Desmond Walter Guinness (born 8 September 1931) is an Anglo-Irish author on Georgian Art and Architecture and a conservationist.
He is the second son of the author and brewer Bryan Guinness, 2nd Baron Moyne and Diana Mitford (later Lady Mosley).
He was educated at Eton, Gordonstoun and Christ Church, Oxford.In 1958, he bought Leixlip Castle, Leixlip, County Kildare, Ireland, where he continues to live with his second wife, the former Penelope Cuthbertson, whom he married in 1984.
As a member of the extended Guinness family, he has a number of well-known relatives, such as Garech Browne.