| Honorific Prefix: | His Grace |
| The Duke of Westminster | |
| Birth Date: | 23 December 1894 |
| Resting Place: | Eccleston Church |
| Parents: | Lord Henry Grosvenor Dora Erskine-Wemyss |
| Office: | Duke of Westminster |
| Term Start: | 19 July 1953 |
| Term End: | 22 February 1963 |
| Predecessor: | Hugh Grosvenor |
| Successor: | Gerald Grosvenor |
William Grosvenor, 3rd Duke of Westminster (23 December 1894 – 22 February 1963) was a British landowner and aristocrat.
William Grosvenor was the son of Lord Henry George Grosvenor (1861–1914), a son of Hugh Grosvenor, 1st Duke of Westminster. His mother, Dora Mina Erskine-Wemyss, was the daughter of James Erskine Wemyss, and a great-granddaughter of William IV.
He was brain-damaged at birth and required constant assistance. He succeeded his cousin, the 2nd Duke, as 3rd Duke of Westminster in 1953. After the death of his mother, he lived with his stepmother, the former Rosamund Angharad Lloyd, in a small house in the south of England. After his stepmother's death, the Duke lived in another house in Bath with a carer.
The Duke died in 1963 at the age of 68, unmarried and childless. He is buried in the churchyard of Eccleston Church near Eaton Hall, Cheshire. His titles passed to his cousin Gerald Grosvenor.