At 14, Shooter began selling stories to DC Comics, writing for both "Action Comics" and "Adventure Comics", beginning with "Adventure Comics" No. 346 (July 1966), and providing pencil breakdowns as well. Shooter created several characters for the "Legion of Super-Heroes" including Karate Kid, a teenage superhero who predated the martial arts fad of the 1970s; Ferro Lad, a teenage superhero who can transform to living iron; and Princess Projectra, who could cast realistic illusions; as well as the Sun-Eater and the group of ultra-powerful villains known as The Fatal Five. He also created the Superman villain the Parasite in "Action Comics" No. 340 (Aug. 1966). Shooter and artist Curt Swan devised the first race between the Flash and Superman, two characters known for their super-speed powers, in "Superman's Race with the Flash!" in "Superman" No. 199 (Aug. 1967). Shooter wrote the first issue of "Captain Action" (Oct.-Nov. 1968), which was DC's first toy tie-in.