Kryptonians are an extraterrestrial humanoid species from the planet Krypton in another galaxy in the DC Universe. Kryptonians are human in their appearance, but developed superpowers like super speed, heat vision, x-ray vision, and super breath. The source of their immense energy metabolizing abilities lies in their cells which are advanced organic power storage units, and are enhanced by exposure to a yellow sun. They are a mighty technological power but when their planet was destroyed some of them escaped to other galaxies, ranging from individuals in spacecraft to entire cities shrunk and transported away. Since the destruction of Krypton, its radioactive remains have been spreading throughout the universe as Kryptonite and so they are vulnerable to its many forms.