K0 may refer to:
- Spectral class K0, a star spectral class
- the 1965 first model of the Honda CB450 motorbike
- the Grothendieck group in abstract algebra
- the Lateral earth pressure at rest
- the neutral kaon, a strange meson with no charge in nuclear physics
- K0 may refer to Khinchin's constant
- K0 the order-zero graph