Muse Watson - Charles Westmoreland (18/22 episodes).
Frank Grillo - Nick Savrinn (18/22 episodes).
Phillip Edward Van Lear - Louis Patterson (19/22 episodes).
Stacy Keach - Henry Pope (20/22 episodes).
Rockmond Dunbar - Benjamin Miles "C-Note" Franklin (16/22 episodes).
Robert Knepper - Theodore "T-Bag" Bagwell (19/22 episodes).
Paul Adelstein - Paul Kellerman (19/22 episodes).
Sarah Wayne Callies - Sara Tancredi (22/22 episodes).
Wade Williams - Brad Bellick (22/22 episodes).
Peter Stormare* - John Abruzzi (17/22 episodes).
Marshall Allman - Lincoln "LJ" Burrows Jr (11/22 episodes).
Amaury Nolasco - Fernando Sucre (22/22 episodes).
Robin Tunney - Veronica Donovan (22/22 episodes).
Wentworth Miller - Michael Scofield (22/22 episodes).
Dominic Purcell - Lincoln Burrows (22/22 episodes).
Paul Adelstein and Robert Knepper were credited as guest stars before episode 3 Peter Stormare was credited as a guest star after episode 13 and Rockmond Dunbar was credited as a guest star before episode 14.