Edward Teller, often called the “father of the hydrogen bomb,” was a Hungarian-American physicist who played a central role in the development of nuclear weapons during the Cold War. He worked on Robert Oppenheimer’s team at Los Alamos during World War II and later championed the hydrogen bomb, as well as peaceful applications of nuclear energy and improved reactor safety standards. Teller’s career embodied both the scientific breakthroughs and moral controversies of the nuclear age.