Doom of the Star Diamond
Green Arrow joins the Justice League in a story that suits his natural talents. Although they have only shared half a dozen adventures thus far, the League decide it is time to expand their ranks and Green Arrow gets the vote. (Some have claimed that the DC editorial team just "forgot" to include Green Arrow in the original line up, but as they were imitating the old Justice Society who began with 7 members this is unlikely in my opinion).
After a brief (3 panel) conversation during which both Adam Strange and Hawkman are suggested as well, Batman suggests Green Arrow be invited to join the team. Before the heroes can cast their votes however, a mystical arrow appears from nowhere into their midst. This is the work of the villainous Carthan who is holding Green Arrow prisoner and who now challenges the JLA to overcome the three engines of doom he has strategically placed on earth.
Splitting into teams (as they always did way back then) the JLA overcome the menaces and free Green Arrow only to then find themselves trapped inside a huge diamond from which there is no escape (from the inside). The only hope they have is if Green Arrow can hit the diamond's weak spot with his own diamond tipped arrow. Can he do it? What do you think? This classic - semi - key - early JLA is a must have for all Silver-Age comic fans.