John Dollard was an American psychologist known for his work in social psychology and personality theory. He was born in 1900 and made significant contributions to the understanding of aggression and frustration. Dollard is best known for the Dollard-Miller theory, which emphasizes the role of learned behaviors in shaping personality. In addition to his research, Dollard co-authored the influential book Personality and Psychotherapy with Neil E. Miller. This work integrated psychological theories with practical applications, helping to bridge the gap between theory and therapy. Dollard's ideas have had a lasting impact on psychology, particularly in the study of human behavior.