Green Arrow first appeared in More Fun Comics #73 in 1941 with a costume drawn by Mort Weisinger. Mort was inspired by a movie serial, The Green Archer. Green Arrow's second appearance graced the cover of Leading Comics #1.
Green Arrow's costume basically did not change for the next 28 years, until 1969 when Neal Adams revamped it in The Brave and the Bold #85. He updated the character's visual appearance by giving him a Vandyke beard and a new costume.
What is interesting is that Neal Adam's design is much closer to the Green Archer design then Weisinger's design.
The Neal Adams costume was Green Arrow's primary design for the next 18 years. This design was used in cartoons and toylines through the 70's and 80's. Alex Toth did this design for the Super Friends.
In 2008, WB's Batman: The Brave and Bold airing on Cartoon Network brought back Weisinger's original Green Arrow costume.
So Neal Adam's changed it in a Brave and Bold comic and then it was changed back in the Brave and Bold cartoon. That's kind of funny!
Dork Note: I still prefer Neal Adams's costume to the original.