Lady Cynthia Mary Evelyn Asquith (27 September 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.
In 1913 she met D. H. Lawrence in Margate, and became a friend and correspondent. 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.
One of Asquith's stories, "The Follower", was adapted for BBC Radio, along with stories by Algernon Blackwood, Marjorie Bowen and Noel Streatfeild; all these stories were later reprinted in the Cecil Madden anthology My Grimmest Nightmare (1935). 
- The Ghost Book (1927), editor
- The Duchess of York(1927), biography
- The Black Cap (1928), editor
- Shudders (1929), editor
- When Churchyards Yawn (1931), editor
- My Grimmest Nightmare (1935), editor
- The Spring House (1936), novel
- Dreaming Lips (1937), screenplay
- One Sparkling Wave (1943), novel
- This Mortal Coil (1947), stories
- Haply I May Remember (1950)
- What Dreams May Come? (1951), stories
- The Second Ghost Book (1952), editor
- Portrait of Barrie (1954)
- The Third Ghost Book (1956), editor
- Married to Tolstoy (1960), biography
- Thomas Hardy at Max Gate (1969)
- Richard Dalby, The Virago Book of Ghost Stories.Virago, London, ISBN 0-86068-810-0, 1987 (p. 236).
- See Mark Kinkead-Weekes, D. H. Lawrence: Triumph to Exile, 1912-1922 (Cambridge, 1996), pp.69ff.
- Birkin, Andrew: J. M. Barrie & the Lost Boys, Constable, 1979; revised edition, Yale University Press, 2003
- Telfer, Kevin. "Captain Scott and J M Barrie: an unlikely friendship", Telegraph, 9 March 2012
- Chaney, Lisa. Hide-and-Seek with Angels - A Life of J. M. Barrie, Hutchinson, 2005
- Mike Ashley and William Contento, The Supernatural Index: A Listing of Fantasy, Supernatural, Occult, Weird, and Horror Anthologies. Greenwood Publishing Group, 1995. ISBN 0313240302 (p. 728-9)
- Film Reviews. Sydney Morning Herald [Sydney] 25 October 1937, p.8. Web. 17 Apr. 2013.
- The Diaries of Cynthia Asquith 1915-1918 (1968)
- Best Friends: Memories of David and Rachel Cecil, Cynthia Asquith, L. P. Hartley and Others (1991) Julian Fane
- Tuck, Donald H. (1974). The Encyclopedia of Science Fiction and Fantasy. Chicago: Advent. p. 23. ISBN 0-911682-20-1.