John Davy Rolleston FSA FRCP (25 February 1873 – 13 March 1946) was an English physician and folklorist, who published extensively on infectious diseases and the history of medicine. Overshadowed by his brother, Sir Humphry Rolleston, he established himself as an epidemiologist, gave the Fitzpatrick Lecture at the Royal College of Physicians in 1935-1936 and became involved in numerous other learned societies and medical bodies, including The Royal Society of Medicine and the Society for the Study and Cure of Inebriety.