Famous Fantastic Mysteries was published by the Frank A. Munsey Company based in New York, USA.
Published originally as bi-monthly, it had a short spell as a monthly magazine before reverting to bi-monthly. It ran from 1939 to 1953 for a total of 81 issues.
A fantasy fiction magazine offering reprints of scientific and fantastic classics from earlier decades. Some of it's more famous authors included G. K. Chesterton, H. G. Wells, and H. Rider Haggard. Renewals seem to have taken place in 1982 which would make magazines 1943 and earlier in public domain.