OC MC FRSC (/t͡ʃaʊn/; November 10, 1893 – July 3, 1986) was a Canadian medical doctor who researched the blood factor known as the Rhesus factor and discovered an Rh immune vaccine, Rh gamma globulin, which helps to prevent Erythroblastosis fetalis.
During World War I, he served in the Canadian Field Artillery and received the Military Cross.
After the war, he received his medical degree from the University of Manitoba in 1922.
He completed his postgraduate work in pediatrics at Babies' Hospital, Columbia University (1922–1923); Harriet Lane Home, Johns Hopkins University; and Nursery and Child's Hospital, Cornell University (1925–1926), becoming one of only a few trained pediatricians in Canada and the only one in Manitoba.
In 1970, he was made a Fellow of the Royal Society of Canada.