This chapter outlines a few of the more common mental traps also encountered by intelligence analysts. It focuses on the first systematic study of the specific pitfalls lying between an intelligence analyst and clear thinking carried out by Richards Heuer, a thought leader in the field of intelligence analysis. Analyst bias fall primarily into specific types or categories: personality bias, confirmation bias, target fixation, improper use of analogy, and organizational culture. Lack of information and negative organizational culture can combine to force the selection of the wrong analogy and push the analysis process down the wrong track toward incorrect answers or at minimum divert critical analytical and collection assets toward useless research and wasted time. Organizational culture can foster collaborative and extremely productive analysis; it can just as well foster groupthink. The chapter explores the several types’ cognitive bias encountered by intelligence analysts as well as other professional and scientific vocations.