Fenrir or Saturn XLI (provisional designation S/2004 S 16) is a moon of Saturn. Its discovery was announced by Scott S. Sheppard, David C. Jewitt, Jan Kleyna, and Brian G. Marsden on May 4, 2005, from observations taken between December 13, 2004, and March 5, 2005.
Fenrir is about 4 kilometres in diameter, and orbits Saturn at an average distance of 22,611,000 km in 1269.362 days, at an inclination of 163° to the ecliptic (143° to Saturn's equator), with an eccentricity of 0.131.
- Institute for Astronomy Saturn Satellite Data
- Jewitt's New Satellites of Saturn page
- IAUC 8523: New Satellites of Saturn May 4 2005 (discovery)
- MPEC 2005-J13: Twelve New Satellites of Saturn May 3, 2005 (discovery and ephemeris)
- IAUC 8826: Satellites of Jupiter and Saturn (subscription-only) 2007 April 5 (naming the moon)