Earth-K

Anna Atom and Max Atom, of Earth-K. (PROSE: Anna Atom vs Max Atom)

Earth-K was the code-name of a version of the planet Earth in one reality, which was often known as “Earth-K” itself for short.

It was home to superhero Max Atom, who took part in the multiversal Indefinite Crisis of the Universe. He had a daughter called Anna Atom, who inherited his powers; drifting apart in ethical opinions over a number of years, the two eventually came to blow, only for their usage of their full, nuclear-fueled powers to create a rift which hurled the two of them through a transdimensional maelstrom to Reality Z-25 31-H. (PROSE: Anna Atom vs Max Atom)

Behind the scenes

The designation “Earth-K” as the name of the home universe of open source characters Max Atom and Anna Atom is itself open-source, being mentioned as part of the Atoms' version of the Paragraph:

Earth-K, Anna Atom, and Max Atom were created by Michael P. and are available for use by anyone, with only one condition: This paragraph must be included in any publication involving Earth-K, Anna Atom, and Max Atom in order that others may use these properties as they wish.

—The Paragraph