Just as Superman was the harbinger of supers in spandex, his counterpart on Earth-X was likewise... albeit ever so briefly.
Arn Munro was raised by his mother, never knowing his father Hugo Danner who had gone missing decades ago. Turns out, Hugo's father (and Arn's grandfather) injected his pregnant wife with an experimental drug which imbued his soon-to-be-son with super-human strength, speed, and nigh-invulnerability.
These same traits were based down to Arn, who unlike his father had not become disillusioned with humanity. Thus rather than seek retreat in a tropical jungle like his sire, Arn soon drew the attention of not only the public-at-large but his fellow teen titans. Joining alongside fellow superhumans, the lad adopted the alias Iron Munro and admirably built a modest legend in comparison to his more colorful contemporary across the cosmos.
How, though, can we say with certainty that Murno lived on Earth-X? Well, writer Roy Thomas mentioned how the Young All-Stars absorbed the energy left over by heroes that ceased to exist during the 1940's, including the golden age Superman. Since Earth-S already had Captain Marvel, Earths One and Four had their heroes arrive (mostly) during the 1960s and 70s, the only surviving Earth of the five that merged together is Earth-X (another Earth, Earth-8, was stated as having existed wherein the modern Huntress, Green Lantern and Firestorm came from... however this world had their heroes start even later than Earths One and Four).
Additionally, later texts of the merged Earth indicate that Iron Murno had two ties with members of the Freedom Fighters... as Phantom Lady's boyfriend decades ago, and later on as the roommate of the Human Bomb. Alas, as with most heroes on the Nazi-dominated Earth-X, Munro evidently didn't not survive to see his world liberated from the German conquerors.