Source: (1st) Young All-Stars #1 (1987)
Type: Replacement/AnalogWhen the original Crisis wiped the Golden Age Superman from history, Roy Thomas, the re-architect of both DC and Marvel's Golden Ages and never one to leave a continuity hole unfilled for long, had to re-cast the role. It's not a perfect plug, of course, since Iron Munro, the character chosen to fill Superman's boots, only started operating in 1942, leaving a four-year gap there if every single story needs to have happened. Still, 1942 being where we left the All-Star Squadron off, we could pick up again without missing the erased Superman, Batman&Robin, Wonder Woman and Aquaman, even though they played a very small part in ASS (yes, I'm using the abbreviation, live with it). But not only did the Big 5 get replaced, those replacements now became the focus of the revitalized ASS, re-named Young All-Stars (which at least proved one thing: Roy Thomas could never write New Teen Titans). Well, despite being a huge fan of the Golden Age era and of ASS (keep laughing), I tuned out at that point. Well... truth be told, the book was Direct Sales only, and I was still living a comic book storeless town. But I wasn't enthusiastic about the issues I did find and read.
Iron Munro is not a perfect analog of Superman, of course. He doesn't come from another planet, yada yada yada. He does have similar powers, including strength, invulnerability and jumping over tall buildings, a telltale "S" curl, and the tendency to appear on comic book covers busting out of chains (that's totally a Superman thing). His actual origin makes him the son of the 20th century's first superhuman, his powers of hereditary gift. But like I said, Arn "Iron" Munro was NOT a total invention. Roy Thomas dug him out of Shadow Comics #1 (Street & Smith, June 1940), a strip based on Aarn Munro, a 1930s pulp hero written by John W. Campbell. Furthermore, Roy made his superhuman father, Hugo Danner, the protagonist of Philip Wylie's 1930 novel "Gladiator" (even though the book explicitly says those powers cannot be passed on). I call that the League of Extraordinary Gentlemen school of writing.
Though none of the Young All-Stars seemed destined for greatness - after all, where were their legacies in the present day? - they all managed to appear later in supporting roles, except for Flying Fox (a rare Canadian hero for DC) who was admittedly a rather strange and poor replacement/analog for Batman. Iron Munro got the most and best attention, I think. It was revealed that he had a child with the original Phantom Lady (va-va-voom!), a child that became a psychotic killer but also the father of the current Manhunter, Kate Spencer. The powers seem to be inherited only by males, so Kate's young son has them. Iron Munro is currently a part of their lives, but he was also a father figure to Damage.
And most recently, a link was finally drawn between him and Superman in the pages of "Grounded" (Superman #710). Superman and Batman flash back to a time before they put on costumes when they were walking the Earth and crossed paths. Each of them had an inspiration, and Clark's was reading old Iron Munro comics. Chicken and egg keep mixing it up, folks!