Kyle "Ace" Morgan was a veteran World War II air pilot, and was friends with Richard Flag, Martin Jordan, and King Faraday. Morgan later served in the Korean War and befriended with the son of the late Martin Jordan, Hal Jordan. By the end of the war on July 27, 1953, Morgan and Hal made one last recon over the Yalu River Delta to draw exact positions at the time of the cease fire. However, not everyone had known the war was over and Hal and Ace were attacked by Korean MiGs. Morgan then witnessed Hal bailing from his downed jet and was knocked out from falling debris. Morgan jettisoned himself out of his aircraft and position himself toward Hal and pulled his parachute cord. Morgan landed safely within American territory while Hal inadvertently landed in North Korean held ground, in which he suffered a post-traumatic moment when he had to killed a North Korean soldier.
By 1957, Morgan went out with Hal at Las Vegas and witnessed the exciting battle between the Flash and Captain Cold. Afterward, Morgan and Hal went to Nellis Air Force Base where Ace showed the B-47 jet plane prototype that Ace will be piloting cross-country. There Hal admitted his still lingering problems from the war to Morgan in which his friend gave him words of encouragement. Also, Morgan revealed that he managed to give Hal a job from Carol Ferris in Ferris Aircraft. Hal was overjoyed to hear this as his father had also worked for the company. Morgan then left on his prepared flight and picked up three guests for the flight as part of publicity: Red Ryan, Prof. Walter Haley, and Rocky Davis. However, Morgan and his guests were unprepared for what happened next during their flight. The B-47 suffered a major malfunction while flying over the Rocky Mountains. Morgan tried to steer the jet clear from a mountain and inadvertently causing it to spiral out of control before the cockpit was torn apart, sending the occupants to fly out onto the ground. Miraculously, no one was injured on the perilous flight. Though, the event was never forgotten by the men involved, Morgan and the others later met together on the site of the crash, believing that it was fate that kept them alive. It was then that Morgan and the survivors created their adventurer team known as the Challengers of the Unknown and decided to use their abilities to protect people and Earth itself from the unknown.
Morgan and the Challengers became involved in the disaster of Operation Flying Cloud and attempted to rescue the astronauts, Task Force X, led by his friend Richard Flag. The head of the operation, King Faraday, dissuaded them from interfering as Faraday secretly acknowledged the fact that the rocket Flying Cloud contained weapons of mass destruction. But, Morgan ignored it, and in the end the Challengers were unable to save Flying Cloud.
The Challengers were then heeded to Florida's Cape Canaveral due to a attack from a giant mutant pterodactyl. There they and along with reporters Lois Lane and Jimmy Olsen witnessed Superman subduing the dinosaur and the subsequent appearance of the Centre. After Superman was apparently killed by the Centre, Morgan alongside his friends Hal Jordan and Nathaniel Adam became a part of a second stage assault in harming the Centre from within with nuclear warheads. Once they were inside, the three suffered heavy mental attacks from the being as it produced, in each of them, a vision suited to each of their personal mentalities (from Morgan's perspective a vision of Challengers Mountain that he almost crashed into). Morgan and Adam were engulfed by the Centre's biological matter in which the later detonated his warheads in self-sacrifice. Before Ace made a similar last stand as Nathaniel, he was saved at the last moment by Jordan, who became the Green Lantern, and his warhead was enough to harm the Centre. After escaping from the Centre, Morgan and Jordan witnessed the weakened creature making its last attempt in destroying everyone on land. Morgan was necessarily dumped into the sea by Jordan as he himself used his power ring to drag the Centre far into space where it safely exploded. Morgan later celebrated with the other heroes over their victory after Superman was returned safely alive.
- In the animated adaption of Justice League: The New Frontier Kyle "Ace" Morgan was voiced by John Heard.
- 7 Appearances of Kyle Morgan (Earth-21)
- 7 Images featuring Kyle Morgan (Earth-21)
- 1 Quotations by or about Kyle Morgan (Earth-21)
- Character Gallery: Kyle Morgan (Earth-21)