Robert Howard Grubbs (b. 27 February 1942 near Possum Trot, Kentucky) is an American chemist and Nobel laureate. Grubbs received the 2005 Nobel Prize in Chemistry, along with Richard R. Schrock and Yves Chauvin, for his work in the field of olefin metathesis.

Grubbs studied chemistry at the University of Florida (B.S. and M.S.), where he worked with Merle Battiste, and Columbia University, where he obtained his Ph.D. under Ronald Breslow in 1968.
In 1978 he moved to California Institute of Technology where he is presently Victor and Elizabeth Atkins Professor of Chemistry.
Grubbs's many awards have included: Alfred P. Sloan Fellow (1974–76), Camille and Henry Dreyfus Teacher-Scholar Award (1975–78), Alexander von Humboldt Fellowship (1975), ACS Benjamin Franklin Medal in Chemistry (2000), ACS Herman F. Mark Polymer Chemistry Award (2000), ACS Herbert C. Brown Award for Creative Research in Synthetic Methods (2001), the Tolman Medal (2002), and the Nobel Prize in Chemistry (2005).