**Ronald Kantowski** is a theoretical cosmologist, well known in the field of general relativity as the author, together with Rainer K. Sachs, of the Kantowski–Sachs dust solutions to the Einstein field equation. These are a widely used family of inhomogeneous cosmological models.

Kantowski received his Ph.D. in 1966 from the University of Texas at Austin, where he wrote a dissertation on cosmological models. He was a research scientist at the South West Center for Advanced Studies during 1967-1968. He was hired by the Physics & Astronomy department of the University of Oklahoma in 1968, where he became a full professor in 1981.

Besides the Kantowski-Sachs solutions to the Einstein's field equations, Kantowski's second widely recognized contribution to cosmology was developing the now used theory of transparent gravitational lenses. This theory was completed some four years before multiply imaged quasars were detected. There were only four papers written in all at that time. Kantowski was also among the first to study the distance-redshift relation in inhomogeneous Universe using Swiss cheese universe models.

His recent research has centered on issues of mass inhomogeneties and topological quantum field theories.