Sir Frank Baines, KCVO, CBE, FRIBA (1877–1933) was chief architect at the British Office of Works from 1920 to 1927.
His most famous work was Thames House and its neighbour Imperial Chemical House (1929–30) in London. Thames House is currently the headquarters of the British Security Service (MI5) and Imperial Chemical House was built as the headquarters for Imperial Chemical Industries (ICI).