| Adewale Akinnuoye-Agbaje | Simon Adebisi |
| 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 |
| Robert John Burke | Special Agent Pierce Taylor |
| Reg E. Cathey | Martin Querns |
| Christopher Meloni | Chris Keller |
| George Morfogen | Bob Rebadow |
| Luna Lauren Velez | Dr. Gloria Nathan
(as Lauren Vélez) |
| BD Wong | Father Ray Mukada |
| Granville Adams | Zahir Arif |
| Charles Busch | Nat Ginzburg |
| Philip Casnoff | Nikolai Stanislofsky |
| Robert Clohessy | Officer Sean Murphy |
| Lord Jamar | Kevin 'Supreme Allah' Ketchum |
| Erik King | Moses Deyell |
| Tom Mardirosian | Agamemnon Busmalis |
| Craig muMs Grant | Poet
(as muMs) |
| Pepa | Officer Andrea Phelan |
| Lance Reddick | Desmond Mobay |
| Kristin Rohde | Officer Claire Howell |
| Scott William Winters | Cyril O'Reily |
| David Zayas | Enrique Morales |
| Jerome Preston Bates | Officer Travis Smith |
| Peter Hans Benson | Reporter
(as Peter Benson) |
| Timothy L. Brown | Officer Jason Armstrong |
| Dylan Chalfy | Patrick Keenan |
| Carl DiMaggio | Officer Len Lopresti |
| Sean Dugan | Timmy Kirk |
| Gano Grills | Raymond 'Mondo' Browne |
| Ra Hanna | Nacim Bismilla |
| Jon M. McDonnell | Prison Guard |
| Connie Nelson | Det. Guinevere McGorry |
| Harry O'Reilly | Bruno Gergen |
| John Palumbo | Don Zanghi |
| Michael Quill | Mark Miles |
| R.E. Rodgers | James Robson |
| Otto Sanchez | Chico Guerra |
| Philip Scozzarella | Officer Joseph Mineo
(as Philip V. Scozzarella) |
| Evan Seinfeld | Jaz Hoyt |
| Jacques C. Smith | Leroy Tidd
(as Jacques Smith) |
| Chuck Zito | Chucky Pancamo |
| Whitney Allen | Miss Sally
(uncredited) |
| Frank Bonsangue | Sicilian Crew
(uncredited) |
| Claude Jay | OZ Correction Officer
(uncredited) |
| Mick Leroy | Security Officer
(uncredited) |
| Steven Wishnoff | Tony Masters
(uncredited) |