Final answer:
David McCullough is the author of Pulitzer Prize-winning biographies of John Adams and Harry Truman.
Step-by-step explanation:
The author who has written Pulitzer Prize-winning biographies of John Adams and Harry Truman is David McCullough. McCullough wrote the biographies 'John Adams' and 'Truman', both of which received the Pulitzer Prize for Biography or Autobiography. His works provide in-depth insights into the lives and political careers of these two presidents.