Solomon West Ridgeway Dias Bandaranaike (,; 8 January 1899 – 26 September 1959) frequently referred to as S.W.R.D. Bandaranaike, was the fourth Prime Minister of Ceylon (later Sri Lanka) and founder of the left wing and Sinhala nationalist Sri Lanka Freedom Party, serving as Prime Minister from 1956 until his assassination by a Buddhist robe wearer in 1959.