Earth-One

In Superman: Earth One Volume 1, Kal-El crash-landed in Kansas and was discovered by Jonathan and Martha Kent, who barely managed to escape the site before the military arrived and took custody of his ship. When Jonathan and Martha revealed to Clark that he came to Earth in a spaceship, and that he was an alien, Jonathan gave Clark a piece of metal from his ship. At some point in Clark's teenage years, Jonathan died. Arriving at Metropolis, he tries out several jobs: pro footballer, Major League baseball player, and positions in a scientific research company, and in financial services and media industries. His last job stop is at the Daily Planet newspaper. The metal piece of Clark's rocket, emits some kind of energy and Clark discovers Kryptonian symbols in the fragment's atoms. Just as this is happening, an invading alien force suddenly arrives and attacks Earth's major cities. After he stops the invasion, Clark returns to the Daily Planet, and presents Perry White an interview he wrote about the new hero. Amazed by Clark's story, Perry gives him a job as a reporter. Perry promotes Clark to write articles to help rebuild the Daily Planet‍ 's reputation. Lois is suspicious of Clark and the authenticity of his Superman article, so she decides to investigate his past. In Volume 2, a week later, Perry promotes Clark to write articles to help rebuild the Daily Planet‍'s reputation. Lois Lane is suspicious of Clark and the authenticity of his Superman article, so she decides to investigate his past. Clark later meets his neighbors Lisa Lasalle, whom he starts dating. Superman later goes head to head with the villain Parasite, whom he defeats with the help of warsuit, in which he can fight Parasite on equal terms. In Volume 3, Lois subsequently warns Superman that she learned from her uncle, a United Nations delegate, that the U.N is developing fail-safes against Superman. She later reveals that she has ceased her investigation because she now sees Clark is a decent person of good character, and not the type of person to fabricate a story. Superman later meets another super-powered being, named Zod-El, who says he is Superman’s biological uncle. Zod claims that he has been searching for Kal-El ever since Krypton exploded. Superman later discovers that Zod not only intends to kill Superman but has convinced the world's governments that he is an enemy. After Zod's death, Superman announces that although he is disappointed that the United Nations aligned against him, it will not deter him from his mission to protect Earth. Seeing their fear, Superman asks Lois to be his political conscience.

In Batman: Earth One Volume 1, Bruce Wayne is the eight-year-old son of Dr. Thomas Wayne, a mayoral candidate for Gotham City, and Martha Wayne (née Arkham). During an outing with his parents, Bruce is taken hostage by a mugger. He demands that the Waynes pay a ransom for the return of their son and as Thomas tries to intervene and the criminal shoots them both in front of Bruce. As a teenager, Bruce befriends his classmate, Jessica Dent, and develops a rivalry with her twin brother, Harvey Dent. He also learns about Arkham Manor, where his mother lived as a child. Bruce later convinces his guardian Alfred to train him in various forms of martial arts and acrobatics. Bruce also learns investigative techniques. Following this training, he discovers evidence that Mayor Oswald Cobblepot was involved in his parents' assassination. In his mid-twenties, Bruce dons a bat-themed costume as a disguise, inspired by his pre-training experience at Wayne Manor. Following an altercation between Cobblepot's bodyguards and Bruce at a function organized by the mayor, Bruce's alter ego is named "Batman" by the press and the topic becomes a public sensation. In a subsequent confrontation between Batman and Cobblepot, the mayor reveals that he intended to murder the Waynes, but the couple ran into the mugger instead. Cobblepot then prepares to kill an unmasked Bruce but is fatally shot by Alfred. Bruce is left disappointed by the truth behind his parents' death, but with Alfred's encouragement, decides that he will continue on to refine his new persona as Batman. In Volume 2, six months later, after losing track of one of the drug dealers he fought during a car chase, Wayne had Lucius Fox to build him a custom-made race car. A mysterious serial killer who calls himself "The Riddler," is murdering people in Gotham, hoping to get Batman’s attention. Seeing Gordon’s excellence as a detective, Batman asks Gordon to train him in forensics and deduction. Bruce is later accused of being the Riddler after the real one frames him in an attempt to divert James Gordon's investigation, but Jessica Dent, who knows about Brice's double identity, is able to provide Bruce an alibi so he is not arrested. After chasing the Riddler Batman subdues the killer. After he is cleared of all charges, Bruce generously writes a check to help the city's police department rebuild their precinct.

In Superman: Earth One Volume 2, Jensen was a troubled youth who bullied his classmates and mutilated animals. During his adult years he would become a criminal who would do anything to get what he wanted. After an accident at S.T.A.R. Labs, he becomes a serial-killing metahuman with the ability to absorb energy and life force through physical contact and to convert that energy into health and power for himself. By absorbing Superman's life force, he gains his powers and renders the Man of Steel powerless. Later, the two fight once again, until Jensen's sister arrives, only to be unwillingly murdered by him, who then blamed her death on Superman. He was later defeated by Superman, arrested and is currently under the military's custody.

Alexandra "Lex" Luthor

In Superman: Earth One Volume 2, Alexander Luthor has a genius intellect surpassing most people but has trouble relating to people. An inventor with degrees in many fields, specializing in particle physics, he married Alexandra, a xenobiologist who had an intellect rivaling his own. The two started their own consulting firm, jokingly calling it "Lex-squared" after their common nickname. Major Lee recruits the wealthy couple of scientists, as independent contractors, to initially study Superman's ship, and later on find a way to neutralize Superman, in case he would pose a threat to national security. Alexander actively argues with his wife on the subject of researching ways to kill Superman, believing it is distasteful but Alexandra, who is the more aggressive of the two, sees it as an intellectual exercise. In Volume 3, the couple figures out that Superman is vulnerable to red solar radiation. During a battle between Superman and Zod, Alexander sacrifices himself helping Superman and succeeds to greatly weaken Zod with his red solar weapon. Alexandra, consumed by rage and grief, murders Zod but blames Superman for her husband's death. She then vows to dedicate her life to destroy him. She subsequently places her husband's corpse in suspended animation and takes Zod's green kryptonite from his ship.

In Superman: Earth One Volume 3, Zod-El was a Kryptonian soldier, the brother of Jor-El and the one responsible for Krypton's destruction. Starting a coup against the Science Council, Zod went behind his brother's help to no avail, starting a long and painful civil war that lasted six months until Zod's forces were on the run and Zod himself forced to flee Krypton to avoid arrest. On his defeat, Zod went towards Krypton's old enemy, the Dheronians, and gave them the means of finally destroy Krypton, and in return they will hunt any surviving Kryptonian and, should they fail, Zod will do it himself. He arrived Earth sometime after Tyrell's defeat at the hands of Superman. To gain Kal-El's trust, he purposely placed several lives at stake in order to stage the idea that he, too, arrived to help, immediately gaining the trust of his nephew. Luring Kal to a trap, he intended to use his longtime saved Kryptonite in order to finally kill him, but Superman outsmarted him and destroyed his protective Skin-Suit, forcing him to seal the Kryptonite while Kal escaped. Later when Zod was ready to kill Kal-El, Alexander Luthor shot him with his red solar weapon leaving him completely powerless but before that Zod was able to deliver a fatal stroke to Alexander. Being powerless, Zod was later killed by the revengeful wife of Alexander.

Zor-El

In Batman: Earth One Volume 1, Oswald Chesterfield Cobblepot was the mayoral competition for Dr. Thomas Wayne. Cobblepot holds a grudge against the Wayne family, believing the Waynes have disgraced the Cobblepot legacy. He planned for the Waynes to be murdered, but was not ultimately responsible for their death. He is the current, corrupt mayor of Gotham City, whom Batman fights against. When Batman confronts him, he sticks Batman with a trick stiletto from his umbrella then he removes Batman's cowl, finding out that Batman is Bruce Wayne. Fortunately, Alfred arrives on the scene and empties two barrels into Cobblepot's chest. The blast sent Cobblepot's body out of the window where he landed into the street below. After his death, his crimes were finally outed to the public.

Jessica Dent

In Batman: Earth One Volume 1, Harvey Dent along with his twin sister Jessica were friends with young Bruce Wayne from preparatory school, though Harvey had a rather antagonistic relationship with him. In their adult years, Harvey becomes Gotham City's District Attorney, and Jessica is the president of the city's board of supervisors. After taking office, the two were known for investigating Mayor Oswald Cobblepot due to rumors of his illicit activities. Jessica was appointed Mayor of Gotham City after the death of Cobblepot. In Volume 2, Jessica discovers that Bruce is Batman, and they each reciprocate the romantic affection they had for each other since childhood. Harvey is later murdered by former Cobblepot henchman, Sal Maroni, during a prison riot, having a molotov cocktail smashed into his face after being stabbed in the back with a knife. Seconds before he dies, his grieving sister puts the left side of her own face onto his, burning her. After the incident, it is implied she has developed a dissociative identity disorder; half of the personality she refined is based on her late brother's.

In Batman: Earth One Volume 1, Riddler is a serial killer who is obsessed with riddles and targets Batman, attempting to learn his secret identity to satiate his curiosity. In Volume 2, it is revealed that he once worked as Oswald Cobblepott's lieutenants, and is targeting his fellow members, staging a coup to take over Cobblepott's criminal empire. He starts murdering people in Gotham, hoping to get Batman's attention. Using discovered clues, Batman deduces that these killings were not random. Bruce Wayne is later accused of being the Riddler after the real Riddler frames him in an attempt to divert James Gordon's investigation. He was subsequently arrested by the Gotham City Police Department alongside Maroni, and brought up on 43 charges of murder.

In Superman: Earth One Volume 1, she is the staff reporter of the Daily Planet. Clark Kent develops a crush on Lois at first sight and is impressed by her dedication and idealism towards her career during the Dheronians' invasion. Lois, along with Jim, also saves Clark when he, in his Superman persona, is trapped in Tyrell's gravity field. She later writes an editorial praising Superman's heroism during the crisis and eventually becomes his ally. She also currently has a yet-to-be-named boyfriend. Lois also has an uncle, Bill Lane, who is an U.N. delegate and initially is against Superman.

In Superman: Earth One Volume 1, he is the staff photographer of the Daily Planet. Jim is known for his dedication to his job, deliberately putting himself in harm's way and risking life and limb for a perfect photograph. The photographs Jim has takes during the invasion have saved the Daily Planet from financial failure, and other news companies begin seeking reprint rights for Olsen's pictures.

In Superman: Earth One Volume 1, he is the editor-in-chief of the Daily Planet. White struggles to keep the once-great metropolitan newspaper running and refuse to give up. After the Dheronians' invasion and Superman's debut, the Daily Planet's in-depth coverage from Lois, Jim, and Clark of the event has saved the newspaper and return to its former glory, and Perry is proud that the Daily Planet is back on top.

In Superman: Earth One Volume 1, the couple are Clark's adoptive parents who, despite their awareness of Clark's extraterrestrial origins, rescued him as an infant from the wreckage of his spaceship. Clark is especially close to his adoptive father, and was deeply affected when Jonathan died. Martha Kent is supportive towards her son, and has faith that Clark will choose the right path. She made Clark's Superman costume using the indestructible Kryptonian clothing Clark was wrapped in when they found him.

In Batman: Earth One Volume 1, he is a former soldier of the Royal Marines and a skilled martial artist and sharpshooter. He has a daughter living in Seoul, South Korea with her mother, where Alfred had previously worked at a security firm. In the military, Alfred lost a leg in an explosion. After Thomas Wayne saved his life following the explosion, he helps create a prosthetic leg to replace the one that Alfred lost, leaving Alfred indebted to Thomas's generosity. After his friend's murder, Alfred become Bruce Wayne's legal guardian and trains him in martial arts. Alfred's experiences with violence and the conditions in Gotham have caused him to develop a pessimistic and cynical view towards the world and people in general, though Bruce seems to have restored his faith a little. Alfred kills Cobblepot, shooting him in the chest, when the villain unmasks Batman.

In Batman: Earth One Volume 1, he was an idealistic cop but the mysterious death of his wife has left him disillusioned. He tries to protect his daughter from the crime-ridden Gotham City. Faced with his new partner, Harvey Bullock, and the subsequent emergence of the vigilante dubbed as Batman, Gordon's own principles are ultimately revived, and sets to once again become the moral and just policeman he once was in order to fight the corruption of Gotham. In Volume Two, Gordon is promoted as police captain after he arrests his predecessor Christopher Black; Black is exposed as one of Oswald Cobblepott's lieutenants. Gordon begins a secret alliance with Batman to rid the corruptions within his department.

In Batman: Earth One Volume 1, he is a young but brilliant intern at Wayne Medical, who wishes to develop a cybernetic prosthetic for his niece, who has lost her arm in an accident. After helping repair and even perfected Bruce Wayne's grapnel, he deduces that the young billionaire is the vigilante Batman after witnessing him using the same device on the news. It is implied in the end of the story that Lucius has come to accept his new role as a silent equipment developer for Batman, preparing a set of Batarangs for use. In Volume Two, he is promoted as the head of Wayne Enterprises' Research and Development division, provides Wayne a new Batsuit and additional tools and is tasked to build the Batmobile.

In Batman: Earth One Volume 1, he is a decent yet arrogant police detective from the Los Angeles Police Department, and the host of the cancelled reality show "Hollywood Detectives". Bullock requests to transfer to Gotham to look for the chance to revive his fame. He works together with his unwilling partner, James Gordon, at first to attempt to solve the Waynes' cold case murder, then to rescue James' daughter Barbara from the serial killer, the Birthday Boy. It is strongly implied that Harvey takes up drinking as a coping mechanism after witnessing the travesties that occurred in Arkham House, the Birthday Boy's dwelling.

In Batman: Earth One Volume 1, she is a 17-year-old library assistant and daughter of James Gordon, who lost her mother at an early age. Taking on a supportive role for her increasingly disillusioned father, Barbara is soon captured by Mayor Cobblepot's henchman, the Birthday Boy. Her rescue by Batman then inspires her to consider a role in vigilantism. In Volume Two, she is enrolled in University of California, Berkeley, majoring in computer science. Despite her relocation, she hacks into the city’s mainframes for her father to help him find the Riddler and his targets.

In Batman: Earth One Volume 2, he is a social outcast with a severe ichthyosis condition, who is forced to hide in Gotham's sewers and is befriended by Batman. Due to his genetic deformity, his mother sold him to Haley's Circus whom its owner have him filed his teeth and billing him as the "reptile boy." Waylon soon escaped from the circus when it was passing through Gotham City. He helped Batman in capturing the Riddler but was wounded in the process. In gratitude, Batman offered Waylon a place at Wayne Manor. Jones is also tasked in finding a safe house for his benefactor.

In Batman: Earth One Volume 2, Selina Kyle appears and helps Batman tending his wounds after he falls in her apartment, while chasing the Riddler. She introduces herself as a single mother to Batman, during the time they spent together. Batman later discovers that she is neither the apartment's tenant or a mother, but a burglar who was robbing the building at the time.