R. J. Dwayne Miller FRSC (born April 18, 1956) is a Canadian chemist and a professor at the University of Toronto. His focus is in physical chemistry and biophysics. He is most widely known for his work in ultrafast laser science, time-resolved spectroscopy, and the development of new femtosecond electron sources. His research has enabled real-time observation of atomic motions in materials during chemical processes and has shed light on the structure-function correlation that underlies biology.