Superman: Whatever Happened to the Man of Tomorrow? reference to one of the nicknames of Superman as the "Man of Tomorrow", and was later again used in the title of another Superman . The comic book, "Action Comics" #1, published in April 1938 by "National Allied Publications" (later renamed DC Comics), marked the first publication of the character of Superman created by Jerry Siegel and Joe Shuster. The comic quickly became a success, and its editor soon realized that it was because of the popularity of the character. In an unprecedented move at the time, National Allied Publications introduced a second comic book, "Superman", exclusively featuring the popular
Superman (Earth-One) several DC characters continuously published throughout the 1950s, there isn't a clear dividing line between the Earth-One and Earth-Two versions of Superman. Several stories published before the mid-1950s took place on Earth-One, such as "Superman" (volume 1) #78 from September–October 1952, the first appearance of the adult Lana Lang in Superman comics. Also, any Superman stories published before the mid-1950s that featured or mentioned Superboy also took place exclusively on Earth-One, as the Earth-Two Superman, per the earliest Superman comics, never had a Superboy career. The Earth-One Superman's first appearance in comics was in "Superman" (volume 1) #46 (May 1947),