Frederic Middlebrook Richards (August 19, 1925 – January 11, 2009), commonly referred to as Fred Richards, was an American biochemist and biophysicist known for solving the pioneering crystal structure of the ribonuclease S enzyme in 1967 and for defining the concept of solvent-accessible surface. He contributed many key experimental and theoretical results and developed new methods, garnering over 20,000 journal citations in several quite distinct research areas. In addition to the protein crystallography and biochemistry of ribonuclease S, these included solvent accessibility and internal packing of proteins, the first side-chain rotamer library, high-pressure crystallography, new types of chemical tags such as biotin/avidin, the nuclear magnetic resonance (NMR) chemical shift index, and