GREEN LANTERN CORPS: OA

Oa is one of the oldest planets in the DCU. It is the home and headquarters of the Guardians of the Universe, an alien race of blue-skinned, white-haired scientifically powerful humanoids. These aliens have evolved from a planet called Maltus. The Guardians administer their brand of policing the Universe by creating champions know as the Green Lantern Corps, a group of powerful universal police officers. Each member of the Green Lantern Corps is equipped by the Guardians with Green Power Rings and a Green Lantern Power Battery with which to charge the rings. Oa was chosen to be the headquarters of the universe, because it is said by the Guardians that it lies in the center of the universe if we imagine the universe as a sphere. This sphere is divided equally into segments all leading to Oa and those are the patrolling sectors of the Green Lantern Corps.

Oa appears to have no indigenous life. The plant of Oa's only features are what the Guardians have created on its surface.

During Emerald Twilight story arc, the Guardians of the Universe sacrificed themselves to create one final power ring. This power ring is extremely powerful and may be the strongest power ring held by a Green Lantern. This Power Ring was given to the "Torch-bearer" Kyle Rayner. The legendary Green Lantern Corps member Hal Jordan, the Green Lantern of sector 2814, who has now gone rogue under the influence of the evil entity Parallax, killed all but one of the Guardians, Ganthet, and most of the Corps before draining Oa's Central Power Battery of its energy. The planet is later destroyed during a battle between Jordan and his successor, Green Lantern Kyle Rayner.

What was the remains of the planet Oa served as a base of operations for the villain Oblivion during the Circle of Fire story arc.

In the graphic novel Legacy: The Last Will and Testament of Hal Jordan Oa is rebuilt as the final wish of Hal Jordan's former power ring. The Central Battery is recharged and the now resurrected Guardians promote Kyle Rayner to the near-omnipotent Ion, solidifying him as the Torch-Bearer and a key element to Oa.

The Guardians later decide that the Green Lantern Corps is not enough protection for the plant Oa. Now fortified by creating a planet-wide armor and defensive system to prevent attacks, Oa can defend itself. The outer shell is eventually destroyed by the Scarred Guardian in order to make Oa vulnerable for the coming of Blackest Night.

In the 31st Century Oa is a barren wasteland with only one Green Lantern, Rond Vidar, and one Guardian, Sodam Yat, remaining. When Rond Vidar is killed during the events of Legion of 3 Worlds, a downtrodden Yat believes this is the end of the Corps because he has not been able to recreate the Green Lantern Corps for a long time. Eventually he regains the Willpower to restart the Corps, reigniting the Central Power Battery and sending the inert rings out into the universe to find suitable bearers.