Øystein "Sid" Ringsby (born 16 February 1961) is a Norwegian bassist best known for playing with TinDrum, The Snakes, TNT, Wild Willy's Gang and Jørn Lande's solo band.
His recording rock career started 1983 as he became a member of the band Road, and since then he has been in bands such as Tindrum, The Snakes, Diezel, Jorn, Vestlandsfanden, Ken Hensley & Live Fire and TNT.
He is recognized as one of the most versatile bassplayers in the Norwegian Rock scene, with a lot of other recording artists to his credit