Lord Francis Douglas Marquess of Queensberry; a younger brother, Lord Archibald Edward Douglas (1850–1938), who became a clergyman; and a younger brother and sister, the twins Lord James Douglas (d. 1891) and Lady Florence Douglas (1855–1905), who married Sir Alexander Beaumont Churchill Dixie, 11th Baronet. He was an uncle of Oscar Wilde's lover Lord Alfred Douglas, and a younger brother of John Douglas, 9th Marquess of Queensberry. In 1858, Douglas's father, Lord Queensberry, died in what was reported as a shooting accident, but his death was widely believed to have been suicide. In 1862, his mother, Lady Queensberry, converted to Roman Catholicism and
Charles Douglas, 5th Lord Mordington Charles Douglas, 5th Lord Mordington Charles Douglas, 5th Lord Mordington (d. after 1746), son of George Douglas, 4th Lord Mordington by his wife Catherine née Lauder, was a Jacobite. He went to sea when he was young and did not return to Britain until after his father's death. Engaging in the 1745 Jacobite rebellion, he was captured at Carlisle, and tried on 11 September 1746 under the designation of Charles Douglas, Esquire. He then pleaded his peerage, which was objected to by the counsel for the Crown, but upon proof being provided his trial was postponed and he was imprisoned