Roy Jay Glauber (September 1, 1925 – December 26, 2018) was an American theoretical physicist. He was the Mallinckrodt Professor of Physics at Harvard University and Adjunct Professor of Optical Sciences at the University of Arizona. Born in New York City, he was awarded one half of the 2005 Nobel Prize in Physics "for his contribution to the quantum theory of optical coherence", with the other half shared by John L. Hall and Theodor W. Hänsch. In this work, published in 1963, he created a model for photodetection and explained the fundamental characteristics of different types of light, such as laser light (see coherent state) and light from light bulbs (see blackbody). His theories are widely used in the field of quantum optics. In statistical physics he pioneered the study of the dynamics of first-order phase transitions, since he first defined and investigated the stochastic dynamics of an Ising model in a largely influential paper published in 1963. He served on the National Advisory Board of the Center for Arms Control and Non-Proliferation, the research arms of Council for a Livable World.