The Green Lantern Corps patrols the reaches of space at the behest of the Guardians of the Universe, a race of immortals as old as the universe, vastly powerful, noble-minded and hyper-intelligent, but also arrogant and obstinately committed to ancient traditions. The Guardians created the Green Lantern Corps some three billion years ago and the force has survived multiple rebellions, murders and collapses from within and outside. The Guardians administer the Corps from the planet Oa at the center of the universe. The Guardians divided the universe into 3,600 “sectors” and choose two natives of each sector to serve as that sector's protectors. Thus the Corps holds 7,200 members, plus additional numbers serving in roles not linked to particular sectors (such as drill instructors and the honor guard). Each Green Lantern is given a power ring, a fantastic weapon and artifact granting the bearer incredible power limited only by their willpower.
In the early days of the universe, natives of the overpopulated planet Maltus evolved into immortals of great power. They subsequently settled the planet Oa and declared themselves the Guardians of the Universe and enemies of evil after one of their own, the renegade Maltusian scientist Krona, performed a forbidden experiment that had terrible consequences for the universe at large.
Exactly what those consequences were have varied with different versions of the stories; originally, it was supposed to have unleashed evil in the first place. Later, it was attributed to have created the Antimatter Universe of Qward. Later still, it was used as the explanation for the existence of parallel universes in the DC Multiverse (and the creation of the Monitor), which eventually led to the rearrangement of Time itself, as seen in the Crisis on Infinite Earths. Finally, it has been stated that it accelerated entropy, shortening the duration of the universe by a billion years.
Some of the Guardians, however, disagreed on how to deal with the chaos that had been unleashed. One group, calling itself the Controllers, separated itself from the others and favored using more violent methods to achieve their ends (a later interpretation says they left over a disagreement on how to use the Manhunters - see below). They would later found the Darkstars organization. The female Maltusians, feeling no need to involve themselves in the situation, also left, becoming later known as the Zamarons.
In their first attempt to enforce their will and guard against menaces of all sorts, about 3.5 billion years ago the Guardians created a legion of robotic sentinels called the Manhunters. At first serving faithfully to enforce order, in time the Manhunters came to resent their servitude and the moral restrictions the guardians decreed of them. They were also found to be inherently flawed due to their inability to recognize or feel emotions. They rebelled against the Guardians and fought a millennia long war that culminated with an attack on the planet Oa. The Guardians overcame their android servants, stripped them of their power and banished them across the universe. Eventually, the surviving Manhunters formed their own robotic society and pursued their own interpretation of their original mission (which often included interfering with and foiling the plans of the Guardians).
In the Martian Manhunter series, the Guardians first get the idea for an intergalactic police force from the Martians' own Manhunters. They offer the Martian race the opportunity to be that force. They turn it down, but the Guardians take the name for the androids.
Although the connection between the Guardian Oans and the origin of the Green Lantern symbol has yet to be clarified, it has been revealed that the lantern itself has its roots in the first life in the universe. Allegedly, the first life in the galaxy emerged on an unnamed foggy world, and when they developed a police force - the first in the universe - the constabulary carried a lantern lit with a green chemical flame, hence a corp of Green Lanterns. It is intimated that this ideal was adopted and spread throughout the galaxy as a symbol for law and justice and its ability to pierce confusion and uncertainty, eventually resulting in the formation of the Green Lantern Corps, with requisite Power Rings and Lantern-shaped batteries along traditional lines. Initially consisting of only a few dozen agents at a time, the Corps radically increased its numbers approximately 1000 years ago. The Guardians sought to bring order to the planet known as Apokolips. Home to Darkseid, a galactic tyrant, Apokolips was and is a stronghold of evil. Green Lantern Raker Qarrigat sought to remove Darkseid from power, only to be humbled by Darkseid's might. Raker returned to Oa, where he convinced the Guardians that taking Apokolips would require an army. Authorized to start a massive recruitment, Raker and his fellow Lanterns inducted thousands of new members, bringing total membership up to 3600.
The Guardians eventually returned to Oa and began the reconstruction of the Corps, assigning Guy Gardner to Earth, John Stewart to the Mosaic World, and Hal Jordan to recruit new members. Ironically, Jordan himself would eventually be responsible for destroying the incarnation of the Corps that he had helped create.
The Green Lantern Corps ranks were decimated by the Parallax-possessed Jordan. The Corps' power source, the Central Power Battery, was extinguished; and Oa was destroyed, removing the original power source for the rings.
After the fall of the Corps, other organizations tried to fill in the power vacuum left by the Guardians. Two organizations had initial notable successes: the Darkstars and L.E.G.I.O.N. However, neither ever achieved the power and reach of the Green Lantern Corps.
The Lost Lanterns were members of the Corps at the time Parallax overcame Hal Jordan, and made up the group that was trying to stop Parallax from reaching Oa. Parallax defeated them in space and left them for dead (they were most of the GLs that were popular and well-known to readers at the time, which made Hal's/Parallax's actions all the more controversial). After Parallax destroyed the Corps, they were assumed to be dead, so all the time that Kyle was GL, nobody was looking for them. As it turns out, instead of being dead, they were captured by the Manhunters and taken to Biot, the Manhunter homeworld in Sector 3601. They were used in various experiments to design and power new Manhunter models. They were eventually found and rescued by the resurrected Hal Jordan (who was after a new Manhunter who had come to Earth) and Guy Gardner, and they re-joined the Corps. They've had some trouble getting over their captivity, and still more or less blame Hal for it. They each have their own sectors, but tend to stick together when on Oa.
With 3600 sectors and two Green Lanterns per sector, it may be many years before the Corps can regain its former strength, as it presently lacks both the manpower and the political influence it once had due to its years-long absence from many sectors. This has left the Corps currently unable to intervene in situations it might have before Parallax destroyed the old Corps, including conflicts such as the Rann-Thanagar War. The Guardians remain staunchly uninvolved in what they see as a conflict that could destabilize many sectors, but that has not stopped Kyle Rayner and Kilowog from helping refugees.
Despite these difficulties, the Corps played a key role in defeating Superboy-Prime. Several Lanterns were killed slowing the renegade Superboy's advance on Oa, a sacrifice that enabled Earth's most powerful heroes to execute their plan to restrain him. Mogo, a sentient planet and Corps member, positioned himself to act as a final battleground between Superboy-Prime and two Supermen. Responsibility for imprisoning Superboy-Prime was undertaken by the Guardians who charged the Corps with its undertaking, incarcerating him inside a small red Sun-Eater with fifty Green Lanterns on constant guard duty. "Prime Duty" is considered one of the lowlier functions of the Corps, and Guy Gardner was sentenced to a month of such duty for one of his frequent rules infractions.
As of the "One Year Later" timeframe, the Green Lantern Corps had increased its numbers, with many former trainees now full-fledged officers. A lack of truly experienced GLs remained an issue, with Guy Gardner being called upon often to assist the rookies.
Rogue Green Lantern Sinestro, working with the Anti-Monitor, has created his own version of the Corps. Dubbed the "Sinestro Corps", it recruits beings capable of generating great fear. Armed with yellow Power Rings and Lanterns manufactured on Qward, the Sinestro Corps recently staged an attack on Oa, killing dozens of GLC officers, kidnapping Kyle Rayner and freeing Superboy-Prime, Parallax and the Cyborg Superman from the Corps' supervision.
As the Sinestro Corps' campaign of terror spreads, the Guardians, in desperation, rewrite the first Law of Ten in the Book of Oa, enabling the remaining Lanterns to use lethal force.
Hidden in the Book of Oa is the forbidden chapter of Cosmic Revelations; In Cosmic Revelations is the prophecy called the "Blackest Night". In the prophecy, seven different colored corps are at war with each other and will eventually destroy each other and the universe.
Following the Sinestro Corps War, Ganthet and Sayd are banished from the Guardians. Realizing that the "Blackest Night" prophecy will come to be, they create a blue ring powered by hope. The remaining Guardians have created the Alpha-Lanterns and will be revealing the new laws to the rest of the Green Lantern Corps as time goes on.
The seven corps involved in Blackest Night include:
Further complicating matters is the Black Lantern Corps. The Black Lantern power rings reanimate the dead and draw power from a Central Power Battery that contains the Anti-Monitor. The Black Lantern power rings bear the symbol of Black Hand. It remains unknown by what emotion they are powered, or who is in control of the group.
The specific arrangement of the sectors has changed over the years. If the universe is viewed as a sphere (or oblate spheroid), the sectors were originally described as wedges of that sphere, each 1/10 of one degree wide. This effectively meant that each Lantern had a sector of infinite size, since the universe is theoretically infinite. Later, sectors were described as being of non-standard location and size. A large area of vacuum between galaxies might be one large sector, while a galaxy like the Milky Way may comprise several sectors. The latest description amends the original one - sectors are now a one-degree by eighteen-degree section of the sphere-shaped universe, with the origin points meeting at Oa, which is located at the center of the universe. While this still results in an infinitely-sized sector, is not as spread out. Since the sectors all meet and begin on Oa, this means that Oa is in every lantern's sector, and while a Lantern is on Oa, he is technically still patrolling his home sector.
Each member has a great deal of autonomy as to their methods in their jurisdiction, subject to review by the Guardians if they feel the Green Lantern in question has abused their assigned authority. The individual Lanterns are responsible for arranging their replacements (when possible) if they are near retirement or death. If a Lantern dies before that obligation is met, the ring will find and seek another to be trained on its own, It is recently reveled Mogo plays a key role in this. Which is why the sinistro corps tryed to destroy him. In rare circumstances, Guardians will personally go out into the field to recruit a replacement.
Upon recruitment each Green Lantern in the original Corps received a Power Ring, a Power Battery shaped like a lantern (with which the ring is recharged), and a uniform. The default uniform design for humanoids was a green section covering the torso and shoulders, black arms and leggings, green boots, white gloves, green domino mask and a chest symbol of a stylized Green Lantern icon on a white circle. Lanterns were allowed to customize their uniforms as long as the color scheme and the symbol were present. When the nature of the being precludes a standard uniform, an equivalent arrangement is expected as a substitute. For instance, Mogo, a sentient planet, arranges his foliage to create a green circling band and lantern symbol on his body. Jack T. Chance, a humanoid, refused to wear a uniform, but conceded to wearing a badge on the lapel of his coat. Lanterns were also allowed the option of a secret identity as a security measure and it is implied that the Corps were instructed to honor that choice by taking care not to expose them. Training in the use of the ring was optional and appropriate facilities and personnel were available on Oa upon request. In addition, a senior Lantern can be assigned to coach a recruit while in the field in their sector.
The New Green Lantern Corps being built by the Guardians is far more formal and structured than the old one that was destroyed by Parallax. Recruits, after being found by their Power Rings, are taken to Oa for training. Not all recruits will make it through training - indeed a great many of them might even fail, forcing the ring to find another candidate. Lantern trainees have a simplified version of the old Green Lantern uniform (with green covering more of the torso) with the white circle on their chest blank, presumably until the Lantern insignia is added upon completion of their training. Additionally, all Power Rings, not just Kyle Rayner's ring, now work on the color yellow, provided the user can feel the fear behind the color and overcome it.
Upon recruitment, a Green Lantern is expected to uphold certain principles of their duty. These principles include:
To enforce these principles, the Guardians closely monitor the activities of the Lanterns. If they feel a violation of Corps regulations has occurred, they will summon the offender to Oa and hold a trial in which the charges are read and the Lantern is allowed to explain their actions. If the Guardians are not satisfied by the explanation, they have a number of disciplinary options which include:
Green Lantern Corps headquarters are on the planet Oa, in the center of the universe. Oa was destroyed shortly after Hal Jordan became Parallax, but was later reconstituted by Jordan's friend Tom Kalmaku. Formerly a natural if barren planet, the reconstructed Oa is now a vast labyrinthine planet-sized construct. Primary features include a great hall for the Guardians to meet in conference, training facilities for recruits, prisons called Sciencells for dangerous criminals, and tombs dedicated to honoring fallen lanterns. Oa's most prominent feature is the Central Power Battery, a gigantic version of the Lanterns' personal power batteries. The central battery channels the same green energy of the Guardians and amplifies it, broadcasting energy to the individual power batteries across the universe which can then be used to charge the Lanterns' power rings. Particularly dangerous beings, such as Sinestro or Parallax, are sometimes imprisoned within the central battery. Maintaining security on this device is vital as major damage to it would prevent individual Corpsmen throughout the universe from recharging their power rings, thus depowering the entire Corps in a single blow.
The Guardians recently increased the capabilities of Oa's defensive systems by creating an armored structure that protects the planet.
"The Corpse" is an elite, top-secret Black Ops division of the Green Lantern Corps. Members of The Corpse are not restricted by the same rules that regular Lanterns follow, and they perform the darkest, most dangerous missions. These members do not use Power Rings; instead, they swallow special coin-like disks that give them all of the powers of the standard ring for a limited time. These disks produce purple energy instead of the traditional green. Members of the "Corpse" do not wear Green Lantern uniforms, or display the Green Lantern symbol. Instead, they seem to prefer black uniforms that have no symbol. They are also not bound to rules such as the restriction of using lethal force like the main Green Lantern Corps, though since The Sinestro Corps War, the main Green Lantern Corps have been enabled use of lethal force against Sinestro Corps members, and later all enemies of the Green Lantern Corps.
Very few Lanterns are even aware of the existence of the "Corpse". Guy Gardner said that in all of his years in the Corps, he never heard of them and after participating in a mission with the Corpse, his memory of them was erased. With the recent authorization of lethal force for the Corps in the aftermath of the Sinestro Corps War, the future and necessity of the Corpse remains unknown.
After the Sinestro Corps War, the Guardians create a new class of Green Lantern called the Alpha Lanterns. The Alpha Lanterns are seasoned Corpsmen who have been fused with their Power Rings and Batteries. Boodikka, Varix, Kraken, Green Man and Chaselon are all confirmed Alpha Lanterns; Hal Jordan is notably not chosen, and John Stewart is chosen but he declines the position. Geoff Johns stated in an interview with IGN that the Alpha Lanterns function as Internal Affairs for the Green Lantern Corps - Hal Jordan refers to them in the same manner. They have "the sentient drive and thought process of the Green Lanterns and the efficiency and logic of The Manhunters," as the Guardians turn them into cyborgs using Manhunter technology, and mainline their minds directly to The Book of Oa and the Central Battery. After the transformation, an Alpha Lantern would receive an additional power ring and their power battery is surgically implanted into their body so they need never recharge it. Similarly to the most recent generation of Manhunters, Alpha Lanterns have a secondary face which can drain a Power Ring of its energy. The Alpha Lanterns tend to chant the Manhunter-like slogan "No Lantern escapes the Alpha Lanterns."
Laira was the first Green Lantern to be punished by the Alpha Lanterns; for the crime of killing Amon Sur she was stripped of her powers and expelled from the Corps.
The Power ring must be recharged regularly (though apparently not at the standard 24-hour period as was originally described) by touching it to its lantern shaped power battery for a period of several seconds. When recharging their weapons, some Corps members recite an oath. This oath differs from Corps member to member, but the most popular seems to be Hal Jordan's.
The Green Lantern Corps made an appearance in Duck Dodgers in an episode titled "The Green Loontern". After Dodgers accidentally takes Hal Jordan's uniform from the dry cleaners, he is teleported to the Corps location by the ring, where they are in a fight with a large number of Sinestro's robots. During the fight, the entire Corps is kidnapped by Sinestro to act as a power source for a doomsday device. Duck Dodgers manages to save them (more through accident than skill) before giving the uniform back to Hal Jordan and being stranded in Sinestro's hideout.
The Green Lantern Corps appear in a few episodes of the Justice League and Justice League Unlimited animated series, including "In Blackest Night," "Hearts and Minds" and "The Return." Several Corps members also make cameos in the Superman: The Animated Series episode "In Brightest Day," which featured Kyle Rayner.