From the National Academy of Sciences:
Roger Dashen was a profoundly insightful theoretical physicist who made major contributions to our modern understanding of how the phenomena of particle physics emerge from the mathematics of quantum field theory. He was also deeply interested in applied physics and made innovative contributions to acoustics, wave propagation in random media, and oceanography. His intellectual generosity and broad interest in physics made him an exceptional mentor of young theorists and, later in his career, a wise and effective institution builder. He was, more than anything else, a theoretical physics natural— gifted with an uncanny ability to quickly grasp the essence of complex physical problems and to create, seemingly effortlessly, effective mathematical realizations of his insights.