Lieutenant-Colonel Lord William Walter Montagu Douglas Scott MC (17 January 1896 – 30 January 1958) was a Scottish aristocrat and politician.
The 2nd son of John Montagu Douglas Scott, 7th Duke of Buccleuch, he was educated at Eton College and at the Royal Military College, Sandhurst. He was commissioned into the 10th Hussars. Promoted Lieutenant in 1915, he won the Military Cross in 1918 and was shortly afterwards promoted Captain. From 1925 to 1926 he was ADC to the Governor-General of Canada. He retired in 1927. He rejoined the Army in the Second World War, serving in Italy and reaching the rank of Lieutenant-Colonel.
He was Unionist Member of Parliament (MP) for Roxburgh and Selkirk from 1935 to 1950, taking over the seat from his elder brother Walter on the death of their father.
In 1937 he married Lady Rachel Douglas Home (10 April 1910 – 4 Apr 1996), younger daughter of Charles Douglas-Home, 13th Earl of Home. The couple had one son and four daughters, and lived at Eildon Hall, St Boswells, Roxburghshire.