Robert L. Griess Jr., the John Griggs Thompson Distinguished University Professor of Mathematics, is one of the 120 scientists elected to the National Academy of Sciences in 2020. Griess, a member of the UM faculty since 1971, has made pioneering discoveries in the areas of finite groups, finite aspects of Lie theory, vertex algebras, and rational lattices.  His 1980 construction of the Monster, the largest of the sporadic simple groups, represented a breakthrough in theory and helped open new connections within mathematics and with theoretical physics.