Perhaps the most widely recognized personality assessment in the world, the MBTI has been implemented as a valuable predictive and diagnostic tool by innumerable businesses, coaches, psychologists, and interested individuals. However, recent research has shown that the MBTI is host to a variety of significant validity issues, and the test altogether fails to address any aspects of deviant personality. A review will draw attention to the consequential validity issues of the MBTI, its overlooking of deviant personality characteristics, and the repercussions of using such an unsound and exclusive personality test. The suitability of HEXACO as a viable alternative for the MBTI will demonstrate the capability of HEXACO in assessing deviant personality.