- Alfred A. Knopf (1892–1984), American publisher
- Edwin H. Knopf (1899–1981), American film producer, director and screenwriter
- Heinrich Knopf (1839–1875), German luthier
- Jim Knopf, computer specialist
- Maike-Katrin Knopf (born 1959), German footballer
- Philip Knopf (1847–1920), member of the United States House of Representatives from Illinois
- Rainer Knopff, Canadian political scientist
- Sigard Adolphus Knopf (1857–1940), a German-born American physician.