Jax-Ur

"The worst criminal in the Phantom Zone" (Act No.310,Mar 1964 "Secret of Kryptonite Six!") and one of "the most dangerous evil-doers in the universe!" (Act No.294,Nov 1962 "The Kryptonite Killer!")

Jax-Ur used to be a scientist on Krypton before in exploded. During an illegal experiment with a powerful rocket explosive, which he was planning to use to become the “Master of the World”, with which he was trying to test on a falling meteor, however it missed and hit one of Krypton’s moons. It sliced it into four pieces and sent the four pieces whirling into Krypton’s sun. Tragically, this moon was inhabited and all life on it was killed thanks to Jax-Ur failed illegal experiment. Jax-Ur was ultimately sentenced to the Phantom Zone. (Adv No.289, Nov 1961 "Clark Kent's Super-Father")