Aaron T. Beck, M.D. (born 1921), "The Father of Cognitive Behavior Therapy", is a professor at the Psychopathology Research Unit of the University of Pennsylvania.His areas of focus are psychotherapy, psychopathology, studies of suicide, and development of assessment techniques.

He is also well known for the "Beck Depression Inventory (BDI)", a 21 question multiple choice survey that is one of the most widely used instruments for measuring depression severity.