William Leach
William Leach may refer to:
- William Elford Leach, English zoologist and marine biologist
- William Leach (politician), British Labour Party politician, minister in the first Labour government
- William Turnbull Leach, Canadian clergyman and academic
- William Leach (canoeist), American sprint canoer
- William Leach (cricketer, born 1851), English cricketer
- William Leach (cricketer, born 1883), English cricketer
- William Leach (Canadian Army officer)
- William Leach (historian), American historian