Björn Birnir is a Professor of Mathematics at the University of California at Santa Barbara (UCSB).

He obtained his PhD in Mathematics at the Courant Institute in 1981 and held positions at the Unversity of Arizona Tucson, University of California Berekely and University of Iceland before UCSB. He served as the UCSB coordinator for nonlinear science from 1985-1990. He is currently the director of the Center for Complex and Nonlinear Science at UCSB. His current research interest are: Stochastic nonlinear partial differential equations (SPDEs) and turbulence; dynamical systems theory of PDEs; mathematical seismology and geomorphology; nonlinear phenomena in quantum mechanical systems; complex and nonlinear models in biology and applications of the above.