John Sholto Douglas, 9th Marquess of Queensberry (20 July 1844 – 31 January 1900), 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.

John Douglas was born in Florence, Italy, the eldest son of Conservative politician Archibald, Viscount Drumlanrig, and Caroline Margaret Clayton.

He died, two months after a stroke, and after a period of mental decline believed to be caused by syphilis, in his club room in Welbeck Street, west London,[4] aged 55, nearly a year before Oscar Wilde's death.

[7] His eldest son and heir apparent was Francis, Viscount Drumlanrig, who was rumoured to have been engaged in a homosexual relationship with the Liberal Prime Minister, the 5th Earl of Rosebery.

[8] Lord Alfred "Bosie" Douglas, his third son, was a close friend of famous author and poet Oscar Wilde.

Eventually it became known that Lord Alfred and Wilde had engaged in sexual intercourse on multiple occasions, severely damaging the reputation of both men and enraging Queensberry.

That year he published a long philosophical poem, The Spirit of the Matterhorn, which he had written in Zermatt in 1873 in an attempt to articulate his secularist views.

In 1882, he was ejected from the theatre after loudly interrupting a performance of the play The Promise of May by Alfred, Lord Tennyson, the Poet Laureate, because it included a villainous atheist in its cast of characters.

His divorces, brutality, atheism, and association with the boxing world made Queensberry an unpopular figure in London high society.

In 1893 his eldest son Francis was made a baron in the Peerage of the United Kingdom, thus giving him an automatic seat in the House of Lords.

The trial opened at the Old Bailey on 3 April 1895 before Justice Richard Henn Collins amid scenes of near hysteria both in the press and the public galleries.

Queensberry's lawyers, headed by barrister Edward Carson, presented Wilde as a vicious older man who seduced innocent young boys into a life of degenerate homosexuality.

Queensberry then sent the evidence collected by his detectives to Scotland Yard, which resulted in Wilde being charged and convicted of gross indecency under the Criminal Law Amendment Act 1885 and sentenced to two years' hard labour, which he served (1895-1897).