| Anna Torv | Olivia Dunham |
| Joshua Jackson | Peter Bishop
(credit only) |
| Lance Reddick | Phillip Broyles
(credit only) |
| Blair Brown | Nina Sharp |
| Jasika Nicole | Astrid Farnsworth
(credit only) |
| John Noble | Dr. Walter Bishop /
Walternate |
| Jenni Blong | Dr. Carla Warren |
| Orla Brady | Alternate Elizabeth Bishop |
| Michael Cerveris | September |
| Peter Woodward | August |
| Serge Houde | General Hayes |
| Quinn Lord | Young Peter |
| Julian Christopher | General Tonks
(as Julian D. Christopher) |
| Eugene Lipinski | December |
| John Shaw | Medical Examiner
(uncredited) |
| Jamie Switch | Lloyd Becker
(uncredited) |