Gary Cohn attended Michigan State University, earning his Bachelor’s degree in Creative Writing, and graduated from Bowling Green State University with an M.A. in 1980. Cohn and longtime friend Dan Mishkin entered the comics industry together following a correspondence with Jack C. Harris, an editor at DC Comics. Their first work for the company was the three-page short story “On the Day of His Return” published in Time Warp #3 (Feb.–March 1980) and drawn by Steve Ditko.
In 1983, Cohn and Mishkin created Amethyst, Princess of Gemworld with artist Ernie Colón. The following year, the writing team and Paris Cullins introduced Blue Devil. DC gave both series a promotional push by featuring them in free, 16-page insert previews.
Cohn and artist Ron Randall co-created the “Barren Earth” feature as a backup in The Warlord #63 (Nov. 1982) and it was spun off into a four–issue limited series in 1985. In the mid-1990s, Cohn wrote several stories for William Tucci’s Crusade Comics including an intercompany crossover between Crusade’s Shi and Marvel Comics’ Daredevil.
Cohn has written three Hardy Boys and two Nancy Drew novels.