Sylvain Marcaillou (8 February 1911 – 28 September 2007) was a French cyclist.
Professional 1932 to 1945, he was the winner of Bordeaux-Saintes and second of Paris–Nice in 1937. He won Paris-Angers and was second place in the French National Road Race Championships in 1938. He participated in the Tour de France five times. He was 5th in 1936 and 6th in 1938.