Comic Title: Challengers of the Unknown #21
Publisher: DC (National Comics Publications, Inc.)
Address: 575 Lexington Avenue, New York, NY
Cover Date: Aug/Sep 1961
On Sale Date: June 13, 1961 Copyright Date June 13, 1961
Source: Library of Congress, Periodicals 1961

Frequency: Bi-monthly
Cover Price: $0.10
Page Count: 32
Editor: Jack Schiff

Title: "The Challengers' Space-Pet Ally"
Pages: 13

Feature(s):
Challengers of the Unknown (of Earth-1)

Artist: Bob Brown

Reprinted In:
Showcase Presents:Challengers of the Unknown Vol. 2 TPB (2008)

Feature Character(s)

• Challengers of the Unknown (last appearance in Challengers of the Unknown #21; next appearance in Challengers of the Unknown #22)
• Ace Morgan (last appearance in Challengers of the Unknown #21; next appearance in Challengers of the Unknown #22)
• Rocky Davis (last appearance in Challengers of the Unknown #21; next appearance in Challengers of the Unknown #22)
• Red Ryan (last appearance in Challengers of the Unknown #21; next appearance in Challengers of the Unknown #22)
• Prof. Haley (last appearance in Challengers of the Unknown #21; next appearance in Challengers of the Unknown #22)

Supporting Character(s)

• June Robbins (last appearance in Challengers of the Unknown #21; next appearance in Challengers of the Unknown #22)
• Cosmo (last appearance in Challengers of the Unknown #18; next appearance in Challengers of the Unknown #25)

Villain(s)

• Zardoc and his gang (no further appearances)

Other Character(s)

• Henry Perkins and his wife (farmers; no further appearances)

Synopsis:
While training their pet Cosmo, the Challs learn of some strange phenomenon which get their attention. Investigating, they learn that Zardoc, an underworld mystic has been causing the disasters with a helmet powered by a meteorite.

Cosmo helps the Challs track Zardoc, who summons a dragon with his mind over matter power to deal with the alien pet. The Challs rescue their pet and realize that Zardoc considers Cosmo to be the biggest threat, so they trick the crook into attacking a mirror image of Cosmo, allowing them to close in and stop the thief.