The River Nar is a river in England, and tributary of the River Great Ouse. It rises at Mileham near Litcham in Norfolk and flows 15 miles west through Castle Acre and Narborough (the latter giving the Nar its name), joining the Ouse at King's Lynn. It has had a variety of alternative names, such as the Setch, the Sandringham, and Lynn Flu, though these are rarely, if ever, used today.