Quite surprisingly, even The Jokerhimself may not have started out as a bad person. Alan Moore's The Killing Joke shows how losing your pregnant wife and getting disfigured on the same damned day can turn even a decent human being into a mass-murdering maniac. Bear in mind, however, that this story was the trope namer for Multiple-Choice Past, as the Joker later admits he remembers his "bad day" differently from day to day.
"All it takes is one bad day to reduce the sanest man alive to lunacy. That's how far the world is from where I am. Just one bad day. You had a bad day once. Am I right? I know I am. I can tell. You had a bad day and everything changed."
But contrary to this, Gordon fails to break under the Joker's torments. Batman tells the Joker: "Gordon's fine. Maybe it was just you all along."
Pre-New52 Tim Drake, Robin III, was hit with an extreme angst upgrade. His mother was killed, then a couple years later his girlfriend was apparently killed and his father, stepmother, and both best friends and a number of his other friends were killed within a period of two months. He was adopted by Bruce to be greeted by two brothers making multiple attempts on his life. He blamed himself for the deaths of several innocent bystanders. After Dick fired him as Robin to replace him with his unrepentantly homicidal little brother he cut himself off from any healthy emotional support. Tim, as Red Robin, left Gotham City in search of the supposedly deceased Bruce Wayne while his old allies tried to convince him he'd gone mad rather than listen to his reasoning. While it looked like he was about to become a Fallen Hero he determinedly kept himself from taking that plunge.
Weirdly enough, Tim Drake's mentor, the goddamned Batman himself is a type F. He's lost sidekicks, allies both superpowered and non-, and has had multiple efforts to try to make something out of his life crushed. But he's still the same person he was at the beginning of his Darker and Edgier remake as he is now.
His transition from young Bruce Wayne to Batman is type E though. But when he is Batman, he stays at type F.
Not only is Krypton destroyed but Supergirl survives on Argo City but then it's destroyed. So she's orphaned twice in most continuities.
In the Post-Crisis continuity her parents survived Krypton and Argo City's destruction only to die on New Krypton. Which was subsequently destroyed. In other words, she has lost her home planet three times.
Kara becoming a Red Lantern in Red Daughter of Krypton is the result of one: she woke up with missing memories, on an alien world, all alone and was promptly attacked by men in Powered Armour. Shortly after that, she encountered a grown man claiming to be her baby cousin. Shortly after that she's lured in and kidnapped by an amoral trillionaire who wants the secrets of Kryptonian technology, poisoned with Kryptonite, and then the guy who rescues her is murdered in cold blood. After she gets away from all of that, she's utterly alone in an alien world, then finds a link to her very dead home. She follows it... and finds that her home is basically a ghost city, whereupon she is beaten up by a Kryptonian supersoldier called a Worldkiller. After escaping all that, she has to fight four Worldkillers, then, exhausted, is promptly attacked by the US Army and Police, with only one human standing up for her (and is, conveniently, an Omniglot). Said human befriends her, then turns out to be the Silver Banshee, who is being hunted down by her father, the Black Banshee. After briefly being absorbed, body and soul, she fights her way out. Then she gets attacked again, while on a date. Oh, and the first man she falls in love with is H'el, who's manipulating her, using her affection for him to trick her into a brief FaceHeel Turn. Then, in defeating H'el, she's poisoned with Kryptonite. Again. And then there's the revelation that her father was experimenting on her. And then she ran into Lobo, who taunted her until she blew up.
The 90s were a bad time for Aquaman with all the stuff that happened to him there. His infant son was murdered by Black Manta, and not only does his wife Mera blame him and his "weak genes" for their son's death, but she goes insane and has to be committed to an asylum. Oh, and Aquaman has his telepathy stolen and his hand eaten by piranhas. Not to mention nearly having his place as ruler of the seas almost stolen by the corrupt god Triton. And people wonder why Aquaman was so angry at this time in his life.
Roy Harper, the former sidekick of Green Arrow, has had it pretty rough recently. In Cry for Justice he got his arm chopped off by Prometheus. Then Prometheus and his accomplice the Electrocutioner unleashed a Kill Sat on Star City, killing thousands including Roy's daughter Lian. This drove him back to drug abuse, which just made things worse. To add insult to injury, when he and Cheshire got involved, he couldn't perform, so to speak. He became a Type E Jerkass, railing against his former friends and teammates, going so far as to blame Mia for Lian's death and calling Donna a whore when she tried to sympathize with him. Later he became a full-on Type B when he agreed to join Deathstroke's Titans (a team of assassins for hire), though this is because he is emotionally blackmailed into joining the team by Cheshire so they can kill Deathstroke. And then, he finds out Deathstroke had secretly gotten him addicted to an even worse drug, Bliss, which is literally made from human children. Thankfully, the end of that volume of Titans had Roy stopping Deathstroke and reclaiming the Titans name. And it wasn't until Convergence when it was shown that Roy had successfully managed to beat his addiction on his own, reconciled with his friends, and regained a semblance of peace leading into Lian being brought back to life.
In The Trial of the Flash, the Rogues' Gallery and corrupt lawyer N.D. Redik make the Flash's life miserable. Redik arranges for Flash's lawyers to be killed, and while they're rescued, he's very shaken up by it, and the Pied Piper mind controls the mayor and innocent civilians to hate the Flash.
Blame Executive Meddling for that. Spider-Man has progressed in his life - he was happily married, and he may be a Hero with Bad Publicity but other heroes know perfectly well how amazingly good he is, both as a person and at what he does. And he even made some improvements here and there on the publicity. But then One More Day came and reset most of the above.
Before that, Spidey had a Type A origin, and has lost, in no particular order, his robo-parents, his actress-aunt, his first true love, his marriage (talking about the brief separation that ended through the Straczinsky run), his best friend Harry, some love interests and pals (we still miss you, Captain DeWolff), has suffered by every one of them, and then he grew a few more. In fact, before One More Day, this trope could have been called "The Parker".
Daredevil on the other hand is a Type E, especially after Kingpin put him through the wringer in his excellent Born Again series.
It would take an entire page to describe the shit Cyclops has put up with, all to push him down deeper the Anti-Hero scale, and he gets blamed for each and every action and reaction, whether he's accountable or justified or not.
X-Men's Rahne Sinclair/Wolfsbane. To say she's had it rough is putting it lightly. When killing and eating your monster of a father is considered one of the better moments in your life (by anyone who isn't you; you were heartbroken about his death even before realising you were responsible), well...
Ultimate Reed Richards, as of the end of Ultimatum, cementing himself as a hybrid between Types B & F.
Iron Man: Tony Stark's entire life consists of one traumatic event after another, mixed with a morass of personal issues covering everything from alcohol to troubled romantic relationships, an angst-and-tragedy-ridden personal and professional life that include, but is not limited to, traitorous/murderous friends and business partners who have tried to destroy him and his friends multiple times, all combined with a ridiculous amount of overwork note (running Stark Industries, churning out new inventions to keep it running, managing the Avengers' legal and financial problems, being constantly on-call to consult other superheroes on technology-related crises, being a founding Avenger and occasionally the group's leader, being a superhero on his own time, and dealing with enemies who want to kill him on both superhero and business fronts) that is directly responsible for most of the aforementioned trauma, to the point where he has had to basically completely rebuild his life from the ground up on several different occasions.
His origin story alone is pretty terrible, but it's never addressed that, after going through that trauma conga linenote Being kidnapped by terrorists, being in fear of his life every day for months while being forced to build highly destructive weapons with his own tech, watching his only ally die and then suffering severe Survivor's Guilt over that which he has not gotten past, having to kill at least fifty people while escaping, and his heart being severely damaged to the point that he was only being kept alive by his own tech., he had to go back to the States and run a company. A company that was in severe danger of collapsing after he pulled the plug on the weapons department. He couldn't afford to show weakness, There Are No Therapists, and his only support system at the time was his secretary and his chauffeur. Let's not even get into the lack of support he gets from The Avengers, who seem to operate on the general policy of "if Tony's issues aren't affecting us, we aren't going to ask." He basically spends his life swinging between Type A, then Type C when some new trauma occurs, then back to Type A.
When John Byrne took over West Coast Avengers, his first act was to put Scarlet Witch through a seemingly endless trauma conga line: first her synthezoid husband, the Vision, was dismantled and his personality erased, effectively ending her marriage. Then she was kidnapped by a secret society trying to use her to create a race of super-mutants. Then her children were revealed to be made from pieces of the devil's soul and erased from existence. Then her memories were erased, and she was driven to catatonia and temporary insanity. Byrne managed to do all this in only a little over a year on the title.
X-23. It starts with her being created to be the perfect assassin and a Living Weapon, and just goes downhill from there. She's abused and tortured physically, mentally and emotionally for thirteen years. When she finally escapes, she's forced to kill her own mother with a chemical trigger that sends her into an Unstoppable Rage. She eventually finds her way to her only other family and starts to build a happy life, until her creators come looking and she's forced to send them into hiding and never see them again to protect him. Then she spends a year or two as a Street Walker under a sadistic and violent pimp. After joining the X-Men (who could probably provide a whole page of examples themselves) she's nearly killed by Nimrod, joins X-Force and is recaptured by the Facility and tortured with a chainsaw, leading her to a mini-Heroic BSoD over how she'll never be able to escape them, is driven into an existential crisis by a demon over whether she has a soul, and just as she's starting to piece things together gets shanghai'ed by Arcade to fight other teens to the death for his amusement. And after that she's tortured by Purifiers, who reveal that the whole world has seen her in a trigger scent rage. The poor girl just can't catch a break!
RachelGrey. Oh ye Gods, Rachel Grey. Put succinctly, dying was not the worst thing that ever happened to this poor girl. She grew up in a dystopian hellhole, has seen her loved ones killed before her very eyes more than once, been brainwashed and Made a Slave repeatedly, and almost never seems to catch more than a few seconds break before the next horrific thing comes along.
All-New X-Men: Teen Jean Grey, a 16 year old girl, has her powers blooming early, with her attempts to deal with Power Incontinence adding to her troubles. She finds out she is going to die (repeatedly) and is, as far as she knows, still dead, while her teammates survive to the current day.
Robert Kirkman's The Astounding Wolf-Man. Hoo boy, it's impressive how crappy the title character's life got so quickly. So he was a wealthy CEO shredded by a werewolf, became one himself, lost his multi-million dollar company, got an oh-so-brief respite of awesome when he got some control over his wolf form and became a superhero, found out he still became a murderous beast during a full moon by killing a well-known superhero, became estranged from his wife and daughter, found out that his vampiric mentor killed his wife, got framed for said murder (including, worst of all, in the eyes of his daughter), became a fugitive, got another minor respite when he became friends with a prominent superhero, reluctantly got a minor alliance with someone he already knew was hugely bad news, was thrown into prison, and was stabbed in the chest by his own daughter, who'd turned to the previously mentioned vampiric mentor to avenge her mother's death (and let him drink some blood from her), not knowing she was training with the real killer! Whew! It was only in issue 17 that his life took any appreciable change for the better.
Femforce: Jen Burke's life has been horrible. She never wanted to be a superhero, but because she was Ms. Victory's daughter she was compatible with V-47. When Ms. Victory went rogue, she was asked to take her place. She refused, and Tom Kelly responded by ruining her life to the point, including arranging for husband's legs to be broken, where it was either do it, or face financial ruin. Once in Femforce, the girls resented her for being forced on them, and refused to accept her. In addition, she couldn't tell her husband what was going on, badly straining their marriage eventually leading to an affair and divorce. Then her son Jason gets killed by collateral damage from one of Garganta's rampage. Then she gets manipulated into becoming Rad II, by the mad God Capricorn. Finally she just snaps.
Zomax, the villain of a 1941 Jungle Comics story by the notoriously grim cult-favourite cartoonist Fletcher Hanks. It begins when Zomax goes hunting in the jungle and is jumped and mutilated by a lion he'd mortally wounded and was about to finish off when his gun jammed. Then a "man-hating" elephant tosses him into a pond where he's stung by poisonous gnats, causing his face to swell. Upon crawling out of the water, he encounters a boa constrictor that crushes several of his bones. Next, an ape takes him to its lair, where for several months it beats him like a drum with bones. Small wonder that Zomax, after escaping the jungle and emerging from the hospital severely crippled, vows to exact revenge on all jungle animals by causing a massive tidal wave.