Other forms: screenwriters
Someone who writes movie scripts or screenplays is called a screenwriter. A novelist whose book is being made into a film might be hired to be the screenwriter.
Every movie has a script, with lines for the actors to speak and directions for certain camera shots and scene changes. The person who writes the screenplay is the screenwriter. Some big-budget Hollywood films might have several screenwriters who collaborate. The word's been used since the 1920s, from the sense of screen that means "cinema world," or "surface on which a movie is projected."