IT by Stehen King

IT is a 1986 horror novel by American author Stehen King. The story follows the exploits of seven children as they are terrorized by the eponymous inter-dimensional predatory life-form that exploits the fears and phobias of its victims in order to disguise itself whilst hunting its prey. "It" primarily appears in the form of "Bob Gray" a.k.a. "Pennywise the Dancing Clown", described by characters who see It as resembling a combination of Bozo, Clarabell and Ronald McDonald, in order to attract its preferred prey of young children. The novel is told through narratives alternating between two time periods, which is largely told in a third-person omniscient view. It deals with themes which would eventually become King staples: the power of memory, childhood trauma and the ugliness lurking beneath a façade of traditional small-town values. The novel "IT" won the British Fantasy Award in 1987, and received nominations for the Locus and World Fantasy Awards that same year. Publishers Weekly listed It as the best-selling book in America in 1986.
"It" apparently originated in a void containing and surrounding the universe, a place referred to in the novel as the "Macroverse". It's most commonly used name is Bob Gray or Pennywise (at several points in the novel, It claims its true name to be Robert Gray) and is christened "It" by the group of children who later confront It. Likewise, It's true form is never truly comprehended. It's favorite form is that of a clown... (Summary by Wikipedia)