Green Lantern" is the codename of a number of fictional superheroes who appear in comic books published by DC Comics. They fight evil with the aid of rings which grant them a variety of extraordinary powers.
The first Green Lantern was created in 1940 during the first superhero craze that began with Superman. His name was Alan Scott, and mostly fought common criminals in New York with the aid of his magic ring. His series was cancelled in 1949 during a general decline in the popularity of superhero comics.