Dr. Hervey Cleckley was an American psychiatrist known for his work on psychopathy. He published the influential book, The Mask of Sanity, in 1941, which detailed the characteristics of psychopathic behavior. Cleckley's observations helped shape the understanding of this personality disorder and its impact on individuals and society. In his research, Dr. Cleckley emphasized the importance of recognizing the emotional and behavioral traits of psychopaths, such as charm and manipulation. His work laid the foundation for future studies in psychology and psychiatry, influencing both clinical practice and the portrayal of psychopathy in popular culture.