Leopold Guy Francis Maynard Greville, 6th Earl of Warwick MVO (10 September 1882 – 31 January 1928), styled Lord Brooke between 1893 and 1924, was a British soldier.
Greville was the son of Francis Greville, 5th Earl of Warwick and his wife Daisy Greville, Countess of Warwick. Educated at Eton, he eventually ran away from the school, supposedly selling his fur coat and gun to travel to join the Second Boer War.
He succeeded his father in the earldom in January 1924.
Lord Brooke fought in the Second Boer War (1899–1901). He was promoted to 2nd Lieutenant in the Life Guards on 3 November 1900. From August 1901 he served as Aide-de-Camp to Lord Milner, High Commissioner for South Africa, an appointment he held until the conclusion of the war in 1902. He was also a Reuters correspondent during the Russo-Japanese War (1904–1905). In 1907 he was Aide-de-Camp to the Inspector-General of the Forces. In 1905 he was appointed a Member of the Royal Victorian Order (MVO).
During the First World War he was Aide-de-Camp to the General Officer Commanding of the British Expeditionary Force from 1914 until 1915. He was then promoted to Brigadier General later that year and commanded 4th Canadian Infantry Brigade and then 12th Canadian Infantry Brigade until 1918.
Letters and passports indicate that Leopold was present in Russia during 1917 and probably witnessed the beginnings of the Russian Revolution. There are no comprehensive records as to the reasons for his visit, however, which sparked rumors that he may have been a spy for the Russian or the British royal families.