Green Arrow is a character in DC Comics, and was first written in 1940 by Morton Weisinger and George Papp.
Green Arrow is Oliver Queen's vigilante alter ego. He is unlike most of the others in the Justice League because he focuses more on street crime than large scale crimes.
His character was first created as a way to get spotlight off of Batman and Superman. His character is very similar to Batman, as they are both billionaires turned vigilante. Though, there are many differences between the two.