| Kirk Acevedo | Miguel Alvarez |
| Ernie Hudson | Warden Leo Glynn |
| Terry Kinney | Tim McManus |
| Rita Moreno | Sister Peter Marie Reimondo |
| Harold Perrineau | Augustus Hill |
| J.K. Simmons | Vern Schillinger |
| Lee Tergesen | Tobias Beecher |
| Eamonn Walker | Kareem Said |
| Dean Winters | Ryan O'Reily |
| Adewale Akinnuoye-Agbaje | Simon Adebisi |
| Edie Falco | Officer Diane Whittlesey |
| George Morfogen | Bob Rebadow |
| Luna Lauren Velez | Dr. Gloria Nathan
(as Lauren Velez) |
| BD Wong | Father Ray Mukada |
| Austin Pendleton | William Giles |
| Eddie Malavarca | Peter Schibetta |
| Kathryn Erbe | Shirley Bellinger |
| Dylan Baker | Schillinger's Defense Attorney |
| Melina Kanakaredes | A.D.A. Marilyn Crenshaw |
| J.D. Williams | Kenny Wangler |
| Craig muMs Grant | Poet
(as muMs) |
| Scott William Winters | Cyril O'Reily |
| Tom Mardirosian | Agamemnon Busmalis |
| Geoffrey Nauffts | Clifford Sprague |
| Granville Adams | Zahir Arif |
| Timothy L. Brown | Officer Jason Armstrong
(as Tim Brown) |
| Bryan Callen | Jonathan Coushaine |
| Sean Dugan | Timmy Kirk |
| Tim Hopper | Rick Donn |
| Jordan Lage | Richie Hanlon |
| Annika Peterson | Shannon O'Reily |
| Floyd Resnick | Officer |
| Leif Riddell | Mark Mack |
| Philip Scozzarella | Officer Joseph Mineo
(as Philip V. Scozzarella) |
| Frank Senger | Frank Manhardt |
| Lexington Alexander | Junior Pierce
(as Malé 'Big X' Alexander) |
| Chuck Zito | Chucky Pancamo |
| Tony Devon | Dr. Meadows |
| Todd Etelson | Mario Seggio |
| Ali Merhi | Luis Batista |
| Brian Smyj | Alexander Vogel |
| Frank Bonsangue | Sicilian Crew
(uncredited) |
| Brett Gillen | Philip Featherstone
(uncredited) |
| Edgar Nicholson | Muslim Inmate
(uncredited) |
| Nick Stellate | Prisoner in Gym
(uncredited) |