Contributors to Warren’s magazines included such significant artists as Neal Adams, Richard Corben, Bernie Wrightson, Johnny Craig, Reed Crandall, Steve Ditko, Frank Frazetta, Russ Heath, Esteban Maroto, Alex Niño, Sanjulián, John Severin, Tom Sutton, Angelo Torres, Al Williamson, and Wally Wood, and writers/editors including Archie Goodwin, Louise Jones, Don McGregor, and Doug Moench.

He appointed Billy Graham as the first known African-American art director in mainstream, nationally distributed comic books/comics magazines.

[2] He attended the University of Pennsylvania School of Architecture and served in ROTC, leaving his junior year to enlist in the United States Army when the Korean War began.

I learned the hard way about Teamsters, truckers, loading docks, slowdowns at printing plants and bankers who welsh on you.

[3]Through After Hours, Warren met his future collaborator, Hollywood literary agent Forrest J Ackerman, who submitted the pictorial feature "Girls from Science-Fiction Movies.

A few weeks later I was in Forry Ackerman's living room in California, choosing the photos and article content for a one-shot magazine called Famous Monsters of Filmland, which went on sale that January with a February 1958 cover date."

[3] He financed the first issue, for which the upstate New York printer wanted payment upfront, through "some advance money from my distributor," Kable News, ...but I was $9,000 short.

[3] Warren moved to New York City in the 1960s, with his "Captain Company" (the mail-order service he concurrently founded to sell horror-related items in Famous Monsters of Filmland) remaining in Philadelphia, where overhead was cheaper.

[3] In the mid-1960s, inspired by the EC Comics of the 1950s, Warren launched the black-and-white horror-comics magazines Creepy, Eerie and Vampirella.

In July 2024, Warren received the Will Eisner Hall of Fame Award[4] from the San Diego Comic Con committee.