No single figure in 20th century American history inspires such opposing opinions as J. Edgar Hoover, the iconic first director of the Federal Bureau of Investigation. In his time, he was arguably the most powerful non-elected figure in the U.S. government. Serving under 8 presidents (and outliving 2 of them), he remains the longest-serving head of a major government office. In essence, Hoover died as he began - a civil servant, having been appointed by the Attorney General and serving at the pleasure of the president. 

By the 1960s and 1970s Hoover the hero had become Hoover the villain. Various exposes and investigations revealed a darker side to the legend, one that included serious violations of the civil liberties of individuals. Hoover's G-Men, it was discovered, engaged in illegal break-ins and wiretaps of suspected subversives; they wrote fake letters that undermined the reputations of public individuals; they paid informants for information and push the groups they belonged to into committing illegal acts. It was alleged that Hoover led a personal vendetta against Martin Luther King, Jr., and the entire civil rights movement. Hoover, it was said, had stayed in office so long by gathering secret files of damaging information about politicians (including presidents).

To this day, Allen Dulles' eight-year tenure in that office is the longest, and as one of the country's leading experts in international law, intelligence, and spycraft, he became renowned for his unwavering anti-communist ideology and readiness to take decisive measures to counter what he perceived as a menace to American safety. As such, it would be Dulles who sanctioned many of the CIA's most notorious operations, including the ousting of Iran's democratically elected government in 1953, spying and experimentation on American citizens, and the disastrous Bay of Pigs.