| Nathan Fillion | Richard Castle |
| Stana Katic | Kate Beckett |
| Susan Sullivan | Martha Rodgers |
| Jon Huertas | Javier Esposito |
| Seamus Dever | Kevin Ryan |
| Tamala Jones | Lanie Parish
(credit only) |
| Molly C. Quinn | Alexis Castle |
| Penny Johnson Jerald | Captain Victoria Gates
(credit only) |
| Lisa Edelstein | Rachel McCord |
| Yancey Arias | Chief Carl Villante |
| Jocko Sims | Matt Hendricks |
| Warren Christie | Brad Parker |
| Glenn Morshower | Defense Secretary Michael Reed |
| Omid Abtahi | Rasheed Waqas |
| Ellen Bry | Mary Elizabeth Reed |
| Jack Kennedy | Jack Bronson |
| Myko Olivier | Pi |
| Peter James Smith | Agent Richmond |
| Celeste Den | Julie |
| Dan Glenn | Security Detail Member |
| Cedric Scott | Admiral Johnson |
| Dan Warner | House Security Detail |
| Len Anderson IV | Pilot
(voice) (uncredited) |
| Michael Bofshever | Dr. Goldberg
(uncredited) |