Superheroes created for All-American include the original Atom, Flash, Green Lantern, Hawkman, and Wonder Woman, all in the 1940s' Golden Age of Comic Books.

As Jones describes, Gaines saw the end of the superhero fad coming and wanted to get into something more durable, like children's books and magazines.

[1]: 223 During All-American's existence, much cross-promotion took place between the two editorially independent companies, so much so that the first appearance of the Justice Society of America, in All Star Comics #3 (Winter 1940/41), included in its roster All-American characters the Atom, the Flash, Green Lantern and Hawkman, and the National characters Doctor Fate, Hour-Man (as it was then spelled), the Spectre, and the Sandman — creating comics' first intercompany crossover,[6][note 3] with characters from different companies interacting — although National's Sandman, Spectre and Hour-Man had previously appeared in solo adventures in All Star Comics #1 (Summer 1940).

The first of its six issues through Aug. 1939 adapted no fewer than five films: Son of Frankenstein, Gunga Din, The Great Man Votes, Fisherman's Wharf, and Scouts to the Rescue.

The next two comics were Mutt & Jeff,[note 2] which ran 103 issues from Summer 1939 - June 1958; and the company's superhero debut, Flash Comics #1 (Jan. 1940), which introduced the super-speedster title character, created by writer Gardner Fox and artist Harry Lampert, as well as the Golden Age Hawkman and future Hawkgirl, by Fox and artist Dennis Neville, and Johnny Thunder, by scripter John Wentworth and artist Stan Aschmeier, among other features.