Otto Kratky (German: [ˈɔtɔ ˈkʁatki]; born 9 March 1902 in Vienna – died 11 February 1995 in Graz) was an Austrian physicist.
He is best known for his contribution to the small-angle X-ray scattering method, for the Kratky plot, and for the invention of the density metering using the oscillating u-tube principle.
After completing his university education, he became an assistant at the Kaiser Wilhelm Institute in Berlin-Dahlem in 1928, a position he held until 1933.
He then worked as a university lecturer at the University of Vienna until he returned to the Institute for Physical Chemistry and Electrochemistry of the Kaiser Wilhelm Institute in Berlin in 1937 as the head of the X-ray department.
He became a full professor at the Czech Technical University in Prague and from 1943 to 1945 head of the institute for physical chemistry there.