Brother of Boris Katz and Mikhail Katz. Kac studied mathematics at Moscow State University, receiving his M.S. in 1965 and his Ph.D. in 1968. From 1968 to 1976, he held a teaching position at the Moscow Institute of Electronic Machine Building. He left the Soviet Union in 1977, becoming an associate professor of mathematics at MIT. In 1981, he was promoted to full professor. Kac received a Sloan Fellowship in 1981 and a Guggenheim Fellowship in 1986 and the Medal of the Collège de France (1981). He received the Wigner Medal (1996) "in recognition of work on affine Lie algebras that has had wide influence in theoretical physics". In 1978 he was an Invited Speaker at the International Congress of Mathematicians (ICM) in Helsinki. Kac was a plenary speaker at the 1988 American Mathematical Society cen- tennial conference. In 2002 he gave a plenary lecture, Classification of Supersymme- tries, at the ICM in Beijing. Kac is a Fellow of the American Mathematical Society, an Honorary member of the Moscow Mathematical Society, Fellow of the American Academy of Arts and Sciences and a Member of the National Academy of Sciences. The research of Victor Kac primarily concerns representation theory and mathemati- cal physics. His work appears in mathematics and physics and in the development of quantum field theory, string theory and the theory of integrable systems. Victor Kac was awarded the 2015 AMS Leroy P. Steele Prize for Lifetime Achievement.