Mundilfari or Saturn XXV, is a moon of Saturn. It was found by Brett J. Gladman, et al. in 2000, and given the designation S/2000 S 9.
Mundilfari is about 5.6 kilometres in diameter, and orbits Saturn at an average distance of 18,360,000 km in 928.806 days, at an inclination of 170° to the ecliptic (150° to Saturn's equator), with an eccentricity of 0.198.
Mundilfari may have formed from debris knocked off of Phoebe by big impacts at some point in the solar system's history.