Sigmund Freud is recognized as the founder of modern psychology, known for establishing the field of psychoanalysis. His innovative theories regarding the unconscious mind, defense mechanisms, and childhood experiences reshaped how we understand human behavior and thought processes. Freud's ideas, though controversial, laid the groundwork for various branches of psychology and therapeutic practices. His exploration of the psyche and emphasis on the importance of early experiences have influenced not just psychology but also literature, art, and broader cultural understandings of human nature.