Comic Title: Justice League of America #21
Publisher: DC (National Periodical Publications, Inc.)
Address: 575 Lexington Avenue, New York, NY
Cover Date: August 1963
On Sale Date: June 20, 1963 Copyright Date June 20, 1963
Source: Library of Congress, Periodicals 1963

Frequency: Monthly, with the exception of Jan., April, July and Oct.
Cover Price: $0.12
Page Count: 32
Editor: Julius Schwartz

Title: "Crisis on Earth-One"
Pages: 25

Feature(s):
Justice League of America (of Earth-1)

Writer: Gardner F. Fox
Penciller: Mike Sekowsky
Inker: Bernard Sachs

Reprinted In:
DC 100-Page Super Spectacular #6 (1971)
Greatest Team-Up Stories Ever Told HC (1990)
Greatest Team-Up Stories Ever Told TPB (1990)
Justice League of America Archives Vol. 3 HC (1994)
Crisis on Multiple Earths Vol. 1 TPB (2002)
DC 100-Page Super Spectacular Replica Edition #6 (2004)
Showcase Presents:Justice League of America Vol. 2 TPB (2007)
Justice League of America Omnibus Vol. 1 HC (2014)
Justice Society of America:A Celebration of 75 Years HC (2015)
Justice League of America:The Silver Age Vol. 3 TPB (2017)
Crisis on Infinite Earths Box Set HC (2020)
Crisis on Multiple Earths:Crossing Over TPB (2021)

Feature Character(s)

• Justice League of America (last appearance in Justice League of America #20; next appearance in Justice League of America #22)
• Superman of Earth-1 (last appearance in Action Comics #302; next appearance in Justice League of America #22)
• Batman of Earth-1 (last appearance in Batman #157; next appearance in Justice League of America #22)
• Flash of Earth-1 (last appearance in Flash #138; next appearance in Justice League of America #22)
• Wonder Woman of Earth-1 (last appearance in Wonder Woman #139; next appearance in Justice League of America #22)
• Green Lantern of Earth-1 (last appearance in Green Lantern #22; next appearance in Justice League of America #22)
• Martian Manhunter (last appearance in Detective Comics #317; next appearance in Justice League of America #22)
• Aquaman of Earth-1 (last appearance in Aquaman #10; next appearance in Justice League of America #22)
• Green Arrow of Earth-1 (last appearance in Justice League of America #20; next appearance in Justice League of America #22)
• Atom of Earth-1 (last appearance in Justice League of America #20; next appearance in Justice League of America #22)

Guest Star(s)

• Justice Society of America (last appearance in Flash #137; next appearance in Justice League of America #22)
• Doctor Fate (Kent Nelson; first Silver Age appearance; last appearance in Wonder Woman #242; next appearance in Justice League of America #22)
• Hourman (Rex Tyler; first Silver Age appearance; last appearance in Adventure Comics #83; next appearance in Justice League of America #22)
• Black Canary (of Earth-2; Dinah Drake Lance; last appearance in Adventure Comics #466; next appearance in Justice League of America #22)
• Flash of Earth-2 (last appearance in Flash #137; next appearance in Justice League of America #22)
• Green Lantern of Earth-2 (last appearance in Flash #137; next appearance in Justice League of America #22)
• Hawkman of Earth-2 (last appearance in Flash #137; next appearance in Justice League of America #22)
• Atom of Earth-2 (last appearance in Flash #137; next appearance in Justice League of America #22)

Villain(s)

• The Crime Champions (next appearance in Justice League of America #22)
• Wizard (W.I. Zard; first Silver Age appearance; last appearance in Action Comics #484; next appearance in Justice League of America #22)
• Icicle (Joar Makent; first Silver Age appearance; last appearance in All-Star Comics #41; next appearance in Justice League of America #22)
• Fiddler (last appearance in Flash #123; next appearance in Justice League of America #22)
• Chronos (last appearance in Atom #3; next appearance in Justice League of America #22)
• Felix Faust (last appearance in Justice League of America #10; next appearance in Justice League of America #22)
• Dr. Alchemy (last appearance in Showcase #14; next appearance in Justice League of America #22)

Comments:
Batman is the chairman of the JLA meeting in this story.

Snapper Carr is absent studying for and writing his college entrance exams during the stories in this issue and next.

The respective parallel worlds inhabited by the Justice League and the Justice Society are first referred to as Earth-1 and Earth-2 in this story. This two-part story also begins the annual tradition of a JLA-JSA team-up, usually containing the word "crisis" in the story title, which culminates in the Crisis on Infinite Earths series in 1985.

This story continues in Justice League of America #22.

Synopsis:
While the Justice League battles Felix Faust, Chronos, and Dr. Alchemy, who have united as the Crime Champions, they are unaware of a similar struggle taking place on the parallel world of Earth-2 between their counterparts, the Justice Society, and another team of Crime Champions composed of the Wizard, the Icicle, and the Fiddler. Having discovered the existence of the dual Earths, the two teams of villains have schemed to hide out on each other’s worlds after committing crimes. To safeguard their secret, they capture and imprison the two Flashes, who alone know of the alternate worlds and the method of traveling between them.

Disguising themselves as the Earth-1 villains, the Earth-2 Crime Champions battle and defeat the Justice League, magically trapping them in their Secret Sanctuary. The super-heroes use a crystal ball to contact the missing Flash, who tells them of his adventures on Earth-2, after which they summon the Justice Society to Earth-1.

The JLA then journey to Earth-2 while the two Green Lanterns race to free the captive Flashes, who are trapped in the transition zone between the Earths.