Woobie / One Piece

Considering that it's a series that capitalizes on giving its characters tragic backstories, One Piece has tons of them, especially for the main cast.

Jerkass Woobie

• Nami, the self-centered, mood swinging, thieving Insufferable Genius of the Straw Hat Pirates, comes off this way in the East Blue Saga. She's rather hostile to Luffy and Zoro, views her association with them as an alliance of convenince, and eventually steals their ship. However, her personality, in particular, her obsession with money, is explained as a result of being an orphan raised by the Marine officer Bellemere, along with another girl Nojiko. The family was too poor to afford the things Nami wanted, and when Arlong came along and imposed a tax on the people in her village, with the penalty for not paying as death, Bellemere only had enough money to either pay for herself and hope they don't find out about Nami & Nojiko or pay for the two of them; she chose to save her children rather than herself, and was shot in front of her children's eyes. Arlong then forced Nami to be a part of his crew, even going so far as to forcibly tattoo her, and said that if she manages to get 100 million belli, her village will be freed as well as herself. Even worse is that Arlong had no intention of keeping his end of the bargain, and wanted to enslave her for the rest of her life. Good thing she met Luffy and the other Ragtag Bunch of Misfits who dealt with Arlong personally. She ends up becoming nicer after the end of the Arlong arc.
• Kuina, Zoro's childhood friend/rival, came off as rather arrogant and insulted Zoro a lot but she was covering up her huge self-esteem issues about her gender and being a swordswoman, being told that despite her talent, she will not be able to pursue being the best swordswoman in the world, or inherit her family dojo. Her father's suggestion in the anime that she might just have overcome her own limitations if she hadn't died makes her sudden and pointless death in an accident that much more tragic.
• Montblanc Cricket had to deal with the shame of his heritage because of the legacy left behind by Norland. His own (original) crew abandoned him when he decided to resolve his issues with the shame placed upon his ancestor. He initially was annoyed with the Masira and Shoujou for being fans of the tale. But came to love them and admitted he was glad they came along as the loneliness after being abandoned by his original crew was unbearable.
• Boa Hancock was introduced as a puppy-kicking Vain Sorceress. She showed herself to be an aloof, arrogant, complete Jerkass who wasn't above defenestrating her grandmother for giving the sincerest of warnings and petrifying her subjects for allowing a man (Monkey D. Luffy) onto their island. She was even complacent with her two younger sisters, Marigold and Sandersonia, breaking them in their petrified state just to mess with Luffy — just a hair's breath of crossing the Moral Event Horizon. However, when Luffy defeated the sisters and spared their pride by hiding their tattoos, this brought to light another side of Hancock unseen before: as she explained to Luffy, the tattoo was forced upon Hancock and her sisters (sensing a pattern here...), and is an eternal source of shame from slavery under the World Nobles, descendants of the founders of the World Government and, as shown in the previous arc, a whole 'nother ball of the MEH wax, known for kicking, shooting, and blowing up their slaves if they get frustrated or bored with them. The three sisters, who were just pre-teenage girls back then, spent four whole years enslaved to those bastards and were force-fed a Devil Fruit strictly for their entertainment. Hancock's own experience was such that she couldn't even talk about it without being reduced to tears. The very fact that she kept the law of her island to the letter could be explained due to her personal experience with one particular World Noble who was in her words "the very object of terror itself", which jaded her view on the opposite gender. It's only that Luffy didn't care that she and the other two were slaves, and hates the World Nobles anyway (for shooting a friend of his, who wasn't even one of their slaves) that caused her icy persona to warm up a bit, and even fall in love with the guy.
• The Whole Cake Island arc shows that Charlotte Pudding is one. She spent years being abused by her family for her Third Eye, Big Mom included, until she snapped and became the sadistic actress we see in the present. Even after she earned her keep, Big Mom still antagonizes her about not unlocking her eye's potential, and her role as the family's Honey Trap doesn't seem to help her sanity much, either. When Sanji says her eye is beautiful, she breaks down on the altar and has her first real case of Inelegant Blubbering in the story.
• Even Gecko Moria is this. Losing all your crew to someone like Kaido would fuck anybody up; he’s lucky to even be alive! Yes, he does attempt his take on a Zombie Apocalypse, but given his desire for a crew that’ll never die, you almost feel bad for the guy; especially since he barely made it out of Marineford alive.
• Eustass Kid is a Jerkass to the nth degree, and his first mate Killer isn't exactly all that nice either, but it's hard not to have at least some sympathy for everything that happened to them since the end of Dressrosa. It turns out that one of their allies, Apoo, completely screwed over them and their other ally, Hawkins, as he was working for Kaido all along and him joining the alliance was a trick from the start. Hawkins, despite not being in on this deception, chose to save himself and bend the knee to Kaido, and did nothing at all to help Kid and Killer when they fought Kaido, lost, and were beaten up and imprisoned. Kid later finds out that, while he was in jail, Killer (his best friend since childhood) was forced to eat a faulty SMILE Fruit that made him laugh all the time (even though Killer deeply hated his laugh) and work for Orochi, and Hawkins speculates that the rest of Kid's crew was forced to work for the shogun as well. Apoo's and Hawkins's respective betrayals, and what happened to Killer in the aftermath, seems to have deeply jaded Kid, who states that the only people he'll trust from now on are his own crewmates.

The Woobie

Straw Hat Pirates

At this point, you could say that a tragic backstory is a requirement for joining the Straw Hats.

• Luffy apparently never knew his parents (or at least his father, though he don't seem to care) and was raised by mountain bandits and an abusive, but well-intentioned, grandfather. He still had a great time though, mostly because of his two "brothers" Ace and Sabo. Then, Sabo, in Luffy's flashback, is considered dead with nothing left behind but a letter to Ace, and Ace dies in Luffy's arms after the latter has gone through hell (almost literally, with it being the theme of Impel Down) and sacrificed 20 years of his life span to save him.
• Zoro's childhood friend and rival got killed by falling down a set of stairs, the day after they had promised each other that one of them would become the world's best swordsman.
• Nami was orphaned as an infant, and raised in relative poverty with her loving adoptive mother, Belle-mère, and adoptive sister, Nojiko. When she was 10 years old, she and Belle-mère got in a fight, causing Nami to run out. After a conversation with family friend Genzo, Nami returned home... only to see Belle-mère being murdered by Fishman pirate Arlong because Belle-mère didn't have enough money to save the lives of both her and her children. And then after Arlong's men looked through Nami's house and found the maps that Nami made. Arlong, seeing Nami's talent for navigation and map-making, kidnapped her and forced her to join his crew. After Arlong promised her that she'd free her village if she collected a hundred million beries, Nami agreed to work with her mother's murderer if it meant saving her loved ones. She returned to her village, where she was shunned by the villagers for seemingly deciding to work with the man who took Belle-mère for the sake of money. Although Nojiko would later tell the villagers about what really happened, they didn't want Nami to feel as though she had no choice, opting to pretend to know nothing. Nami, at ten years old, choose to bear the village's burden on her own, sacrificing her freedom and happiness in the process. And after years of mistreatment, Nami finally gathered up 93 million berries... only to make the mistake of revealing her money's location to Arlong, leading him to steal every berry she saved up, rendering her eight years of suffering moot.
• Usopp's mother was dying from sickness, and he made up lies of his pirate father returning with a miracle medicine to cheer her up. After she died, he continued to tell lies.
• Sanji was constantly bullied by his brothers, while his father dismissed him as a weakling due to a failed experiment to turn him into a remorseless monster of a Tyke-Bomb while still in his mother's womb. Sanji was eventually left for dead in a dungeon, but he was able to escape thanks to his older sister. He subsequently joined a cruise ship as its cook, but two years later, he lost the entire crew of the ship to a storm. He was then stranded at a rock in the sea for many weeks with a bag of food and the captain of a pirate crew who had raided mentioned crew before the storm struck, almost starving to death until he was finally rescued.
• Chopper was always bullied by the other reindeers for his blue nose, and it really hit the roof when he ate a Devil Fruit which gave him the ability to transform into a "human". Rejected by both reindeers and humans (his human form resembled an abominable snowman), he was brought in and raised by a quack doctor — who then was killed in front of Chopper's eyes. See a recurring theme?
• Robin was raised by an abusive aunt and indifferent uncle, and was constantly bullied by other kids because of her Devil Fruit powers, making her a "monster." She befriended a cheery giant, who died trying to save her, and a group of historians, who were killed along with the entire rest of her home island for researching forbidden subjects. Her mother finally returned after many years the day the genocide took place, giving the two about 5 minutes together before she promptly died along with everyone else. Then she was branded a wanted criminal for the same reason as her historian friends and was forced to spend the next 20 years (starting at the age of 8) on the lam, where everyone who took her in was either only pretending to hide her so they could attempt to give her up to the government for the reward, or an uncaring criminal organization that cast her aside as soon as her powers weren't of use to them anymore. Oh, and she was constantly told that she shouldn't be allowed to live. It isn't any wonder that even after joining the Straw Hats (the first people in 20 years to not treat her like toilet paper), she had suicidal tendencies and trust issues.
• Franky ran away from home and lived in a scrapyard before he was taken in by a shipwright, who was scheduled for execution but was to have his sentence pardoned in exchange for building the Sea Train. Then Franky got framed by the Government and, in order to save him, Tom asks that the pardon be used for the crime that Franky had been framed for. So Tom still has to be punished for building Gol D. Roger's ship, but in truth is sent to his doom because Franky left his creations lying around for other people to steal and frame him with.
• Brook, the first one who was actually a grown-up during his tragic past, is the sole survivor of a very close and friendly pirate crew who died of poisoning around him while playing their favorite song. He came back to life because of his Devil Fruit, but seeing as the steering mechanism of his ship was broken, and he was in the middle of the One Piece equivalent of the Bermuda Triangle, he spent several decades drifting alone in the eternal mist.
• Finally, Jimbei, the latest member and the second who was a grown-up during his tragic past, was a member of the Sun Pirates whose captain got caught in a trap after sending Koala back to her home and died after refusing blood transfusion due to his hatred of humans. Soon after, Jimbei took over as captain, joined the Warlords in order to strengthen the co-existence between humans and Fish-Men, and got Sun Pirate crewmate Arlong released from Impel Down. Arlong didn't sit well with Jimbei's decision and, after a fight, Jimbei lets Arlong run loose on East Blue, a decision he would come to regret as this resulted in Nami's tragic past ensuing as detailed above.

Other Characters

• Kyros is more of an Iron Woobie. After committing multiple murders to avenge a dead friend, he was put into the coliseum, where he won many victories but could never live down his murders. Eventually, after 3,000 victories King Riku, who had seen through him initially as a good man, decides to let him go and become the captain of his army. He's tasked with guarding Riku's daughter, Scarlett, who is initially on bad terms with him due to his past, but after saving her from pirates, she falls in love with him and the two elope (with Riku's blessing) and have a child, Rebecca. He considers himself unworthy of touching the "pure" Rebecca, but with Tears of Joy promises that he will always be by her side. Then Doflamingo arrives in Dressrosa, framing the king for massacring its citizens. Kyros arrives to save him, but one of Doflamingo's crew curses him by turning him into a toy, which has the side effect of causing everybody to forget about him (ironically the exact wish he had when he was in the coliseum). He told Scarlett to stay behind, but since Scarlett forgot about him, Scarlett left her hiding place and was found and shot by another of Doflamingo's executives. As Kyros held her dying in his arms, her unable to recognize him, he lamented the horror of the situation and how with his tin arms, he can't even feel the warmth leaving her body. He returns to Rebecca with Scarlett's corpse, apologizing that he couldn't protect her; because Rebecca doesn't recognize him either, she blames him for her death, but he swears that he will protect her, and that he will always be by her side. Cut to years later, and Rebecca, who has joined the coliseum to gain the Mera Mera no Mi from Doflamingo, snaps at Kyros, telling him he's not her real father.
• Yamato's entire life has been filled with rotten luck. The biological child of one of the Four Emperors, he was inspired by Kozuki Oden's death and told his father Kaido he wanted to be him - which led to his father Kaido locking him up in a cave with several samurai, expecting that they'd kill him. They showed mercy, spared Yamato, and taught him how to read using Kozuki Oden's journal... and when it looked like they'd starve, they decided to break out knowing Kaido would kill them so that Yamato could live. More than a decade later, Yamato meets Ace when the latter comes to Onigashima to save children that were kidnapped, and becomes friends with him, to the point of making a Vivre Card for him - and then getting to see it burn to ash when Akainu kills Ace. Twenty years after Oden's death, he finally gets freed by Luffy when he makes it to Onigashima - only for him to discover, as a final and cruel twist, that the explosive bracelets Kaido slapped on him years ago were in fact real, and that his father didn't mind killing him if he thought it was needed. He's freed from them safely, and understandably hurt by the revelation, and a Friendless Background where all of the friends he made were killed... but in Iron Woobie fashion, he never lets it break his spirit.
• Bartholomew Kuma. Where do we even begin? At first he’s introduced as emotionless but then it’s revealed to be because of what’s been done to him. He was turned into a cyborg and the prototype for the Pacifistas, cybernetic enforcers for the World Government. His final act of humanity is protecting the Thousand Sunny while the Straw Hats are separated and from the looks of it he’s taken so much punishment that he’s just about ready for the scrap heap by the time Franky returns after 2 years. And that’s without even getting into his past with Bonney, his daughter…