Superman "Superman", and released in 1979 for the Atari 2600. The last game centered on Superman was "Superman Returns" (adapted from the movie) in 2006. Superman has, however, appeared in more recent games starring the Justice League, such as "Injustice 2" (2017). In a contract dated 1 March 1938, Jerry Siegel and Joe Shuster released the copyright to Superman to their employer, DC Comics (then known as Detective Comics, Inc.) prior to Superman's first publication in April. This was normal practice in the comic magazine industry and they had done the same with their previous published works (Slam Bradley, Doctor Occult,
Superman 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 lifetime 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 sales of "Action Comics" and "Superman" probably peaked in the mid-1940s and thereafter steadily declined as part of a general trend in comic book sales.