The Superman of Earth-Two is a fictional character, a comic book superhero published by DC Comics. The character first appeared in Justice League of America #73 (August 1969). He is a version of the Kryptonian superhero Superman from an alternate reality called Earth-Two. Unlike the more popular Superman, the Earth-Two Superman is portrayed as decades older and is given the birth name of Kal-L.
When the Golden Age of Comic Books came to a close in the 1950s, most of DC Comics' superhero comic books ceased publication. The commencement of the Silver Age saw characters such as the Flash and Green Lantern revamped for more modern times, ignoring or abandoning established continuity and thus creating a clean break between the two eras. It was later established that the Golden Age heroes and Silver Age heroes actually lived on Earth-Two and Earth-One respectively, separate parallel Earths in a single Multiverse.
However, Superman was one of the few exceptions; his stories had been published without interruption since his debut in 1938's Action Comics #1. This caused a continuity problem, specifically that Superman was simultaneously a member of the Justice Society of America on Earth-Two and also member of the Justice League of America on Earth-One. It was eventually established that there were two Supermen. The "current", Silver Age Superman was Kal-El from Earth-One, while the Golden Age Superman was Kal-L from Earth-Two.
Several minor differences between the two Supermen were established to make the distinction clearer. The names "Kal-El", "Jor-El" and "Jonathan and Martha Kent" on Earth-One became "Kal-L", "Jor-L" and "John and Mary Kent" on Earth-Two. Kal-L's S-shield symbol was slightly different. Stories featuring both Supermen also indicated that Kal-L was the older of the two, being depicted as late middle-aged with greying hair at the temples, while his Earth-One counterpart was a youthful man of modern times.
Read more about Pre-Crisis Superman (Earth-2) at Wikipedia
Official Site: DC Comics
Researched by: Adam Safran