John Sholto Douglas, 9th Marquess of Queensberry, was a British nobleman of the Victorian era, remembered for his atheism, his outspoken views, his brutish manner, for lending his name to the "Queensberry Rules" that form the basis of modern boxing, and for his role in the downfall of the Irish author and playwright Oscar Wilde.

The Marquess of Queensberry Rules, also known as Queensbury Rules, are a code of generally accepted rules in the sport of boxing. Drafted in London in 1865 and published in 1867, they were named so as the 9th Marquess of Queensberry publicly endorsed the code, although they were written by a Welsh sportsman named John Graham Chambers from Llanelli, Carmarthenshire. The code of rules on which modern boxing is based, the Queensberry rules were the first to mandate the use of gloves in boxing.