Sidney Maynard Smith CB KStJ FRCS (20 September 1875 – 18 March 1928) was a British surgeon and freemason.
He was educated at Epsom College and St Mary's Hospital Medical School, as was his older brother Percy Montague Smith (1871-1961), who was also a doctor and became FRCS.
For service during the First World War, he served in the Royal Army Medical Corps and was awarded the CB by Britain and the Croix de Guerre by France; he was thrice mentioned in dispatches.
[8] He became Senior Surgeon at St Mary's Hospital, London in 1922 following the retirement of Ernest Lane.
In later life John Maynard Smith described his father as being "a poor boy made good" who married into "landed gentry", and recalled of their relationship prior to Sidney's death when John was eight years old "I hardly knew him; we saw him sort of Sunday lunch - literally".