Thoron
From superman.nu: Supermanica
Thoron. A far-distant planet, orbiting in the same solar system as that once occupied by the planet Krypton, which is described as "a smaller world than mighty Krypton--but still much larger than Earth!" Thoron is the home planet of the alien Halk Kar (S No. 80/1, Jan/Feb 1953; "Superman's Big Brother!").