Colossus was originally announced as a forthcoming publication by Arkham House as early as 1965.

[2] Phil Rahman and Dr. Dennis Weiler approached the Wandrei estate with the hopes of publishing the collection.

In 1999, in honor of their 10th anniversary, Fedogan & Bremer issued a second edition of the book (ISBN 1-878252-45-3).

The second edition contained an updated introduction, replaced the note by Philip J. Rahman with a newly discovered preface that Wandrei had done for an unpublished collection, and added two stories in place of the bibliography.

[3] Fedogan and Bremer published a chapbook containing the ending of the story as Wandrei originally wrote it.