Rainbow Girl was most recently a part of Action Comics who introduced what major superhero charcater?
Rainbow Girl:  She did not appear again for nearly 20 years until "Action Comics" #862 as a member of the Legion of Substitute Heroes, an organization of teenage heroes that exists one thousand years in a future universe. Action Comics: Action Comics is an American comic book series that introduced Superman, one of the first major superhero characters as the term is popularly defined.
Superman