Zaron
From superman.nu: Supermanica
Zaron
A planet populated by humanoids, including ten evil scientists who wreak havoc there and then plan to conquer Earth. In July 1960, Superboy befriends a "monster" who is sent from the planet to bring those scientists (now disguised as citizens of Smallville) to justice (Adv No. 274/1, Jul 1960: "The Monster That Stalked Smallville!").
The name Zaron is also given to the homeworld of Tharok, the 30th century half-robotic leader of the Fatal Five (Adv No. 352, Jan 1967: "The Fatal Five!"), although the chronicles do not specifically state whether or not this is the same planet.