Justice League of America Vol 1 21

"Crisis on Earth-One!"
	Writers Gardner Fox Pencilers Mike Sekowsky Inkers Bernard Sachs Letterers Gaspar Saladino Editors Julius Schwartz

Appearing in "Crisis on Earth-One!"

Featured Characters:

Supporting Characters:

Adversaries:

Other Characters:

Locations:

Secret Sanctuary
Alfalfa City
Casino Town
- Golden Egg (Casino)
Clayville
- Natural History Museum
Central City
- Central City Community Center (Appears in flashback and main story)
Gotham City
Happy Harbor
Powers City
Rhode Island
Three Corners (City)
Missouri

Items:

Vehicles:

This issue features the first team-up between the Golden Age Justice Society of America and the Silver Age Justice League of America, both of which are the creations of writer Gardner Fox. This begins a series of annual team-ups between both groups which continues until Justice League of America #231. This story also expands upon the concept of the Multiverse - an ever-evolving plane of parallel dimensions where each reality contains a planet Earth, but with vast differences between them. The concept of the Multiverse was first introduced in Flash (Volume 1) #123 in a story called "The Flash of Two Worlds". In that story, Barry Allen, the Flash of mainstream Silver Age continuity traveled to the dimensional home of Jay Garrick, the Flash of Golden Age continuity. It is not until this issue that the individual dimensions are provided with name designations. The reality corresponding to Jay Garrick and the rest of the Justice Society is established as Earth-Two, whereas the reality of the Justice League is known as Earth-One.

The absence of Snapper Carr is explained when Green Arrow reveals that he is away at college finishing his final exams.

Multiversal Crossover
The events from this issue or series involve a Multiversal Crossover between Pre-Crisis worlds and characters. This template will categorize articles that include it into the Pre-Crisis Multiverse Crossover category.

See also Post-Crisis Multiverse Crossovers.

It is revealed that the Fiddler is actually bald in this issue and wears a wig to disguise his features.

An homage to the cover of this issue would be used in Alan Moore's Image Comics series Supreme. This comic within a comic was The Allies #21, wherein the Allies meet their WWII counterparts, the Allied Superman of America.