Walter Willett (born 1945), Professor of Epidemiology and Nutrition at the Harvard School of Public Health
William Willett (disambiguation), multiple people, including:
William Willett (1856–1915), English builder and promoter of daylight saving time
William Willett, Jr. (1869–1938), U.S. Representative from New York (state) from 1907–1911
William Willett (Royal Navy officer) (1919–1976), an officer of the Royal Navy and Private Secretary to His Royal Highness the Duke of Edinburgh, consort of Queen Elizabeth II
Given name
Willett Main (1828-1902), American politician from Wisconsin