Ray Fletcher Farquharson MBE (4 August 1897 – 1 June 1965) was a Canadian doctor, university professor, and medical researcher. Born in Claude, Ontario, he attended and taught at the University of Toronto for most of his life, and was trained and employed at Toronto General Hospital. With co-researcher Arthur Squires, Farquharson was responsible for the discovery of the Farquharson phenomenon, an important principle of endocrinology.