Kai Bird is an American author and historian, known for his biographies and works on American history. He was born on August 2, 1951, and has written several acclaimed books, including American Prometheus, a biography of J. Robert Oppenheimer, which won the Pulitzer Prize for Biography or Autobiography in 2006. Bird has also co-authored works with Martin J. Sherwin and has written about various historical figures and events, focusing on themes of politics and science. His writing often explores the complexities of historical narratives and the impact of individual actions on broader societal changes.