Jax-Ur is a Kryptonian villain. He was imprisoned in the Phantom Zone for destroying Wegthor, one of the planet's inhabited moons when experimenting with space travel. (In the World of Krypton miniseries, he is shown launching a nuclear warhead, intended to explode in space, but a collision with a spaceship piloted by Jor-El sent it off-course.) Because of this, space travel was forbidden. He first appeared in Adventure Comics #289 (Oct 1961). He calls himself "the worst criminal in the Phantom Zone".
Jax-Ur did not appear after the Crisis on Infinite Earths for some time, as until the recent appearance of Supergirl there was a rule that no Kryptonians survived except Superman. On the occasions that a pseudo-Kryptonian villain was required, writers have usually gone for General Zod.
A “notorious outlaw” on planet Krypton prior to its destruction (SA No. 5, Sum 1962), Jax-Ur, a renegade scientist as brilliant as he is evil, was exiled into the Phantom Zone for what has been described as “the most monstrous” crime ever committed by a Phantom Zone prisoner: The Destruction, perhaps deliberate, of an inhabited moon of Krypton.Although whether Jax-Ur committed this heinous act with an experimental “nuclear rocket” (Act No. 284, Jan 1962: "The Babe of Steel!") or a diabolical “ray” (Act No. 310, Mar 1964: "Secret of Kryptonite Six!") of his invention cannot be established with absolute certainty. Nor can the length of his sentence be firmly established,
for he is described as having been “exiled into the Phantom Zone to serve a thirty-year sentence” in one account and as serving a life sentence in another (Act No. 310, Mar 1964: "Secret of Kryptonite Six!").
Described as “the worst trouble-maker in the [phantom] Zone,” Jax-Ur has attempted to escape from the Zone on numerous occasions. Indeed, although its is the goal of all Phantom Zone prisoners to escape from the Zone and “take over the Earth” (Act No. 310, Mar 1964: "Secret of Kryptonite Six!"), at least one text makes it abundantly clear that Jax-Ur would like nothing better =than to “blow the Earth to smithereens!” (Act No. 284, Jan 1962: "The Babe of Steel!").
Before embarking on a life of crime, Jax-Ur was a young Kryptonian scientist engaged in studying the unique “jewel-minerals” that made up Krypton’s Jewel Mountains. His “secret lab” was located somewhere in these mountains, carved into the face of one of its “glittering peaks.” After one of his experimental devices had obliterated one of Krypton’s moons, Jax-Ur was exiled into the Phantom Zone. But, as was to be the case with all Phantom Zone prisoners, banishment into the Phantom Zone proved to be a blessing is disguise for Jax-Ur, for it enabled him to survive when Krypton exploded. (Act No. 310, Mar 1964: "Secret of Kryptonite Six!")
In January 1962 Jax-Ur and his fellow prisoners seem on the verge of escaping from the Phantom Zone after “the electrical ions of the Aurora Borealis have opened a small hole in the Phantom Zone which is steadily widening,” threatening to release the exiled “super-villains” into the earthly dimension as soon as it becomes “big enough for the Phantom Zone criminals to squeeze through!” Alerted to the threat, however, by their friend Mon-El, Superman, Supergirl, and Krypto the Superdog use the combined power of their X-ray vision to burn up the Aurora Borealis, thereby sealing up the opening through which Jax-Ur and his cohorts had hoped to make their escape. (Act No. 284, Jan 1962: "The Babe of Steel!")
In November 1962, when Superman puts the finishing touches on the new Hall of Enemies in his Fortress of Solitude, Jax-Ur is amoung the villians represented there by colorful wax busts. (Act No. 294, Nov 1962: "The Kryptonite Killer!")
In March 1964, Jax-Ur, feigning repentance for his past crimes, pleads for a chance to redeem himself, and perhaps even win an early parole from the Phantom Zone, by helping Superman find a cure for the “ghastly spotted plague” that is sweeping Atlantis. Released from the Phantom Zone by Superman for a conditional twenty-four hour period, Jax-Ur journeys with Superman through the time space barrier to the planet Krypton “a few months” prior to its destruction, where, in Krypton’s famed Scarlet Jungle, he does indeed lead Superman to the gigantic mushroom-like fungi whose stalls contain “the spore-dust which is the sure for the spotted plague.” Unbeknownst to the Man of Steel, however, Jax-Ur also uses his day of freedom to set in motion a convoluted scheme designed to enable Jax-Ur and his fellow Phantom Zone convicts to blackmail Superman into freeing them all from the Phantom Zone so that they can “take over the Earth!”
The scheme involved duping Superman into believing that exposure to a hitherto unknown type of Kryptonite, so-
called “Jewel Kryptonite”, has “turned [him] into a threat against the whole world” by “causing [him] to detonate any explosive material” he approaches, as when he appears to cause a conflagration at a fuel-oil depot, for example, merely by flying overhead. In actuality, there is no such substance as Jewel Kryptonite and the Man of Steel has not really become a menace, but Jax-Ur has succeeded in devising a means whereby he and the other Phantom Zone outlaws can covert their “mental commands” into “energy beams which detonate any material” outside the Phantom Zone they desire, thus enabling them, for a time, to make Superman believe that his very presence on Earth is a threat to Human life, so that he will give in to Jax-Ur’s agreeing to cure him of his supposed “affliction.” Ultimately, however, Superman uncovers the details of Jax-Ur’s “diabolical plot” and takes the necessary steps to prevent the Phantom Zone criminals from ever again being able to use their mental energy to detonate explosive materials on Earth.
“You could have been a free man now! ... A hero to the people of the world!” exclaims Superman to Jax-Ur, referring to the parole the villain would undoubtedly have received in gratitude for his having cured the dreaded Atlantean plague. “But you outwitted yourself!”
“Who wants to be a hero?” sneers Jax-Ur contemptuously. “I’d rather be notorious as the worst criminal in the Phantom Zone!” (Act No. 310, Mar 1964: "Secret of Kryptonite Six!")
Jax-Ur reappeared in Action Comics 846, written by Geoff Johns and Richard Donner as one of the criminals unleashed from the Phantom Zone by Zod. In the current continuity, Jax-Ur destroyed Krypton's moon during an attempt at intersteller space travel. When the moon was destroyed, Kandor was lost as well, though the city has been shown in recent monthes. The story mentions that Kandor's true fate was never known. Jax-Ur subsequently became the first prisoner banished to the Phantom Zone.
Jax-Ur appeared in Superman: The Animated Series, where he was voiced by Ron Perlman (who by that point had voiced Clayface on Batman: The Animated Series and would later voice Slade on the Teen Titans animated series). Possibly due to an embargo of some sort, he appears in name only, and directly based on General Zod, a military genius who had attempted to overthrow the Science Council. His co-conspirator, and possible lover, is a female Kryptonian named Mala (based on Faora).
During Jax-Ur and Mala's last appearance on Superman: The Animated Series, it has been revealed that they had seized control over a planet. Jax-Ur revealed to Superman that a rift into the Phantom Zone had been torn open and they were released into space. They were saved by nearby voyagers and soon took control over their planet. Upon seizing control of the planet, they had the inhabitants rebuild everything so that it was very reminiscent of Krypton. The inhabitants also wore clothes similar to that of Kryptonians. After meeting with a rebel, Superman found out that Jax-Ur and Mala intended to invade Earth. After Superman battled in space with Jax-Ur and Mala, the pair were sucked into a black hole.
Man of Steel
Jax-Ur, played by Mackenzie Gray appears in the 2013 feature film Man of Steel as one of Zod's crew members and a scientist as well. When Superman is on Zod's ship, Jax manages to extract the Growth Codex (a device containing the genetic code for all future Kryptonians, and stolen from Jor-El and storing the Codex in Kal El's DNA) from him, he is later sent back to the Phantom Zone, along with the crew, when a black hole is generated by the military.