| Will Rosser | ... | Narrator (voice) | |
| Anthony Summers | ... | Himself - Author of 'The Secret Life of J. Edgar Hoover' | |
| John Fox | ... | Himself - FBI Historian | |
| William Gallinaro | ... | Himself - Crime Detective | |
| Athan Theoharis | ... | Himself - Author of 'The FBI and American Democracy' | |
| Curt Gentry | ... | Himself - Author of 'J. Edgar Hoover: The Man and the Secrets' | |
| John M. Dowd | ... | Himself - US Justice Department (as John Dowd) | |
| William Turner | ... | Himself - Former FBI Agent (as Bill Turner) | |
| Bill Bonanno | ... | Himself - Son of Mafia Boss Joseph Bonanno | |
| rest of cast listed alphabetically: | |||
| Inga Arvad | ... | Herself, Danish journalist (archive footage) | |
| Milton Berle | ... | Himself (archive footage) | |
| Joseph Bonanno | ... | Himself, mobster (archive footage) | |
| Judy Cerda | ... | Louisa Stewart | |
| Frank Costello | ... | Himself, mobster (archive footage) | |
| John Dillinger | ... | Himself (archive footage) | |
| Sam Giancana | ... | Himself, mobster (archive footage) | |
| John Benjamin Hickey | ... | Narrator, National Geographic Channel version | |
| J. Edgar Hoover | ... | Himself (archive footage) | |
| Lyndon Johnson | ... | Himself (archive footage) | |
| George Kelly | ... | Himself, gangster, aka 'Machine Gun Kelly' (archive footage) | |
| John F. Kennedy | ... | Himself (archive footage) | |
| Robert F. Kennedy | ... | Himself (archive footage) | |
| Rose Kennedy | ... | Herself (archive footage) | |
| Martin Luther King | ... | Himself (archive footage) | |
| Meyer Lansky | ... | Himself, mobster (archive footage) | |
| John Mitchell | ... | Himself, U.S. Attorney General (archive footage) | |
| Marilyn Monroe | ... | Herself (archive footage) | |
| Richard Nixon | ... | Himself (archive footage) | |
| Eleanor Roosevelt | ... | Herself (archive footage) | |
| Franklin D. Roosevelt | ... | Himself (archive footage) | |
| Ethel Rosenberg | ... | Herself (archive footage) | |
| Julius Rosenberg | ... | Himself (archive footage) | |
| Dean Rusk | ... | Himself (archive footage) | |
| Clyde Tolson | ... | Himself (archive footage) | |
| Harry S. Truman | ... | Himself (archive footage) | |
| Episode Crew |
Writing credits(in alphabetical order) | ||
| Jason Cohn | writer | |
Original Music by | |||
| Justin Melland | |||
Cinematography by | |||
| Jon Shenk | |||
Film Editing by | |||
| Jeremy Stuart | |||
Production Management | |||
| Ken Harris | .... | production manager | |
| Marie Wiljanen | .... | production manager | |
Sound Department | |||
| Philip Perkins | .... | sound editor | |
| Philip Perkins | .... | sound re-recording mixer | |
| Frank Scheuring | .... | post-production audio | |
Editorial Department | |||
| Craig Hickerson | .... | assistant editor | |
Other crew | |||
| Bradley Everett Wilson | .... | production coordinator | |
| Series Crew These people are regular crew members. Were they in this episode? |
Production Management | |||
| Brook Holston | .... | production manager | |
| Main series | Episode guide | Full cast and crew |
| Company credits | IMDb TV section | IMDb History section |
| IMDb USA section |