Guardians of the Universe

Origins
The Guardians of the Universe evolved on the planet Maltus, and were possibly the first intelligent life forms in the Universe. At this time they were tall greyish blue humanoids with black hair. They became scientists and thinkers, experimenting on the worlds around them. One experiment led to the creation of a new species, the Psions. In a pivotal moment, billions of years ago, a Maltusian named Krona used time-bending technology to observe the beginning of the Universe. This experiment flooded the beginning of the Universe with entropy causing it "to be born old".

Feeling responsible for this, the Maltusians relocated to the planet Oa (at "the center of the Universe") and became the Guardians. Their goal was simple: combat evil and create an orderly universe. And they acted quickly on that goal. During this period they also changed to their current appearance.

Modern History
The Guardians were almost wiped out when Parallax took control of Hal Jordan, the only survivor being Gantht. They sacrificed themselves to create one final power ring, a power ring perhaps more powerful than all others before it. Oa was itself destroyed in a battle between Parallax and Kyle Rayner, but rebuilt as the final wish of Hal Jordan's former power ring. The Guardians were restored when Kyle Rayner, as Ion, recharged the central battery. Rayner lost his power and role as Ion but this sacrifice released all the Guardian's life forces from the dormancy in his ring. The immortals first appeared as children but aged quickly and many seemed to return to the identities they had before they created Kyle Rayner's power ring. Unlike before however: the Guardians were male and female, rather than just male. While Kyle had made them children in order for them to grow up and become less cold than their predecessors, this did not work. Instead the Guardians were as cold and manipulative as they were before. Also one of them (Lianna) seemed to revert to the original Malthusian appearance in the process. With their revival they began to rebuild the Green Lantern Corps using veterans to train the new ring-bearers. Kyle Rayner's recent metamorphosis into Ion again seemed to be part of a new Guardian experiment, the evolution of the Corps. Alongside this experiment, the Guardians refortified Oa by creating a planet-wide armour and defensive system to prevent successful attacks against them.

Sinestro Corps War
The Sinestro War forces them to rewrite the Book of Oa and to add ten new laws. They also expelled Ganthet and Sayd from their rank, because they have experienced emotions, which they consider to be not permitted. The first law allowed the lethal force against the Sinestro Corps. During the Sinestro Corps' invasion of Earth, the Guardians decided to reassign Ion to Sodam Yat, a Daxamite who develops Superman-like abilities under Earth's yellow sun.

When the Anti-Moniter begins absorbing the positive matter of Earth, the Guardians joined the battle and unleashed their combined might on the so-called "Guardian of Fear", partly out of anger for being rendered nonfactors during the First Crisis. However, the Anti-Monitor is able hold his own against the combined group, and successfully manages to burn Scar (a female Gaurdian). Fortunately, Green Lanterns John Stewart and Guy Gardner come up with a plan to use Warworld and its mobile power battery as a weapon against the Anti-Monitor, seriously weakening him. Following Superboy-Prime's betrayal of the Anti-Monitor, the Guardians turn their attention to him, and one of the Guardians sacrifices his life to warp Prime out of the New Earth reality by acting as a human bomb. With Hal Jordan's arrest of Sinestro, the re-imprisoning of Parallax, and the supposed deaths of the Anti-Monitor, Hank Henshaw, and Superboy-Prime, the leaderless Sinestro Corps withdraws.

War of Light
Following the Sinestro Corps, the Guardians, at the lead of the increasingly militant Scarred Guardian, decided to take steps to prevent the War of Light from coming to pass. They created a new division called the Alpha-Lanterns, which serves as a sort of "internal affairs" group. The selected Lanterns were subjected to invasive surgery that allows them to store Power Batteries in them and directly links them to the Book of Oa. However, it also appeared to strip the Lanterns of all emotion, a sort of Lantern-Manhunter hybrid. Also, the Alpha Lanterns have a rigid, literal following of the Book of Oa, not allowing circumstances to be included in their decisions. Additionally, the Guardians authorized the use of lethal force against all enemies of the Green Lantern Corps after they detected a surge of red energy of hate on the emotional spectrum belonging to the Red Lanterns.

While this occurs, the Sinestro Corps, though leaderless and fighting off a hostile takeover by Mongul ll, embarked upon a campaign to terrorize the Green Lantern Corps by targeting their families. Additionally, the Zamarons, having long harnessed the violet energy of love, form their own Star Sapphire Corps to spread love throughout the Universe,. The Guardians decided to try a diplomatic mission to dissuade the Zamarons from continuing, where they discover that the Zamarons have captured multiple female Sinestro Corpsmen and crystallized them in an effort to fill their hearts with love. The Guardians request that the Zamarons stop their experiments, but they refused. Recognizing the threat from the Sinestro Corps and the Star Sapphires, the Guardians add a third law forbidding romance or physical relationships between Green Lanterns.

Unknown to the other Guardians, however, the Scarred Guardian had been exposed to the power behind the Blackest Night while she burned at the Anti-Monitor's hand. She no longer sought to protect the Universe, but leave the Green Lantern Corps weakened when the Blackest Night occurred.

When the Guardians discovered that not only had Atrocitus harnessed the red light of rage, but Ganthet and Sayd had harnessed the blue light of hope and created their own Blue Lantern Corps in which it displeasure the Guardian to declaring Ganthet and Sayd's actions tantamount to treason; in which the Guardians even went far as to attempt to forcibly remove the Blue Ring acquired by Hal Jordan, even resorting to using green light to try and destroy it, only to discover that it would not go so quietly. However, the Guardians soon learned that Green Lantern Stel had been attacked on the outskirts of the Vega System, and had been branded with the seal of the Orange Lantern Corps. Soon, a hologram of Larfleeze, also known as Agent Orange and the leader of the Orange Lanterns, burst from the seal and accused the Guardians of sending the Controllers to steal the orange light from him. The Guardians insisted that the Controllers had severed all ties with them billions of years ago, but Larfleeze refused to listen, declaring the treaty between himself and the Guardians null and void. Scar then blasted the hologram and proposed repealing the Vega system ban.The Guardians agreed, but some had reservations on both the plan and Scar herself.