Carl Gustav Jung was a Swiss psychologist and psychiatrist who was a follower of Freudian theory but then departed from it to some extent because he disagreed with Freud's emphasis on sexual causation in some personality dysfunctions. Jung founded Analytic Psychology, in response to Freud's Psychoanalysis. It was Jung who named and developed the concepts of Extraversion and Introversion, so much part of our thinking today.
His theory of archetypes has also been prominent in the field of literature, even religion, as well as psychiatry. Jung also proposed the concept of a Collective Unconscious, thus developing Freud's work on the Unconscious in driving behaviour. His knowledge of history and understanding of personality led to a gentler, more restorative psychiatric approach. His life span was 1875-1961 but his influence remains as strong as when he lived.