The article presents fanaticism as a universal phenomenon that can manifest itself in almost every sphere of human activity. Although many expressions of fanaticism are negative and destructive, some can be almost neutral or even positive. The article describes the characteristics of the fanatic and explains some factors that predispose people towards fanatical behavior. It also highlights some differences between fundamentalism and fanaticism which can sometimes seem quite similar. Describing fanaticism in its multi-faceted nature, the article aims to show the reader that fanaticism is a much wider phenomenon than sometimes thought.