After the events of the massive story arc Flashpoint the entire DC Comics Multiverse was re-imagined in the 2011 Rebirth. It is meant to make a blank slate for the entire DC Comics continuity, telling and re-imagining the origin stories and adventures of the classic heroes.
Origin: Jor-El and Lara Lor-Van sent their infant son Kal-El to the Yellow Sun System called Sol where he landed on the planet Earth in Ancient Sumer. He was taken in be two farmers in their small village learned the greatest values the human race could offer. Gifted with incredible powers from the Yellow Sun radiation, Kal-El survived long after Sumer and for thousands of years traveled the world doing good wherever he can. His actions inspired the mythology of many cultures that involved aliens, saviors and other powerful beings. In modern times he took on the identity Clark Kent and worked in the city of Metropolis at the Daily Planet. Still doing good everywhere, even though the human race has grown bitter over the years Kal-El remains as hopeful as he did as a boy.
Lex Luthor - Alexander "Lex" Luthor's parents died in a car crash as a young child, leaving him and his sister Lana alone in the world. Through extremely hard work and dedication Lex had earned his way to the top creating the Multi-Billion dollar science conglomerate Lexcorp in Metropolis. After Kal-El had started to serve the city as Superman Lex developed a deep hatred for the Kryptonian. Thinking it was unfair how Superman could be born with all these amazing powers, while Lex had to work for everything he had. He started to become obsessed with proving Superman wasn't strong by trying to humiliate and defeat him using his Company's resources, but constantly failed to do so, which only drove Lex further into insanity.
Doomsday - An experiment created by Jor-El on Krypton to stop the Brainiac from colonizing their lands any further. Doomsday was created to survive and evolve to handle anything. Physically it was success, but getting there gave the creature so much torment it's only purpose in life was to destroy every Kryptonian it could find. Doomsday's sheer power managed to destroy Krypton it's self. But even that wasn't enough for satisfy the creature's blood lust, it afterwards searched the entire universe for every last Kryptonian that managed to survive the planet's destruction. Finding it's way to Earth and rumbling time and time again with the Man of Steel.
Vandal Savage - Vandar Adg was born in the year 12,000 BC. He was the son of the Tribal Chief, who he eventually grew jealous of and beat to death with a rock. The nature of the betrayal caused the spirits of his ancestors to be absorbed by Vandar, granting him with special magic powers and even immortality. He destroyed his tribe and lived on his own for the next millenniums. But became so bored he started using his magic to try and take over the world as the ultimate tribe. He tried to do this for the next couple thousand years but his Empires kept on collapsing, especially due to the heroics of Superman. The two immortals fought for many years, and when Superman reappears as a protector of Metropolis, his old enemy now called Vandal Savage isn't far behind.
General Zod - Dru-Zod was originally a General in the Kryptonian Army. But his xenophobia and brutal nature eventually lead to him being caught and exposed for committing war crimes against countless species. He was dishonorably discharged from the Kryptonian Government and exiled to the Phantom Zone along with his closest subordinates. The creature Doomsday eventually broke into the boundaries of the Phantom Zone to try and permanently destroy all Kryptonians hiding there, but failed to do so and let Zod free. Learning what came of his race General Zod became determined to re-instate them by any means necessary. Trying to recruit Superman, one of the only remaining Kryptonians to help in his imperialistic conquests, but he always refuses.
Silver Banshee - Siobahn Smythe was born in Ireland. After losing her job in an economic recession, she stole from an old Irishwoman, who happened to know the secrets of the ancient celts and planted the curse of the Silver Banshee on her. Which would be initiated after someone wronged her, like she had done by stealing. Siobahn tried to escape this by just immigrating to the United States and settling in Metropolis for a new life. She got a job at the Daily Planet and worked alongside Clark Kent and Lois Lane. Siobahn was soon after caught in the middle of a scandal and fired by Perry White. The anger she felt for that made her curse start to emerge and turn Siobahn into the monstrous Silver Banshee. The only way to subdue it was to remove the obstacle that caused it in the first place. She frequently has made multiple attempts on Lois Lane, Jimmy Olsen, and most of all Perry White for screwing her over only to be stopped by Clark Kent, or Superman.
Origin: After seeing a production of Zorro in one of Gotham City's famous theaters, young Bruce Wayne witnessed his parents get assassinated by a Talon from the Court of Owls. Young Bruce disgusted by Gotham City after that, traveled the world and eventually got involved with the legendary League of Assassins. He eventually left the league after a falling out with it's leader Ra's al Ghul. Having no where else to go, Bruce returned to Gotham and used his newfound skills to hunt down and destroy the Court of Owls. He took on a secret identity called Batman, the antithesis to the Owl. Batman managed to find and beat the Talon from before, and when asked why his bosses put a hit on the Waynes, he claimed all their actions were for the good of Gotham City. Which had been victim of endless crime and corrupt government for decades now. In his time back Batman had noticed the very same thing. Wanting to prove that the Court of Owls method ruthless and cruel methods were unnecessary for saving Gotham, Bruce make Batman a hero and symbol of hope for the people of Gotham. To use his strength to stop the evil that scarred him so young.
The Joker - The Joker's real name and past are largely unknown. But it is said that at one point he was a Detective for the Gotham City Police Department with ambitions to help make the city a genuinely better place. He was driven mad and horribly disfigured in the process and not only gave up on his dream of a better Gotham, but decided to embrace the city's chaotic nature and start seeing the "humor" in everything. How much of this story is true or not is up to debate, but what is known is that The Joker is one of Batman's most bitter rivals and most dangerous criminals Gotham City has ever seen. Breaking almost every single law and being motivated to simply cause as much chaos and misery as possible with an unclear end game for his madness.
The Penguin - Oswald Cobblepot grew up in one of Gotham's most elite families. Despite that, he was shunned by his family and peers for his bizarre looks being nicknamed The Penguin out of mockery. After years of resentment towards those who had bullied him, Oswald plotted to have his siblings and father murdered and became heir to the Cobblepot fortune. Personally taking the Cobblepot family heirloom (an umbrella) as a sign of his control. Oswald did poorly in formal business and to keep up with his luxurious lifestyle he established himself in Gotham's sprawling criminal enterprises as a Kingpin called The Penguin. This put him in the way of both Batman and the Court of Owls. The latter of which he and The Bat have needed to team up against.
The Riddler - Edward Nashton was the youngest of seven children, almost never attention for his overworked parents. This caused Edward to develop a compulsive need for attention, that he originally tried to fulfill by writing mystery novels and puzzles. But after his series sold poorly Edward grew frustrated, still being ignored despite his obvious "genius". After he was about to sent on the street due to his job failing he took up a criminal career as The Riddler and committed crimes left only complex and bizarre Riddles as clues to solve them. These extreme acts and how he stumped the GCPD caused him to make national headlines. But Batman (the World's Greatest Detective) was always able to solve his Riddles and put him back in Arkham Asylum for his crimes.
Catwoman - Selina Kyle was abandoned by her con artist parents when she was young and had to survive in Gotham's harsh streets at a young age, taking refuge in a small shack full of different strays from across the city. She made ends meet by committing thievery and as an adult took on the costumed identity of Catwoman continuing to do this. She has time and time come across Batman, and managed to hold her own. Both heroes gaining sympathy for one another's struggles and even becoming friends, romantic or otherwise.
Scarecrow - Jonathan Crane's son had died in a house fire, an event that scarred him for life and caused his wife to abandon him soon after. All because he was too scared to go into the burning house and save the boy. Jonathan began to study Psychology afterwards and became obsessed with the concept of fear, and how to successfully conquer it. Crane took on a criminal career as the mighty Scarecrow. Where he invented a Fear Gas substance that caused it's victims to hallucinate what they fear the most. In these states, Crane could observe first hand just how the brain and body react to fear and how he as an individual can evolve past it. If anyone was truly capable of being the Batman's greatest rival outside Joker, it would most definitely be Scarecrow.
Diana was born the daughter of Queen Hippolyta and Zeus, the King of the Gods. Her birth was meant to signify a new era of peace between the waring Amazons and Olympians. In those years she was trained by the Amazons and Olympians in their cultures and forms of combat too. Showing incredible strength, in addition to Mercy and Compassion. Truly inheriting the best from both worlds. This made peace for years until Diana's grandfather, Ares, grew weakened from the lack of conflict and used Black Magic to bare her from entering Themyscira or Olympus. This re-instated conflict between Zeus and Hippolyta's people. Knowing she had to de-power him to save her family, Diana made the pilgrimage to Earth where the war and hatred of humanity's worst kept Ares fed. Diana used her skills to bring peace and kindness onto the planet, working alongside A.R.G.U.S. and Steve Trevor to achieve those ends, being known as Wonder Woman the Goddess of Truth. She eventually overthrow Ares and saved the Gods, but continued to come back and use her power to bring good to the humans she had grown fond of over these many years.
Cheetah - Barbara Ann Minerva was an Agent of A.R.G.U.S. who was largely jealous of Wonder Woman, largely because her love interest Steve Trevor was infatuated with the Goddess. Minerva was assigned by Amanda Waller herself to investigate a hostile cult dedicated to the African plant god Urzkartaga, a being that had a deep abhorrence for the gods of other pantheons. She managed to go undercover and find out more about the cult before they figured her out. Barbara was beaten and abused by them before being sacrificed to Urzkartaga himself. The god however, saw the jealousy inside of her and "blessed" Minerva with the spirit of the Cheetah, giving her an incredible hunger for the flesh of Olympians and Amazonians alike. She attacked and tried to devour Wonder Woman and other God-like beings on numerous occasions, but always managed to be stopped.
Ares - Ares is the son of Zeus and Hera, as well as the the God of War in the Olympian Pantheon. His daughter Hippolyta and her Amazons had gone to war with the Gods of Olympus which fueled Ares' being, until Zeus and Hippolyta conceived Princess Diana as a peace offering. Refusing to let the power of their war be cut off, Ares barred Diana from their lands using his own magic. He didn't simply destroy her however, knowing an Olympian-Amazon hybrid to be too powerful, and have too much potential for possibly being a war-monger. This proved to be an arrogant mistake, since Diana went to Earth quelling war and conflict there, which cut off a significant amount of Ares power, which allowed Diana to actually defeat him in combat and save the Gods. He has returned more than once in the effort to cause war and destruction for his own means, but Wonder Woman was born to stop him and always will.
Doctor Cyber - Adrianna Anderson was a wealthy socialite who's family fortune was heavily invested in Weapon development & distribution. After Wonder Woman had worked to end multiple conflicts that she was profiting from. After years of this Anderson became increasingly frustrated and made physical alterations to her body, replacing almost all of it with enhanced Cybernetics to become an equal to Wonder Woman and stop her. She never managed to do this, but continues to use her company and never-ending technological improvements to eventually overcome the Goddess the Truth.
First Born - The First Born of Zeus and Hera was foretold from the ancient prophecy that he would one day destroy his father and rule over Olympus. Zeus, not wishing to be slain by him demanded he be killed. But Hera feeling pity for her child, simply had him imprisoned within the core of the Earth. After thousands of years he managed to dig himself out and wondered the Earth with no memories of who he is. But eventually, in an Ancient Mediterranean Tomb, he came across the very prophecy that told of his destiny, and realized that was his calling, to overthrow Zeus and lead the Gods. He has attempted to fight his parents and rule over Olympus by any means necessary, often clashing with Wonder Woman and his siblings, but the First Born knows his fate, and will not be distracted from it!
Origin: Benjamin "Ben" Allen was walking home from school one day until an old woman got her purse stolen by a hooded teen. Ben Allen, inspired by comic book superheroes, decided to help her and chase down the thief. Ben had gotten the purse from him, and as he was coming to return it, the Thief pulled out a hand gun and shot young Ben right in the base of his spinal cord. He was completely paralyzed from the waist down, an experience that inspired him to become a Forensic Scientist for the Central City Police Department. With his scientific knowledge, Ben spent years working on a Velocity serum he thought could potentially cure his handicap. But no matter, his legs never moved. On a dark rainy night in the middle of his CCPD Laboratory, Ben had created the formula Ben called Velocity 9. He was sure this would work, and made multiple bottles of it. After injecting himself, he still couldn't walk! He started to throw a tantrum in frustration, until a mysterious bolt of lightning stuck him and knocked Ben out of his wheelchair and into an entire shelf of velocity serum. He woke up nine months later, where not only could he now walk, but he could run at incredible speeds. The lightning and the huge amount of Velocity Serum had connected Ben to the Speedforce which completely granted him multiple Metahuman powers including super speed, minor regeneration, and phasing. Still being a fan of Superheroes, he took on the identity of The Flash and protected/defended Central City.
Reverse-Flash - Eobard Thawne was born in the 23rd Century. A very logical, order based, repressive society. But nonetheless, Thawne was a very wild and energetic child who deeply resonated with The Flash, a historical icon of his home town Central City from the Golden Age of Superheroes, hundreds of years in the past. Eobard's parents tried to cure their son's erratic behavior with brain surgery and extreme shock therapy. It worked and he calmed down, but ever since had a very warped perception of reality. Thawne never lost his admiration and love for The Flash, but with his mind now calm it became apparent he was a scientific prodigy and used his genius to study The Speedforce. As he delved deeper into his research it became evident how powerful The Flash truly was, but for some reason the history books clearly put him below the likes of Batman, Superman, and Wonder Woman. Dying before any of them were even middle aged! This deeply upset Eobard who thought his idol got cheated out of an amazing legacy because he was never able to fully utilize his limitless ability. Thawne through more thorough research figured out many memorable superheroes had Archenemies, someone to challenge and push them towards greatness and figured out The Flash never reached his true potential because he had no real rival to push him far enough. Eobard, being the genius and super fan he was, realized if he could gain The Flash's abilities he could push himself to go back in time and change history by being his archenemy. Through years of science he replicated The Flash's super speed, stole a costume for his museum and dyed it inversed colors, deeming himself the Reverse-Flash. Determined to make The Flash a better hero by being his greatest enemy!
Captain Cold - Leonard Snart was the son of Lewis Snart, a packaged Ice salesman. The first few years of his life were happy and he grew an appreciation for ice and the cold. After the business stopped making enough money, Lewis became alcoholic, criminal and abusive towards his family. Forcing his son to partake in crime to make ends meet, and if he refused would get "extra" beatings. One day Lewis told Leonard to go get a hundred dollars for another bottle of Vodka "any way he can". Desperate, he stole an elderly woman's purse hoping it would have the money to avoid another beating. But Ben Allen chased after him and took the purse back, Leonard had to take drastic action and shot in the young boy in the back so he could get what he needed. After his father died of a heart attack, Snart ran away from home and (like Lewis) got caught up with criminal life and gangs. He was one day, caught by The Flash himself who recognized him as the man with the gun from his childhood and personally took out his entire crew and sent him to Iron Heights prison. Leonard was angry at The Flash for his harshness against him, and with the help of Ex-S.T.A.R. Lab scientists created a special cold gun that could slow even The Flash's super speed to a crawl. He has since been one of the Speedster's most daring enemies. Fighting him frequently and creating the Central City crime gang The Rogues. Though he is insist of having a sense of honor and a strict "no killing" rule. He still has a heart after all.