| David Duchovny | Fox Mulder |
| Gillian Anderson | Dana Scully |
| Mitch Pileggi | Walter Skinner |
| William B. Davis | Smoking Man |
| Charles Cioffi | Section Chief Scott Blevins |
| Tom Braidwood | Melvin Frohike |
| Dean Haglund | Richard 'Ringo' Langly |
| Bruce Harwood | John Fitzgerald Byers |
| John Finn | Michael Kritschgau |
| Steve Makaj | Scott Ostelhof |
| Ken Camroux-Taylor | Senior Agent
(as Ken Camroux) |
| Barry W. Levy | Dr. Vitagliano |
| Julia Arkos | Holly |
| Don S. Williams | Elder |
| Fidel Castro | Self
(archive footage) (uncredited) |
| Dwight D. Eisenhower | Self
(archive footage) (uncredited) |
| Ian Gregson | Amputee Patient
(uncredited) |
| Lyndon B. Johnson | Self
(archive footage) (uncredited) |
| John F. Kennedy | Self
(archive footage) (uncredited) |
| Nikita Khrushchev | Self
(archive footage) (uncredited) |
| Joseph McCarthy | Self
(archive footage) (uncredited) |
| Ashley Montagu | Self
(archive footage) (uncredited) |
| Richard Nixon | Self
(archive footage) (uncredited) |
| John Sampson | Sentry
(uncredited) |
| Harry S. Truman | Self
(archive footage) (uncredited) |
| Mao Zedong | Self
(archive footage) (uncredited) |