Hans Zinsser (November 17, 1878 – September 4, 1940) was a American bacteriologist and a prolific author. The son of German immigrants, Zinsser was born in New York City in 1878. Zinsser received his undergraduate degree from Columbia University in 1899 and completed both a masters degree and a doctorate in medicine there in 1903. After holding a series of academic medicine positions, Zinsser became an associate professor at Stanford University in 1910. In 1913, Zinsser moved to a position at his alma mater. Ten years later, he was hired away by Harvard Medical School, where he stayed until his death. He is interred in Sleepy Hollow Cemetery in Sleepy Hollow, New York.

Zinsser's scientific work focused on bacteriology and immunology and he is greatly associated with Brill’s disease as well as typhus. He is known for his work in isolating the typhus bacterium and developing a protective vaccine. He wrote several books about biology and bacteria, notably Rats, Lice and History, a "biography" of typhus fever. Rats, Lice and History was republished in 2007 by Transaction Publishers.