Harry Leonard Swinney (born April 10, 1939) is an American physicist noted for his contributions to the field of nonlinear dynamics.
In 1968 he was awarded a Ph.D. in physics by Johns Hopkins University; his advisor was Herman Z. Cummins.
Since 1978 Swinney has been on the faculty of the University of Texas at Austin, where he is now Sid W. Richardson Foundation Regents Chair of Physics and director of the Center for Nonlinear Dynamics.
He was a Guggenheim Fellow (1983–84) and he was inducted into The Johns Hopkins University Society of Scholars (1984).
Swinney conducts research on instabilities, chaos, and pattern formation in diverse systems, including fluid, chemical, and granular media.