Legion of Super-Heroes: Brainiac 5 (also as Superman); Element Man (behind-the-scenes); Sun Man (behind-the-scenes); White Witch (behind-the-scenes, introduction) Superman; Lex Luthor (villain); Jimmy Olsen; Supergirl; Mordru (villain, voice only)
Superman [Clark Kent]; Supergirl [Kara Zor-El]; green earthite; Interstellar Council of United Planets
Synopsis
In his Fortress of Solitude, Superman disassembles a strange machine he found in space. When the machine explodes and destroys the Earth, Superman, Supergirl and Krypto are the only survivors.