William Waldorf Astor, (August 13, 1907 - March 7, 1966), was a businessman and politician and a member of the prominent Astor family.

Known as Bill Astor, he was the son of William Waldorf Astor II and Nancy Witcher Langhorne. He was educated at Eton College and at New College, Oxford. In 1932, he was appointed to the office of Secretary to the Earl of Lytton, League of Nations Committee of Enquiry in what was then known as Manchuria.

First elected to the British House of Commons in 1935, he served as a Unionist Conservative for the constituency of East Fulham. He held the office of Parliamentary Private Secretary to the First Lord of the Admiralty between 1936 and 1937 then was made Secretary of State for the Home Department.

Active in thoroughbred horse racing, he inherited Cliveden Stud, a horse farm and breeding operation in the village of Taplow near Maidenhead.

He left politics for a time, but returned as the Conservative member of Parliament for Wycombe in 1951, serving for two years. On his father's passing in 1952, he inherited his title, becomg the 3rd Viscount Astor and took over the Cliveden estate in Buckinghamshire where he and his family continued to live until his passing in 1966. During the Profumo Affair he was accused of having an affair with Mandy Rice-Davies.

William Waldorf Astor married three times:

1. 1945: Sarah Kathleen Elinor Norton - divorced 1953. They had one son, William Waldorf Astor, 4th Viscount Astor (born 1951)
2. 1955: Phillipa Victoria Hunloke - divorced 1960, They had a daughter, Emily Mary Astor (born 1956)
3. 1960: Janet Bronwen Alun Pugh. They had two children, Janet Elizabeth Astor (born 1961) and Pauline Marian Astor (born 1964)