Rydberg can refer to:
- Rydberg (crater), a crater on the moon
- In physics,
- Rydberg constant
- Rydberg formula
- Rydberg atom (an atom in a state of high principal quantum number)
- Rydberg molecule
- a unit of energy, derived from the Rydberg constant, equal to half the Hartree energy
- Johannes Rydberg, Swedish physicist and deviser of the Rydberg formula, in whose honour the constant, the unit and the crater are named, as are Rydberg atoms
- Viktor Rydberg, Swedish author and poet
- Per Axel Rydberg, Swedish-American botanist