Classic Biographers:
* James Boswell: While Scottish, his biography of Samuel Johnson is considered one of the greatest biographies ever written, and he is considered a founding figure in the genre.
* Carl Sandburg: A poet, but also known for his multi-volume biography of Abraham Lincoln.
* Arthur Schlesinger Jr.: Known for his Pulitzer Prize-winning biographies of John F. Kennedy and Robert F. Kennedy.
* David McCullough: Renowned for his detailed and engaging historical biographies, including those of Harry Truman, John Adams, and the Wright brothers.
* Doris Kearns Goodwin: A historian who has written acclaimed biographies of Lyndon B. Johnson, Franklin D. Roosevelt, and Theodore Roosevelt.
Modern Biographers:
* Ron Chernow: Known for his in-depth biographies of historical figures like Alexander Hamilton and John D. Rockefeller.
* Walter Isaacson: A prolific biographer who has written about Steve Jobs, Albert Einstein, Leonardo da Vinci, and Benjamin Franklin.
* Robert Caro: Known for his monumental multi-volume biography of Robert Moses, a powerful figure in 20th-century New York City.
* Stacy Schiff: A Pulitzer Prize-winning biographer who has written about Cleopatra and Vera Nabokov.
* Stephen King: Though primarily a novelist, he also wrote a critically acclaimed biography of Richard Bachman, his pseudonym.
Other Notable Biographers:
* Edmund Morris: Known for his innovative biographical approaches, including his "novelistic" biography of Theodore Roosevelt.
* Peter Ackroyd: A British author, but his biography of Charles Dickens is considered a masterpiece.
* Leon Edel: Known for his multi-volume biography of Henry James.
This is just a small sample of the many talented American biographers. To narrow down your question, you could provide more specific information about the time period, the subject, or the style of biography you're interested in.