Iain Somerled Macdonald-Smith , (born 3 July 1945 in Oxford, Oxfordshire) is a British sailor and Olympic champion. He competed at the 1968 Summer Olympics in Mexico City and won a gold medal in the Flying Dutchman class, together with Rodney Pattisson.
He was educated at Marlborough College and Selwyn College, Cambridge, before becoming a solicitor.