Lady Cynthia Mary Evelyn Asquith (1887 – 31 March 1960) was an English writer, now known for her ghost stories and diaries. She also wrote novels and edited a number of anthologies, as well as writing for children and on the British Royal family.
Her father was Hugo Richard Charteris, 11th Earl of Wemyss (1857–1937) and her mother Mary Constance Wyndham (see The Souls). She married Herbert Asquith in 1910.
In 1913 she met D. H. Lawrence in Margate, and became a friend and correspondent. During World War I, to supplement her husband's income, she took a position as secretary to Peter Pan creator J. M. Barrie, with whom she became close friends, continuing to work for him until his death in 1937. Barrie left the bulk of his estate – minus the Peter Pan works – to her. The author L. P. Hartley became a lifelong friend after they met in the early 1920s.