important later.
Fishman Island arc:
The History of racism against Fishman and Merfolk was told again, this time from a more personal perspective of Jinbei, a Fishman who at one time and another support both Otohime and Fisher Tiger, the two major equal right leaders. Also, Koala's story was told.
The Riku Royal Familys story was told fairly early in the arc.
Law. His past is up there with Robin's for how bad it is. Law was born in the country of Flevance, also known as "The White City". It was said to be a land straight out fairytales — everything, from the grass to the trees to even the buildings was pure white. Eventually, this phenomenon was discovered to be the result of a mineral beneath the country, callled Amber Lead. The people of Flevance began mining this mineral, bringing them untold amounts of prosperity. However, a hundred years before the beginning of the Amber Lead industry, the World Government conducted a geological survey and determined that the mineral was poisonous. Both they and the royal family of the country knew of its true nature, but kept it a secret due to the economic growth it brought Flevance. Though eventually, the buildup of Amber Lead poisoning became too great and a horrible breakout of disease struck Flevance, causing neighboring kingdoms to believe it to be an epidemic and quarantine the island (though the royalty of the country managed to escape thanks to the World Government). With the doctors unable to cure the disease, despair over being abandoned and desperate to escape, the population used the remaining Amber Lead as weaponry and went to war. The resulting conflict would kill almost all of the people of the White City, including Law's former friends and family; Law himself only managed to survive by hiding himself amongst corpses being carted out of the quarantine zone.
The Donquixote's backstory was very dark and tragic but with an unique twist. Doflamingo and his brother Rocinante both experienced the same tragic past but only one turn into a monster. Perhaps the only time in the series that Oda took Nature side in the Nature Vs Nurture debate. note This is before Doflamingo met Trebol, Diamante, Pica and Vergo who would then nurture his evil side even more.
Whole Cake Island arc:
The abovementioned "stranded on an island" example turns out to actually mark the rough end to Sanji's horrible past. He was born part of the Vinsmoke family, a family of assassins whose head, Sanji's father Vinsmoke Judge, leads a massive army with ambitions of reconquering North Blue. To that end, Judge had his children genetically modified and subjected to Training from Hell, to draw out their hidden potential and turn them into Super Soldiers. However, unlike his siblings, Sanji failed to make any progress, instead remaining a regular human being, causing his father and brothers to brutally abuse him mentally and physically while his sister just laughed (Though to be fair, she had no choice but to do so to avoid being bullied herself). Eventually, Judge got too fed up with Sanji's lack of progress to bother continuing to raise him, and instead faked his son's death before locking him in a dark room and forcing him to wear an iron mask. Keep in mind that this happened before that aforementioned traumatic example with Zeff! No wonder Sanji hates his family's guts.
Lola's, but more importantly her twin sister Chiffon's Dark and Troubled Past was revealed during the Straw Hats meeting with Bege. Basically, Lola ran away from the wedding with the Giant Prince, Chiffon was forced to take her place but couldnt fool them. This lead to Elbaf and the Giant army virtually out of Big Mom's reach and Chiffon was severely mistreated by her as a result. Lola seemed fairly oblivious to her mother nature and the trouble she caused her sister; to the point she asked Nami to tell Big Mom that shes still OK.
Ichigo is the badass hero because his mother died in front of him just before his ninth birthday. He vowed to protect others from ever experiencing the pain he went through that day, and spends years blaming himself for her death.
Rukia was an outsider who longed to fit in. The first person who treated her as an ordinary person was her mentor, Kaien. Unfortunately, he is possessed by a Hollow and Rukia is forced to kill to protect both herself and her captain. It takes her many years to forgive herself for his death; part of the reason why she gave Ichigo her powers in Chapter 1 was because she secretly was hoping to die.
Orihime was rescued from abusive parents when her much older brother kidnapped her to save her life. She was raised by him until he was killed in a car accident when she was twelve. She was bullied in school for her unusual hair, and it's not until she meets Tatsuki that she's able to grow her hair again. Even after meeting Tatsuki, she's been raising herself alone ever since her brother died. Her brother eventually comes back as a Hollow that tries to kill her and almost succeeds until Ichigo manages to save her just in time.
Sado lost his parents at the age of eight and was sent to live with his grandfather in Mexico where he became a big, strong bully. Only his grandfather's wisdom saved him from a violent life. After his grandfather dies, he returns to Japan, but refuses to fight to protect himself, so gets bullied for his non-Japanese appearance and height. It's only after he meets Ichigo, who tells him that they should fight to protect the other, that he begins to have friends.
Uryuu's mother died when he was eight years old, and he has a nasty estrangement from his father because, his grandfather once implied, he completely misunderstands his father's heart (only pretending to be a jerk). He witnessed his grandfather being killed by Hollows right in front of his eyes and blames the Shinigami who didn't arrive in time to save his grandfather's life. He later learns that Mayuri delayed the Shinigami from saving his grandfather because he wanted Souken to die so that he would have a Quincy soul to experiment on. When he shows Uryuu the Souken's post-experiment remains, he gets one-shotted by an icily infuriated Uryuu. It's eventually revealed that his mother and Ichigo's mother were killed at the same time for the same reason, and that their killer had tried - but mysteriously failed - to kill Uryuu at that moment, too. Uryuu's been a target for Yhwach's mysterious end-game ever since.
Fate Testarossa herself, who grew up under the "care" of an abusive and thoroughly monstrous Evil Matriarch who wanted her as a Replacement Goldfish for her daughter, Alicia, but grew to hate her for having her own personality before Nanoha entered her life. Her reason for taking in Erio and Caro was so that they wouldn't have to grow up like her.
The backstory of Kagura from Ga-Rei involves her being forced to kill her own older sister. In the beginning, it doesn't bother her too much, but, later on, it comes back to hit her hard.
Blue (Green in the English version) and Silver from Pokémon Adventures. Although the Mask of Ice DID kidnap them in order to use them for his plans, you see that he's got a heart for the kids. This is seen in the FRLG chapter, in the flashback of Silver and Blue/Green escaping Mask of Ice. Before, you see a large ice statue of all the kidnapped children and Mask of Ice, all wearing their masks and everything. After the kids run away, you see Pryce change the sculpture into one of all the kids standing around Pryce, who is in a wheelchair, all of them smiling. So you gotta assume that Pryce loved the kids like they were his own, even if he did kidnap them. Then again, whether or not he loved the kids, there is no doubt that Pryce had absolutely no clue how to raise them. One panel actually hints that he physically hit Blue just because she wanted to nickname her Jigglypuff. Judging by that panel, it's pretty obvious that Blue and Silver had an awful childhood.
Mitsumi in Pokémon: Diamond and Pearl Adventure! was raised by Cyrus to be devoid of all feelings toward Pokemon and human, her only purpose to defeat her opponents. Rowan eventually softened her up though, and made her realize that there's more to Pokemon than fighting.
Ciel was a happy, loving, carefree child before his tenth birthday. Then, his parents were murdered, the mansion set on fire, and he's kidnapped. He's locked in a cage with other children his age and eventually made a child sacrifice until he accidentally called upon a demon in his desperation to live. His past is still being pieced together so more details will probably surface. No wonder he's a bitter, driven 13-year-old.
The children in Noah's Circus had a pretty bad past, too. Too bad the man who helped them turned into a crazy Stalker with a Crush and, with some psycho doctor, killed children so their bones could be used in the making of prosthetics.
In Soul Eater, Crona was used as an experiment for his/her mother, and ended up becoming the host to a Living Weapon, driven insane through physical and psychological abuse, and forced to kill unknown (but probably large) numbers of people in order to harvest their souls. Crona gets a brief respite when Maka defeats them, only to be forced back into working for Medusa.
From what little we know, Liz and Patti's history is probably a troubled one, but this is hardly referred to.
The characters in D.Gray-Man. Specifically, a whole bunch of the main Exorcists. Kanda and Lenalee, in particular, had their traumatic pasts inflicted on them by the "good guys" so they could fight the "bad guys". Allen was abandoned, beaten, and such until he met Mana, who died shortly after. Miranda was always teased for being wimpy and useless and broke down when she was fired for the 100th time. Krory was bullied by the people in the village near his castle because of his grandfather's reputation and therefore chose to never leave even when his grandfather died. Lavi used to be cold and emotionless due to all the cruelties of humanity that he had been exposed to such as numerous wars, since recording such events is part of his life as a Bookman. Kanda used to be an exorcist in a previous life, before he was killed by an Akuma. His brain was extracted and transplanted into his current body, to undergo multiple, painful and fatal synch attempts with his Innocence. He also killed his best friend. Twice
Pandora Hearts is full of characters with this trope, though it's not very obvious at first. Gilbert, Vincent, Alice, Leo, Echo, and Break are probably the best examples.
And then it finally revealed that Oz, whose dark past was thought to only being neglected by his own father, actually have the most tragic past of all: born as a plushie, forced to murder so many people and caused the legendary Tragedy of Sablier, and his owner Alice, who was the only one who cared for him and gave him his name, killed herself to save him.
Sheryl grew up as a homeless orphan in the Galaxy fleet before being "discovered" by her manager, Grace. Also, even when she does get past that and works her way to the top as an Idol Singer, she finds out that everything she's ever achieved was actually part of Grace's plan, leading to her breakdown later in the series.
It doesn't help that Grace is the source of her v-type infection and is likely the reason why she's an orphan in the first place.
Ranka is also an orphan who lost her family during a Vajra attack on their research fleet, an event so traumatic that she lost her memories and, for a time, the ability to speak before her adoptive brother got to her. It's made worse for her that the cause of the attack was her singing, which, thanks to the Vajra germs she got from her mother, allowed her to unknowingly communicate with the Vajra.
Chrono is the most obvious example, having once been part of the Sinners and accidentally killed the woman he loved.
In the manga, all of the Sinners are refugees from their home and only betrayed the other demons because it was that or be killed. Aion's reasons for leaving are particularly troubled (but crazy).
Rosette and Joshua are orphans. This would be Conveniently an Orphan if it wasn't for the fact that both of them have some flaws explained by their parents' deaths (particularly in the manga).
Satella watched as her home burned to the ground and her family was killed by a demon around the age of 9 or so. Fiore is the sister she lost in the massacre, who Came Back Wrong.
Azmaria's parents either abandoned her or were killed (possibly during the first world war). She was then taken in by a group of traveling musicians, who were killed by a man so he could adopt her and use her powers to bring back his dead wife. Yep, he was killed too.
Practically everybody. Ed and Al lost their mother when they were young, tried to resurrect her, and failed; and, as a result, Ed lost two of his limbs and Al his entire body. Roy and Hawkeye, among others, participated in the Ishvalan genocide and feel extremely guilty about it. Scar lost his brother in said genocide, Winry's parents were killed on the battlefield, Hohenheim unknowingly helped kill off the population of an entire country, and Bradley grew up as a test subject, was injected with the Philosopher's Stone, and does not know whether his present personality is the one he had prior to the injection.
This is how the +Anima children are usually depicted gaining their animas, animal spirits of sorts which grant them the animal's abilities. It comes from the need for help to escape from a dangerous situation, such as being close to death.
Soubi from Loveless was orphaned at the age of six, raised by a teacher who wanted to control him completely and sexually abused him, and then handed off to Seimei, who viewed him as a possession and physically and emotionally abused him before abandoning him without explanation. Ritsuka is a little young for this trope, but is well on his way to acquiring one.
For all that it's a gag series, Gintama features characters with these.
Gintoki was an orphan living among the corpses on the battlefield when he was found and taken in by Shoyou sensei who raised him with the samurai values he still holds today. A few years later Shoyou sensei was arrested and his school was burned down. When Gintoki and his friends fought in the Joui war, they lost, and lost badly. He was then forced to choose between his teacher and his friends. He chose to kill Shoyou. After the war, Gintoki ended up in jail and was nearly executed. Upon his release, he wandered around and nearly starved before Otose found him at her husband's grave.
Kagura comes from a lethally Dysfunctional Family. Her mother died when Kagura was young, and her father left her and her brother, because he was afraid he might kill one or both of them someday. Her brother, unable to beat their father in a fight turned into the cheerful sociopathic Blood Knight he is today.
Kyuubei (raised with gender confusion), Katsura (family deaths, lonely childhood), Takasugi (Shoyou's death), Hijikata (family issues, spree killer), Tsukuyo (sold into prostitution, maniac mentor), Hinowa (sold into prostitution, crippled by Housen), and others also have difficult pasts.
A lot of characters in Speed Grapher, but none more so than Chōji Suitengu, the Big Bad of the series. Near the end of the series, after showing how much of a bastard he is, one episode finally delves into his history and gives him a hell of a Freudian Excuse.
Despite being a fairly lighthearted series, Keiko from Stretch appears to fit this trope. Something to do with her mother, apparently.
Puella Magi Madoka Magica: most characters just have a Dark And Troubled Present, but Kyouko had her attempt to help her father spectacularly backfire when he finds out, causing him to go nuts and kill the family, Mami lost her family in an accident and contracted with Kyubey to save her life, and Homura has been resetting time in a futile attempt to save Madoka for years now.
In Wild Fangs, it turns out Syon was artificially engineered and grew up in a lab where he was constantly experimented on but had no one who remotely cared for him. Subverted in that he doesn't remember it all that well so it's not as big a deal as others think it is.
If anyone in Monster appears not to have a Dark and Troubled Past, just keep reading/watching and one will be revealed. Ironically, the king of this trope in the series is none other than that irredeemable Johan Liebert. Or is he? The debate goes on and on...
Shinobi in general have blood on their hands before they reach chunin rank. Also, considering they are essentially soldiers, whose relatives and friends are also soldiers, living in a warzone, nearly every character has lost someone important to them at some point.
Itachi saw the end of the 3rd Ninja War and the Kyuubi attack before he was even a ninja and decided to do ANYTHING to pevent war.
Kakashi saw his father take his own life at 7, then his friend Obito seemingly dies before giving him his Sharingan; he is forced to kill his remaining teammate Rin in order to prevent the tailed beast inside her from falling into the hands of the enemy; and finally his teacher, the 4th Hokage, dies when he sacrifices himself to protect the village from the Kyuubi. And to think, when he was first introduced he seemed like such a laidback person who was simply wise and pragmatic about the nature of being a ninja...
Sasuke, at 8, stumbled upon the aftermath of his clan's massacre by his older brother under order of Danzo and killed said brother at 16, only to learn the truth after the act, and set himself on the Asura path
Gaara, of course, was feared by his village and his family for the one-tailed demon inside of him. His attempts at connecting with others proved fruitless and at times were rebuffed harshly by other kids. Not only that but out of self-defense he was forced to kill the only person who stood by him and protected him. This tragedy and the realization that he was truly alone led him to look to his literal inner demon for solace, giving us the emotionless death machine which is initially introduced to us.
Kimimaro was of the now-extinct Kaguya clan had been born with his clan's special kekkei genkai and the leader, fearing its power, locked him up in a dark cage except on the occasions where he was needed for battle (which was often, since they were a war-like tribe). The Mist Village, deciding they had enough with this clan's bellicose nature, decided to commit an act of genocide and wipe them all out in one fell swoop. Kimimaro managed to escape this culling and wandered aimlessly and without purpose, until he met Orochimaru...
Haku was born with a special kekkei genkai-Ice Release-which was all well and good except that within the Land of Water where his small village resided, the people still held extreme anger and pains from the death and destruction that a previous war had caused them due to both sides using people with kekkei genkai. He had inherited this ability from his mother, who hid it from her husband in order to maintain the illusion that they were normal and perhaps that one day they could reveal the truth to the man in hopes that love could trump the prejudice that still remained. Unfortunately, it was not to be. Haku had discovered his ability and while his mother quickly stifled it, Haku's father witnessed it and rounded a mob of villagers to attack them. Haku watched his mother be killed in front of him and was about to be murdered as well but he used his abilities to kill all of his assailants, thus rendering himself an orphan.
Naruto lost his parents and any chance of a relatively normal life the very night he was born. He was also taken hostage by The Heavy at the age of one minute. That's gotta be some kind of record.
Most characters in Boruto intentionally subvert this. In contrast to their parents, the newest generation live in times of peace. Their problems are more down-to-earth, such as Boruto and Sarada's father's being distant due to job reasons.
No mentions of Ai Enma from Hell Girl yet? That girl was made an outcast by her village, and was selected to be sacrificed to a mountain god at the age of 7. She escaped that fate, only to be faced with a worse one 6 years later, where she was betrayed by her only friend and she and her family were buried alive. Then she tried to deliver vengeance on her village and was condemned to carry souls to Hell for eternity.
It's mentioned in Fairy Tail that everyone in the guild has some sort of hidden pain in their pasts. A lot of them are explored in each arc of the manga as it goes on.
Inspector Himuro of Remote has one that is regularly hinted at but not revealed until the last few volumes
Accelerator in A Certain Magical Index. Due to his seemingly invincible powers, he's been attacked ever since he was a child by people who either wanted to "prove their strength" or by people who thought he was too dangerous to let live. He survived all of this without a scratch, but having that much violence directed at him all his life has left him rather messed up. And if people aren't trying to kill him, they're trying to use him in inhumane experiments. When he's introduced, he's willing to do just about anything to make sure people never attack him ever again.
Most of the main characters in A Cruel God Reigns. If they don't have one, they are well on their way to getting one.
Jeremy is physically and sexually abused for months before he snaps and kills Greg, and then has to deal with living as a murderer.
Ian grew up knowing his mother committed suicide and wondering why his family was dysfunctional. Later on in the series he has to deal with his Broken Pedestal view of his father.
Lindon become estranged from his first wife and daughter because he was so rigid and neurotically morose.
Nadia's mother blames her for her sister's preoccupation with suicide. Her parents also fought bitterly and cheated on each other during her childhood.
Natasha suffered Greg's beatings and eventually had to leave Lynn Forest for her own wellbeing, as well has knowing her little sister Liliya killed herself.
Cass' parents are abusive alcoholics, which is why he works so many jobs (legal and illegal), in an attempt to earn money for school and to escape his house, eventually ending in his drug addiction and Hooker with a Heart of Gold.
Even Bratty Half-Pint Matt, who grew up unwanted because Greg believes that he is not his actual son.
Haruka's life story, to put it bluntly, is the destruction of the lives of a born telepathic girl.
Yuriko has one too. When she was a child, her mother was a famed psychic, but Driven to Suicide after being accused as a fake. This is why she is so eager to prove psychics exist.
In Anatolia Story, Nakia was forced by her father to become a concubine to the Hittite king, who was basically the enemy of her country of Babylon at the time. Also, the king was old enough to be her father. When she got to his palace, she quickly became scared and lonely, since he already had a lawful wife, a huge harem full of other concubines, an elected crown prince and four more sons. It's later revealed that she also went through a period of time when people gossiped openly about the legitimacy of her child, Juda, since he shared few features with the king.
Ursula was orphaned when her family died of the plague and grew up in poverty, becoming desperate for any chance, however brief, of knowing wealth and comfort.
The end of the series also reveals that Urhi was the child of a noble family in another country. When his home was invaded, the conquering army killed all of his family, took him as a Sex Slave, and castrated him so that he couldn't run the risk of having children and furthering the now-extinct bloodline of his country's royal family. ''Then', he was shipped off to Anatolia to be a junior priest, which is where he meets Nakia.
Pretty much every experiment in Project ARMS. To name a few:
Hayato watched his home village and his father (or at least, the man he thought was his father) get destroyed when he was a child. Immediately after, a stranger (the same one who killed his dad in front of him) cuts off his arm and replaces it with the ARM replica.
Kei was raised as a soldier instead of a child, harshly treated by the Blue Men. In the manga, she and some other children were playing in a church when a madman comes in. The children try to run, instead of listening to her and staying hidden, leading to her watching them die and her getting her eyes stabbed out. In the anime, she tries to save some children from a burning building, only for them to die and her eyes to get burned out. In both cases, this leads to her own ARMS being implemented.
The Bowen twins were ostracized by their peers and their parents, all of whom were unable to cope with the fact that the elementary school-aged boys were super-geniuses. A flashback reveals that Jeff murdered their parents, which even freaked out Al.
Carol was sent to the Egrigori as a test subject because her parents were terrified of their creepy daughter who had the power to bend things into knots with her mind. She grew up believing that the horrified reactions her powers got from people were the same things as love and respect.
Cliff and Yugo Gilbert spent their childhood having their mental powers tested, meaning they were both horribly abused by the scientists.
Kyklops spent his entire life kept by the Egrigori, taught to kill with a knife as soon as he was old enough.
All of Keith White's "children", who were just clones of himself that he made to implant ARMS into. They weren't even given names (they simply were known as "Keith [Color]") and the surviving ones (Black, Green, Blue, Red, and Violet) all had to watch as their brothers and sisters died horrifically painful deaths from the experiments.
Quite possibly the ultimate example of them all is poor Alice. She's yet another Egrigori experiment who is confined to the labs, where she sees how lonely and sad the other children are. She wants nothing more than for them all to see the outside world, even for just one day, but her attempt to make this happen end with all of the children being shot to death by Keith White. She then gets absorbed by an alien life form and splits into "White Alice" and "Black Alice", both of whom keep their desire for love, but one of whom (guess which?) expresses this in the form of wanting to destroy all life on Earth.
Tenjou from Murasakiiro no Qualia. As a child, Tenjou fell off a jungle-gym, getting her body fatally wounded. And that's when the traumatizing part begins. Completely conscious, she then watches her best friend replacing her "damaged body parts" with jungle gym parts. This obviously still doesn't sit well with her for long years after. Justifies her acting like a jerk toward Yukari.
The majority of the cast in Attack on Titan, due to the nature of the series:
Levi is a former criminal, with his past shrouded in mystery and fodder for many rumors.
Eren, Mikasa and Armin are all refugees from Wall Maria, having lost everything when Titans destroyed their villages.
Mikasa's parents were murdered in front of her, by human traffickers that intended to sell her into sexual slavery at the age of nine. Eren killed two of them to rescue her, but she was forced to kill the third man on her own.
Reiner, Bertolt, and Annie are Tyke Bombspies sent to carry out genocide against mankind, and committed an act of mass murder at the age of 12 and 11 respectively on the orders of their superiors. All three are deeply traumatized as a result of their actions, with special mention to Reiner who was extremely broken] even before their mission started, due to Parental Abandonment by his father (his parents had a forbidden relationship between an Eldian and a Marleyan. Reiner's father wants nothing to do with Reiner or Reiner's mother, as he'd be punished severely for it.
Ymir and her vague comments about having been hated, tormented, and expected to "die for the happiness of others". She was an orphan with no name who was taken in by a strange man who made her take on the name Ymir and pretend to be a reincarnation of Ymir Fritz, the creator/founder of the Titans (maybe). She gained a massive following, but when the cult was found out by officials, they betrayed her. She ended up being sent to Paradis Island and spent 60 years as a mindless Titan before unknowingly stealing the Jaw Titan's powers from Reiner, Bertolt and Annie's friend Marcel (which becomes Reiner's greatest failure, as he feels responsible for not protecting Marcel).
Krista is the daughter of a significant nobleman, born out of wedlock to his mistress. A conflict between her relatives concerning her potential as a successor caused her to be driven out and forced to take up a false identity. She joined the military to escape, with the hopes of getting herself killed in a suitably tragic and heroic fashion.
Grisha Yeager, Eren's father, may take the cake. Everything started going downhill for him when he and his little sister Faye snuck out of their ghetto to watch a blimp land. They were caught by military officials, and as Eldians aren't allowed outside of the ghetto, were punished. Grisha was kicked several times and Faye was taken away by a sergeant and fed to his dogs. The sergeant claims that he found the girl's body there and has nothing to do with it. Several years later, Grice, who's part of the Eldia Restoration Movement, tells Grisha what really happened to Faye, and Grisha decides do join the cause. Through this, he marries Dina Fritz, who is the last remaining member of the royal family on the continent. They have a son, Zeke, who they raise with the intention of being the last hope for Eldia and its people. Unfortunately, Zeke betrays his parents and their friends, and they're sent to Paradis Island as punishment. Everyone is turned into titans (including Dina), except for Grisha, who is saved by Kruger, a military offical who Grisha met the day he went out with his sister. Kruger is revealed to be responsible for the Eldia Restoration Movement getting leaked information. Grisha is then entrusted with the Attack Titan's powers and the mission to retrieve the Founding Titan from within the walls...
This is revealed to be the case of Ymir, the Founding Titan, whose story has largely been lost to legend. She was a slave to a small clan of raiders until one day the other slaves blamed her for a crime and she was "freed" to be hunted as sport by the warriors. While fleeing she discovered an unusual symbiote which merged with her body, transforming her into the first Titan. Despite this she was still unthinkingly loyal to the clan's chieftain, Fritz, who exploited her power to rise in power and build a kingdom. Ymir bore Fritz three daughters before ultimately dying to save his life. Her body was then butchered and her daughters forced to eat it so they could inherit the Titan power. Even in death she felt compelled to obey Fritz and so continued to maintain the Titan powers and serve his descendants even to the current day.
Pretty much everyone established as a character has this, no matter what side they're on.
Mei from Yurara was madly in love with his teacher. Then a malevolent spirit pulled her off the roof of the school to her death. He never quite got over it.
Ramblerthe RamblingRabbit◊ from the Happy Happy CloverAnime/Manga series by Sayuri Tatsuyama. Is an adult rabbit who usually visits Crescent Forest at random. He would usually go on dangerous adventures and travels around the world. Clover the main protagonist of the series, really admires him and wants to go traveling with him. But each time she would ask him that same question, he would refuse to answer her question. He says that she will have to wait until she gets older. In the characters mini-bio in the 3rd,4th and 5th volume for the main characters. It reveals that Rambler's homeland has been destroyed by humans. In the 4th volume of the manga, one story involved Rambler coming to stay with Clover for the night. Clover and her parents wants him to stay at her home for the night. Rambler refuses and prefers to sleep outside. However Clover, starts getting very worried about him and continues to ask him to stay for the night. Later, Clover starts looking for him in the rain just to let him stay. But when she finally, finds him out in the rain. She tries to let him come to her home, and starts pulling his arm hard. Rambler responds by snatching his hand away from her, causing Clover to cry and believes she really was a busybody and starts running back home. The next morning, Clover finds Rambler crying and starts asking him whats wrong. He then explains to Clover why he didn't want to stay at her house. He tells her that, sleeping in a bed and staying at her house reminded him of his old home and forest before it got destroyed. After he finished, he tells Clover to keep it a secret between him and her.
In Umi Monogatari, everyone was afraid of Kanon as a child due to her evil aura, which made her grow up aloof and unwilling to trust herself and others.
The Sailor Moonanime may not have many notable instances of these, but the manga has one for at least half of the characters, including the majority of the Senshi barring Usagi, and possibly Haruka and Michiru. And that's only if you don't count their past reincarnations as Serenity's guardians. Examples:
Usagi Tsukino/Sailor Moon, of all people, may count as a dark and troubled past life, as being Princess Serenity, she'd committed suicide upon seeing her Prince Endymion killed by the Dark Kingdom.
Rei Hino/Sailor Mars was raised by a neglectful father and an ailing mother, and when her mother died, her father seemingly didn't care, leading Rei to grow a strong distrust of men. Also, in Casablanca Memories, she was shown to have had her heart broken by a man who seemingly fell in love with another woman, furthering her conviction against males.
Makoto Kino/Sailor Jupiter lost her parents in a plane crash, compelling her to have to learn to take care of herself. All of her peers feared her and refused to have anything to do with her because of her strength and her height. She was even dumped by her boyfriend, who deemed her not feminine enough for him.
Minako Aino/Sailor V/Sailor Venus was the first Senshi to have been awoken, and had to fight all the youma by herself for a year. Within that year, she'd not only had to kill her first crush, who turned out to be a youma, she is implied to have lost many friends because she was too busy being Sailor V to have a social life. At the end of Codename: Sailor V, she learned that Kaitou Ace, her one true love was Danburite, a member of the Dark Kingdom, leaving her no choice to kill him and her only chance at happiness. Also, she remains cognizant of the Moon Kingdom's past life, Serenity's suicide, and the subsequent destruction of the Moon Kingdom, and shoulders the blame, thinking that it was her duty to protect Princess Serenity at all costs.
Mamoru Chiba/Tuxedo Mask, like Makoto, lost his parents in a crash, and wound up with Laser-Guided Amnesia with regards to his identity. This is his stated reason for looking for the Silver Crystal, the same thing the Senshi were looking for.
Menace of Amara has a particularly nasty one. Yes, she was a Bad Boss, being more concerned with ceaseless sexual pleasures and perversions with her vast harem oflesbian love slaves than actually ruling. But her favorite slave Anarista, possibly the one woman she actually loved, grew so sick of her petty hedonism that she betrayed Amara to a foreign power. Menace's people were destroyed, her kingdom toppled into ruin, and the former queen was flung to the hands of her former slaves, who beat and gangraped her until she died.
Sasami of Tenchi Muyo!. When she was a toddler, she took a terrible fall that nearly killed her, only to be rescued and bonded with Tsunami. Her young mind couldn't process the tragic events and she reasoned herself into thinking that Sasami died when she fell and that she's nothing more than a vessel for Tsunami. She spent 700 years afraid that if she told Ayeka, she'd hate her. Thankfully, that last bit proved untrue as she revealed her 'past' and both Ayeka and Tenchi (who had been hunting her down after an incident involving everyone spotting Sasami's reflection) revealed that they'd still love her no matter what.
Bleed Kaga from Future GPX Cyber Formula. He has a best friend named Eiji Aizawa, who was also The Rival. But in one of the races, Kaga made contact with the Zero Zone and crashed with Eiji horribly. Kaga then tried to rescue him while gas was pouring from his wrecked car when suddenly, the car explodes and the debris from the pipe cuts his forehead and he and Eiji's wife watched helplessly as he burned to his death inside the flaming car. This is the reason why he warned Hayato of the Zero Zone in ZERO.
In Guardian Fairy Michel, Kim set out for revenge against Salome after she stole her father's inventions and killed him during the escape.
Yuto and Kurosaki from Yu-Gi-Oh! ARC-V are genocide survivors and Child Soldiers in an inter-dimensional war, during which they lost many friends and allies, including Kurosaki's younger sister. Their entire home city was utterly destroyed for no apparent reason other than the sick entertainment of their assailants. To make matters worse, the war was waged using weaponized Duel Monsters, which in this universe are supposed to be the ultimate source of happiness and entertainment. As a result neither of them can see dueling as anything more than a bloody tool of war, and by extension have a hard time feeling any joy.
Aruosumente: Almost every member of the main cast has a dark and troubled past, and the further the story progresses, the more is revealed in bits and pieces, all weaving together to form the events of ten years ago:
Lante and Dante were refugees taking in by Oracle Kian and the former Emperor just to prevent an enemy kingdom from getting their hands on Dante's fighting abilities, then sent out to certain deaths when Kian decided Dante was uncontrallable.
Moeran saw his beloved teacher killed in connection to Oracle Kian, then got threatened with lifelong imprisonment unless he never tells anyone a word of what happened.
Legna, the protagonist, was supposed to be raised in seclusion but then given to his father to be raised by him, only to lose his father and have to take over his position, without ever being told what actually happened.
In Brave10, Anastasia and her family were shipwrecked in Japan, where her family died and she was sold into sex slavery, then later trained to be a ninja. While looking for the last heirloom of her family, Hanzo appeared to have it. He then coerced her to join the Iga Grotesque Five and infiltrate the Braves as The Mole. This is also why the concept of 'family' is a Berserk Button for her and what made her hate the easy bonds between the rest of the Braves.
In Westwood Vibrato, many of Cornelia's customers have these. As well as Cornel herself.
City Hunter: Ryo, big time. Orphaned at such a young age he doesn't even know his actual birthday? Check. Becoming a Child Soldier to survive being orphaned? Check. Being the initial test subject of the experimental drug Angel Dust, and the only man who has ever recovered from its withdrawal symptoms? Ouch!
Diane: A group of Liones knights intended to kill her and Matrona for glory. Although she survived the incident, Diane was made into a scapegoat for the massacre that had happened.
Ban: Ban's childhood wasn't all that great, and his life before joining the Sins was so bad that he wanted to become immortal to see if anything good would happen in his life.
King: He failed to save his captured best friend, lost his memory, fell in love with Diane, killed said best friend after having remembered everything, wiped Diane's memories of their common past and came back to the Fairy King's Forest to see it was destroyed and his sister was dead.
Gowther: He was given a magic heart by his creator. he was found 3000 years later by Baltra's sister and fell in love. Unfortunately her heart gave out on Their First Time. Since he didn't understand human anatomy, he tried to replace her heart with his magic heart. When guards entered, they thought Gowther raped and killed the princess.
Escanor: He was born a prince, but forsaken and nearly murdered when his powers first manifested. He barely escaped alive and was found by Merlin, at which point Meliodas apparently invited him to join the Sins.
Meliodas: His girlfriend died in front of him. she was the reincarnation of his girlfriend from 3000 years ago. She was cursed to resurrect, fall in love with him and die within 3 days if she remembered her previous lives. Meliodas on the other hand has been cursed with immortality and loses a bit of himself each time he dies forcing him to relive the loss repeatedly.
Outside of the Sins, Gilthunder saw the murdered body of his father and was forced into not revealing the truth to keep Margaret safe.
Yuliy from Tenrou Sirius the Jaeger. His tribe is decimated by the Vampires and it is made worse when Yuliy watches his mother died in front of him. When his brother, Mikhail, protects him from the vampires, Yuliy watches him getting slaughtered by the Vampires and thinks that he is dead. It's not until the present day when Yuliy meets with him that he ends up getting turned into a vampire as a result.
Yami's backstory parodies this in Black Clover. He sums up his backstory as roughly, "I'm from another place. I fell off a boat. I washed up in a foreign land. I beat the crap out of anyone who have me a hard time and adjusted." At least part of this was mocking the Big Bad's backstory, which plays this straight. He was an innocent elf boy who watched everyone he knows and loves get (supposedly) slaughtered by humans at a wedding designed to promote coexistence between them, sparking his centuries-long grudge against humanity.
Vampire Knight: Zero and Kaname both. Zero witnessed his parents murdered at the hands of a pureblood as an 11-year old, next to being bit and transformed by the same pureblood and seeing his twin brother smiling at the scene. Kaname is an ancestor of vampires who had been alive thousands of years ago along with an unnamed pureblood woman who ended up sacrificing herself for the creation of the vampire hunters and furnace, leaving Kaname to lead the battle between purebloods and the misery of being alone, after which he decided to enter his slumber that was later interrupted by Rido.
Dear NOMAN: Bazu was once a crow who was taken care of by a human after getting injured. When she decided to go back to check up on her, another human grabbed her and cut off her wings and feet. She then became a noman based on her encounters with humans.