Dr. Xadu

• Also known as Dr. Xa-Du

Dr. Xadu was sentenced to 30 Kryptonian sun-cycles (41.1 Earth years) for breaking the law which forbids the use of suspended animation in any scientific research. He later escaped the Phantom Zone with a prisoner named Erndine Ze-Da when a south sea volcano exploded and opened a temporary gap in the Phantom Zone. They concocted a plan to trap Superboy in the Zone, but he became aware of their scheme and stranded them on the planet Exon. Years later, Dr. Xadu and Erndine, who had since married and acquired the secret of the cosmic power-grip, escaped from Exon and returned to Earth. Superman defeated them again, and placed them in separate cells on two different worlds.