Intercompany crossover

DC Comics, Inc. is an American comic book publisher and the flagship unit of DC Entertainment, a subsidiary of Warner Bros. Discovery.

A crossover is the placement of two or more otherwise discrete fictional characters, settings, or universes into the context of a single story. They can arise from legal agreements between the relevant copyright holders, unofficial efforts by fans, or common corporate ownership.

In fiction, a canon is material accepted as being authentically produced by an author or an ascribed author.

Elseworlds was the publication imprint for American comic books produced by DC Comics for stories that took place outside the DC Universe canon. Elseworlds publications are set in alternate realities that deviate from the established continuity of DC’s regular comics. The "Elseworlds" name was trademarked in 1989, the same year as the first Elseworlds publication.

Charlton Comics was an American comic-book publishing company that existed from 1945 to 1986, having begun under a different name: T.W.O. Charles Company, in 1940. It was based in Derby, Connecticut. The comic-book line was a division of Charlton Publications, which published magazines, puzzle books, and briefly, books. It had its own distribution company.

Captain Marvel, also known as Shazam and the Captain, is a superhero in American comic books originally published by Fawcett Comics and currently published by DC Comics. Artist C. C. Beck and writer Bill Parker created the character in 1939. Captain Marvel first appeared in Whiz Comics #2, published by Fawcett Comics. He is the alter ego of Billy Batson, a boy who, by speaking the magic word "Shazam!", can transform himself into a costumed adult with the powers of superhuman strength, speed, flight, and other abilities. The character battles an extensive rogues' gallery, most of them working in tandem as the Monster Society of Evil, including primary archenemies Black Adam, Doctor Sivana and Mister Mind. Billy often shares his powers with other children, primarily his sister Mary Batson and their best friend/foster brother Freddy Freeman, who also transform into superheroes and fight crime with Billy as members of the Marvel Family, also known as the Shazam Family.

Captain Atom is a superhero appearing in American comic books, first in the 1960s by Charlton Comics before being acquired in the 1980s by DC Comics. Captain Atom has existed in three basic incarnations.

Doctor Who is a British science fiction television series broadcast by the BBC since 1963. The series depicts the adventures of a Time Lord called the Doctor, an extraterrestrial being who appears to be human. The Doctor explores the universe in a time-travelling space ship called the TARDIS. The TARDIS exterior appears as a blue British police box, which was a common sight in Britain in 1963 when the series first aired. With various companions, the Doctor combats foes, works to save civilisations, and helps people in need.

An antagonist is a character in a story who is presented as the chief enemy of the protagonist.