Professor Leslie Gabriel Valiant is a British-American computer scientist and computational theorist who is currently the T. Jefferson Coolidge Professor of Computer Science and Applied Mathematics at Harvard University.

Professor Valiant is well-known for his work in theoretical computer science. He was awarded the A.M. Turing Award in 2010 for work in machine learning, computational complexity and parallel computation, having been described by the ACM as a heroic figure in theoretical computer science and a role model for his courage and creativity in addressing some of the deepest unsolved problems in science.

Professor Valiant also received the Nevanlinna Prize from the International Mathematical Union in 1986, the Knuth Prize in 1997, and the European Association for Theoretical Computer Science Award in 2008. He was elected a Fellow of the Royal Society (FRS) in 1991, and a member of the United States National Academy of Sciences in 2001.

Professor Valiant was educated at King’s College, University of Cambridge, followed by Imperial College London, and finally at the University of Warwick, where he received his Ph.D. in Computer Science in 1974. He started teaching at Harvard University in 1982, prior to which he taught at Carnegie Mellon University, Leeds University, and the University of Edinburgh.