Greip/ˈɡreɪp/ or Saturn LI is a natural satellite of Saturn. Its discovery was announced by Scott S. Sheppard, David C. Jewitt, Jan Kleyna, and Brian G. Marsden on 26 June 2006, from observations taken between 5 January and 1 May 2006. Greip is about 5 kilometres in diameter, and orbits Saturn at an average distance of 18,066 Mm in 906.556 days, at an inclination of 172.7° to the ecliptic (159.2° to Saturn's equator), in a retrograde direction and with an eccentricity of 0.3735, and is presumably at high risk of eventually colliding with Phoebe.[3] It is unknown whether Greip is more similar to Suttungr or Hyrrokkin in color.[3] Its rotation period is most likely 12.75±0.35 hours with two minima in the light curve,[2] but a longer period of 19 hours cannot be ruled out due to the short observation time by Cassini–Huygens.[3]