Ngo Bao Chau is a Vietnamese-French mathematician at the University of Chicago, best known for proving the fundamental lemma for automorphic forms proposed by Robert Langlands and Diana Shelstad. He is the first Vietnamese national to have received the Fields Medal.

Chau became a professor at Paris-Sud 11 University in 2005. In 2005, at age 33, Chau received the title of professor in Vietnam, becoming the country's youngest-ever professor. Since 2007, Chau has worked at the Institute for Advanced Study, Princeton, New Jersey, as well as the Hanoi Institute of Mathematics. He joined the mathematics faculty at the University of Chicago on September 1, 2010. In addition, since 2011 he has been Scientific Director of the newly founded Vietnam Institute for Advanced Study in Mathematics (VIASM). In 2016 Chau u was Co-General Chair of Asiacrypt the first time that the Asian cryptography conference was held in Vietnam.Chau first came to prominence by proving, in joint work with Gerard Laumon, the fundamental lemma for unitary groups. Their general strategy was to understand the local orbital integrals appearing in the fundamental lemma in terms of affine Springer fibres arising in the Hitchin fibration. This allowed them to employ the tools of geometric representation theory, namely the theory of perverse sheaves, to study what was initially a combinatorial problem of a number-theoretic nature. Chau eventually succeeded in formulating the proof for the fundamental lemma for Lie algebras in 2008. Together with results from Jean-Loup Waldspurger, who had earlier deduced stronger forms of the fundamental lemma from this result, this completed the proof of the fundamental lemma in all cases.

In 2004, Chau and Laumon were awarded the Clay Research Award for their achievement in solving the fundamental lemma proposed by Robert Langlands for the case of unitary groups. Châu's proof of the general case was selected by Time as one of the Top Ten Scientific Discoveries of 2009. In 2010, he received the Fields Medal and in 2011, he received the Legion of Honour. In 2012, he became a fellow of the American Mathematical Society. In 2021, he became an honorary member of the London Mathematical Society.