| Issue | #21 |
| Published | February 1940 |
| Cover Price | 0.10 |
| Pages | 68 |
| Editing | Whitney Ellsworth |
| Characters | Superman |
| Genre | superhero |
| Pencils | Joe Shuster |
| Inks | Paul Cassidy |
| Letters | typeset |
| Reprinted | In Superman: The Action Comics Archives (DC, 1997 series) #2 (1998). |
| Characters | Superman [Clark Kent]; Terry Curtis (I); Metropolis (mentioned); V: Ultra [Ultra-Humanite, as Dolores Winters]; George Taylor. |
| Synopsis | Ultra hears of the invention by Terry Curtis of an atomic disintegrator he has created and vows to get it, all in order to further advance his plan to dominate the world. |
| Genre | superhero |
| Script | Jerry Siegel (signed) |
| Pencils | Joe Shuster (signed) |
| Inks | Dennis Neville? |
| Notes | Oddity: on page 1, Clark Kent mysteriously is shown in a suit, then undershirt, and back to suit again with no explanation. The last panel of the story introduces by illo and text a new feature called The Spectre. Synopsis added by Craig Delich 8-21-08. |
| Reprinted | In Superman: The Action Comics Archives (DC, 1997 series) #2 (1998). |
| Characters | Pep Morgan |
| Genre | adventure |
| Script | Gardner F. Fox |
| Pencils | Fred Guardineer (signed as Gene Baxter) |
| Inks | Fred Guardineer (signed as Gene Baxter) |
| Notes | Writer credit added by Craig Delich 8-21-08. |
| Characters | Chuck Dawson |
| Genre | western |
| Pencils | Homer Fleming |
| Inks | Homer Fleming |
| Characters | Clip Carson |
| Genre | adventure |
| Pencils | Sheldon Moldoff |
| Inks | Sheldon Moldoff |
| Characters | Tex Thomson; Bob Daley; Col. Rushmore; Gargantua T. Potts. |
| Genre | adventure |
| Script | Ken Fitch? |
| Pencils | Bernard Baily (signed) |
| Inks | Bernard Baily (signed) |
| Letters | Bernard Baily |
| Notes | Letterer credit added by Craig Delich 8-21-08. |
| Genre | adventure |
| Script | Gardner F. Fox or Vincent Sullivan ? (signed as Terry Keane) |
| Pencils | ? (spot illos) |
| Inks | ? (spot illos) |
| Characters | Three Aces: Fog Fortune, Gunner Bill, and Whistler Will. |
| Genre | adventure |
| Pencils | Bert Christman (signed as Christopher) |
| Inks | Bert Christman (signed as Christopher) |
| Genre | fact |
| Pencils | Sheldon Moldoff |
| Inks | Sheldon Moldoff |
| Characters | Zatara; Tong. |
| Genre | occult |
| Script | Gardner F. Fox |
| Pencils | Fred Guardineer |
| Inks | Fred Guardineer |