Sheldon Mayer was an early editor at All-American Comics and National Comics from 1939 to 1948. He occasionally wrote and penciled for All-American's early titles. He is most famous for persuading M.C. Gaines to publish Joe Shuster and Jerry Siegel's character Superman in 1938, despite the fact that Gaines had been previously rejected the strip for publication. He retired as an editor in 1948, but continued to work as an artist for National (and its successor, DC) into the 1980s.

At the time, All-American characters (which included Green Lantern, the Flash, Wonder Woman, Hawkman and the Justice Society) were administered separately from those at National (such as Superman and Batman). When the two companies formally merged in 1946, he continued to oversee All-American characters until his retirement in 1948, when Whitney Ellsworth took over editorial duties.