| David Duchovny | Fox Mulder |
| Gillian Anderson | Dana Scully |
| Bryan Cranston | Patrick Crump |
| Michael O'Neill | Patrol Captain Van Gelder |
| James Pickens Jr. | Alvin Kersh |
| Harry Danner | CDC Doctor |
| Junior Brown | Virgil Nokes |
| Linda Porter | Elderly Woman |
| Mindy Seeger | Coroner |
| Scott Alan Smith | Prison Doctor
(as Scott A. Smith) |
| Timothy Dale Agee | EMT
(as Tim Agee) |
| Mark Craig | Trooper #1 |
| Wiley M. Pickett | Trooper #2
(as Wiley Pickett) |
| Ken Collins | Gas Station Attendant |
| Tegan West | Navy Lieutenant |
| Tom Haile | Station Wagon Owner |
| Frank Buckley | Nevada News Anchor |
| Bob Peters | Idaho News Anchor |
| Janine Venable | Vicky Crump |
| Art Pickering | Germ Suit Cop |
| Greg Bronson | Med Tech
(uncredited) |
| Artine Tony Browne | Creep
(uncredited) |