Robin (Super Squad)
Short history of this character - it's a Robin from a parallel dimension (known as Earth 2), where Batman has semi-retired, and Robin has taken over his role as protector of Gotham.
When DC Comics relaunched the Justice Society comic in the 1970's, the older heroes were joined by new, younger heroes, including Robin. The three younger members became a smaller group in the Justice Society known as the Super Squad, and would work with the Justice Society fighting menaces like Brainwave and Vandal Savage.