Mary Gnaedinger edited both series; her interest in reprinting Merritt's work helped make him one of the better-known fantasy writers of the era.

[4] The stated reason was that Famous Fantastic Mysteries "is apparently the favorite title", but it seems likely that production difficulties caused by World War II played a part.

It was apparently a sudden decision; the final issue had announced plans to reprint Otis Adelbert Kline's Maza of the Moon.

[3] Gnaedinger observed that "Everyone seems to have realized that although [the] set-up of five to seven stories with two serials running, was highly satisfactory, that the long list of novels would have to be speeded up somehow".

[7] When the new magazine was launched, Famous Fantastic Mysteries was partway through serialization of Austin Hall and Homer Eon Flint's The Blind Spot, with the third episode appearing in the May/June 1940 issue.

[3] Over the next four issues she printed Ray Cummings' People of the Golden Atom, Ralph Milne Farley's The Radio Beasts, and two novels by A. Merritt: The Snake Mother and The Dwellers in the Mirage.

Gnaedinger's interest in reprinting Merritt's work helped make him one of the better-known fantasy writers of the era.

Works by George Allan England, Victor Rousseau, Ray Cummings, and Francis Stevens (the pen name of Gertrude Barrows Bennett) appeared,[4][9] as well as (occasionally) reprints of more recent work, such as Earth's Last Citadel, by Henry Kuttner and C. L. Moore, which had been serialized in Argosy in 1943.