| Issue | #20 |
| Published | June 1961 |
| Frequency | monthly |
| Cover Price | 0.10 USD |
| Pages | 36 |
| Editing | Stan Lee |
| Notes | Distributed to newstands in March 1961. This issue includes 10 pages of paid advertisements. Distribution date from Joseph Marek's Marvel Comics Group history website. |
| Characters | X |
| Genre | monsters |
| Pencils | Jack Kirby |
| Inks | Dick Ayers ?; Jack Kirby ? |
| Notes | Nick Caputo suggested the possibility of the Kirby inks credit via the GCD Error List (30 January 2009). |
| Reprinted | in Fear (Marvel, 1970 series) #2 (January 1971); in Marvel Masterworks: Atlas Era Tales to Astonish (Marvel, 2006 series) #2 (2008) |
| Characters | Charles Bentley; X (introduction, origin) |
| Synopsis | A comic writer's monsters keep coming to life, until he creates one that can't be defeated. The monster is unstoppable physically, but he wills it out of existance. |
| Genre | monsters |
| Pencils | Jack Kirby |
| Inks | Dick Ayers |
| Notes | Narrated in the first person. This story is divided into four untitled parts (5 pp, 5 pp, 3 pp, 5 pp). X next appears in Alpha Flight (Marvel, 1997 series) #17 (December 1998). |
| Reprinted | in Fear (Marvel, 1970 series) #2 (January 1971); in Marvel Masterworks: Atlas Era Tales to Astonish (Marvel, 2006 series) #2 (2008) |
| Characters | Jim Branner; Bill Toney |
| Synopsis | The manager of an auto parts shop develops a sudden tolerance for "human variation" in parts, possibly linked to otherworldly strangers in the shop at night. |
| Genre | science fiction |
| Pencils | Joe Maneely |
| Inks | Joe Maneely |
| Letters | typeset |
| Notes | Text story with illustration. |
| Reprinted | from Journey Into Mystery (Marvel, 1952 series) #34 (May 1956) |
| Characters | Adam Gree |
| Synopsis | A heartless tycoon spends great resources and eliminates jobs in order to build a machine that will transport him forty years into the future from the current moment to one forty years hence because his scientists have predicted an end to disease, war, and poverty in the year 2001, but he neglects to consider his body will age forty years in what seems to his mind merely an instant and since the machine has only enough power to move forward the one time he's lost most of the years of his life. |
| Genre | science fiction |
| Pencils | Steve Ditko |
| Inks | Steve Ditko |
| Reprinted | in Fear (Marvel, 1970 series) #2 (January 1971); in Marvel Masterworks: Atlas Era Tales to Astonish (Marvel, 2006 series) #2 (2008) |