Origin story

In comic book terminology, an origin story is an account or back-story revealing how a character or team gained their superpowers and/or the circumstances under which they became superheroes or supervillains.

In order to keep their characters current, comic book companies, as well as cartoon companies, game companies, children's show companies, and toy companies, frequently rewrite the origins of their oldest characters. This goes from adding details that do not contradict earlier facts to a totally new origin which make it seem that it is an altogether different character.

"Origin story" or pourquoi story is also a term used in the study of myths. It can refer to narratives of how the world began, how creatures and plants came into existence, and why certain things in the cosmos have certain qualities.

Notable examples
Heroes
 * Batman - His parents murdered by a mugger, Bruce Wayne used his vast family fortune to become Batman and wage a one-man war on crime.
 * Spider-Man - Bitten by a radioactive spider granting him spider based superpowers, Peter Parker was motivated to fight crime by his uncle's death, which he blames on himself.
 * Superman - Born on the planet Krypton, infant Kal-El was sent to Earth before an explosion destroyed his home planet. His strong moral code motivated him to fight for justice.
 * Wonder Woman - Diana, the princess and appointed champion of the Amazon warrior women, who left her homeland to battle injustice.
 * Iron Man - American industrialist Tony Stark was captured by Communist Vietnamese military and forced to build weapons for them. Instead, he built powered armor to escape. He then uses his armor to fight crime.
 * Fantastic Four - Four astronauts (Reed Richards, Sue and Johnny Storm, and Ben Grimm) who were exposed to cosmic rays, which gave them superpowers.
 * The Flash - Barry Allen, a forensic scientist, was struck by lightning and bathed in electrically-charged chemicals, connecting him to the Speed Force and giving him super-speed.
 * Incredible Hulk - Doc Bruce Banner, belted by gamma rays, now turns into the super-strong Hulk whenever he gets angry.
 * Green Lantern - Test pilot Hal Jordan receives a power ring from the dying alien police officer, Abin Sur, and becomes a member of the Green Lantern Corps.
 * James Tiberius Kirk - Inspired by both the adventures of Captain Jonathan Archer, and his own father, Kirk joined starfleet in order to explore the stars and defend the united federation of planets. In the 2009 film, Kirk was inspired by his father's sacrifice and chose to bring back the honour that his name once held.
 * Sabrina Spellman - In a 1970s cartoon show, Hilda and Zelda Spellman mixes magic potions and ingredients to create a evil, wicked witch. Unfortunately when Hilda got bumped by Zelda, an accidental spill of girls' stuff into the mixture results as a extra ingredients and then Sabrina Spellman is born.
 * Judge Dredd - Awoken from his sleep with his clone Rico, Joseph Dredd witnesses nuclear war going on. They then split up. Rico becomes an evil-doer, Joseph becomes the toughest judge yet-- Judge Dredd.
 * Gigantor - Built as the 28th creation of a kind professor.
 * Astro Boy - Having being killed by a car in the anime and by a robot in the film, Astro Boy was resurrected as a robot.
 * Turbo Teen - Brett and his car were driving through a stormy mountain, and then-- a tree swerved them off the road into the path of Dr. Chase's experiment. He and his car are now one-- Turbo Teen.
 * The Teenage Mutant Ninja Turtles - When a boy was walking with his four turtles in a bowl of water, a toxic slime truck stood in his way. All four turtles and the slime fell into the sewers, where Splinter raised the turtles. They then came to fight an evil that invaded New York in the form of the Shredder.
 * SuperTed - He was a discarded toy given life by Spotty and powers by Mother Nature.
 * Optimus Prime - In the cartoon, Optimus Prime, his Autobots, and the Decepticons, led by Megatron, are at war with each other until they crash landed here on earth in a 4-million-year-old sleep. That is until they scanned vehicles, weapons, and animals in order to become the Transformers we know. Optimus Prime scanned the truck he is now.
 * The Mighty Morphin' Power Rangers - They were five ordinary teenagers chosen by Zordon to become the world's colorful superpowered heroes, the Power Rangers.
 * Masked Rider - Dex was given powers by his grandfather, the king of Edenoi, and is sent to our world to protect it from the advancing evil of Count Dregon. Dex was raised by a family, and learns to live as a human. With his companion Ferbus by his side, Dex is ever vigilant, ready to call on his powers in order to become Masked Rider.
 * RoboCop - Officer Alex Murphy was killed in the line of duty and resurrected by a team of scientists as a crime-fighting cyborg called RoboCop.
 * Captain America - While taking on the Red Skull, Captain America fell into the sea where he was frozen until the present day.
 * Thor - Thor was banished from his home world and ended up on Earth.
 * He-Man and She-Ra - They were brother and sister twins. They were separated due to their enemies Hordak and Skeletor. He-Man lived in Eternia, She-Ra lived in Etheria.
 * Xena - Xena was the chosen one to fight all that is evil, although she was separated from her parents during war.
 * Conan the Barbarian - Conan's family was killed in the films or turned to stone in the cartoon. He swears to destroy all evil within his land.
 * Daredevil - He was blinded by chemicals, and he devotes to fight crime as Daredevil, but he's normally Matt Murdock.
 * The Punisher - His family were killed by terrorists, and Frank Castle devotes to fight crime as the Punisher.
 * Harry Potter - He is a wizard and his parents were killed by Voldemort, who left him with a scar.
 * Wolverine - After he got bone claws, his claws fused with adamantium, and he escapes the pool he was in, the very same pool which made his bones become adamantium.
 * Ghost Rider - He is a motorcycle stuntman. Possessed by a demon to take on crime.
 * Machete - Machete was a man with an injured leg befriended b his priest brother.
 * The Biker Mice From Mars - They came from Mars, their world that was enslaved by Plutarkians (1993) and Catatonians (2006), to our world. They consist of Modo, Vinnie, and their leader Throttle.
 * The Guardians of the Galaxy - Have various origin stories. These include Star-Lord, Rocket Raccoon, and many other Guardians.
 * Captain Marvel (Shazam) - A boy named Billy shouts "Shazam!" to become Captain Marvel.
 * Strider Hiryu - A brave assassin sent by the Striders to kill Grandmaster Meio.
 * Mega Man - Mega Man was the second creation of Dr. Light/Dr. Wright after the failed Proto Man. Dr. Wily, a world dominator-to-be, wanted Mega Man dead or alive by turning Dr. Light's creations against the good doctor.
 * King Arthur - According to legend, when he was a boy, he pulled out Excalibur from the stone, thus becoming king.

Villains
 * The Joker - Famous for not having a definitive origin story - sometimes, he remembers it one way and sometimes another way, but the generally accepted (though not definitive) origin is described as follows : An unnamed criminal using the persona of the Red Hood fell in a vat of chemicals that turned his hair green, his skin pale, and his lips red. Driven insane by this trauma, he then makes various gag-themed weapons and a toxin that kills people and leaves them with hideous grins frozen on their cadavers' faces. During his criminal career, he becomes Batman's arch-foe.
 * Two-Face - District Attorney Harvey Dent had the left side of his face horribly scarred after criminal Salvatore Maroni threw acid in his face on trial. Harvey took a two-headed silver dollar and carved one side to make a coin he'd use to decide if he would do an act of good or evil. Since that moment, Harvey Dent became the criminal Two-Face.
 * Green Goblin - Norman Osborn became the insane and malevolent Green Goblin after a side effect to his experimental super serum. He then invented weapons to use to combat Spider-Man.
 * Doctor Octopus - Otto Octavius became one of Spider-Man's greatest enemies after an accident fused four mechanical tentacles to his body.
 * Bizarro - An imperfect and evil duplicate of Superman formed from an attempt to clone the Man of Steel.

Comic book depictions

 * Batman: Year One (1987)
 * Wonder Woman: Gods and Mortals (1987)
 * Judge Dredd: Origins
 * Secret Origins
 * The origin of Superman
 * Superman: Birthright (2004)
 * The Man of Steel (1986)
 * Rise of Apocalypse (1997)
 * Origin - Wolverine