Superman XX (usually just called Superman) is a direct descendant of Superman, living in the 30th Century. He is the twentieth member of his family to take up the Superman identity. Like his forefather, he also has a secret identity as a news reporter. This Superman has developed an immunity to Kryptonite. However, he is unable to go into the Earth's oceans because radioactivity from a nuclear war has made the water toxic to him.
He was eventually confronted by the super-villains Muto and the Joker XX, who managed to outmatch him on every occasion. Superman then learned of the existence of Batman XX and together they managed to stop the villains.
- Vulnerability to Water (Sea Water Only)
- This version of Superman XX, including all history and corresponding appearances, was erased from existence following the collapse of the original Multiverse in the 1985–86 Crisis on Infinite Earths limited series. Even though versions of the character may have since appeared, this information does not apply to those versions.
- The Dominus Effect involved an "updated" version of this Superman.
- 9 Appearances of Klar Ken T5477 (Earth-One)
- 1 Images featuring Klar Ken T5477 (Earth-One)
- 2 Quotations by or about Klar Ken T5477 (Earth-One)
- Character Gallery: Klar Ken T5477 (Earth-One)