Sir Selwyn Macgregor Grier KCMG (1878 – 1946) was a British colonial administrator, Governor-in-Chief of the Windward Islands from 1935 to 1937.
He was the eldest child of Richard Macgregor Grier (1835 – 1894), the then rural dean of Rugeley and prebendary of Lichfield, and his wife, Grace Allen.
His sister, Lynda Grier, was a British educational administrator, and the principal of Lady Margaret Hall, Oxford, from 1921 to 1945.
Grier was Colonial Secretary, Colony of Trinidad and Tobago.