AH, WHAT could have been? Kirby signed on to do the art for this second-string DC character in 1958 in the pages of Adventure Comics and World's Finest Comics.
The King tried to add his creative input - a few interesting sci-fi elements were briefly developed, then cast aside by DC's conservative editors - but, in the main, the writers churned out pretty staid fare.
Even Kirby's one written strip "The Case Of The Super-Arrows" (Adventure #251, August 1958) was mediocre. Usually, the plots revolved around Green Arrow and his lame sidekick Speedy beating villains by pulling trick arrows out of their arses: a balloon arrow, a dry-ice arrow, a fountain-pen arrow, a boxing glove arrow. Oh, for fuck's sake! Give me a break!!
Kirby got the shits with DC's stifling ways - and they got sick of his chunky artwork and pushy ways - and he pissed off in early 1959.
DC's loss was truly Marvel's gain.
As for Green Arrow, he floundered for another decade until Neil Adams tried to turn him into some kinda Easy Rider-style rebel.
He was still lame though.