While the original Superman is no longer active in the pages of DC comics, he had a very eventful life and then death as he unwittingly became a member of the Black Lantern Corps.
While the current iteration of Superman running around in the pages of DC comics is widely recognized as the main Superman, he is not the same Superman who first appeared in Jerry Siegel and Joe Shuster’s Action Comics #1. That distinction belongs to Kal-L, the Superman of Earth-Two. Kal-L is the Superman from the Golden Age of comics before the idea of a multiverse was established in the Silver Age, allowing both Supermen to operate separately. While the two Supermen have similar origins, Kal-L eventually grew into an older man and mostly ceased heroics, unlike his Earth-One counterpart who has remained young and consistently operated as Superman.
Kal-L and Earth-Two would later be erased in the legendary Crisis on Infinite Earths event that provided a clean reset of DC’s continuity. However, he was not killed as he was later revealed to have been watching Earth-One from a pocket universe. He would return in the Infinite Crisis event, busting out of his pocket universe and teaming up with the villainous Superboy-Prime and Alexander Luthor Jr. Kal-L was hoping to put a stop to what he called “A growing darkness” in the prime earth, which he seemed to mostly blame on the indecisiveness of his Earth-One counterpart. Kal would attempt to recruit the Earth-One versions of Batman and Power Girl but was quickly turned down by both heroes who refused to help destroy their world.
However, Kal-L would eventually realize he was wrong after a fight with Kal-El and Power Girl showed him his actions would not provide the results he was hoping for. Kal-L then joined the heroes, hoping to prevent Superboy-Prime from committing any more murders. Kal-L would later attack Superboy-Prime head-on after depowering him in the Red Sun, but was easily outmatched by him and then killed for turning against their plan in Geoff Johns, Phil Jimenez, George Perez, Ivan Reis, and Joe Bennet’s Infinite Crisis #7. Despite it leading to his death, Kal-L’s attack on Superboy-Prime gave Kal-El an opening to defeat the villain. Kal-L would then die in Power Girls arms, he was later buried on Earth-One.