Hartle, J.

Introduction: Stephen Hawking overcame the limitations of a debilitating disease to make major contributions to science. He did this through remarkable persistence, determination, conviction, courage, and will. He was supported in this by his family, his students, and his colleagues. Stephen said, “My goal is simple. It is a complete understanding of the universe.” Stephen’s many contributions to science moved us significantly toward that goal. Much of his work was in two major areas—cosmology and the physics of black holes. I mention only one contribution in each that stands out—his work on the beginning of the universe and his work on the end of black holes.