Personal relationships, particularly romantic ones, can be the INTJ's Achilles heel. While they are capable of caring deeply for others (usually a select few), and are willing to spend a great deal of time and effort on a relationship, the knowledge and self-confidence that make them so successful in other areas can suddenly abandon or mislead them in interpersonal situations.
This happens in part because many INTJs do not readily grasp the social rituals; for instance, they tend to have little patience and less understanding of such things as small talk and flirtation (which most types consider half the fun of a relationship). To complicate matters, INTJs are usually extremely private people, and can often be naturally impassive as well, which makes them easy to misread and misunderstand. Perhaps the most fundamental problem, however, is that INTJs really want people to make *sense*. :-) This sometimes results in a peculiar naiveté', paralleling that of many Fs -- only instead of expecting inexhaustible affection and empathy from a romantic relationship, the INTJ will expect inexhaustible reasonability and directness.
Augustus Caesar (Gaius Julius Caesar Octavianus), Emperor of Rome
Hannibal, Carthaginian military leader
Ivan Lendl, tennis champion
Martina Navratilova, tennis champion
John F. Kennedy
Hannibal Lecter (Silence of the Lambs)
Professor Moritarty, Sherlock Holmes's nemesis
Ensign Ro (Star Trek - the Next Generation)