William James Harris, 6th Earl of Malmesbury TD (18 November 1907 – 11 November 2000), styled Viscount FitzHarris until 1950, was a British peer.
The son of James Harris, 5th Earl of Malmesbury, Harris was educated at Eton and Trinity College, Cambridge and, as a surveyor, joined and served in the Royal Hampshire Regiment. After leaving the army, he served in a variety of positions, all of which involved forestry, agriculture, or surveying work. He succeeded his father in the earldom in 1950. In 1973 he became Lord Lieutenant of Hampshire, a position he held until 1982. From 1966 to 1974 he was Official Verderer of the New Forest.
The family seat was Greywell Hill House, near Farnham in Hampshire.
He was on the Yachting Committee twice - from 1956 to 1959 and then again from 1968 to 1971.