Professor Corey Creekmur cited in New Yorker article about the Marvel Universe and Avengers: Endgame
“At first, comic-book editors said, ‘Who’s paying attention to this?,’ ” Corey Creekmur, a colleague of Altman’s, at the University of Iowa, who teaches classes on film and comic books and is the head of the film-studies program, told me. Then attentive readers began writing in. “Responding to fans, the editors started to say, ‘Well, maybe we can think of all of these stories as linked, or connected.’ ” This led to the creation of teams such as the Justice League (which includes both Superman and Batman—residents of Metropolis and Gotham City, respectively) and the Avengers. Superheroes began living in shared worlds.