Z0

{{distinguish|text=ZO (disambiguation), Z followed by the alphabet O}}

Z0, Z₀ or Z⁰ may refer to:

• Characteristic impedance, a ratio used in electronics
• Impedance of free space, a physical constant
• Z boson, an elementary particle that mediates the weak force
• a rare rail transport modelling scale
• Roughness length, a factor used in wind speed calculations
• Z0 sex-determination system in some moth species, also referring to biological females under this system