The Mandarin from Iron Man was orphaned at an early age, and raised by an aunt who hated him. Instead of raising him to be a decent human being, she raised him to be a sort of super-soldier; a savage master of martial arts, science, and deviousness. Worse, she spent every last bit of the gold he inherited doing this, robbing him to pay for twisting him. By adulthood, he was a twisted monster/Übermensch combo without enough money to even pay his property taxes.
Subverted in the Brian Michael Bendis run on the comic book Daredevil. Daredevil has spent his life tormented by the monstrous Bullseye. When Daredevil discovers Bullseye had a horrible childhood, the hero feels no sympathy, and says he will never fear Bullseye again. A mass murderer is scary; a mass murderer who kills because he had a crappy childhood is merely pathetic.
Possibly because of Daredevil's ownBack Story. Maybe not everyone can spin "Blinded by toxic spill at age twelve and single father was coerced into not suing due to carelessly negligent waste handler's mob ties" into "hot-shot lawyer AND superhero", but still...
Many of the Batman villains: Anyone born looking like Waylon "Killer Croc" Jones would have trouble leading a normal life; Bane was forced to live out his escaped father's life sentence, and so on. Some are a bit suspect — Scarecrow was bullied as a child, yes, but so were a lot of us, and yet we didn't turn evil.
Inverted by Batman himself, who, after seeing his parents murdered by a criminal, devotes his life to fighting crime and improving the quality of life in Gotham.
Lampshaded in Batman Beyond: Return of the Joker, wherein Terry gets the better of the titular villain by, among other things, mercilessly mocking his past, although in this version it's just the chemical bath.
The Joker himself likes to make fun of this trope, by making up horrible child abuse stories in order to mess with people's minds. He did this most notably in Mad Love.
Oh, and Killer Croc once teamed up with fellow biological misfit Baby Doll, and they were quite successful—but apparently being a Jerk Ass at heart, he decided to ditch her, at which point she snapped on him.
One of the few "abusive father" backstories that really works: Harvey Dent/Two-Face's violent, sadistic alternate persona, called "Big Bad Harv" in the cartoon, emerged as Harvey's way of coping with a drunken, abusive father. In the comic in which this element of the character was introduced, it's revealed that his father would take Harvey and "play a game" with him, flipping a silver dollar and beating the child if it came up heads. The coin had two heads.
The nature of Two-Face's father's abuse varies slightly depending on the story. One story suggested that his dad had a split personality himself, and would violently beat Harvey when he was angry with him before realizing in horror what he was doing.
The Riddler is another of the "abusive father" strain. In particular, his father would savagely beat him every time he lied, so the Riddler feels the compulsion to always tell the truth... albeit in convoluted riddles.
In the Batman: Arkham Asylum video game, Riddler tells his Arkham shrink that his abusive father (who constantly called him a moron), accused him of cheating on a school logic puzzle, and beat him for lying. When the shrink tells him she's sorry to hear that, Riddler proudly proclaims that father was right and he HAD cheated.
This even extends to non-villain characters. Much of Jason Todd's problems lie from his childhood (mother died when he was young, father was a Two-Face mook who was eventually killed). When he is adopted by Batman, Jason lives for the "Well Done, Son!" Guy, and his desire to see his real mother (who he has never even met) led to his death at the hands of the Joker. Since he was revived, he's been unable to fully understand why Batman got a new Robin, but still lives for his old mentor's approval. This reached a head in "Battle for the Cowl" where his inability to accept Batman's death resulted in Jason snapping completely, trying to take his Batman's place (as a murderous Batman), and nearly killing Tim Drake.
A perfect example of the slimy psychiatrist appears in Frank Miller's Batman: The Dark Knight Returns, in the form of Dr. Volper, who attempts to present the Joker as being a mere victim of Batman's psychosis. In thanks, the Joker snaps his neck on live television (while gassing the studio) - although it's suggested that the psychiatrist, irritating, blinkered and naive jerk though he may be, might have a point, as the Joker had spent the period that Batman had been absent from Gotham City in a catatonic state that he only emerged from when Batman returned.
Alan Moore's The Killing Joke, during which the Joker has his Freudian Excuse explained as an extended flashback. Joker explains that the story might be entirely false due to his own unreliable psyche, but DC seems to be treating it as canon, given a later story arc where Riddler says he witnessed the murder of "Jack's" wife and offers to tell Joker who did it in return for protection.
The whole point of The Killing Joke is Joker trying to prove that all it takes is "one bad day" for even the sanest person to go off the deep end. He tries to drive Commissioner Gordon insane by shooting and brutalizing his daughter Barbara, then forcing Gordon to look at photographs of her naked, broken body. However, Gordon doesn't break and, when Batman rescues him, he tells Bats to bring Joker in by the book, to prove "our way works".
This is turned on its head in Batman Begins, in which the corrupt psychiatrist, when his "clients" cease to be useful to him, uses a neurotoxin to render them legitimately insane.
The Batman: The Animated Series episode "Trial" has the villains putting Batman on trial for ruining their lives. Even they end up admitting that they had problems, some self-inflicted, before Batman became involved. Being villains, they try to follow up the verdict of innocence with an execution, regardless.
Roman Sionis a.k.a. Black Mask also had an abusive childhood. Whenever he suffered an accident that should have him taken to some hospital, his parents were more concerned with their image and covered the incidents. Despite hating the Waynes and not hiding it from Roman, his parents forced him to befriend Bruce for the sake of being connected to one of Gotham's elite families. When Roman started dating a secretary from his father's company, they opposed it. That was the last drop for Roman, who burned down the family home with his parents inside it. Not being as good as a businessman as his father was, he drove the company bankrupt. His girlfriend left him, the irony being that his parents were right about opposing the relationship. Using a defective product from his company (the very same one that drove him into bankruptcy), he exacted his revenge on her. Feeling humiliated that Bruce Wayne took over the company, Sionis (now Black Mask) started kidnapping executives of Wayne Enterprises.
Victor Fries' animated origin of losing his wife and being mutated in a Freak Lab Accident is expanded in an adaptation comic that explains he had abusive parents that eventually disowned him and shipped him to boarding school for trying to preserve animals he cared about through freezing, and that Nora (said wife) was the only person who had ever loved him.
Subverted with Mr. Zsasz, who had a happy, pampered childhood and youth; he ruined his life himself after his parents' death by becoming a compulsive gambler who later took to murder to make sense out of his life.
Has been used at times to explain the motives of Spider-Man villains, and to possibly contrast them with Spidey himself, who did not exactly have the best childhood. The worst example was when Venom was given a cliched tragic backstory (complete with the drunk, abusive father) as part of a bad idea to turn the character into a hero. Some other examples:
Doctor Octopus: Bullied as a child, with an overprotective mother who forbade him from pursuing a relationship with the woman he loved, but selfishly tried to pursue one of her own, then died of a heart attack when he confronted her about it. In many ways, his guilt from this caused his carelessness that created the accident that made him a villain.
Electro: Abusive father who left him and his mother, followed by his mother being overprotective and discouraging him from pursuing his goals. To make this worse, after she died, a marriage that went sour and ended in divorce only made him more bitter.
Tombstone was an albino born to black parents in Harlem, making him a black kid in a white kid's body; as one might expect, his childhood wasn't very pleasant, abused by both his family and his peers. To cope, he bullied the other students in school, and only got worse as an adult, becoming a hitman by trade.
The Green Goblin: While some say Norman had very little of an excuse, he didn't become evil on his own. His father was an abusive alcoholic, which made Norman resolve to become a breadwinner for his family. Then things got worse. His wife died shortly after Harry was born, driving him to work harder and neglect his son. Eventually, he framed his business partner Mendel Stromm for embezzlement, used Stromm's research equipment to develop a new line of chemicals, and it all led to the Goblin Formula, and the birth of a nightmare.
Flash Thompson wasn't truly a villain, but this was the reason he was such a jerk in high school. His dad was an angry alcoholic who abused both him and his mom. Indeed, a story arc in the 90's involved Flash succumbing to alcoholism himself.
This was actually addressed in Ultimate Spider-Man, where Nick Fury reveals that the reason he had given Spidey such a hard time was because he has assumed, due to the tragedy in his life, Peter was almost certain to become a villain.
In Issue #7, it is explained that on Victor Van Damme's tenth birthday he was presented with his family history dating back to Vlad Tepes Dracula and the blueprint for his villainous mindset, and from that day on at dinner he was required to recite said family history from memory, receiving beatings when he got it wrong and being forced to start over until he got it right. Not much of a Freudian Excuse, but... the last page of the flashback shows 10-year-old Victor sitting in the chair where he received the original lecture and instruction in five panels depicting it slowly getting darker. In the last one, he says "It's my birthday."
The Maker a.k.a Reed Richards. Abused by his father, not respected by his peers, bullied in high school, and the world didn't change the way he wanted it to nor would anyone let him change it for the better.
In mainstream continuity, the Fantastic Four's old enemy the Mole Man claims he was ostracized and treated cruelly by his peers as a child and even as a young man because he was so ugly, eventually choosing to abandon humanity entirely because of it. However, this is impossible to verify; seeing as all accounts of his youth have been related by him (with no proper names ever given of his tormentors), they are likely subject to his biased version of the facts.
616 Doctor Doom has traces of this as well. His mother sold her soul to Mephisto in order to acquire greater magical powers, and she got killed when he was still a babe. His father tried to use science for the good of mankind, only to be oppressed by an local baron forcing him and Victor to run. Depending on the book you're reading, either Victor saw his father freeze to death or they were saved just in time.. only for his father to die of an illness... And then when he is about to save his mother, his most magnificent machine blows up... Because of that Richards.....
It later turned out that his machine was actually tampered with, but not by Reed Richard. Instead, it turned out Ben Grimm had purposefully tampered with Doom's machine.
Played for laughs: In the one-shot special The Fantastic Four Roast (February, 1982), Dr. Doom explains the cause of the accident that turned him evil: he wasn't invited to go on a panty raid with Reed and his college buddies.
Dr. Doom: If I had been invited to go on that panty raid, the Dr. Doom you see before you would not exist! I could have been a fun guy!!
And then, once he and his soon-to-be wife Magda settled in Ukraine, a mob burnt down the inn where they were staying, and he was unable to do anything while his daughter burned to death. And then, when he lost control of the powers he didn't know he had and killed the mob, Magda ran from him, calling him a monster. Later, when he was hunting Nazis for a living, the people he worked for (heavily implied to be the CIA) killed a female friend of his because he went after the "wrong" Nazis. Oh, and his powers make himbipolar. The man has so many issues it's a wonder he's still able to function.
On the two occasions when Magneto decided to try the more ethical path of establishing a separate nation as a sanctuary for mutants and otherwise leaving flatscans entirely alone, both times his attempted 'Mutant Israel' was almost immediately nuked off the map. With literal nukes. We might not agree with Magneto's subsequent urges to burn the world, but we can definitely understand why he's having them.
Another X-Men villain, the mutant-hating Graydon Creed, was a victim of Parental Abandonment, and his parents were both mutants (Mystique and Sabertooth) even though he is not. When he discovered this, he grew to resent mutants as a result, to the point of founding hate groups like the Friends of Humanity and the Upstarts.
"Everyone's looking for someone to blame. Society. Culture. Hollywood. Predators. Looking everywhere but the right place. Children are very simple, Mr. Jerusalem. Very easy devices to break, or assemble wrong. You want to know who did this to these kids? Only their parents. That's the thing no one wants to hear. Every time you stop thinking about how you're treating your kid, you make one of these. It really is as simple as that. It's got nothing to do with the failure of the society or any of that. It's got everything to do with the responsibility of making a human."
Junior from Secret Six has this turned all the way up to eleven. Her father was the original Golden Age Ragdoll, a psychopathic mass murderer and cult leader in the Charles Manson style. He beat his son because he wasn't triple jointed like he was and when it came to Junior (Real name Alex) he would repeatedly rape her, from a very young age. It doesn't excuse the horrific crimes she later commits (Junior is a sadist, rapist, mass murderer, and torturer whose crimes are so horrifying there are people in Arkham who are scared of her), but her father's character explains some of it.
Sistah Spooky's rather pathological hatred of blondes (like her teammate Empowered) was summed up thusly to said teammate by an ex-lover:
"It's a messy High School (Über-Aryan Mean Girls) trauma, to oversimplify things considerably."
The Terror Titans miniseries by DC is based around this trope. Every issue features one member's backstory, usually involving a terrible childhood.
Arguably every member of The Umbrella Academy, and definitely Vanya. Hargreeves is a dick and terrible parent, for instance his habit of sorting his children by their apparent worth.
Backblast from G.I. Joe. He grew up next to one of the busiest airports in the world, and whenever a plane landed or took off his whole house shook with the force of an earthquake. When he signed up for the military, the first thing he asked was "Where can I go to shoot airplanes out of the sky?"
Similarly, Charbroil used to have to heat the water pipes in his family's basement as a kid with a blowtorch to keep them from freezing in the winter, and as a teenager worked at a mill, feeding coal into blast furnaces. When asked by the recruiting sergeant what kind of job he was interested in, he replied, "What have you got with open flames?"
Subverted in the MAD parody of Touched by an Angel. The somewhat jerky boss objects to a flashback of him being abused by his father that is used to explain his behavior, saying that it isn't real, but the angel showing it tells him that they need it for Tear Jerker material.
Superman: Birthright gave Lex Luthor a small excuse. His father was emotionally distant and he felt alienated from everyone because of his money and intellect. However, he was also a raging sociopath with a superiority complex that dwarfed the heavens and many people point out that Luthor made his own choices. It's still better than his excuse in the Silver Age: that he blames Superman (then Superboy) for a botched chemistry experiment that made him bald.
In the New 52, it's established that as a teenager, Lex had the chance to develop a cure that could have saved his dying sister Lena. Instead, he sat by and did nothing because he was afraid of what would happen should he fail. When Lena died later that year, a grieving Lex vowed to never let anything stand in the way of him reaching his goals ever again. This turns out to be a lie. Lex DID try to find a cure, but it failed and left her an invalid. However, unlike his fictionalized account, Lex claims this failure made him stronger.
In the Conduit saga, Conduit's father's emotional abuse of him (disparaging him for always coming in second to Clark Kent) partially made him the unstable person he became.
While not a villain per se, Rorschach from Watchmen was raised by a prostitute who never cared for him. The Comedian is implied to have had a rough childhood as well.
Rorschach states his reason for becoming a crime-fighter in a deconstruction of the superhero origin story. The therapist he speaks with sees it as nothing more than a shallow excuse for his violent life.
Ozymandias had an (unspoken) excuse of his own in the movie, or at least from the POV of the actor who played him. Matthew Goode decided to portray Veidt as being shamed by being the son of a Nazi, and that his Well-Intentioned Extremist views arose out of a desire to shed his family guilt and save the world.
Barracuda from The Punisher MAX series. Though an Affably Evil character to the point of almost being likable, he turns on allies in an instant, given sufficient reason to do so, and tries to get revenge on Castle by kidnapping his infant illegitimate daughter and planning to torture her to death in front of him. However, during a scene in which the tortured Barracuda snaps completely and utterly, a dialogue in his head reveals that his father had been abusive to the point of torturing his young son. When he goes off the deep end, Barracuda screams "Never found him! Never fuckin' found him! Hadda take that shit out onna muthafuckin' world!"
Nicky Cavella was manipulated and sexually abused by his aunt. She also made him kill his parents, although the Slasher Smile on his face heavily implies that he wasn't quite normal to begin with. When he's grown up and finally suffocated his aunt with a pillow, he gleefully pisses on the remains of Frank Castle's family and murders the youngest son of one of his opponents before cooking and serving him to said opponent.
One King of the Homeless, while not abused, did not have a normal childhood. His mother was beyond morbidly obese and he was bullied for it, and while hugging him one day she fell over and couldn't get up. He had to eat his way out of her corpse, which explains why in adulthood he only finds confort when swimming Scrooge McDuck-style through the corpses brought to him by his mooks.
One future Mafia boss had a little brother with dwarfism who he humiliated in a variety of ways. When both are adults, the dwarf recruits other short criminals to form his own empire, proposing that Wolverine and the Punisher join them. It ends badly for the criminals and Wolverine (who gets his face and ballsack shot off before being run over by a steamroller).
The Tiny Ugly World arc has a Ned Flanders-looking creep whose mother had severe issues, slept with her son, and cut off his penis (he keeps it in a jar) and killed herself. He's even worse.
Even Jake Gallows, the Punisher in 2099, runs afoul of guys with backgrounds like this. Kron Stone claims his family never loved him, leaving a robot to care for him but never bothering to program it, causing it to default to veterinarian mode. "Do you know what it's like to be fitted with a collar, live in a kennel, and be fed on dog meat?!" "No, but I know what it's like to have your family butchered by a crazy with a sob story."
Alex Hutton, alias Hazard, has a lot of open hostility for the police. His cop father was killed by a car bomb right in front of his eyes and he was raised by his government-hating survivalist grandpa.
Defied in X-Men Noir; Jean Grey's Motive Rant includes lamenting that Professor Xavier never truly accepted that she was always extremely immoral and manipulative. "Nobody touched me, nobody corrupted me. This is me."
Parodied in a Fun with Milk & Cheese story called "Society is to Blame!", where the titular dairy-products-gone-bad commit their usual horrific fit of violence, but this time decide to do so all the while spouting cliched Freudian excuses as to why they're doing it.
An early Silver AgeCaptain America story had Cap the prisoner of the Red Skull where he told of his tough early life as a homeless child, exploited by street criminals and who could only find work in menial labor until he met Adolf Hitler. However, Cap tells him to Quit Your Whining, noting that he himself struggled with poverty in his youth (although he had a loving mother) and is in no mood for sob stories.
Although it could simply reinforce Cap's arguments. Both Cap and the Skull went through hard times but Cap might have been able to work hard enough in school and out to go to college, possibly on a scholarship.
Cap himself is sometimes an inversion: Some versions of his family history portray his father as an abusive alcoholic.
In the IDW Transformers continuity, Megatron forms the Decepticons because he is oppressed by the corrupt Autobot Government, with his band originally formed as freedom fighters. In a sense, most of the Decepticons fall under this trope.
Drift definitely falls into this category, though his excuse is a pretty limp manner to justify his faction switch.
Whirl used to be a successful watchmaker until the Senate took away his hands to press-gang him into their service, thus ruining his life. He uses this as an excuse to justify his sociopathic actions and essentially ignore his conscience.
Shockwave went through the same procedure as Whirl and had a lobotomy on top of that. There is nothing left of the compassionate senator that once saved Orion Pax.
In Star Wars: Knights of the Old Republic, both of the big bads (Chantique and Haazen) have the excuses; Haazens is that he failed to make the grade as a jedi, and was treated indifferently by a well meaning but somewhat classist employer, while Chantique was sold into slavery by her own father, sold when she failed to be ruthless enough to survive, and was raped by her owners. In Haazen's case it's subverted, since a large part of it was his failure to grow and learn from experience. Chantique's excuse is why she has a Villainous Breakdown when Zayne returns to save Jarael.
Marvel's Loki would probably count. First, there is the fact that he is a midget giant who was abused by his real father for being weak and small. After he helps kill said father, he is adopted by Odin, who does so only because he is convinced that it is the only way to appease the spirit of his own dead father. After he is adopted, it is implied that Odin neglected him wholly in favor of his real son, Thor. Thor, in return, is implied to be one of maybe a hand full of people who like Loki, as well as maybe being one the only people who actually love him. For Loki, this boils down to a seething self-hatred, which he in turn projects onto Thor, which he only does because he knows that his brother will never completely turn him away. Lampshaded by Valeria Richards and Loki in issue #7 of Loki: Agent of Asgard:
Verity: What makes hate easy?
Valeria: Mommy and daddy.
Loki: Harsh! But yes.
Gorr from Jason Aaron's run was born on a deeply religious desert planet that was in the midst of a horrible drought. At a young age, he witnessed his mother being violently killed and eaten by a pack of wild animals shortly after she had expressed her faith in a higher power. Then, as a young man, he watched his pregnant wife fall to her death while she screamed for their gods to save her. After that, his children all starved to death, with the last one dying in his arms. The final humiliation came when the other members of his tribe attacked him and kicked him out after he tried to bury his son's body, which went against their religious customs. All of this inspired a deep, seething hatred of gods within Gorr, and when two injured deities fell from the sky one day, he killed them both and took their enchanted weapons. Adopting the name Gor the God Butcher, he set off across the cosmos to kill any gods he stumbled upon, with the ultimate goal of creating a universe free of religious tyranny.
Averted in Johnny the Homicidal Maniac as little/nothing is mentioned of Nny's backstory. Jhonen himself even mentioned that the reason he avoided going into Nny's backstory was to avoid this trope. He then proceeds to parody it in a hypothetical scenario... "YAAAARGH!! I have been pantsed!! I kill like the damned now!!!"
The Flash has a pile of unhappy backstories subverted (and not) to varying degrees, including —
Captain Cold and Golden Glider's father was an abusive alcoholic.
The second Mirror Master was left at an orphanage as a baby. One of the other boys there tried to rape him; he fought back and ended up drowning his attacker.
Cobalt Blue was Barry Allen's twin brother, but at birth he was given to the abusive Thawnes and used as a living prop in their scams because the doctor who was overseeing both deliveries accidentally killed the Thawnes' baby and figured the Allens had one more kid than they needed.
The first Trickster came from a family of aerialists and his father mocked him for his fear of heights—never mind that this fear came about partly because Dad was constantly Distracted by the Sexy and often came close to dropping his son from a height during their trapeze routines.
Magenta developed her Extra-ore-dinary powers at a very young age, but the emergence of her power caused her father and brother's deaths in a car accident. Her mother believed she was demon-possessed and abused her constantly out of resentment, never forgiving her for the aforementioned deaths even after it was revealed that it was Dr. Polaris' interference that caused the girl's powers to emerge in the first place. Consequently, Magenta would grow up with a seriously-creepy Split Personality.
The second Zoom/Reverse-Flash, Hunter Zolomon, had a father who was a Serial Killer and who would eventually kill his mother when she finally got brave enough to call the cops, then the dad got gunned down by the cops—both deaths happening the same day Hunter was to leave for college. While this incident wasn't what led him to later become a super-villain, it did set the foundation for his belief that tragedy makes better heroes, which in turn led to him wanting to "improve" Wally West, who he felt didn't appreciate that a hero should be willing to do whatever it takes to prevent tragedy from repeating.
In the New 52, Nightwing's foe Saiko (which appropriately enough sounds a lot like "psycho") is really his former friend and fellow former circus boy Raymond. The circus was a front for the Court of Owls who would repeatedly take children from the circus and put them through Training from Hell to make them into new Talons. The Owls kidnapped Raymond and put him through that training before deciding he was a failure and left him to die in the woods with his eyes pecked out by birds. His entire murderous grudge against Dick is that it should have been Dick instead of Raymond. The Owls originally wanted to make Dick into a Talon, but they had to "settle" for Raymond after the Flying Graysons died and Bruce Wayne adopted Dick in the wake of the tragedy. Saiko then engages Dick in a fight during a reunion show at Haly's Circus while threatening the lives of everyone present with a bunch of bombs. Dick rightfully calls Saiko out on his bs, stating that his suffering is no excuse for endangering so many innocent lives.
In EC Comics' "...So Shall Ye Reap!" (Shock SuspenStories #10), a 20-year-old boy about to be executed reflects on the sad course of his life, as do his parents. The son's recollections, juxtaposed with those of his parents, show them to have been jealously overprotective and morally hypocritical, yet in the final panel he only blames himself for not having listened to them.
It's not entirely unreasonable to see Doomsday as a Woobie, Destroyer of Worlds when one remembers that he's carrying the genetic memory of untold thousands of times he was brutally killed by the various predators, parasites, aggressive herbivores, Man Eating Plants and other horrors of the Death World that was prehistoric Krypton. The trauma of which has driven him insane with fear to the point he lashes out blindly at all other living things because he thinks the only way he can be safe is if everything else is dead.
The second story in the tenth and final issue of the Madballs comic book published by Star Comics (a defunct subsidiary of Marvel Comics) had the Madballs battle a villain named Grammar Moses. After she is beaten, she explains to the Madballs that she became a villain because she wanted to be an English teacher, but no one would hire her. The Madballs take pity on her crushed dreams and allow her to be their own private tutor.
Dex-Starr is a homicidal kitty cat in the Green Lantern books (he's also a Red Lantern, which helps a lot with the "homicidal" part ... helps him actually be homicidal, that is). One story shows how he got that way, and it's pretty heartbreaking.