Martin Greenberg (June 28, 1918 – October 20, 2013) was an American book publisher and editor of science fiction anthologies.
After leaving the Army, Greenberg was associated with the small press publisher New Collector's Group founded by Paul Dennis O'Connor and Hannes Bok.
Greenberg and O'Conner clashed about the direction of the press, causing Greenberg to leave, taking the rights to The Carnelian Cube by L. Sprague de Camp and Fletcher Pratt as his buyout fee.
He was involved in disputes with authors concerning payment, and Isaac Asimov called him a "crook".
Greenberg, with Gnome Press, was the first publisher of Asimov's epic Foundation Trilogy, but those rights were long ago transferred to Doubleday.