Key's comics appeared under many imprints: Media Publications, Timor Publications, Aragon Magazines, Medal, SPM Publications and Gillmore Magazines.
Key Publications, founded by Stanley P. Morse, was active between 1951 and 1956. The first issue was Mr. Mystery, a horror comic, which ran for 19 issues was illustrated by Mike Esposito and Ross Andru. Morse horror comics were considered by critics to be rehashed, plagiarized and "vile". Morse himself spoke of these comics as – "I do not know what I printed. I never read the things!"
Steve Ditko, who was soon going to co-create Spiderman, started illustrating his books professionally at Key publications in 1953.
Some of the more popular titles under different imprints include Battle Fire, Navy Task Force, Weird Tales of the Future, Mr. Mystery, Real Adventure Comics, Daring Love, Flying Aces, Weird Mysteries, Western Rough Riders, Peter Cottontail, Tender Romance Battle Squadron, Warpath, Battle Cry, Crime Detector, Animal Adventures, Algie and Pete the Panic.