Characters from DC Comics were originally suggestive of each existing in their own world, as superheroes never encountered each other. However, this was soon changed with alliances being formed between certain protagonists. Several publications, including All-Star Comics (publishing tales of the Justice Society of America), Leading Comics (publishing tales of the Seven Soldiers of Victory) and other comic books introduced a "shared-universe" among several characters during the 1940s until the present day.
Alternative reality Earths had been used in DC stories before, but were usually not referred to after that particular story. Also most of these alternative Earths were usually so vastly different that no one would confuse that Earth and its history with the so called real Earth. That would change when the existence of another reliable Earth was established in a story titled "Flash of Two Worlds in which Barry Allen, the modern Flash later referred to as Earth-One (the setting of the Silver Age stories) first travels to another Earth, accidentally vibrating at just the right speed to appear on Earth-Two, where he meets Jay Garrick, his Earth-Two counterpart.
Superman, Kal-L is the first costumed superhero to surface on Earth-Two. Most of his history is based on his initial appearance, ignoring later Golden Age and early Silver Age history. In order to distinguish him from the primary version of the character, this Superman is called "Kal-L", using the spelling of Superman's Kryptonian name in his early appearances. He was specifically introduced as an Earth-Two character in Justice League of America #73 (1969). Most superheroes from the Golden Age later followed this trend.
Following the end of the known Multiverse, more alternate realities were discovered. Even though Earth-Three was destroyed in the Anti-Monitor's anti-matter wave attacks, a new Crime Syndicate (called the Crime Syndicate of Amerika rather than the old America) developed in the antimatter universe of Qward which was far larger than the Earth-Three group. After the Kingdom event, Hypertime and divergent realities were revealed but never supposed to be accessed as stated in the Zero Hour event and later revealed when a directly parallel Flash (Walter West aka the "Dark Flash") entered the mainstream DC Universe and threatened to destroy it. These alternate realities are usually addressed as "Elsewhere" and "Elseworld" stories.
Kal-L, Lois Lane, Superboy-Prime, and Alexander Luthor returned during Infinite Crisis. Unknown to Superman, Luthor's plan was to resurrect the Multiverse. He wanted to mix and match elements from each reality to create a "perfect world." The fallout of the conflict brought the short lived return of Earth-Two and the deaths of Superman, Lois Lane and Luthor Jr. of Earth-Three. It is unclear what happened to the Wonder Woman of Earth Two. Inexplicably, Earth-Two was the only returning world that was devoid of people, except the Justice Society, Superman, and Lois. The world appeared to be new and recently manufactured, instead of completely resurrected.
Before their "deaths," each felt they were being pulled somewhere.
|Aquaman||Arthur Curry||Arthur Curry of Earth-Two was a member of the All-Star Squadron. He was retconned out of existence by the events of Crisis on Infinite Earths and All-Star Squadron #60 (the only visual difference from his Earth-One counterpart, initially, were yellow gloves instead of green, and yellow fins on the backs of his boots).|
|The Atom||Al Pratt||The Atom of Earth-Two was college student turned physicist Al Pratt. Pratt's tenure as the Atom was particularly notable, inasmuch as he was barely five feet tall, and had no superpowers for much of his career. Through intense training, he achieved peak physical condition and became a fierce brawler. Among Golden Age members of the Justice Society, only Wildcat and Batman were considered more formidable in hand-to-hand combat.|
|Batman||Bruce Wayne||Batman of Earth-Two was raised by his paternal uncle, Philip, following the murder of his parents. Along with his close friend Superman, Batman participated in the Justice Society and the war-time All-Star Squadron. Eventually, he retired and became the police commissioner of Gotham City. Wayne married Selina Kyle (Catwoman), and had a daughter named Helena Wayne, who became a costumed adventurer known as the Huntress. In 1979, he died battling escaped convict Bill Jensen (Adventure Comics #462), who had been granted powerful magical abilities by Fredric Vaux (Adventure Comics #463) as part of a failed plot to remove all superheroes, and all memory of them, from the world. Although this Batman was retconned out of existence by the events of Crisis on Infinite Earths and All-Star Squadron #60, he was restored to continuity (still deceased) in JSA #85, as a result of the events of Infinite Crisis. His Earth-One counterpart was also Bruce Wayne, who is currently active with the Justice League.|
|Catwoman||Selina Kyle||The Catwoman of Earth-Two was Selina Kyle. She was originally a criminal in Gotham City, and was initially one of the primary foes of Batman and Robin. Selina reformed in the 1950s (after the events of Batman #69) and married Bruce Wayne. Soon afterwards, the couple gave birth to their only child, Helena Wayne (the Huntress). Selina eventually died in 1976 after being blackmailed by a criminal into going into action again as Catwoman (as shown in DC Super-Stars #17). She was retconned out of existence by the events of Crisis on Infinite Earths and All-Star Squadron #60.|
|Crimson Avenger||Lee Walter Travis||The Crimson Avenger of Earth-Two was wealthly newsman Lee Walter Travis. He and his partner Wing were among the first "mystery men", beginning their crimefighting careers in 1938. They were both members of the All-Star Squadron and the Seven Soldiers of Victory. Wing sacrificed his life to defeat the Nebula Man (as revealed in Justice League of America #100), while a terminally ill Crimson Avenger died piloting a ship away from the docks before it could explode (DC Comics Presents #38).|
|Doctor Fate||Kent Nelson||Doctor Fate was Kent Nelson, who was orphaned as a child after his archaeologist father was killed for opening the tomb of the wizard Nabu. The wizard raised Nelson and taught him the ways of magic, eventually giving him a mystical amulet and the Helmet of Fate, which contained Nabu's essence. Whenever Nelson wore the helmet, his personality melded with that of Nabu. Nelson's Earth-One counterpart was a college research assistant named Burt Belker, who acquired a helmet containing a Lord of Chaos and became the supervillain Doctor Chaos. He was soon confronted by Earth-One's teenage Superboy, who removed Belker's helmet and jettisoned it into space (New Adventures of Superboy #25).|
|The Flash||Jay Garrick||The Flash of Earth-Two is Jason Peter Garrick. As a college student, Garrick accidentally inhaled hard water vapors, (later stories would change this to heavy water vapors), after falling asleep in his laboratory where he had been smoking. As a result, he discovered that he can run at superhuman speed and had similarly fast reflexes. Decades later, Garrick became the first Justice Society member to learn of Earth-One's existence when he met his counterpart, Barry Allen.|
|Green Arrow||Oliver Queen||Green Arrow of Earth-Two was a member of the All-Star Squadron and the Seven Soldiers of Victory. He died in 1985 during Crisis on Infinite Earths, and was retconned out of existence by the events of that series and All-Star Squadron #60.|
|Green Lantern||Alan Scott||Green Lantern of Earth-Two is engineer Alan Scott. The source of Scott's power is the mystical "Starheart", the magical characteristics of the Earth-One universe gathered by the Guardians of the Universe. This collective force was hidden in the heart of a star and eventually became sentient. It also helped to retard Scott's aging process.|
|Guardian||Jim Harper||The Guardian of Earth-Two was police officer Jim Harper. He was the uncle of Roy Harper, who was better known as Green Arrow's teen sidekick, Speedy. Decades later, Earth-One produced two counterparts: the first was another version of Jim Harper. The second was Mal Duncan, a nonpowered Teen Titan who discovered the original costume and strength-augmenting exoskeleton of the Earth-One Harper and briefly assumed the Guardian identity.|
|Harlequin||Molly Mayne||The Harlequin of Earth-Two is former criminal Molly Mayne. In 1948, Mayne betrayed her Injustice Society teammates in order to save the lives of the Justice Society. A subsequent deal with the U.S. government allowed her to work as an undercover agent for the FBI in return for amnesty for her past crimes. During the events of Crisis on Infinite Earths, Mayne and Alan Scott (Green Lantern) were married. The Harlequin of Earth-One is Duela Dent, a former Teen Titan who claimed to be the daughter of Batman villain Two-Face.|
|Hawkgirl||Shiera Saunders||Hawkgirl of Earth-Two was Shiera Saunders, companion of Carter Hall (Hawkman). Saunders and Hall were eventually married and had a son named Hector Hall, who became a costumed adventurer known as the Silver Scarab.|
|Hawkman||Carter Hall||Hawkman of Earth-Two was archaeologist Carter Hall. He and his companion Shiera Saunders (Hawkgirl) were eventually married and had a son named Hector Hall, who became a costumed adventurer known as the Silver Scarab.|
|Johnny Thunder||Johnny Thunder||Johnny Thunder of Earth-Two -- the seventh son of a seventh son -- was born at 7 AM on the seventh day of the seventh month in 1917. As an infant, he was kidnapped by a group of men from the country of Badhnesia. He was given possession of the genie-like Thunderbolt during a mystic ritual performed on his seventh birthday. Thunder's Earth-One counterpart was a petty criminal who was also capable of controlling the Thunderbolt (who apparently has no counterpart). The Johnny Thunder who remains following Crisis on Infinite Earths is the one from Earth-Two.|
|Manhunter|| - Dan Richards|
- Paul Kirk
|During World War II, Earth-Two had two costumed vigilantes who assumed the name Manhunter: Dan Richards and Paul Kirk. Richards was a member of the Freedom Fighters, while Kirk joined the All-Star Squadron.|
|Plastic Man||Patrick "Eel" O'Brian||Plastic Man was a Quality Comics character, the rights to which were later acquired by DC Comics. Initially, DC stated that he hailed from Earth-X, along with all the Quality characters. Later, an Earth-One Plastic Man was introduced, and the original version was depicted as a native of Earth-Two who joined the All-Star Squadron during World War II and subsequently moved to Earth-X. The Earth-Two/Earth-X Plastic Man was retconned out of existence by the events of Crisis on Infinite Earths and All-Star Squadron #60.|
|Power Girl||Kara Zor-L||Power Girl, cousin of Superman, is the Earth-Two counterpart of Supergirl. She arrives much later in Superman's career. Instead of placing her in an orphanage, Superman decides to raise her with his wife Lois Lane Kent.|
|Red Tornado||Abigail Mathilda "Ma" Hunkel||The original Red Tornado of Earth-Two is a widow known as "Ma" Hunkel. While her children were in their youth, Hunkel ran a small Manhattan grocery store. One of the first superhero parodies, her costume consisted of longjohns and a cooking pot which she wore on her head. Because of her roly-poly build, she was able to successfully masquerade as a man. Although a costume mishap prevented her from attending the first meeting of the Justice Society of America, she eventually became an honorary member. Many years later, an android calling himself the Red Tornado joined the Justice Society, but he eventually migrated to Earth-One and joined the Justice League of America.|
|Robin||Richard Grayson||The Golden Age version of Dick Grayson was born in the late 1920s, and continued to be Robin even as an adult, having no successors even after Batman's death. His allies included the All-Star Squadron along with Batwoman and Bat-Girl. He eventually became a member of the Justice Society of America. During his later years, he adopted a more Batman-like look for a time, and by the 1960s had become a lawyer and the ambassador to South Africa. He died in 1985 during Crisis on Infinite Earths, and was retconned out of existence by the events of that series and All-Star Squadron #60. However, this Robin's exploits were re-acknowledged in JSA Classified #4.|
|Robotman||Robert Crane||Robotman of Earth-Two was scientist Robert Crane. He was a member of the All-Star Squadron during World War II. His Earth-One counterpart, Cliff Steele, was a member of the Doom Patrol.|
|Speedy||Roy Harper||Speedy of Earth-Two was a member of the All-Star Squadron and the Seven Soldiers of Victory. He was retconned out of existence by the events of Crisis on Infinite Earths and All-Star Squadron #60.|
|Superman||Kal-L||Superman of Earth-Two was born on the planet Krypton, and arrived on Earth as a baby near the start of Earth's First World War. As Clark Kent, he was a reporter for the Daily Star, eventually becoming editor-in-chief and marrying its star reporter Lois Lane. Although he was retconned out of existence by the events of Crisis on Infinite Earths and All-Star Squadron #60, he was restored to continuity in The Kingdom #2. He was killed by hero-turned-villain Superboy-Prime in Infinite Crisis #7.|
|Vigilante||Greg Sanders||The Vigilante of Earth-Two is Greg Sanders, a country singer who became a western-themed "mystery man" in the 1940s. He was a member of the All-Star Squadron and the Seven Soldiers of Victory. Decades later, Earth-One produced two counterparts: the first was another version of Sanders, while the second was former New York City district attorney Adrian Chase.|
|Wildcat||Ted Grant||Wildcat of Earth-Two is former heavyweight boxer Ted Grant. The Wildcat who remains following Crisis on Infinite Earths is the one from Earth-Two.2|
|Wonder Woman||Diana||Princess Diana of Paradise Island, the Wonder Woman of Earth-Two, was introduced in All Star Comics #8 in December 1941. She served as a member of the All-Star Squadron and soon after became secretary (later full-fledged member) of the Justice Society of America. As Diana Prince, she worked in the U.S. War Department as an assistant to intelligence officer Steve Trevor. Decades later, she and Trevor were married and had a daughter named Lyta (also known as Fury). Although Diana was retconned out of existence by the events of Crisis on Infinite Earths and All-Star Squadron #60, she was briefly restored to continuity in Infinite Crisis #5.|
|Zatara||Giovanni "John" Zatara||John Zatara of Earth-Two was introduced in Action Comics #1, and was a member of the All-Star Squadron.|
In addition, masked crimefighters are introduced decades earlier than in other universes later identified within DC Comics, and these participated in such historic conflicts as World War II. Franklin Delano Roosevelt founded both the Justice Society of America and the All-Star Squadron. Other events taking place decades earlier include the destruction of Krypton and the advent of advanced technology including interstellar transportation and time travel. Contrasting with Earth-One's 30th century, there is no superheroic organization such as the Legion of Super-Heroes in existence during that time period.
Thousands of years ago, the Guardians of Earth-One's Universe expelled the vast majority of magic from their universe, sending it to Earth-Two's. This resulted in a predominance of magic and a weakening of scientific laws within Earth-Two's universe.
At the end of the comic book crossover series Infinite Crisis, the realigned world created is called "New Earth" (which is also known as "Earth-1") In the final issue of the later series 52, it is revealed that 52 duplicate worlds have been created and all but New Earth have been altered from the original incarnation.
It made its first appearance in a single panel of 52 Week 52 where it resembled the pre-Crisis Earth-Two, where a newspaper article says that this world's Superman and Power Girl are missing. This reflects Earth-Two Superman's death in Infinite Crisis, and the revelation during Infinite Crisis that Power Girl came from Earth-Two.
Recently, the Flashes of New Earth (Jay Garrick and Wally West) briefly glimpsed this world with Robin and Huntress in action (during their travel with the Cosmic Treadmill) and Monarch selected Jay Garrick of this earth (amongst others) in the multiversal arena tournament.
Based on comments by Grant Morrison, this alternate universe is not the pre-Crisis Earth-2.
In the Justice Society of America Annual #1 (July 2008), by Geoff Johns and Jerry Ordway, Power Girl travels to Earth-2, which appears similar to the pre-crisis Earth-Two. However, in this world Batman only recently died, while in the original Earth-Two story line he died in 1979. This is, in fact, one of the multiple Earths created during the 52 story line in which Mr. Mind altered the multiple realities of the DC universe, but from the perspective of its inhabitants it was never destroyed in the original Crisis, and was the sole Earth in existence until the Infinite Crisis. Power Girl initially believes she is home at least (the history of the modern and classic Earth-2 being nearly the same), but Earth-2's native Power Girl arrives and declares her an impostor, making the Power Girl, who emigrated from New Earth, not a part of this Earth and considered high priority to JSI.
Power Girl, still on the run, seeks the help of Michael Holt. On Earth-2, his wife never died with his unborn child, Holt was never driven to near-suicide, and he was never inducted into the JSA, opting instead for an academical career as the foremost researcher on the parallel universes theory.