Major Gilbert George Reginald Sackville, 8th Earl De La Warr JP, DL (22 March 1869 – 16 December 1915), styled The Honourable Gilbert Sackville until 1890 and Viscount Cantelupe between 1890 and 1896, was a British landowner, politician and soldier.
Sackville was the second but only surviving son of Reginald Sackville, 7th Earl De La Warr, by the Honourable Constance Mary Elizabeth Baillie-Cochrane, daughter of Alexander Baillie-Cochrane, 1st Baron Lamington. He was educated at Charterhouse School. He became heir apparent to the earldom in 1890 when his elder brother, Lionel Charles Cranford, Lord Cantelupe, died unmarried in a boating accident on Belfast Lough aged twenty one. Sackville, now taking the name Lord Cantelupe as a courtesy title, twice played cricket at first-class level during the 1890s, in the second match captaining a team under the name "Earl de la Warr's XI" against the touring Australians. His brother-in-law, Freeman Thomas, also played at first-class level.
Lord Cantelupe was made a Deputy Lieutenant of Sussex in 1891. He became a second lieutenant in the 2nd (Cinque Ports) (or Eastern) Division of the Royal Artillery in 1891, was promoted to lieutenant in 1893 and to captain in 1894. In January 1896 he succeeded his father in the earldom, aged 25. He resigned his army commission later that year. However, he was re-appointed captain in the 2nd Cinque Ports Division in 1900 and fought in the Second Boer War, where he was wounded at Vryheid. He was promoted to major in 1901 but once again resigned his commission in 1902.