Stanley Mullen (1911-1974), born in Colorado Springs, was a U.S. artist, museum curator and pulp writer who wrote over thirty sf and fantasy stories. He studied writing at the University of Colorado at Boulder and drawing, painting and lithography at the Colorado Springs Fine Arts Center where he was accepted as a professional member in 1937, and went on to work as assistant curator of the Colorado State Historical Museum during the 1940s.
Mullen wrote over 200 stories and articles in a variety of fields. His sf and fantasy stories began with “A Dero Named Clarence” for The Gorgon in 1947. Many of his stories were Space Opera, often in Planet Stories, until about 1959. His three books, from small presses, are Kinsmen of the Dragon (1951), which pits the hero against a secret society whose magical science has roots in a parallel world which, being under the sea, is accessible by submarine; Sphinx Child (1948 chap), a fantasy short story; and Moonfoam and Sorceries (coll 1948). Mullen’s story “Space to Swing a Cat” was nominated for a Hugo Award for Best Short Story in 1959.
He became involved with the small press publisher New Collector’s Group before starting his own small press publisher, Gorgon Press, in 1948.
(Edited from Mullen’s entries on Wikipedia and the Encyclopedia of Science Fiction where you will find further information.)