Martin Karplus is an Austrian-American theoretical chemist at Harvard University and the Université de Strasbourg, recognized as one of the founders of multiscale computational chemistry. Together with Michael Levitt and Arieh Warshel, he developed methods that combine classical molecular mechanics with quantum mechanical calculations — the QM/MM approach — allowing chemists to simulate the behavior of large biological molecules such as enzymes and nucleic acids at atomistic resolution. Karplus's work on molecular dynamics simulations gave researchers the ability to study protein folding, ligand binding, and reaction mechanisms computationally, transforming rational drug design. He also pioneered the use of the Karplus equation relating NMR coupling constants to dihedral angles in biomolecules. Karplus shared the 2013 Nobel Prize in Chemistry with Levitt and Warshel. His methodological contributions are embedded in widely used software packages (CHARMM, AMBER) used daily in pharmaceutical, biotechnology, and academic research laboratories worldwide.