A comic book published by DC Comics. Green Lantern is a superhero who wears a power ring which emits some kind of nifty green energy which can do anything the wearer can imagine.

The first Green Lantern was Alan Scott, who made his initial appearance in All-American Comics #16 in 1940. His power ring was made of a magical artifact called the Starheart -- its only weakness was that it was completely powerless against anything made of wood (which is quite a drawback when you're fighting the evil Dr. Tree). He was a founding member of the Justice Society of America back in the 1940s and is an active member of the current team, as well as one of the people running the Checkmate espionage agency (due to various comic book coincidences, he is still relatively young). He lost an eye during a recent cosmic crisis. For a while, he went by the name of Sentinel, but he recently started using the name Green Lantern again. He is the father of Jade and Obsidian.

Earth's next Green Lantern was a test pilot named Hal Jordan. He was given his power ring by a dying member of the Green Lantern Corps (see Habakkuk's excellent writeup below for a summary of the Corps). His first appearance was in Showcase #22 in 1959. The only weakness of Jordan's ring was that it was powerless against anything colored yellow (again, a big problem when facing the villainy of Captain Pee). For many years, Jordan was the only Green Lantern from Earth, but in later years, Guy Gardner and John Stewart were also given power rings. However, Hal was widely considered to be the greatest member of the Green Lantern Corps ever. But when his hometown was destroyed, Hal went nuts, destroyed the Corps and most of the Guardians, and tried to remake the universe as the supervillain Parallax. He failed and later died restarting the sun when it had been snuffed out by an alien monster. Then he was, bizarrely, chosen to be the human host of the Spectre, God's Spirit of Vengeance.

The last of the Guardians traveled to Earth with the last power ring (and it was the best one, since it was no longer powerless against yellow things). He arrived in an alley and gave the ring to the first guy he saw -- luckily, it was generally nice-guy and freelance artist Kyle Rayner, instead of someone like the Joker. Rayner helped defeat Parallax and continued as the only Green Lantern. Later, when he got hold of some more power rings, Rayner appointed his girlfriend, Jennifer Hayden (the green-skinned and babelicious daughter of Alan Scott), as the newest Green Lantern. Kyle also became, briefly, a god when his ring got supercharged, but he gave up most of that power so he could re-create Oa, the Guardians, and the Central Power Battery. After that, he went into space for several months to try to re-start the entire Green Lantern Corps, while John Stewart stayed behind to be Earth's Green Lantern.

More recently, Hal Jordan was mysteriously returned to life and learned that when he was Parallax, he had actually been possessed by a cosmic horror called Parallax that fed on fear. The Guardians had trapped it in the Central Power Battery, and Parallax's own yellow color had helped cause the rings' weakness to yellow. Parallax was again defeated, and Jordan has resumed his career both as a superhero and as a pilot.

In brightest day,
In blackest night,
No evil shall escape my sight,
For those who worship evil`s might,
Beware my power!
Green Lantern's light

This is the oath he chants when he charged up his ring.
After that, he has enough power for 24 hours before it conks out.

The oath above was created by science fiction writer Alfred Bester. Perhaps due to the constant contact between Green Lantern of Earth and the Guardians of Oa, there has been regular contact between the world of science fiction literature and the comic. In addition to the aforementioned Bester, another famous sci-fi writer who has penned at least one GL tale is Larry Niven, who wrote Ganthet's Tale. Ganthet was the Guardian who bestowed the last ring upon Kyle Rayner.

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.

Notable Green Lanterns of the former Corps have been: Abin Sur (the original Lantern who bestowed the ring to Hal Jordan), Katma Tui (wife of one-time Lantern Jon Stewart, later murdered), G'nort, a stupid dog-humanoid whose uncle gave him a GL ring so he could aparrently create giant green fire hydrants and get in everyone's way, Torquemada (sorcerer), Kilowog (former GL who turned into general handyman for the Justice League, killed by Parallax), Arisia (girl totally infatuated with Hal Jordan, prematurely aged herself using the ring, became a confused supermodel on Earth after the Corps was destroyed), and Stel (robotic GL, heroic who died and then was actually revived by the power of the ring, since he was essentially just software re-booted in his robotic body). Another notable GL was Sinestro, who ended up using his power to dominate his home planet and was therefore exiled by the Guardians to the antimatter planet of Qward, Oa's counterpart. He ended up developing with the Weaponers of Qward a ring capable of duplicating the Lantern power--but using a yellow frequency, a perfect counter to theirs. Still another Green Lantern was the every-annoying and stupid haircut-wearing Guy Gardner.

Guy was originally a decent, mild-mannered guy who was actually supposed to have received Abin Sur's ring, but Hal Jordan turned out to be closer. Due to an accident that put Guy in a coma for a number of years, he emerged with a twisted and brutish personality. When the Guardians were desperate for a Lantern on Earth and Hal Jordan had refused to help them, they gave a ring to Guy. He has recently been stripped of that ring and after a short adventure of self-discovery is now a completely different, non-human superhero who co-owns a superhero-themed restaurant/bar.