Olaf Karthaus (born 1963 in Koblenz) is a German polymer chemist and Professor at the Chitose Institute of Science and Technology in Chitose, Hokkaidō, Japan, researching polymer chemistry, thin films, photonics, and nanotechnology. Karthaus was a co-plaintiff with Debito Arudou and Kenneth Sutherland in an anti-discrimination lawsuit against a hot spring (onsen) in Otaru, Japan, that refused entry to individuals with foreign appearance even if they were Japanese citizens.