Lilias Margitson Rider Haggard, MBE (9 December 1892 – 9 January 1968) was the fourth and youngest child of the British writer Sir Henry Rider Haggard and Mariana Louisa Margitson and a cousin of the naval officer Sir Vernon Haggard and the diplomat Sir Godfrey Haggard.

A member of the Haggard family, she was educated at Saint Felix School in Southwold, Suffolk. For her work as a Voluntary Aid Detachment auxiliary nurse during the First World War, she was awarded an MBE in 1920. She was a member of Norfolk County Council from 1949 to 1952 and in 1953 was elected president of the Norfolk Rural Craftsmen's Guild.

She wrote a number of books, including a biography of her father entitled The Cloak That I Left. Her book Norfolk Life, based on columns she wrote for the Eastern Daily Press, contains an introduction by Henry Williamson.^{[citation needed]}

She is buried at Ditchingham, Norfolk, and is the subject of a 2015 biography by Victoria Manthorpe.