After Roy Thomas decided to cancel his World War II-set comic All-Star Squadron in the wake of Crisis on Infinite Earths,because of all the changes done that eliminated the original multiverse and replaced it with a single earth and universe,he created a follow-up series with a new superhero team, Young All-Stars.
Iron Munro was one of several new characters Thomas created as analogues for popular superheroes written out of the continuity; he stood in for Superman, with comparable powers and appearance.
He was inspired by two 1930s pulp fiction characters who in turn prefigured Superman: John W. Campbell's science fiction hero Aarn Munro, who appeared in comics as "Iron Munro", and Hugo Danner, the protagonist of Philip Wylie's 1930 novel Gladiator, who had powers similar to Superman's and is sometimes seen as an inspiration.
All-Star Squadron depicts a team of Earth-Two versions of characters like Superman, Batman, and Wonder Woman fighting in World War II.
In 1985, DC launched the Crisis on Infinite Earths crossover storyline, which ultimately eliminated the company's Multiverse of parallel worlds in favor of a new unified continuity.
His concept was that the "displaced energy" of the removed superheroes generated analogs to replace them; as such, most of the new cast stood in for the heroes written out of the continuities.
His name comes from Aarn Munro, the hero of John W. Campbell's 1934 science fiction novel The Mightiest Machine and some subsequent works.
Campbell's character had incredible strength and agility from growing up on a high-gravity planet, the same explanation for Superman's powers in early stories.
Notably, this is an inversion of Edgar Rice Burroughs' earlier character John Carter, an earthling whose strength increased on the smaller planet of Mars.
Often viewed as a precursor to and possible inspiration for Superman, Hugo Danner likewise had otherworldly strength, speed, and impervious skin.
[5] In a nod to Superman's debt to Gladiator, Thomas made Iron Munro the son of Hugo Danner.
[6] Loosely following Philip Wylie's novel Gladiator, the comics establish that in 1894, scientist Abednego Danner injected his pregnant wife with an experimental serum.
When Hugo disappeared for good, Blake married a young businessman named John Munro, who never realized the child she bore was not his own.
[14] During the war, Iron Munro also met his future wife, the Squadron member known as Phantom Lady, Sandra Knight.
During the massive war between Imperiex and Brainiac 13, the Justice Society's Sand recruited an army of All-Stars, which Arn joined.
[22] Munro is endowed with superhuman strength and speed, is invulnerable to the point where small firearms will only bruise him, can leap almost an eighth of a mile, has enhanced reflexes, and ages at a slower rate than an ordinary human, hence why despite being in his nineties, he still looks to be in his thirties.