Anthony Ashley-Cooper, 9th Earl of Shaftesbury KP GCVO CBE PC (31 August 1869 – 25 March 1961), was the son of The 8th Earl of Shaftesbury and Lady Harriet Augusta Anna Seymourina Chichester (1836 – 14 April 1898), the daughter of The 3rd Marquess of Donegall and Lady Harriet Anne Butler.
Lord Shaftesbury was commissioned a second lieutenant in the 10th Hussars in 1890, promoted to lieutenant in 1891, and to captain in 1898. From 1895-1899 he served as an Aide-de-camp to the Governor of Victoria. He retired from the regular army in 1899, but continued as a captain of the reserve in the Dorset Imperial Yeomanry. On 12 March 1902 he was promoted to lieutenant-colonel and appointed in command of the North of Ireland Imperial Yeomanry. He later served in the First World War 1914-1918, and was promoted to brigadier-general in 1914.
Lord Shaftesbury was Lord Lieutenant of Belfast from 1904 to 1911, Lord Lieutenant of Antrim from 1911 to 1916, and Lord Lieutenant of Dorset from 1916 to 1952. He was Lord Mayor of Belfast 1907, and Chancellor of Queen's University, Belfast 1909–1923.
At the Court, Lord Shaftesbury served as Chamberlain to Mary of Teck as Princess of Wales 1901–1910 and as Lord Chamberlain to her as Queen of the United Kingdom 1910–1922. That year he was appointed Lord Steward of the Household, serving until 1936.
The 9th Earl of Shaftesbury died in 1961. He was buried in the Parish Church at Wimborne St Giles near the family estate. The earl's titles passed to his 22-year-old grandson, Anthony Ashley-Cooper.
The 9th Earl had carefully arranged financial matters on the Shaftesbury Estate so that his heirs would avoid death duties. When the earl died in 1961, his grandson inherited the family's 17th-century home and large estate in Dorset, several other properties and a collection of art, antiques, and other valuables. By the 1990s the 10th Earl's wealth was said to be in the "low millions".