Jax-Ur is a supervillain appearing in comic books published by DC Comics, usually as an adversary of Superman. Created by writer Otto Binder and artist George Papp, the character first appeared in Adventure Comics #289. He has been described as "the worst troublemaker in the Phantom Zone" and was the first criminal banished there.

The Phantom Zone is a prison-like parallel dimension appearing in American comic books published by DC Comics. It is mainly associated with stories featuring Superman. It first appeared in Adventure Comics #283, and was created by Robert Bernstein and George Papp. It was frequently used in the Superman comics before the continuity was rebooted in the 1980s, after Crisis on Infinite Earths, and has appeared occasionally since.