Siegfried S. Hecker is an American nuclear scientist and metallurgist who served as the Director of the Los Alamos National Laboratory from 1986 till 1997. Austrian by birth, he is a Professor (research) in the Department of Management Science and Engineering in the School of Engineering and a Senior Fellow at the Freeman Spogli Institute for International Studies of Stanford University. He formerly served as Co-Director of the Center for International Security and Cooperation from 2007-2012.