INTP's and INTJ's. Based on their MBTI dominant functions, INTP's should correspond to Jung's Introverted thinking type, and INTJ's to Jung's Introverted Intuiting type. Here are brief summaries of Jung's description of those types:
Introverted Intuiting - ineffectual dreamers, mystics, fantasizers. Sometimes end up as the half-wit wise men in "psychological novels". Incredibly bad with communication (other people simply can't understand them, and they can't understand why), though not necessarily unsociable. Often attacked from the unconscious by a primitive extraverted sensing function which results in obsessions with visual images, places, faces, etc. Further, in the section on Introverted irrationals in general, they are described as good teachers who teach not with words but with their life.
Introverted Thinking - cold-blooded strategists, loners, theoretics. Arrogant, unsociable, having a certain disdain for others whom they consider stupid. Seem to others to be constantly angry, almost hateful. Completely certain in their opinions, strong will. Sometimes shamelessly exploited by strong women. Attacked from the unconscious by a primitive extraverted feeling function which makes them take every criticism, even fair, very personally (and later makes them seek revenge).
Note that MBTI would have INTP's as the latter type and INTJ's as the former! Surely the mistake should be bloody OBVIOUS!