After selling his company for three billion dollars, Oliver "Ollie" Queen became a full time vigilante. He learned to master the bow, dressed himself as Robin Hood, developed an arsenal of trick arrows with various functions, and dubbed himself Green Arrow.
Green Arrow was summoned to enlist in the new expanded Justice League. However, as he failed to reply, John Stewart showed up when he was thwarting a grocery store robbery and teleported him into the JL Watchtower.
There, Green Arrow saw the assembled Superheroes, but he was still skeptical about joining such an organization.
His main concern was helping the underprivileged in society which, according to him, tended to be forgotten by heroes whose main goal is fighting super villains and monsters.
Subsequently, Green Arrow decided to join the League, in part to keep them honest, but mainly due to a sudden infatuation with Black Canary.
Who is Marvel comics' answer to the Emerald Archer? That would be Hawkeye (Clint Barton), soon to be played by Jeremy Renner in the upcoming live-action film "The Avengers". According to Renner, the character will not be wearing his purple costume from the comics, but rather something he refers to as being "a little more reality-based".
Check out the Mego styled Mattel released "Retro-Action: DC Super Heroes" Green Arrow 8" Figure HERE. They are very similar in style and look.