Farbauti or Saturn XL (also called S/2004 S 9) is a moon of Saturn. It was found by Scott S. Sheppard, David C. Jewitt, and Jan Kleyna on December 12, 2004. Farbauti was found using the Mauna Kea Observatory and is the 40th moon from Saturns surface. The public did not know about Farbauti until May 4, 2005.
Farbauti is 5 kilometres wide, and 20,291,000 kilometres from Saturns surface. Farbauti travels around Saturn (orbit) once every 1079 days.
The moon was named in April 2007 after the "storm giant" Fárbauti, father of Loki in Norse mythology.