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.

John Jacob Astor was a German-born American businessman, merchant, real estate mogul, and investor. Astor made his fortune mainly in a fur trade monopoly, by exporting opium into China, and by investing in real estate in or around New York City. He was the first prominent member of the Astor family and the first multi-millionaire in the United States.