Hans Von Hammer was an aristocrat and hunter who was employed by the German government into becoming what was termed by his opponents an "Enemy Ace". a masterful pilot who would defend the skies against opposing forces in his bi-plane. Doctor Charles McNider, after sustained permanent injury to his optical nerves following an explosion during a surgical procedure he was performing, learned he had the ability to see in darkness when an owl crashed through his home's window. Devising infra-red goggles allowing him to see in daylight, while his own vision adapted to grant him sight in total darkness, Charles developed weaponry to aid him in his costumed career as Doctor Mid-Nite.
On one occasion, the Lord of Time plucked Von Hammer from his native time period along with four other historic heroes into the late 20th century to opposed the Justice League and Justice Society. During this adventure, Hans met Charles in their costumed alter egos, initially opposed to one another yet heroically fighting the Lord, although not side-by-side. And interestingly, at one point in the modern era with Doctor Mid-Nite was grappled in a net by alien adversaries, his "closest counterpart" on Earth-One Batman was likewise affected. How could this be, since Von Hammer was McNider's doppleganger on that world? By that point in time, the Enemy Ace had died, although his heroic legacy was passed on to Batman as shown in an air duel he had with the alleged descendant of Hans.
In a third universe, the counterpart to both Enemy Ace and Mid-Nite was the fellow aviator Captain Midnight, who blended the best of both of his cosmic twins. A masterful inventor clad in his own stylish goggles like Von Hammer and McNider, Jim Albright made a legend of his exploits alongside his Secret Squadron, even occasionally aiding fellow heroes of Earth-S such as Spy Smasher.
However, the counterparts of Space Ranger's ally Cryll and girlfriend Myra Mason were the owl known as Hooty and Myra Mason. While Cryll was an intelligent shape-shifting creature from another world, Hooty was an intelligent owl of Earth-Two who aided Doctor Mid-Nite. And Mid-Nite had the beautiful Myra Mason who loyally supported both of his identities as had her identical twin on Earth-One, although the future Myra knew that Rick Starr was the Space Ranger while the original Myra never connected the dots between Doctors McNIder and Mid-Nite... despite their multiple cases together. Nevertheless, both lasses were fine personal assistants to the pair throughout their careers and carried a torch for the masked men.