Sydney Albert 'Syd' Middleton DSO, OBE (24 February 1884 – 2 September 1945) was an Australian Army officer and national representative rugby union player and rower.
He won a gold medal in rugby at the 1908 Summer Olympics and competed in rowing at the 1912 Summer Olympics.
He had a distinguished career in World War I being awarded the DSO and later an OBE.
He captained the Wallabies in a Test series in 1910.
As a rower he was twice an Australian national champion and won the Grand Challenge Cup at the Henley Royal Regatta in 1912.
He was a member of the AIF crew which won at the 1919 Peace Regatta and brought the King's Cup to Australia.