Peter Shand Kydd (23 April 1925 – 23 March 2006) was the former stepfather of Diana, Princess of Wales, and an heir to the wallpaper fortune built by his father Norman Shand Kydd (1895–1962). His mother was Francis Madalein Foy (died 1983). He was half-brother to the former champion amateur jockey William Shand Kydd (1937–2014), who was brother-in-law of John Bingham, 7th Earl of Lucan.
Shand Kydd sold the family business in 1962 and moved his family to Australia, where he became a sheep farmer. After selling the sheep farm and returning to England, he began an affair with Diana's mother Viscountess Althorp, while married to his first wife, Janet Munro Kerr, granddaughter of John Martin Munro Kerr. After divorce proceedings were finalized for both Shand Kydd and the Viscountess, they were married on 2 May 1969 and lived in Buckinghamshire and West Itchenor, West Sussex, finally settling on a 1,000 acre (4 km²) farm on the remote Scottish island of Seil. Their marriage faltered, and Shand Kydd had married Marie-Pierre Palmer, who ran a champagne-importing business in London. Shand Kydd married Palmer in 1993 and their relationship lasted until April 1995. Afterwards he chose to live close to his first wife Janet.
By his first wife, Shand Kydd had three children. Their elder son, Adam Shand-Kydd, was born in 1954 and became a novelist ("Happy Trails"), before dying in Phnom Penh, Cambodia, in 2004, of a suspected drug overdose. Shand Kydd's younger son, John Shand Kydd, known as Johnnie, was born in 1959, and is a renowned photographer, with more than 70 works in the collection of the National Portrait Gallery. His daughter Angela Shand Kydd was born in 1956.
Peter Shand Kydd died on 23 March 2006, at the age of eighty, and was buried on 6 April 2006 in Aldeburgh, Suffolk.