Walter Francis Montagu Douglas Scott, 5th Duke of Buccleuch, 7th Duke of Queensberry, KG, PC, FRS, FRSE (25 November 1806 – 16 April 1884), styled The Honourable Charles Montagu-Scott between 1806 and 1808, Lord Eskdail between 1808 and 1812 and Earl of Dalkeith between 1812 and 1819, was a Scottish politician and nobleman. He was Lord Keeper of the Privy Seal from 1842 to 1846.
A great Scottish land magnate, Buccleuch was a Conservative in politics, and was appointed a Knight of the Garter in 1835 and a Privy Counsellor in 1842. He served as Lord Privy Seal from 1842 to 1846 and as Lord President of the Council from January to July 1846 in Peel's government, when he reluctantly supported Peel's decision to repeal the Corn Laws. After Peel's fall, the Duke's political career largely came to an end. In 1878 he became Chancellor of the University of Glasgow, a post he held until his death in 1884.
On 6 January 1842 he was appointed Colonel of the Edinburgh Militia (a regiment that his grandfather the 3rd Duke had raised in 1798). He was appointed an Aide-de-Camp to the Queen for the militia on 19 March 1857. On resigning from the command on 20 May 1879 he was appointed the first Honorary Colonel of the Queen's Edinburgh Light Infantry Militia, as the regiment had by then become.
He joined the Canterbury Association on 20 May 1848. It was planned to build a town called Buccleuch in his honour near Alford Forest, but this did not eventuate.