Quex-Ul
Quex-Ul was a Kryptonian exiled to the Phantom Zone when he was convicted of killing rondors, an endangered species, to use their healing horns for the purposes of profit. He confessed and spent his time in the Zone, but was released by Superman when his time was up. Not a grateful sort, he attempted to lure Superman into a gold kryptonite trap, until Superman discovered that Quex-Ul had actually acted under the mental control of one Rog-Ar, the true rondor killer. Learning this, Quex-Ul threw himself into the trap to save the hero, losing his powers and memory.
He later came to work at the Daily Planet, but regained his powers and memory after he and Superman were trapped in the Zone by escaping criminals. He sacrificed his life to save the Man of Steel, a final redemption.
Post-Crisis
In the Pocket Universe, which was an alternate version of the pre-Crisis Earth-1, Quex-Ul was freed with General Zod and Zaora by a naive Lex Luthor, whereupon they turned Pocket Earth into a dead world. Quex-Ul and the others were executed by Superman using green kryptonite, a vengeful and uncharacteristic move that haunted him for some time.
Comments
In other non-canon media, such as choose-your-own-adventure-type novels, Quex-Ul was one of the three most prominent Phantom Zone Criminals, notable for the fact that he was already very strong before he was exposed to a yellow sun. However, he was not exceptionally intelligent, and relied on General Zod to tell him what to do. This portrayal was the basis for his post-Crisis incarnation.
