Richard Royce Schrock is an American chemist at MIT renowned for discovering the first well-defined transition metal carbene and carbyne complexes and for developing tungsten and molybdenum alkylidene catalysts for olefin metathesis. His Schrock carbenes are nucleophilic and exceptionally active for ring-opening metathesis polymerization (ROMP) and ring-closing metathesis (RCM), enabling the construction of cyclic and polymeric structures of precise topology. Schrock and Yves Chauvin provided the mechanistic foundation and practical catalyst design for metathesis, while Robert Grubbs developed the ruthenium-based catalysts. Together, these three shared the 2005 Nobel Prize in Chemistry. Metathesis is now a core tool in the synthesis of pharmaceuticals, specialty polymers, and agrochemicals. Schrock co-founded Materia Inc. to commercialize metathesis catalysts. His work fundamentally changed how chemists think about constructing carbon–carbon double bonds and polymer architecture, with broad industrial impact.