Green Lantern is the name of multiple superheroes from the DC Universe, all of whom are characterized by a power ring and the ability to create solid constructs with the ring.
The first Green Lantern (Alan Scott) was created by writer Bill Finger and artist Martin Nodell in All-American Comics #16 (July 1940).
Each Green Lantern possesses a power ring and power lantern that gives the user great control over the physical world as long as the wielder has sufficient willpower and strength to wield it. The ring is one of the most powerful weapons in the universe and can be very dangerous. While the ring of the Golden Age Green Lantern (Alan Scott) is magically powered, the rings worn by all subsequent Lanterns are technological creations of the Guardians of the Universe, who granted such rings to worthy candidates. These individuals made up the intergalactic police force known as the Green Lantern Corps.