Oa

In-Game History
Feeling responsible for the actions of Krona, who might have caused the creation of the original Multiverse, the race of powerful humanoid Maltusians relocated to the planet Oa, one of the oldest planets in the universe, and became known as the Guardians of the Universe. Their goal was simple: combat evil and create an orderly universe. Oa now serves as the home and headquarters for the Green Lantern Corps.

Oa is a desert-like, lifeless planet, with its main feature being the Guardian's city; headquarters of the Green Lantern Corps and the location of the Green Lantern Central Power Battery. When Hal Jordan was under the influence of the entity Parallax, he drains Oa's Power Battery, kills all but one of the Guardians and most of the Corps. What remains of the planet served as a base of operations for the villain Oblivion later. The planet is reformed sometime later by Jordan's old friend and associate Tom "Pie-Face" Kalmaku. The Central Power Battery is later recharged by Kyle Rayner and the Guardians resurrected shortly thereafter by Kyle Rayner after he spends some time as the near-omnipotent "Ion".

After attacks by Superboy-Prime and the Spider Guild, the Guardians fortify Oa by creating a planetwide armour and defensive system to prevent attacks.

Trivia

 * Oa's star is called Sto-Oa (the Light of Oa) by the children of the planet's inhabitants.
 * Oa was formerly located at the centre of the Universe until the events of Infinite Crisis.