Background: Sunset Boulevard (stylized onscreen as SUNSET BLVD.) is a 1950 American film noir directed and co-written by Billy Wilder, and produced and co-written by Charles Brackett. It was named after the thoroughfare that runs through Los Angeles and Beverly Hills, California. The film stars William Holden as Joe Gillis, an unsuccessful screenwriter, and Gloria Swanson as Norma Desmond, a faded silent-film star who draws him into her fantasy world, where she dreams of making a triumphant return to the screen.
Context: The street known as Sunset Boulevard has been associated with Hollywood film production since 1911, when the town's first film studio opened there. The film workers lived modestly in the growing neighborhood, but during the 1920s, profits and salaries rose to unprecedented levels. With the advent of the star system, luxurious homes noted for their often incongruous grandeur were built in the area.  As a young man living in Berlin in the 1920s, Billy Wilder was interested in American culture, with much of his interest fueled by the country's films. In the late 1940s, many of the grand Hollywood houses remained, and Wilder, then a Los Angeles resident, found them to be a part of his everyday world. Many former stars from the silent era still lived in them, although most were no longer involved in the film business. Wilder wondered how they spent their time now that "the parade had passed them by" and began imagining the story of a star who had lost her celebrity and box-office appeal.  The character of Norma Desmond mirrors aspects of the twilight years of several real-life faded silent-film stars, such as the reclusive existence of Mary Pickford and the mental disorders of Mae Murray and Clara Bow. It is usually regarded as a fictional composite inspired by several different people, not just a thinly disguised portrait of one in particular. Nevertheless, some commentators have tried to identify specific models. One asserts that Norma Talmadge is "the obvious if unacknowledged source of Norma Desmond, the grotesque, predatory silent movie queen" of the film. The most common analysis of the character's name is that it is a combination of the names of silent film actress Mabel Normand and director William Desmond Taylor, a close friend of Normand's who was murdered in 1922 in a never-solved case sensationalized by the press.
Question: Who played the role of Norma Desmond?. Whats the answer?