Richard Snyder, a visionary and imperious executive at Simon & Schuster who presided over the publisher’s exponential rise during the second half of the 20th century and helped define an era of growing corporate power, has died.

David McCullough, the Pulitzer Prize-winning author whose lovingly crafted narratives on subjects ranging from the Brooklyn Bridge to Presidents John Adams and Harry Truman made him among the most popular and influential historians of his time, has died.