 Superman is part of the DC Universe, which is a shared universe of superhero characters owned by DC Comics, and consequently he frequently appears in stories alongside the likes of Batman, Wonder Woman, and others.Superman has sold more comic books over his publication history than any other American superhero character.Exact sales figures for the early decades of Superman comic books are hard to find because, like most publishers at the time, DC Comics concealed this data to deny competitors, but given the general market trends at the time, sales of "Action Comics" and "Superman" probably peaked in the mid-1940s and thereafter steadily declined.