Kryptonian

Kryptonians, natives of planet Krypton, were the fulcrum of events that altered the entirety of the cosmos some 50,000 years ago.

Kryptonians were engineered by Celestials as part of a long-term analysis of survivability in low-light environments. An extremely dense upper atmosphere heavily laden with airborne heavy metals kept the planet perpetually dark and cold, borderline inimical to life.

While dwelling on Krypton, most Kryptonians seemed no different than any other mammalian race. It was when they discovered space travel-- in primitive, lurching rockets-- that their true potential was discovered. Exposed to certain frequencies of broad-wave solar radiation, the equivalent of mitochondria in their cells were triggered into overdrive, absorbing not just solar radiation, but supercharged by the endless power of Hyperspace.

Empowered thus, the original Kryptonians were creatures of incalculable strength. Those of average ability could lift dozens of tons and endure tremendous variations in temperature and radiation exposure. Senses were enhanced to the point of being able to sense objects even through solid barriers, and hear discrete noises from vast distances. Even their eyes were weapons, capturing and focusing hyperspace energies into concentrated broad-spectrum radiation that they could use to annihilate their opponents.

More problematically, they had few easily exploited weaknesses. It could take days to de-power a Kryptonian in a blind cell. Their abilities made them significantly less dependent on food, water, and rest. Significant amounts of low frequency cosmic radiation-- such as exposure to a red sun-- could negate their ability to draw energy from Hyperspace.

Supercharged brains could absorb and recall vast amounts of information. When the heavy metals in the atmosphere were depleted, the crystals making up much of the terrain became repositories of energy highly compatible with Kryptonian abilities; using the same building blocks that form the basis of much of advanced alien technology. Researchers made shockingly swift advances in the realm of organic crystallized nanostructures to grow sunstones unaided. The Sunstones amplified the already formidable powers of Kryptonians into battleships capable of annihilating entire armadas.

In the end, containing the Kryptonian threat required a multilayered solution from Oa, Guardians of the Universe. Using magical might from the Demiurge, armies from Asgard, a complex strategy of biowarfare, and their newly formed Green Lantern Corps, the Oans finally beat the Kryptonians back to their home planet and irradiated the upper atmosphere with the only absolutely lethal substance known: Kryptonite.

Each generation after the fall of the Hegemony was successively weaker and more frail. Gene therapies abounded and some families even used secret cloning machines, violating deep Kryptonian cultural taboos. By 1940 CE, their ability to harness latent energy was vastly depleted.

Jor-El was the first Kryptonian in generations to experience empowerment of sunlight, while searching Earth for a cure for the sterility plague. His son Kal-El and his niece, Kara Zor-El, would be born with the genetic damage undone-- the first 'healthy' Kryptonians born in over fifteen millennia.