Siegfried S. Hecker is an American metallurgist and nuclear scientist. He served as Director of the Los Alamos National Laboratory from 1986 to 1997 and is now affiliated with Stanford University, where he is research professor emeritus in the Department of Management Science and Engineering in the School of Engineering, and senior fellow emeritus at the Freeman Spogli Institute for International Studies. During this time, he was also elected a member of the National Academy of Engineering (1988) for outstanding research on plutonium and the forming of materials, and for leadership in developing energy and weapons systems.

Los Alamos National Laboratory is one of the sixteen research and development laboratories of the United States Department of Energy (DOE), located a short distance northwest of Santa Fe, New Mexico, in the American southwest. Best known for its central role in helping develop the first atomic bomb, LANL is one of the world's largest and most advanced scientific institutions.