Sir Walter Langdon-Brown (13 August 1870 – 3 October 1946) was a British medical doctor and writer.

John Brown of Bunyan's Chapel, Bedford and his wife, Ada Haydon Ford (1837–1929).

His mother was a niece of John Langdon Down, describer of Down syndrome.

He was educated at Bedford School and St. John's College, Cambridge.

[2] He was the author of a number of medical textbooks, a lecturer at the Royal College of Physicians, and went on to become Regius Professor of Physic at the University of Cambridge.