Jax-Ur was a scientist on Krypton. For the crime of causing the deaths of over 500 colonists of the Kryptonian moon of Wegthor, he was the first criminal in Kryptonian history to be imprisoned in the dimension known as the Phantom Zone.
Jax-Ur escaped from the Phantom Zone several times and caused trouble for Superman. However, on more than one occasion, he proved himself capable of good, as well as bad, actions.
