Most info from Wikipedia:
THE GREEN LANTERN CORPS:
Created by the Guardians of the Universe. They were the first corps to be formed to serve as protectors of all sectors of space. Their power rings are powered by willpower. The Green Central Power Battery is located on the planet Oa. They have their own separate oath:
"In brightest day, in blackest night,
No evil shall escape my sight
Let those who worship evil's might,
Beware my power...Green Lantern's light!"
THE CORPSE:
"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.
THE BLACK LANTERN CORPS:
Little is known about this mysterious Corps other than the fact that it's members will be dead characters from the DC Universe and it will play a very large role in the Blackest Night storyarc by Geoff Johns.
THE SINESTRO CORPS:
Created by Sinestro and the Anti-Monitor. Their power rings are powered by fear. The Central Power Battery is located on the planet Qward. They have recently lost a large cosmic war fought against The Green Lantern Corps and are picking up the pieces. Mongul is currently trying to usurp control of the Sinestro Corps during the aftermath of the recent war. They have their own separate oath:
"In blackest day, in brightest night,
Beware your fears made into light.
Let those who try to stop what's right,
Burn like his power... Sinestro's might!"
THE RED LANTERN CORPS:
Created by the remnants of the Empire of Tears. Their power rings are fueled by rage/hate. Atrocitus is the first to become a red lantern. A former "lost Lantern," Laira, is quickly recruited as well. Another recent member includes Dax-Ur, an alien cat who is the first to attack a member of another corps. Upon putting on a charged red ring, the wearer's heart is destroyed and ejected in vomit, as is the wearer's blood. The ring then pumps liquified rage into the body, which is also ejected through the mouth. Although the Red Lanterns have been seen creating energy constructs most of their energy blasts appear as flame which can burn in space. Much of the designs of the Red Lanterns has been based on making creatures that look brutal. They have their own separate oath:
"With blood and rage of crimson red,
Ripped from a corpse so freshly dead,
Together with our hellish hate,
We'll burn you all--
That is your fate!"
THE STAR SAPPHIRE CORPS:
Created by the Zamarons. Their rings are powered by the violet light of love. The Star Sapphire functions as their Central Power Battery. The first recruit was Miri Riam of the planet Lartnec, who had just lost her husband to an attack by Mongul. The second Star Sapphire to be recruited is the villain Fatality, who has plagued the Green Lantern Corps in the past. It's unknown if they have any oath. As they are on the direct opposite side of the spectrum as Red, it is likely violet rings have great influence over their wearer as well.
THE BLUE LANTERN CORPS:
Created by Ganthet and Sayd. Their rings are powered by hope. Saint Walker is the first Blue Lantern to appear. The second is an elephant like alien monk named Warth. According to Geoff Johns, there will be a Blue Lantern walrus named Baboo. Blue Lanterns appear capable of harnessing the hope of those around them to fuel their abilities, such as reviving a dying star and saving an entire planet by harnessing the hope of the individuals on the planet. Unlike the Green Lanterns, whose constructs are determined by the one creating them, the Blue Lantern constructs are based on the mind of one they are being used on. The Blue Central Power Battery is located on the planet Odym, which orbits what humans call the North Star. Saint Walker indicated that Ganthet and Sayd intend for Hal Jordan to leave the Green Lantern Corps and become the new leader of the Blue Lantern Corps. Much of the designs of the Blue Lanterns have been based on the friendlier looking aliens from Star Wars, in order to make them look more noble as opposed to the aliens from the other corps. They have their own separate oath:
In fearful day, in raging night,
With strong hearts full, our souls ignite
When all seems lost in the War of Light
Look to the stars...
For hope burns bright!
THE INDIGO LANTERN CORPS:
The Indigo Lanterns wield staffs powered by compassion. The wielders resemble shaman and tattoo their bodies with the symbol of their Corps. They didn't make their presence known but they appear to be neutral in the war helping injured on both sides. It remains to be seen if they'll have their own oath and where their Central Power Battery is located.
THE ALPHA LANTERNS:
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 ring and expelled from the Corps.
They have their own separate oath:
"In Days of peace, in nights of war
Obey the Laws forever more
Misconduct must be answered for,
Swear us the chosen: The Alpha Corps!"
AGENT ORANGE:
His ring is powered by avarice (greed) which is being sought by the Controllers. In interviews writer Geoff Johns mentioned a character named "Agent Orange" to appear soon. Much of the designs of the Orange Lanterns has been based on the idea that the forgotten creatures of sector 666 have been warped by greed and thus appear all dishelveled and disgusting as opposed to the scary looking Sinestro Corps, the brutal looking Red Lanterns and the friendly looking Blue Lanterns. It remains to be seen what will be their oath.
THE GUARDIANS OF THE UNIVERSE:
The Guardians of The Universe are immortal beings that evolved to their state of being long before humans were on Earth. They control the Central Battery of OA, The Green Lantern Corps, and The Green Energy. They use these resources to keep order in the known DC Universe.
The Sinestro War forces them to rewrite the Book of Oa and to add ten new laws. (As of March 26th, 2008, only two have been revealed.) They also expelled Ganthet and Sayd from their rank, because they have experienced emotions along with being discovered to have romantic relationship with each other, which they consider to be not permitted.
In the aftermath of the War, both Ganthet and Sayd have evolved into two new beings on a paradise-like planet Odym, where they are harnessing the blue energy spectrum of hope and creating blue power rings and batteries, planning to create another intergalactic police force in order to be able to aid the Guardians and the Green Lantern Corps against "The Blackest Night". The rank of the Guardians has weakened as well, of originally there were twelve of them as Head Guardians, now there are nine of them, after Ganthet and Sayd left Oa, and one Guardian is dead after a battle with Superman-Prime -this Guardian willfully "detonated" himself in an unsuccessful, last-ditch effort to destroy the insane Kryptonian (who wished to destroy the Universe in his own right). A female Guardian has been left scarred by the Anti-Monitor, and the exposure to his antimatter energy may have had dire consequences. Currently, she's searching the Anti-Monitor's body on Sector 650, seeking the powers he possesses. She may be working as a double agent for an unknown cosmic force, or forces; the pupils of her eyes are drawn -strictly for artistic effect and as a visual cue for the reader -as frequently reflecting the "normal" eyes of a Guardian, the Green Lantern icon, the symbol of the Black Lantern, and the badge of the Sinestro Corps; thus far, her fellow Guardians seem unaware of the changes within her, either physical or behavioral (she is far more militant than is normal for the Guardians). In the Origins and Omens backup stories running through several DC releases in February 2009, she is given the official name of Scar.
SCAR:
Scar is one of the Guardians of the Universe. An attack by the Anti-Monitor has left her with a large, distinctive scar on the right side of her head. Since obtaining this scar, she has began to deviate considerably from the traditional personality of a member of the Guardians. She has been depicted as dark and militaristic, with a fascination with the power of death. Her eyes, which usually bear the symbol of the Green Lantern Corps in the pupil, contains the symbols of the Sinestro Corps and the Black Lantern Corps, whose central Power Battery is made from the Anti-Monitor's corpse.
GANTHET:
During the Sinestro Corps War he and a female Guardian named Sayd are banished from the council for embracing emotions, along to have discovered that they have romantic feelings to each other.
Just as Parallax (now back in his monster form) attacks the Lanterns for freeing Kyle Rayner, Ganthet and Sayd, arrive and draw Parallax into four separate lanterns (Hal, Kyle, John, and Guy's, respectively). As Ganthet explains, he and Sayd were kicked out of the Guardians of the Universe. Ganthet's final act as Guardian is to make Kyle a new power ring. He asks if Kyle is willing to downgrade himself to a normal Green Lantern, which Kyle quickly accepts. The four men then take their lanterns and hearing the Sinestro Corps oath, recite the Classic Green Lantern Oath, and depart to confront Sinestro's Corps.
Ganthet and Sayd also explain to the four about the emotional energy spectrum created at the start of the universe that is separated into seven colors: green (willpower), yellow (fear), violet (love), red (rage), indigo (compassion), orange (greed), and blue (hope), each representing different forms of emotion, with green being the most center balanced of the energies. The further at one end an energy color is, the more wild its power is to control, leading to the energy corrupting its user. Ganthet also reveals that in the coming future, each color will have its own forces like the Lantern Corps, and these forces will fight against the others in a battle across the universe that will lead into the event known as "The Blackest Night", the worst of the hidden prophecies of the Book of Oa.
At the end of the Sinestro Corps War, Ganthet and Sayd are currently living on the planet Odym, where they harness the blue energy of hope and make plans to create another intergalactic police force in order to aid the Guardians and the Green Lantern Corps of their upcoming battle against "The Blackest Night" by creating blue power rings and batteries. The first of the Blue Lanterns is an alien named Saint Bro'Dee Walker or Saint Walker. The second is Warth, an elephant like alien from Sector Two. According to Saint Walker, Warth will select another candidate from a different sector of space and the process will continue from there
HAL JORDAN:
Leader of the Green Lantern Corps in the majority of Corps Members' eyes as well as Earth's. A founding member of the Justice League of America. He was previously under the influence of the fear based cosmic entity known as Parallax. He has since been freed and rejoined the Green Lantern Corps. His arch-nemesis is Sinestro, leader of the Sinestro Corps; with whom a large cosmic war was recently fought against.
KYLE RAYNER:
After the war he's assigned to the Honor Guard, as Guy Gardner's partner, and sent to counsel Sodam Yat, the new Ion. Kyle and Guy decide to move to Oa, giving them better access to performing their duties. Kyle places his mother's painting on the wall of his new Oan apartment.
The Ion is now stated as unrelated to the Starheart Power given to him by Jade: such sudden spike in powers enabled the Guardians to temporarily bond the Ion entity with Kyle. With the loss of the Ion entity, he's returned to the powers and abilities of a standard Green Lantern.
Since his promotion to Honor Guard, Rayner has acted as a troubleshooter for the Corps. He's recently taken part in two integral missions in this capacity: the defeat of Sinestro Corps member Mongul and the capture of Sinestro Corps member Krybb. Following Krybb's defeat, Rayner and Lantern Soranik Natu expressed their mutual romantic interest in each other. Romance has just recently been declared forbidden between Green Lantern Corps members by the Guardian of the Universe.
GUY GARDNER:
Within the aftermath of the Sinestro Corps War, Guy was finally reunited with Ice, a recently resurrected former girlfriend. Despite Ice's uncertainty as to the wisdom of reviving the old romance, Guy's professions of adoration seemed sufficient to convince her to meet him for a proper date on the same spot exactly one month later.
After debating with himself about where to live, Guy decides to move to Oa, and set up a bar and restaurant called "Guy's Place" (later called "The Big "W""). After much cajoling, Salaak agrees to the proposition. Before leaving Earth, Guy leaves Ice a note.
Guy charging his ring reciting the oath on the mission, when he is interrupted by a knock at the door. Guy opens the door with his typical attitude, where he finds Ice standing in his doorway. She tells him she hitched a ride to Oa with a Green Lantern member named Symon Terrynce, and that she is 14 days early for their date. As they are discussing this, Salaak via the ring interrupts and tells Guy to met with Kyle and Kilowog. Guy tells Ice he has to take this and leaves her standing in Warriors with an, "Of course you do." He'll be back soon, to which she says "And I'll be here."
However, their date doesn't go as well as Guy wanted to: Ice refuses his proposal to cohabitate on Oa, and Guy reads her desire to rebuild a new life on Earth with her best friend Beatriz as an attempt to distance from him, accusing Beatriz of pitting Tora against him. The two agree that their current situations will make a relationship impossible, and Guy has a fellow Lantern escort Tora back to Earth.
JOHN STEWART:
John Stewart was approached by the Guardians to become one of the Alpha Lanterns, a new division of the Corps devoted to the internal affairs of the Corps. Stewart, desiring more information about the secrecy of the forbidden prophecies, declined the offer, to the extreme disappointment of the Guardians.
During the Rage of the Red Lanterns story arc, John Stewart is part of the guard assigned to escort Sinestro to Korugar to face execution. However, the Green Lanterns are ambushed by the Sinestro Corps and then the Red Lantern Corps under Atrocitus. The Green Lanterns are left to die in space after Atrocitus captures Sinestro, but they are saved by Saint Walker of the Blue Lantern Corps. John, however, is infected with the Red Lanterns rage. Saint Walker conjures up a blue energy construct of Katma Tui, who heals John and calms him by showing him a vision of flying with Katma. John laters tells Kilowog that he is going to see Katma again, saying that "the universe said so". In that same issue, Fatality is converted into a Star Sapphire, and orders her ring to locate John Stewart
ION (SODAM YAT):_0001.jpg/200px-Sodam_Yat_(New_Earth)_0001.jpg)
Sodam Yat makes his first appearance in regular DC continuity in Green Lantern Corps #12, and part three of the Sinestro Corps War (Green Lantern Corps #14), when Kilowog gathers a group of Lanterns to strike back against Sinestro's forces attack in Space Sector 2263. Salaak singles out Arisia to keep an eye on the newly graduated Lantern Yat, while she wonders why Sodam is so important. Salaak has been charged by the Guardians of the Universe to keep Qull's prophesy from coming to pass, but keeps this to himself, only saying that one day she may know why he is so special. In Green Lantern Corps #16, Sodam destroys the core of Ranx the Sentient City, ending the battle of Mogo.
In Green Lantern Corps #17 Sodam is chosen as the new host for the Ion entity by the Guardians of the Universe and fights Superman-Prime. The two battle each other fiercely through different areas of New York. Ion begins to unleash Superman-like powers, such as heat vision, to hurt his opponent. While the two trade blows, Ion is thrown into a nuclear power plant. The lead lining the walls causes Ion to weaken. Prime takes the opportunity to spear him with several uranium rods, severely injuring him. Ion tries to escape, only to have Prime knock him into a cemetery. They continue to do battle, each drawing blood from their opponent. Although Ion battles courageously, the lead poisoning and loss of blood begins to affect him and he is beaten unconscious. He is later seen receiving medical attention from Soranik Natu.
After the events of the war, The Guardians request Kyle Rayner assist Sodam in adjusting to his new role. While speaking about Sodam's history and attitude as a Lantern, it is revealed that Sodam must now permanently wear a Power Ring (despite his possession of the Ion powers) to prevent the lead in his body from killing him. They are then attacked by Alexander Nero, who had been freed during the initial assault on Oa but had not participated in the overall Sinestro Corps story. Kyle fights to less than his abilities to encourage Sodam to embrace his status as Ion. Sodam eventually defeats Nero by taking control of Nero's own constructs--something Kyle states that he had never been able to do as Ion.
SINESTRO:
Though the Sinestro Corps is set back, they are not truly defeated. By enacting new laws--including giving the Green Lanterns the ability to kill--the Guardians have played into what Sinestro claims is his overall goal. Now the Green Lanterns spread fear by being unchecked. Hal Jordan and Kyle Rayner beat Sinestro in hand-to-hand combat. Following the finale of The Sinestro Corps War, Sinestro is depicted in the custody of the Guardians, imprisoned in Oa's Sciencells where he learns from Hal Jordan that he has received a death penalty. Despite his personal defeat, Sinestro claims victory, as loyalty to the Green Lantern Corps. Sinestro's overall goal through his war was to groom his former corps for a more active, forceful role in the universe. With the enactment of the corps new laws and the approval of lethal force, the Green Lantern corps will inspire fear, creating the same effect as the Sinestro Corps: order through fear.
With the hunt for the members of the Sinestro Corps becoming one of the Green Lantern Corps' highest priorities, many of those who wield yellow power rings have been incarcerated in Oa's sciencells, with their power rings stored in the large chamber that houses the entire detention facility. Sinestro has been shown to have chewed a very large hole in his finger, and he used his blood to paint the insignia of the Sinestro Corps on his cell window. All Sinestro Corps members followed his example, with the result of thousands of emblems across the cosmic jail. Interestingly, when Sinestro formed his insignia from blood, the power rings stationed on Oa seemed to react violently, threatening to break free of their confines.
Although he has been sentenced to death and incarcerated for an indefinite period, no execution date had been set for Sinestro. Atrocitus, the first Red Lantern and Abin Sur's killer, has also become fixated on ending Sinestro's life. In the "Final Crisis: Rage of the Red Lanterns" Special , Sinestro is being taken back to Korugar for his execution but a group of Sinestro Corps members attempt to free him. The escape is marred when Atrocitus and the Red Lanterns attack both sides. In the midst of the battle, a Blue Lantern named Saint Walker tells Hal Jordan that Sinestro's survival is crucial in order to stop The Blackest Night.
After being taken to Ysmault, he is nailed to a cross to await his execution at the hands of Atrocitus. However unlike the guardians, who preferred a quick execution, Atrocitus wishes to make Sinestro suffer greatly by taking his revenge on everthing he has ever cared about. His targets include Korugar, and Sinestro's previously unknown and hidden daughter
ATROCITUS:
Atrocitus is shown in the aftermath of the Sinestro Corps War to be the first to forge a Red Lantern power battery, utilizing the power of rage. He said that his first new victim would be the one who called himself "the greatest Green Lantern:" Sinestro, who had long since abandoned the Green Lantern Corps to forge a Corps in his own namesake. He also murdered Qull of the Five Inversions, a fellow member of the Empire of Tears and the one responsible for telling Abin Sur the prophecy of the Blackest Night (which cause the Guardians of the Universe to continue the Empire of Tears' incarceration on Ysmault, rather than transfer them to Oa's sciencells, closer to the enemies of the Five Inversion). In this way, his Red Lantern power battery was christened with blood.
Atrocitus murders the other members of the Five Inversions, using their blood to create red power rings, power batteries, and a Red Central Power Battery on Ysmault. Atrocitus soon dons his new red power ring, created from the blood of the other members of the Five Inversions, becoming the first Red Lantern. He recruits many other individuals from across the universe who have great anger and hate, including former Green Lantern Laira. Many of them have been wronged by the Sinestro Corps, and Atrocitus promises them that the Red Lantern Corps will eradicate Sinestro himself. He leads his new corps in an assault against Sinestro while he is being transferred by some members of the Green Lantern Corps to his home planet of Korugar for execution.
MONGUL:
In Green Lantern Corps #19, Mongul receives a Yellow power ring after breaking a dying Sinestro Corps member's neck. Green Lantern Corps #20 shows him tracking down the other Yellow Power Rings looking for a new bearer. A later promotional image shows Mongul with the Yellow ring as well a Green Lantern Corps ring. A red ring is also floating above his palm. Mongul begins tracking Sinestro Corps rings, and offering the inductees a choice: to serve him or die. He removes the ring from each one who refuses, and at the moment has gained an extra five rings. He then attacks Arisia and Sodam Yat with Black Mercy plants, and takes them prisoner. He uses his ring to send thousands of Black Mercy seeds, which he had genetically engineered to bring the victims greatest fears to life, instead of their dreams, to several unsuspecting planets. In a confrontation with several members of the Green Lantern Corps, Mongul is defeated when the fly-like Lantern Bzzd flies through his eye, and he is thrown down to the Black Mercy's planet. He is last seen buried in soil, being used as food by the Black Mercys. However, he soon busts free of the Mercy vines that have pierced his flesh and escapes the planet, while keeping his rings and his right arm (his left arm has been severed in the process). He attacks a nearby ship to get food for himself, killing the husband of the pilot. This inadvertently causes the woman to become the first recruit of the Star Sapphire Corps, the violet Power Ring having been drawn to her by the void in her heart created by her loss. Not long after, Mongul sets a course for Daxam. During his travels, Mongul's left arm is ripped off in a fight, but, through the power of his rings, Mongul is able to direct it and use it as a weapon. He then overtakes Daxam with ease. He claims it the new power-base of the Sinestro Corps and appoints himself new leader. He is currently being challenged by some members of the Sinestro Corps.
BLACK HAND:
While being transported to prison, Black Hand experiences a sudden power surge, killing his guards in the detonation and teleporting him to what appears to be the Black Lantern Power Battery.
KILOWOG:
Currently Kilowog maintains the role of Green Lantern drill sergeant, training new recruits (or "poozers" as he often refers to them) for the newest incarnation of the Green Lantern Corps, once again in the service of the Guardians of the Universe.
During the Sinestro Corps War, Kilowog was on the front line during the battle of Mogo. When the conflict moved to Earth, Kilowog battled his Sinestro Corps counterpart, Arkillo. Kilowog defeated the villain and removed his ring. After the war's climax, Kilowog was seen on Mogo, eating dinner with energy constructs of his family members.