Carl Jung

Carl Gustav Jung (26 July 1875 - 6 June 1961) was a Swiss psychiatrist and the founder of Analytical Psychology.
Carl believed that too much of the field of psychology was based on logic, and that much could be learned through the study of dreams, art, philosophy and religion. His work was spread wide, as he studied fields from astrology to alchemy to literature.
Jung proposed many completely original concepts over the course of his studies, including but not limited to The archetype, The complex, The collective unconscious, and Synchronicity.
While working with Freud early in his career, he became fascinated with the unconscious human mind, and devoted his life's work to discovering it's secrets.
Jung introduced many parts of the human unconscious not yet brought out into light. The Individuation is a person's gradual journey towards identifying him or herself. This process is what generally causes the "mid-life crisis" halfway through an adult's life, as they begin to understand long hidden desires and fear wasting the second half of their lifespan.
His Idea of the Anima and Animus within the human psyche was also a first in psychology. The anima is the female component of a male's mind, and the animus is the male component of a female's mind. People not in touch with their anima or animus may seem overly masculine or feminine, off balance from the social norm. Repression of one's Anima/us will result in this part of the human brain attempting to gain attention by manifesting itself in how that person sees others.
Another of his psychological discoveries is the idea of The Shadow. The Shadow of a human mind is the part of each person that we choose not to acknowledge and is generall the exact opposite of how that person portrays him or herself. The shadow of a kind man will be overl cruel, and vice versa. It also works with one's mental projection of ones self, as a person convinced that they are beautiful will have a hidden, ugly shadow beneath.
Jung's further work involves the exploration of different psychological typed of people, including investigation of the introvert versus the extrovert. He also proposed spirituality as a cure for alcoholism.
Connections in his life to the Nazi party overshadowed his work during the years of the war and after, though he was never proven to be part of the Nazi movement, he did write in favor of Hitler's book Mein Kampf, and he served as the president of the International General Medical Society for Psychotherapy, a Nazi dominated organization.

Source:http://en.wikipedia.org/wiki/Carl_jung