Marcus E. Raichle (born March 15, 1937) is an American neurologist at the Washington University School of Medicine in Saint Louis, Missouri. He is a professor in the Department of Radiology with joint appointments in Neurology, Neurobiology and Biomedical Engineering. His research over the past 40 years has focused on the nature of functional brain imaging signals arising from PET and fMRI and the application of these techniques to the study of the human brain in health and disease.