IPAM mourns the death of a colleague and friend, Walter Kohn. Kohn made major contributions to the physics of semiconductors, superconductivity, surface physics and catalysis. Since 1979, he was a professor of physics at the University of California, Santa Barbara, where he was the founding director of the Institute of Theoretical Physics, one of the leading research centers in physics. He received numerous awards including the Niels Bohr/Unesco Gold Medal, the United States National Medal of Science and the Richard Prange Prize. His role in creating Density Functional Theory, the most widely used theory of the electronic structure of matter, earned him the Nobel Prize in Chemistry in 1998. Kohn last visited IPAM in 2012 as the speaker of the first annual Green Family Lecture Series where he gave a talk titled “A Physicist’s Approach to Macular Degeneration.” Read his obituary and a collection of short stories and anecdotes about Walter Kohn published in 2003 on the occasion of his 80^th birthday.