Biography
The Superman of earth D was a hero from a parallel universe, (earth D) where, at difference of the Superman of other worlds, he had came to earth as an adult and after several other heros had already debuted. He had travelled accompanied by his wife, who took the mantle of Supergirl. When the anti-matter wave reach his universe this Superman died fighting the Shadow demons of Anti-Monitor.
His story was revealed in the lost chapter of Crisis on Infinity Earths.
Alternate versions
On the Arrowverse comic adaptation of Crisis of infinite earths, a different version of earth D was presented. Here Superman fought against the shadow demons in his world’s Russia before die along with his whole universe.
On Justice League Infinity, a new version of Superman (Earth D) debuted. This version shared several elements with Calvin Ellis, including his relationship with Wonder Woman (Unati/Nubia)