According to John Beebe, Jung’s type was INTJ. Jung described himself as an introverted intuitive thinking type. One must keep in mind his model had 8 personality types, not the 16 types developed under MBTI.
Sometimes I wonder if Jung’s type was INFJ. There is no doubt his dominant function was introverted intuition; even just a passing familiarity with the Red Book confirms that. These are things about his life that make me wonder if he had parent (auxiliary) extroverted feeling or parent extroverted thinking.
He spent several years at the beginning of his career conducting word association games with patients. This is how he developed his theory of introversion and extroversion and also learned about complexes by the way people would unconsciously react to certain words.
Jung also spent years working with schizophrenic patients, which further confirmed his theory of the collective unconscious.
A childhood friend of his said that when Jung was a child he was terrible at math. Whereas he was good at dominating groups of 50-60 students by engaging in speculative thought, which was foreign to the other students.
The above and other facets of his life make me wonder if INFJ is a serious possibility. If you have an opinion I’d love to hear what you think. For now I’ll default to Beebe’s belief that Jung was INTJ and that Fe was his trickster function.
Sources:
Energies and Patterns of Psychological Type