Zillo Valla is one of the 52 Monitors that keep the mutliverse in check. Sensing the return of Mandrakk the Dark Monitor, she gathered heroes from throughout the multiverse in order to battle him. The heroes gathered were Superman, Ultraman from the Anti-Matter Earth (aka Earth 1 as named in JLA: Earth 2), Captain Marvel from Earth-5, Captain Allen Adam from Earth-4, and Overman from Earth-10. Superman, controlling a thought robot, did manage to overcome Mandrakk, but not before Mandrakk incinerated Zillo Valla for standing against him. It was implied that they were once lovers, making it possible that she is in fact the mother of Nix Uotan.