Marie Adelaide Elizabeth Rayner Lowndes, rođ. Belloc (5. august 1868 – 14. novembar 1947) je bila engleska spisateljica, poznata po izuzetnom plodnom opusu, od kojih je najpoznatiji roman The Lodger, inspiriran ubistvima Jacka Trbosjeka, a kasnije adaptiran u istoimeni rani film Alfreda Hitchcocka.
Rodila se u izuzetno uglednoj porodici; djed s očeve strane joj je bio francuski slikar Jean-Hilaire Belloc, a s majčine strane britanski naučnik Joseph Priestly. Otac joj je bio francuski advokat Louis Belloc, a majka Bessie Parkes je bila britanska feministička aktivistica. Mlađi brat Hillaire Belloc je kasnije postao poznat kao političar i katolički filozof.
- H.R.H. The Prince of Wales: an account of his career. New York & London (1898, anonimno, rev. 1901 kao His Most Gracious Majesty King Edward VII)
- The philosophy of the Marquise" (1899)
- T.R.H. The Prince and Princess of Wales (1902, anonimno)
- The Heart of Penelope (1904, New York 1915)
- Barbara Rebell (1905, New York 1907)
- The Pulse of Life: a story of a passing world (1908, New York 1909)
- Studies in Wives (1909, New York 1910)
- The Uttermost Farthing (1908, New York 1910)
- According to Meredith (1909)
- Studies in Wives. Short Stories (1909)
- When No Man Pursueth: an everyday story (1910, New York 1911)
- Jane Oglander (1911, New York 1911)
- Mary Pechell (1912, New York 1912)
- The Chink in the Armour (1912, New York 1912, London 1935 kao The house of peril)
- The End of Her Honeymoon (New York 1913, London 1914)
- Studies in love and terror (1913, New York 1913)
- The Lodger (1913, New York 1913) (poznat kao predložak za znameniti film Alfreda Hitchcoka iz 1927.
- Noted murder mysteries (1914, pseudonim 'Philip Curtin')
- Told in gallant deeds: a child's history of the War (1914)
- Good Old Anna (1915, New York 1916)
- Price of Admiralty (1915)
- The Red Cross Barge (1916, New York 1918)
- Lilla: A Part of Her Life (1916, New York 1917)
- Love and hatred (1917, New York 1917)
- Out of the War (1918, 1934 kao The gentleman anonymous)
- The Lonely House (1920, New York 1920)
- From the Vast Deep (1920, New York 1921 koa From out the vasty deep)
- What Timmy Did (1921, New York 1922)
- Why They Married (1922)
- The Philanderer (1923)
- The Terriford Mystery (1924, Garden City NY 1924)
- Some Men and Women (1925, Garden City NY 1928)
- Afterwards (1925)
- Bread of Deceit (1925, Garden City NY 1928 as Afterwards)
- What Really Happened (1926, Garden City NY 1926, London 1932 kao drama)
- Thou Shalt Not Kill (1927)
- The Story of Ivy (1927, Garden City NY 1928)
- Cressida: no mystery (1928, New York 1930)
- Duchess Laura: certain days of her life (1929, New York 1933 kao The duchess Intervenes)
- One of Those Ways (1929)
- Love's Revenge (1929)
- The Key: a love drama in three acts (1930)
- With all John's love: a play in three acts (1930)
- Letty Lynton (1931, New York 1931) (adaptiran u istoimeni MGM-ov film sa Joan Crawford 1932)
- Vanderlyn's Adventure (New York 1931, London 1937 as The house by the sea)
- Why be lonely? A comedy in three acts", (1931 with F. S. A. Lowndes)
- Jenny Newstead (1932 New York 1932)
- Love is a Flame (1932)
- The Reason Why (1932)
- Dutchess Laura: further days of her life (New York 1933)
- Another Man's Wife (1934, New York 1934)
- The Chianti Flask (New York 1934, London 1935)
- Who Rides on a Tiger (New York 1935, London 1936)
- The Second Key (New York 1936, London 1939 kao The injured lover)
- And Call it Accident (New York 1936, London 1939 kao And call it an accident)
- The House by the Sea (1937)
- The Marriage Broker (1937, New York 1937 kao The fortune of Bridget Malone)
- Motive (1938)
- Empress Eugenie: a three-act play (New York 1938)
- Motive (1938, New York 1938 as Why it happened)
- Reckless Angel (New York 1939)
- Lizzie Borden: A Study in Conjecture (New York: Longmans, Green and Co., 1939, London 1940)
- The Christine Diamond (New York & London 1940)
- Before the Storm (New York 1941)
- I, too, have lived in Arcadia: a record of Love and Childhood (1941, New York 1942)
- What of the Night? (New York 1943)
- Where Love and Friendship Dwelt (1943, New York 1943)
- The Labours of Hercules (1943)
- The Merry Wives of Westminster (1946)
- A passing world (1948)
- She Dwelt with Beauty (izdana posthumno, 1949)
- The young Hilaire Belloc (New York 1956)