ADVENTURE COMICS (vol. 1) #324 (September, 1964). Cover by Curt Swan and Sheldon Moldoff.
Superboy meets a few members of "The Legion of Super-Outlaws" (the other two members were Duplicate Boy, who could duplicate any super-powers; and Life Lass, who could bring inanimate objects to life).
These were actually the heroes of the planet Lallor, who were duped into thinking the Legion of Super-Heroes were a gang of outlaws. Of course, by the end of the story thins were sorted out, and the real bad guy was imprisoned.
The Beast Boy (Ilshu Nor) on the cover pre-dates the first appearance of the more familiar Beast Boy (Gar Logan) from the Doom Patrol and Teen Titans by more than a year. Logan, who was called Changeling for several years, first made the scene in Doom Patrol (vol. 1) #99 (November, 1965).
