Althaus is a surname. Notable people with the surname include:
Dieter Althaus (born 1958), German politician, Minister-President of Thuringia
Johannes Althusius (1557–1638), also known as Johannes Althaus, German Calivinist philosopher and theologian
Marcella Althaus-Reid, Argentinian professor
Adolf Paul Johannes Althaus, theologian
Kenneth Althaus, U.S. Army, general during World War II
Ernst Freiherr von Althaus, one of the world's first flying aces
