Who's Who in the Superman Comics
Solaris
Far into the future, synthetic suns - the products of supreme 853rd century technology, provide supernatural, life-sustaining heat and light for their intended galaxies. The synthetic suns also contain vast computer systems, creating a "Hypernet" of sorts, far more advanced and extensive in concept than the Internet we utilize today. And so with the advent of these artificial suns, came the birth of Solaris, the Tyrant Sun.
Arch-enemy of the Justice Legion A, Solaris infected the Justice Legion's Hourman, a super sentient cyborg, with a devastating virus. Biotech in nature, this virus was a threat to humans as well as computers. When the Justice Legion traveled back in time to begin a ceremony honoring the Justice League of America, present day Earth was infected with Solaris's devilish virus.
And so, allied with the evil immortal Vandal Savage, Solaris threatened present day Earth and the far future cosmos, simultaneously. The ultimate goal of Solaris was to destroy his most powerful enemy - Superman Prime! The original Superman - who himself is immortal, Superman Prime took refuge within the Earth's sun. Solaris attempted to shoot Superman with what was thought to have been the last remaining piece of kryptonite. However, the kryptonite was actually a Green Lantern ring... still latently powerful after so many years...which Superman then used to destroy Solaris himself, by causing Solaris to cave in on itself and become a less malicious form of matter. While the exact details are fuzzy, it is believed that Superman Prime then transmuted Solaris's remnants into a new version of Krypton.
Despite the fact that Solaris was ultimately destroyed, it is speculated that its time-altering abilities are still a threat to the cosmos; putting all heroes, from the present and the future, under continuous watch. First Appearance: DC One Million #1