Hawkmen & Shadow-Thieves of Thanagar and Ragnor

The existence of planet Thanagar, orbiting the star sun Polaris, was first revealed to humanity when its law enforcement officers Katar & Shayera Hol journeyed to Earth-One. Their task was to learn from the police of this third world from the sun, which would benefit their people. Adopting the aliases of Hawkman and Hawkgirl using anti-gravity metal to fly, the Hols defended Midway City and their adopted world as a crime-fighting duo, and later as members of the Justice League of America. One of their first foes was Carl Sands, a criminal inventor who became the Shadow-Thief, using his Dimensiometer to become a living shadow.

The invading alien queen Hyanthis had saved the Thanagarians from an Equalizing Plague which stymied their civilization, and demanded to be acknowledged as their sovereign. She then recruited Sands, enlisting him into creating a Shadow Squad, with devices like his own. These shadow men, along with the legion of Wingmen, subjugated this once free world under her authoritarian rule. Hyanthis was opposed by the Halls, who were then exiled from the planet of their birth until they liberated it some time after. 

However, given the loss of scientific knowledge during the plague, the Wingmen were replaced by the remaining Shadow Squad, which launched a Shadow War on Earth-One. Their goal, to steal both the anti-gravity and other technology now lost to them, which Hawkman and Hawkgirl possessed.

The inhabitants of Thanagar's dimensional twin planet ventured to Earth-Two over a thousand years before this, founding a city in the Sahara Desert near Egypt named Ragnor in honor of their homeworld. These birdmen brought with them Nth metal which had anti-gravitational properties, allowing them to glide in the air. Their queen eventually tried to initially conquer England and then the world, and so challenged its hero of the time... the Silent Knight... into battle with her hawkmen. The Knight triumphed over them, and later his descendant Carter Hall rediscovered Nth Metal, first acquired by their earlier ancestor Prince Khufu of Egypt from the birdmen's Ragnor city outpost. 

As Hawkman, he and his girlfriend Shiera aka Hawkgirl joined the Justice Society in battling evil scientist Ian Karkull. Karkull had developed shadow transforming technology after visiting the now-deserted Sahara city of Ragnor (where it was hinted he learned the secret to perform this fantastic feat). Transforming himself and his minions into shadows, Ian twice faced Doctor Fate, who defeated him each time. Later, Karkull attempted to plunge America into chaos, only to be stopped by the Hawks along with the remaining allies of the Justice Society of America. Karkull was seemingly destroyed, while his subservient shadow men merged with the Society members... granting them extended lives!