Stephen William Dassenaike (21 December 1874 - 1935) was a Ceylonese engineer and politician.
Upon his return to Ceylon he took up a position in the Public Works Department as an engineer.
Following his retirement he was elected on 13 June 1931 to the 1st State Council of Ceylon, representing Colombo South, and served on the executive committee for Communications and Works.
He married Ethel Louise née Joseph (1876–1926) on 23 February 1903 at the Dutch Reformed Church, Bambalapitiya.
They had a daughter, Leah Boyd (1906–1965), who married Harold Peiris, a lawyer and philanthropist.