Superman; Nor Kann [a Kandorian scientist] (intro); Than Ol (intro, villain); Boz-Tol (intro, villain); Jax-Ur (villain); Prof. Vakox (villain); Phantom Zone inmates (villains); Kandor; Fortress of Solitude; Lois Lane; Perry White; Jimmy Olsen; Brainiac (flashback)
Superman and Jimmy Olsen travel to Kandor to discover how normal sized Kandorians are on Earth and why they are attacking Superman.
Jimmy Olsen; Superman; Legion of Super-Heroes [Mon-El [also as The Collector]; Colossal Boy [also as The Giant Turtle Man]; Bouncing Boy [also as Fat Boy Jimmy]; Cosmic Boy [also as The Human Porcupine]; Chameleon Boy [also as Elastic Lad]; Shrinking Violet (cameo); Sun Boy (cameo); Lightning Lad (cameo); Saturn Girl (cameo); Triplicate Girl (cameo)]; Proty II [also as Wolf Boy Jimmy]; Legion of Substitute-Heroes [Fire Lad; Polar Boy; Night Girl; Stone Boy] (all in cameos)
Jimmy is taken by The Collector to the world Gion-El, which is seemingly inhabited by duplicates of him in the forms into which he has been transformed in the past. But when Jimmy realizes he is being hoaxed, the Legionnaires reveal that he has passed his initiation test and they bring him to the 30th century to officially be made an honorary member of the Legion of Super-Heroes.