| Honorific-Prefix: | The Right Honourable |
| The Viscount Astor | |
| Office1: | Parliamentary Under-Secretary of State for National Heritage |
| Primeminister1: | John Major |
| Term Start1: | 20 July 1994 |
| Term End1: | 6 July 1995 |
| Predecessor1: | Iain Sproat |
| Successor1: | The Lord Inglewood |
| Office2: | Parliamentary Under-Secretary of State for Social Security |
| Primeminister2: | John Major |
| Term Start2: | 16 September 1993 |
| Term End2: | 20 July 1994 |
| Predecessor2: | Ann Widdecombe |
| Successor2: | James Arbuthnot |
| Office3: | Lord-in-waiting Government Whip |
| Primeminister3: | Margaret Thatcher John Major |
| Term Start3: | 11 October 1990 |
| Term End3: | 16 September 1993 |
| Predecessor3: | The Lord Cavendish of Furness |
| Successor3: | The Lord MacKay of Ardbrecknish |
| Office4: | Member of the House of Lords |
| Status4: | Lord Temporal |
| Term Label4: | as a hereditary peer |
| Term Start4: | 4 July 1973 |
| Term End4: | 11 November 1999 |
| Predecessor4: | The 3rd Viscount Astor |
| Successor4: | Seat abolished |
| Term Label5: | as an elected hereditary peer |
| Term Start5: | 11 November 1999 |
| 1Blankname5: | Election |
| 1Namedata5: | 1999 |
| Predecessor5: | Seat established |
| Birth Name: | William Waldorf Astor III |
| Birth Date: | 27 December 1951 |
| Party: | Conservative |
| Alma Mater: | Eton College |
| Children: | 3 |
| Relatives: | See Astor family |
| Occupation: | Politician, businessman |
William Waldorf Astor III, 4th Viscount Astor (born 27 December 1951) is an English businessman and politician who sits as a Conservative hereditary Lord Temporal in the House of Lords. He is a member of the Astor family, which is known for its prominence in business, society, and politics in both the United States and the United Kingdom.
Astor was a Lord-in-waiting (a House of Lords whip) from 1990 to 1993. He was then made a Parliamentary Under Secretary of State at the Department of Social Security. In 1994, he moved to the Department of National Heritage where he served until leaving the government in 1995.
He was a member of the Founding Council of the Rothermere American Institute at the University of Oxford.[1]
Viscount Astor is Chairman of Silvergate Media and director of Networkers Plc (since 2007) and trustee of Stanley Spencer Gallery in Cookham.
Astor was an early opponent of the HS2 high-speed rail project.[2]
Astor married Annabel Lucy Veronica Jones (born 1948), daughter of Timothy Angus Jones and Patricia David Pandora Clifford on 14 January 1976. They have three children:
The heir to the viscountcy is his elder son, Will.[3]
His wife Annabel's stepfather was his uncle Michael Langhorne Astor.
Viscountess Astor was previously married to Sir Reginald Sheffield, 8th Baronet by whom she is the mother of Samantha Cameron, wife of former Prime Minister David Cameron.
| Crest: | From a Mount Vert a Falcon rising proper ensigned by three Mullets Gold |
| Coronet: | A Coronet of a Viscount |
| Escutcheon: | Or, a falcon resting on a dexter hand couped at the wrist proper and gauntleted gules in chief two fleurs-de-lys of the last |
| Supporters: | Dexter: a North American Indian; Sinister: a North American fur trapper; each habited accoutred and holding in the exterior hand a Rifle all proper |
| Motto: | Ad Astra (To the stars) |