Arts
- William Gilbert (1804–1890), an English novelist and surgeon who was the father of W. S. Gilbert
- W. S. Gilbert (1836–1911), a British dramatist who worked with Arthur Sullivan as part of the Gilbert and Sullivan team
- Billy Gilbert (also known as William V. Campbell) (1891–1961), an American silent film actor
- Billy Gilbert (1894–1971), an American comedian whose birth name was William Barron
- Willie Gilbert (1916–1980), an American author and playwright
Politicians
- William Gilbert (active around 1530), served as a member of parliament for Derby
- William Gilbert (1829–1919), member of the South Australian parliament and helped others through charitable work
- William A. Gilbert (1815–1875), American politician
Sports
- William Gilbert (cricketer) (1856–1918), an English cricketer
- Bill Gilbert (baseball) (1868–1927), an American baseball player
- Billy Gilbert (baseball) (1876–1927), a Major League Baseball second baseman
- Willy Gilbert (1881–1956), a Norwegian sailor
- Billy Gilbert (footballer) (born 1959), an English former footballer
- Bill Gilbert (speedway rider), an English speedway rider
Others
- William Gilbert (1544? – 1603), English physicist, doctor, and scientist
- William W. Gilbert (about 1746–1832), American maker of silver items
- William Gilbert (rugby) (1799–1877), British shoemaker and maker of rugby balls
- William Ball Gilbert (1847–1931), American judge
- William Gilbert (pastoralist) (1850–1923), South Australian farmer and wine grower
- Bill Gilbert (intelligence service director) (1916–1987), New Zealand military officer and intelligence service director
- William Gilbert Puckey (1805–1878), New Zealand missionary
- William Gilbert Rees (1827–1898), New Zealand explorer and settler