Loelia Mary, Lady Lindsay of Dowhill, née Ponsonby (6 February 1902 – 1 November 1993), was a British peeress, needlewoman and magazine editor.
Lindsay was the only daughter of the courtier Sir Frederick Ponsonby, later 1st Baron Sysonby, and Victoria Lily, née Kennard, Lady Sysonby, the well-known cook book author. She spent her early years at St James's Palace, Park House at Sandringham and Birkhall. One of the Bright Young People, she met the twice divorced Hugh Grosvenor, 2nd Duke of Westminster. They were married on 20 February 1930 in a blaze of publicity, with Winston Churchill as the best man, but were unable to have children. Her marriage to the enormously wealthy peer failed and was described by James Lees-Milne as "a definition of unadulterated hell". It was dissolved in 1947 after years of separation.
After her divorce, Loelia, Duchess of Westminster, established herself as a skillful hostess at Send, Surrey, occupying herself with needlework and gardening, passions she had inherited from her mother. Her needlework collection was bequeathed to the National Trust. In the 1950s, she worked as a feature editor for House & Garden magazine, and covered the wedding of Prince Rainier III of Monaco and Grace Kelly.
Her second marriage, to the divorced explorer Sir Martin Lindsay, 1st Baronet, came as a surprise to her friends but was much more successful. The couple were married on 1 August 1969. Sir Martin, a devoted husband, died in 1981 and Lady Lindsay chose to spend her last years in nursing homes. Her memoirs, written in 1961 and titled Grace and Favour: The Memoirs of Loelia, Duchess of Westminster, are a significant record of aristocratic life between the First and Second World War.