August Paul von Wassermann (21 February 1866 - 16 March 1925) was a German bacteriologist.
Born in Bamberg, with Jewish origins, he studied at several universities throughout Germany, and in 1890 began to work under Robert Koch at the Institute for Infectious Diseases at the Charité in Berlin. He developed a complement fixation test for the diagnosis of syphilis in 1906, just one year after the causative organism had been identified; this allowed for early detection of the disease (despite its nonspecific symptoms), and thus prevention of transmission. He became head of the department of therapeautics and serum research in 1907.
The Wassermann test remains a staple of syphilis detection and prevention in some areas, although it has often been replaced by more modern alternatives.