Krypton (Kr) is a chemical element with atomic number 36. It belongs to the element group called noble gases, and just like other noble gases, it is more or less completely unreactive. One of the uses of krypton is in fluorescent lamps.
The planet Krypton, which is the fictional birth place of Superman, was named after the chemical element krypton.
There are several stable krypton isotopes, but 84Kr (36 protons, 48 neutrons) is the most abundant.