Earth-B (Batman)

Strictly speaking "Earth-B" was not official until ICG's The Official Crisis Crossover Index and The Official Crisis Index. Later the Crisis on Infinite Earths: The Compendium volume of Crisis on Infinite Earths: Absolute Edition formally broke it up into Earth-Twelve and Earth-Thirty-Two. More over The Compendium presented Earth-Forty as another Earth where elements of Earth-Two, Pre-Crisis Earth-One, and Earth-S were combined. As a result when one talks about the Batman on Earth-B they are actually talking about an amalgamation of two and possibly three different Batmen of different realities.

History: As a boy, Bruce Wayne witnessed his parents' gruesome murder by an unknown gunman in Gotham City on Earth-B and vowed revenge against all who broke the law. Bruce Wayne was the second son of Thomas and Martha Wayne, the other being his older brother, Thomas Wayne, Jr.
 

Early in his career, Batman teamed up with Sergeant Rock at a crucial point in World War II, attempting to help Rock apprehend the Nazi ruler of Germany, Adolf Hitler. Some time later, Batman also adopted a crime fighting partner, Dick Grayson, alias Robin. Batman met Adam Strange some time in his career and the two teamed up briefly in the Brave and the Bold #90. In the Brave and the Bold #99, Batman encountered Barry Allen (Also known as the Flash), a hero who gained superspeed thanks to an alien imp named Mopee directing a lightning bolt to his lab.

After teaming with fellow hero Wonder Woman, Batman was finally able to defeat Catwoman in the Brave and the Bold #131. His last recorded activities included working with the latter against the Joker and Rupert Thorne in Batman: The Last Angel.

The Official Crisis Cross-over Index had some more key details about "Earth-B" not in The Compendium: A variant of Captain Marvel called Captain Thunder existed in this reality. All newspaper comic stories of Batman from 1943-1946 occurred in this reality. Superman had a Superboy career but he worked out of Metropolis rather then Smallville.

Behind the Scenes: This alternate universe of Earth-B was never specifically depicted, but was suggested to exist in a letters column by DC editor/writer Bob Rozakis as a possible explanation for certain non-continuity stories or character traits (for example, stories that showed Catwoman committing murder with no qualms, despite being established that she did not engage in that kind of activity).

Crisis on Infinite Earths: The Compendium formally broke up Earth-B into two separate Earths: Earth-Twelve and Earth-Thirty-Two and fleshed out their respective differences from Earth-One. The Compendium also presented another Earth that mixed elements from Earth-Two, Earth-One, and Earth-S: Earth-Forty. Since each of these Earths has its own Batman the "Earth-B" Batman is actually an amalgamation of several different Batmen from several different Earths.