Guy Breton CM (born April 1, 1950, in Saint-Hyacinthe, Quebec) is a radiologist and academic administrator. In 2010, he was named rector of the Université de Montréal.
Breton received a B.A. from the Séminaire de Saint-Hyacinthe, and a M.D. in medicine in 1974 from Sherbrooke University. After serving a residency in diagnostic radiology at McGill University, he joined the Department of Radiology, Radio-Oncology and Nuclear Medicine at Montréal in 1979, was promoted to full professor in 1994, and became head of the department in 1996. He has also served as president of the Association des radiologistes du Québec from 1987 to 1997 and in 2009 was awarded their Albert Jutras Prize. In 2010 he was appointed as the rector of the Université de Montréal.
In 2014, Breton was named a Member of the Order of Canada.