Dieffenbach is a German surname. Notable people with the surname include:
Edouard Dieffenbach (1897–1972) French military officer, World War I veteran Ernst Dieffenbach (1811–1855), German physician, geologist and naturalist Georg Christian Dieffenbach (1822–1901), German poet and theologian Johann Friedrich Dieffenbach (1792–1847), German surgeon Joseph Dieffenbach (1796–1863), German gardener
See also Diefenbach (surname)