When Hans Bethe, at the age of 97, asked his long-term collaborator, Gerry Brown, to explain his scientific work to the world, the latter knew that this was a steep task. As the late John Bahcall famously remarked: "If you know his (Bethe's) work, you might be inclined to think he is really several people, all of whom are engaged in a conspiracy to sign their work with the same name". Almost eight decades of original research, hundreds of scientific papers, numerous books, countless reports spanning the key areas of 20th century physics are the impressive record of Hans Bethe's academic work. In answering Bethe's request, the editors enlisted the help of experts in the different research fields, collaborators and friends of this "last giant" of 20th century physics. "Hans Bethe and His Physics" is the result. It contains discussions of Hans Bethe's work in solid state physics, nuclear physics and astrophysics; it explains his contributions as a science advisor and his stance on energy and nuclear weapons; and it demonstrates his impact as a teacher and mentor to generations of young scientists. While the book's primary aim is to explain the science behind the man, the different articles also allow the reader to take a glimpse at the man behind the science.