A Thanagarian was a member of the native race of the planet Thanagar. A warlike people, they were recognizable by a pair of large, feathered, flight-capable wings on their backs, but were otherwise indistinguishable from humans.
The people of Thanagar once worshiped a pantheon of extradimensional entities known as The Great Old Ones. At that time, Thanagar was a harsh world and theirs a primitive and savage culture; in return for offerings made to him, the Old Ones' leader, Icthultu, gave the Thanagarians agriculture, mathematics, and philosophy — the foundations of their entire culture. As they matured, however, the Thanagarians stopped worshiping them — modern-day Thanagarians bow down to no higher power. Their knowledge of the Great Old Ones was used in the creation of their personal weaponry. For this reason, their Nth metal weapons — such as Hawkgirl's mace and Hro Talak's battle-axe for example — have mystical properties and can work against Green Lantern's power ring or Superman's invulnerability.
Around 6600 B.C., a pair of Thanagarian law enforcement officers crash-landed on Earth — specifically, the region known as Egypt — and were left stranded. They soon came into contact with the region's native inhabitants, who worshiped them as gods. The two of them used their newfound positions of power to unite the surrounding lands in hopes of bringing peace and prosperity to Earth.
Centuries later, a delegation of Thanagarians arrived, under the command of General Hro Talak, who requested an audience with Earth's leaders. He informed them that for generations, the Thanagarians had been locked in bloody war with a race known as the Gordanians, who had set their eyes on Earth. The Thanagarians offered to construct a planetary-wide force field in order to aid Earth and its inhabitants against the impending threat. In reality, the force field was actually a Hyperspace bypass generator that would allow the Thanagarians access to the Gordanian homeworld, so as to lead a direct assault on the planet, resulting in a quick and decisive victory; however, the force of the bypass opening would lead to Earth's destruction. The Thanagarians soon launched a full-scale invasion of Earth, establishing martial law and depriving citizens of legal rights. Though the invasion was initially successful, their plans were ultimately spoiled by the efforts of the Justice League, who destroyed the bypass; with its destruction, the Thanagarians left Earth as there was no point in staying. When they returned to Thanagar, the planet was already under attack from the full force of the Gordanian fleet. General Hro Talak then ordered his remaining officers to abandon ship before he ran a kamikaze attack on the Gordanian flagship, the subsequent explosion resulting in the destruction of a majority of the Gordanian fleet. However, the general’s sacrifice proved to be in vain, as the remainder of the Gordanian fleet then closed in on Thanagar, securing a Gordanian victory.
The final fate of Thanagar under Gordanian rule remains unknown, but it is known that a resistance movement was formed sometime after. Lieutenants Paran Dul and Kragger — both of whom served under Hro — along with a few other Thanagarians, later left the resistance to pursue Shayera Hol for betraying them.
Despite differences in physiology, Thanagarians were able to have children with humans.