3. Mark Felt
Labeled “Deep Throat” by the Washington Post Bob Woodward and Carl Bernstein, FBI Associate Director W. Mark Felt came forward in 1972 with information about the Nixon White House’s links to the Watergate burglary. This led to Nixon’s resignation two years later, and to this day he remains the only serving U.S. president to walk away from the Oval Office.
The Post reporters stayed true to the journalistic code and their source’s name was kept under wraps until almost three decades. Having provided the facts and leads to confirm Nixon’s role in the affair, Felt’s role as one of America’s most influential whistleblowers is undoubted.