Robert Louis Griess, Jr. (b. 1945, Savannah, Georgia) is a mathematician working on finite simple groups and vertex algebras. Currently, Griess is a professor of mathematics at University of Michigan.
He constructed the monster group using the Griess algebra.
He received the AMS Leroy P. Steele Prize for a Seminal Contribution to Research in 2010. In 2012 he became a fellow of the American Mathematical Society.
- R. L. Griess, Jr, The Friendly Giant, Inventiones Mathematicae 69 (1982), 1–102