Green Lantern is the name of several fictional superheroes that appear in comic books published by DC Comics. The first was Alan Scott and was created by writer Bill Finger and artist Martin Nodell in All-American Comics #16 in July 1940.
The most famous is Hal Jordan and was created by John Broome and Gil Kane in Showcase #22 in October 1959.
Each Green Lantern wears a power ring that allows the Green Lantern to control the physical world by strength of will.
Alan Scott was the Golden Age Green Lantern and his ring was powered by magic.
All of the Green Lanterns since then have worn rings that were not magic, but advanced technology. The Guardians of the Universe created the power rings and granted them to worthy candidates throughout the galaxy. These individuals make up the Green Lantern Corps, an intergalactic police force.
there are other lantern corps which represent different emotions and like Willpower the rings are only given to people who display a lot of a certain emotion, good or bad but not all.
Blue Lantern corps "Hope"
Red Lantern corps "Anger"
Orange Lantern corps "Greed"
Yellow Lantern corps "Fear"
Black Lantern corps "Death"
White Lantern corps "Rebirth"
Indigo Lantern corps "Compassion"
Green Lantern corps "Willpower"
Hal Jordans archenemy is Sinestro of the yellow lantern corps.