The concept of psychohistory was popularized by the science fiction writer Isaac Asimov in his Foundation series. In the series, psychohistory is a fictional science that combines elements of psychology, sociology, and statistics to predict the behavior of large populations over long periods of time. The central character of the series, Hari Seldon, is portrayed as the inventor of psychohistory. However, it is important to note that psychohistory is purely a fictional concept created by Asimov for his novels and does not exist as a real scientific discipline.