The major figure credited with creating psychoanalytic theory is Sigmund Freud. He introduced concepts such as the unconscious mind, and defense mechanisms. Freud's ideas have had lasting impacts on psychology, influencing not just clinical practices but also art, literature, and philosophy. His theories have sparked extensive debates and further research, leading to the development of various psychological schools. Ultimately, Freud's emphasis on the power of the unconscious is fundamental to understanding human behavior and emotions.