Green Lantern Corps

History
The Green Lantern Corps are an inter-galactic police force dedicated to protecting sentient life in every form, established thousands of years ago by the Gaurdians. Officers are chosen for their ability to overcome great fear and given a Power Rings fueled by the strength of their willpower, the mightiest weapon in the universe. They have two representatives for each of the 3,600 sectors in the known universe, their headquarters located centrally on the planet Oa.

Origins
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 Gaurdians of the universe and enemies of evil after one of their own, the renegade 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 Universe (and the creation of the Monitor), which eventually led to the rearrangement of Time itself, as seen in the Crises 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. They would later found the Darkstars organization. The female Oans, feeling no need to involve themselves in the situation, also left, becoming later known as the Zamarons.

First Officers
To enforce their will and guard against alien menaces of all sorts, the Guardians had created a legion of robotic sentinels called the Manhunters about 3.5 billion years ago. The Manhunters eventually came to resent their servitude and were also viewed as flawed due to their inability to recognize and/or feel fear at all. They rebelled against the Guardians and fought a millennia long war that culminated with an attack on the planet Oa. Ultimately, the Guardians overcame their android servants, stripping them of their power and banishing them across the universe. Eventually, they formed their own robotic society where they pursued their own agenda (which often included interfering with and foiling the plans of the Guardians).

Creation of the Green Lantern Ring and Corps
Chastened by the failure of the Manhunters, the Guardians decided that their newest force of soldiers for good would consist of living beings, ones who had free will and strong moral character. To arm this new legion of celestial knights, the Guardians created the Power Rings, rings of inconceivably-advanced technology that allowed their wearers to project green beams of energy with which the bearer could conjure objects of any size or shape, limited only by his or her imagination and willpower.

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 believed 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 3,600.

Crisis and Aftermath
Both the Corps and the Guardians suffered casualties during the Crisis on Infinite Earths. The Guardians' failure to take appropriate action during the Crisis led to their decision to depart Oa in the company of their female counterparts, the Zamarons. Left to their own devices, the Corps underwent a major reorganization. A team of Green Lanterns led by Hal Jordan was stationed on Earth, and the system of assigning one Green Lantern to a sector was temporarily abandoned. The decision of the Corps to execute Thaal Sinestro resulted in the activation of a previously unknown fail-safe that depowered the rings of every Green Lantern except for Hal Jordan, Guy Gardner, G'nort and Ch'p.

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.

Fall of the Corps
The Green Lantern Corps patrolled the DC Universe for over three billion years. In that vast length of time, some Green Lanterns rebelled and fell into evil. A rogue Green Lantern, Universo, was briefly shown to exist in the future epoch of the Legion of Super-Heroes, but multiple retcons have long since eliminated this possible future. Two of the most important rebels were Sinestro, the rogue Green Lantern, and Hal Jordan, driven insane over the loss of his home, Coast City, and possession by Parallax.

The Green Lantern Corps ranks were decimated by Hal Jordan during his madness, its power source, the Main Battery, extinguished; and Oa 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.

Rise of the Corps
Recently Oa was reconstructed by Hal Jordan's old sidekick Tom Kalmaku, and shortly thereafter Kyle Rayner, the last remaining Green Lantern, resurrected the Guardians as children using the power Parallax had stolen. The resurrections did not stop there. It was discovered that Hal Jordan had committed his crimes while possessed by the ancient fear parasite Parallax. Parallax had been imprisoned within the Central Power Battery for billions of years and is the mysterious "Yellow Impurity" within the Corps' green light that leaves them vulnerable against yellow. Once Parallax had been exorcised, the now adult Guardians re-imprisoned Parallax. With that, the Guardians continued the re-construction and expansion of the Corps. The new Corps, under the training of Kilowog, Kyle Rayner, Guy Gardner and other veterans, was primarily filled by new recruits. Only a handful of veteran Lanterns are back in the ranks. Each sector will have two Lanterns assigned to protect it. Due to an ancient pact with the Spider Guild the Vega star system is off limits to all members of the Corps.

With 3600 sectors and two Green Lanterns per sector, it will be many years before the Green Lantern Corps regains its former strength. 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 it currently unable to intervene in situations it might have before Parallax destroyed the old Corps, including conflicts such as the Rann-Thanager 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, the sentient planet and Corps member, positioned himself to act as a final battleground between Superboy-Prime and the two Supermen. The Corps took responsibility for imprisoning Superboy-Prime, 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, as "constant is taken to the most literal sense of the word: there is no sleeping, consuming of nutrition, excremental waste, or talking, as the Ring is to supply and maintain all bodily functions. Guy Gardner was sentenced to a month of such duty for one of his frequent rules infractions.

Blackest Night Event
Hidden in the Book of Oa is the forbidden chapter of Cosmic Revelations, which contains a prophecy called the "Blackest Night". In the prophecy, seven different colored corps are at war with each other, eventually destroying one another 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 create the Alpha-Lanterns and reveal new laws they've written to the Green Lantern Corps.

During the Blackest Night, the Guardians finally realize the accuracy of the prophecy and are imprisoned by the Scarred Guardians; who launches an attack on the Corps by reviving deceased members as Black Lanterns. Command falls to Guy Gardner, Kyle Rayner, and Salaak, a senior Lantern holding the rank of Clarissi.

The Green Lantern Corps is forced to make an alliance with the Sinestro Corps, the Red Lantern Corps, the Indigo Tribe, the Blue Lantern Corps, Agent Orabge, and the Star Sapphires to fight the Black Lanterns to maintain peace and order across the universe.

The leader of the Black Lanterns is revealed to be Nekron, the physical manifestation of death. Nekron's plan is to find the White Entity, the physical embodiment of life and destroy it, thereby destroying all life in the universe.

The Blackest Night ends when Hal Jordan, merged with the White Entity, and the recently created White Lantern Corps defeat Nekron and banish him from the realm of the living.

War of the Green Lanterns
fter the Blackest Night, Hal Jordan forms a loose alliance with Carol Ferris, Atrocitus, Sinestro, Larfleeze, Saint Walker and Indigo-1 to find and protect the emotional entities, who have been kidnapped by a mysterious villain. The kidnapper is revealed to be Krona, who is also revealed to be the one who caused the Manhunters to go on a rampage in the first place.

Carol, Sinestro, Atrocitus, Saint Walker, Larfleeze and Indigo-1 are trapped within the Book of the Black. However, Hal escapes and takes their rings. Krona begins the next stage of his plan, using the Guardians as the entities's hosts. He also places Parallax back into the Central Power Battery, restoring the yellow impurity and brainwashing all the Green Lanterns into serving him. However, Hal, Kyle Rayner, John Stewart, Guy Gardner, and Killowog have a measure of resistance, due to their previous experience with fear. The other Lantern unaffected by the yellow impurity is Ganthet.

Killowog is captured by Krona, and his resistance to brainwashing overcome. To prevent Krona from controlling them, the Earthmen take off their Green Lantern rings and put on the rings Hal rescued from the Book of the Black. Hal takes the Sinestro Corps ring, Guy takes the Red Lantern ring, John takes the Indigo Tribe ring, and Kyle takes the Blue Lantern ring. Hal, John, Guy and Kyle go to the Central Power Battery to remove Parallax and restore the Corps to normal. However, an ambush from the brainwashed Lanterns separates the group. Hal and Guy end up captured by the Guardians, while Kyle and John travel to Mogo with the intention of freeing it from Krona's control.

However, John and Kyle are attacked by Lanterns while they travel to Mogo's core. John harnesses the Black Lantern energy left in Mogo and uses it to destroy Mogo. This allows Hal and Guy to escape from Krona's forces and re-group with John and Kyle. The four Lanterns and Ganthet go to the Battery, where Hal wields the Agent Orange ring while Guy wields the Star Sapphire ring. Hal, John, Kyle and Ganthet fight the brainwashed Lanterns while Guy removes Parallax from the Battery, restoring the Corps.

With the impurity removed, Hal, John, Kyle and Guy recover their Green Lantern rings and join the Corps in the final battle against Krona and the entity-possessed Guardians.

During the final struggle, Hal and Kyle free Carol, Sinestro and the others from the Book of the Black. Also, Sinestro becomes a Green Lantern once again. Hal kills Krona, releasing the entities from the Guardians. However, the Guardians believe Hal to be the most dangerous Green Lantern, so they discharge him from the Corps.

Post Flashpoint and Aftermath
The status of the Green Lantern Corps remained unchanged by the universal alteration after the Flashpoint event. As of 2011, Sinestro is still an unwilling Green Lantern, Hal remains exiled, Kyle has gone AWOL alongside six members of the other Lantern Corps, John is arrested by the Alpha Lanterns for killing a Green Lantern who was about to give in to torture the access codes to the Oan defense network from the Keepers. Guy remains as the only Earth Lantern with a stable position on the Corps.

The Guardians currently consider the Green Lantern Corps a failure and are planning to replace it with a mysterious "Third Army," which will be led by the mysterious "First Lantern." Since they need the Book of the Black to find the "First Lantern" they begin a search for the book and have already shown they are willing to kill to get it.