The Green Lantern Corps was a group of interstellar peacekeepers created by the Guardians of the Universe to keep order. At one time the group numbered 3600 strong, but in recent years and through a number of tragedies that number has dwindled.

The Guardians of the Universe are a group of incredibly advanced aliens who live on the planet Oa. The males of this race are short and blue with white hair and for years were the only members of the race that were ever seen. Their females split from the males for many years and lived on another planet. They were of average human stature and had an affinity for purple. The male Guardians mentally give off an unknown type of green energy. They are able to manipulate this energy for a number of purposes, creating whatever they can imagine. The strength of the energy construct is based upon the willpower of the wielder.

In the past, a member of the Guardians built a machine that would allow him to see the beginning of time. This experiment was forbidden by the other Guardians, but he proceeded with his experiment. In doing so, the Guardian caused the universe to split into an infinite number of universes all proceeding from that one point. In this, the multiverse was formed.

The Guardians sought to undo the wrong they felt their race had committed by creating a cosmic police force. Their first attempt was a group of super-powered androids called the Manhunters. The Manhunters had the ability to tap into the green energy that the Guardians created. The Manhunters eventually became a force for evil, having strayed from their original programming. The Guardians deactivated most of the Manhunter robots, but some escaped and those multiplied and sought to control the universe, later bringing them into conflict with the heroes of Earth.

The Guardians tried a second time to create a cosmic police force, this time arming the bravest members of races in the universe with rings powered by the green energy that the Guardians made. This group became known as the Green Lantern Corps. The Guardians originally split the galaxy up into sectors, with one Green Lantern per sector. Later, they ditched this plan and allowed the Green Lanterns to travel as they wished.

The power rings worn by the Green Lantern Corps members hold a charge equal to the time period of one day on the wearers native planet. After the prescribed time, the wearer has to recharge the ring using a lantern shaped device that is linked to the central power battery on Oa. Due to a flaw in the central power battery's design, the ring's energy is unable to affect any object that is yellow.