Note: Unknown, which also went by the titles Unknown Fantasy Fiction (Feb 1940 - Aug 1941), and Unknown Worlds (Oct 1941 -Oct 1943), was the fantasy companion to Astounding. It was edited by John W. Campbell, Jr. for its entire print run (1939-1943).
Despite its short life, Unknown was highly praised, even though a later attempt in 1948 to revive the magazine failed. The later Galaxy fantasy companion, Beyond Fantasy Fiction was an imitator of the magazine; a number of anthologies gleaned from Unknown were published: The Unknown, The Unknown Five, and Hell Hath Fury.
All of the Unknown data was supplied by John Boston (jboston@mindspring.com)