Robert Davies Defries (July 23, 1889 – October 25, 1975) was a Canadian physician and Director of Connaught Medical Research Laboratories.

Born in Toronto, Ontario, he received his M.D. from the University of Toronto in 1913.

Honours

• In 1955 he was awarded an honourary Doctor of Laws from the University of Saskatchewan.
• In 1955 he received the Albert Lasker Public Service Award
• In 1970 he was made a Companion of the Order of Canada.