Esposito gradually began freelancing for Marvel Comics, starting with his uncredited inking of industry giant Jack Kirby's cover of "Fantastic Four Annual" #3 (1965). For his inking of Bob Powell in the "Human Torch and the Thing" feature in "Strange Tales" #132, and his inking of Don Heck's "Iron Man" in "Tales of Suspense" #65 (both May 1965), he took the pen name Mickey Demeo (occasionally given as Mickey Dee or Michael Dee) to conceal his Marvel work from his primary employer, DC. He also occasionally worked under the pseudonym Joe Gaudioso for the same reason. The pseudonym Mickey Demeo, he explained, "was a name I had in the 1950s when I was doing ] stories" — considered disreputable at the time — "and I didn't want certain guys in the business to know who I was us. Mickey Demo was a relative's name up in Boston."