Robert Gaunt is the devil. He goes from place to place to sow discord and cause destruction and death for his own pleasure. He sees it as a sort of entertainment. He cannot be killed, only defeated. He comes to Castle Rock for that purpose. HHe opens a shop called Needful Things and from there he manages to seed destruction, death and discord, but is defeated by Sheriff Pangborn in the nick of time, who manages to make people realise who he is.One of them, in revenge destroys his shop in an attempt to kill him.
However, he appears from the ruins unscathed and promises, that he will return, since it is what he always does and promises Pangborn he will meet his grandson in Jakarta in 2053 and that he will make headlines with him. After that he goes away with his car.