| Sonny Valicenti | ADT Serviceman |
| Holt McCallany | Bill Tench |
| Stacey Roca | Nancy Tench |
| Michael Cerveris | Assistant Director Gunn |
| Anna Torv | Dr. Wendy Carr |
| Jonathan Groff | Holden Ford |
| Joe Tuttle | Gregg Smith |
| Lauren Glazier | Kay Manz |
| David Healy | Commonwealth Attorney |
| Nate Corddry | Detective Art Spencer |
| Emily Bergl | Mavis Leland |
| Zachary Scott Ross | Brian Tench |
| Elijah Everett | CMF Guard #2
(as Eli Everett) |
| Cameron Britton | Edmund Kemper |
| Brian Stapf | CMF Guard #1 |
| Damon Herriman | Charles Manson |
| Liza Fernandez | Gate Agent |
| Erik Jensen | Dr. Moritz |
| Christopher Backus | Tex Watson |
| Tammy Felice | Gretchen Gunn |
| Robert Farrior | Warren |
| Christopher Grove | AD Wyman |
| Albert Jones | Jim Barney
(voice) |
| Mike Ancas | Airport Traveler
(uncredited) |
| Cole Elliott | FBI Agent
(uncredited) |
| Mark Falvo | FBI Executive
(uncredited) |
| Julianne Kalec | Waitress
(uncredited) |
| Damion Le Vias | Prisoner
(uncredited) |
| Kevin Mahler | Drunk party guest
(uncredited) |