Alex Eskin (born May 19, 1965) is an American mathematician, born in the former USSR. He works on rational billiards and geometric group theory. For his contribution to joint work with David Fisher and Kevin Whyte establishing the quasi-isometric rigidity of sol, he was awarded the 2007 Clay Research Award.
Eskin was born in Moscow. He is the son of a Russian-Jewish mathematician Gregory I. Eskin (b. 1936, Kiev), professor of UCLA. The family emigrated to Israel in 1974 and in 1982 to the United States.
Eskin earned his doctorate from Princeton University in 1993, under supervision of Peter Sarnak. He has been a professor at University of Chicago since 1999.
In 2012 he became a fellow of the American Mathematical Society. In April 2015 Eskin was elected a member of the U.S. National Academy of Sciences.