Caroline Webster "Lina" Schermerhorn Astor was a prominent American socialite of the second half of the 19th century who led the Four Hundred. Famous for being referred to later in life as "the Mrs. Astor" or simply "Mrs. Astor", she was the wife of yachtsman William Backhouse Astor Jr. They had five children, including Colonel John Jacob Astor IV, who perished on the RMS Titanic. Through her marriage, she was a prominent member of the Astor family and matriarch of the male line of American Astors.

William Backhouse Astor Sr. was an American business magnate who inherited most of his father John Jacob Astor's fortune. He worked as a partner in his father's successful export business. His massive investment in Manhattan real estate enabled major donations to the Astor Library in the East Village, which became the New York Public Library.