Donnie Wahlberg
Detective Joel Stevens (24 eps)
Neal McDonough
Assistant District Attorney David McNorris (24 eps)
Mykelti Williamson
Police Department Detective II Bobby 'Fearless' Smith (24 eps)
Gary Basaraba
Police Department Police Officer III Ray Hechler (24 eps)
Lana Parrilla
Teresa Ortiz, paramedic in season one, rookie police officer in season two (24 eps)
Jason Gedrick
Police Department Police Officer II Tom Turcotte (24 eps)
Nina Garbiras
Andrea Little, a reporter (season one) (18 eps)
Megan Ward
Kelly Stevens (7 eps)
Vanessa Williams
Detective Katherine Pierce (6 eps)
Dorian Harewood
Captain Ronald Hicks (6 eps)
Kelly Rowan
Marian McNorris (3 eps)
Rick Gomez
Detective Daniel Ramos (2 eps)
Chase Ellison
Willie Stevens (2 eps)
Kelly Hu
Rachel Durrel (2 eps)
Matt Craven
Dr. Michael Hirsch (2 eps)
Kim Murphy
Susan (2 eps)
David Proval
Paul Turcotte (2 eps)
Rino Romano
Paul Turcotte in 1976 (1 eps)
J.C. Brandy
Chandler (1 eps)
Wendy Schaal
Darlene Beechem (1 eps)
Derek Hamilton
Jimmy Black (1 eps)
Alia Shawkat
Denise Stein (1 eps)
LeVar Burton
Marvin Lloyd (1 eps)
John Kapelos
Hugo Pinkston (1 eps)
Kathleen Wilhoite
Sally McBride (1 eps)
Daniel Zacapa
Carlos Ramirez (1 eps)
Stacy Keach
Jack 'Mac' McNorris (1 eps)
Nathan West
Zack Berman (1 eps)
Bob Clendenin
Doofus (1 eps)
Virginia Madsen
Erika Ashland (1 eps)
Cody Kasch
Trevor 'T.J.' Jankowski Jr. (1 eps)
Shannon Sturges
Cherie Hechler (1 eps)
Chris Gartin
Jonny Rand (1 eps)
Peter Trencher
Coroner (1 eps)
Beau Billingslea
Police Academy Commandant (1 eps)
Tyler Christopher
Holden McKay (1 eps)
Alimi Ballard
Young Marvin Lloyd (1 eps)
Jennifer Sky
Vanessa Griggs / Laura (1 eps)
Lisa Cerasoli
Mia Lang (1 eps)
Sheeri Rappaport
Janice Edwards (1 eps)
Arlen Escarpeta
Cantrel LaFontaine (1 eps)
Alexander Gould
Tom at 8 (1 eps)
Christian Camargo
Bradley Dawson (1 eps)
Kate Flannery
Tracey (1 eps)
Larry Joshua
Chet (1 eps)
Miguel A. Núñez Jr.
Freaktown (1 eps)
Raja Fenske
Puppet (1 eps)
Rick Ravanello
Sean Dornan (1 eps)
Trent Cameron
Bernie Leonard (1 eps)
Howard Hesseman
Mel Castle (1 eps)
Kevin Dunn
Ron Berman (1 eps)
Erin Daniels
Officer Karen Crane (1 eps)
Stephen Macht
John Donadoni (1 eps)
Megan Henning
Emily (1 eps)
Wade Williams
Paul Barnes (1 eps)
Joe Penny
Les Van Buren (1 eps)
Ken Davitian
Jewelry Store Owner (1 eps)
Alex Meneses
Vicki Pineda (1 eps)
Tracey Walter
Dwayne (1 eps)
Michael Muhney
Chris Griggs (1 eps)
Katee Sackhoff
Holly (1 eps)
Ernie Grunwald
Charlie Graham (1 eps)
Jessica Lundy
Vivian Colson (1 eps)
Mimi Paley
Rachel Stein (1 eps)
Robert Wisdom
Chronic (Daryl C. Norcott) (1 eps)
Fran Bennett
Beatrice Rahming (1 eps)
Mark Moses
Don Schneider (1 eps)
Marquise Wilson
Friend #3 (1 eps)
Gina Hecht
Doreen Stein (1 eps)
Michael Paul Chan
Lobo Chan (1 eps)
Dan Byrd
Eddie Colson (1 eps)
Ramón Franco
Luis Valdoriso (1 eps)
Rebecca Lowman
Lisa (1 eps)
Dayo Ade
Banger (1 eps)
Tommy Hinkley
Mr. Flannery (1 eps)
Jason George
Thomas Paltrow (1 eps)
Doug Hutchison
Wally Pollard (1 eps)
Christopher Gorham
Gordon Sinclair (1 eps)
Robert LaSardo
Pope (1 eps)
Nigel Gibbs
Alex Leonard (1 eps)
Ali Hillis
Melanie Stone (1 eps)
Loren Lester
Homeowner (1 eps)
Paige Hurd
Grace Adams (1 eps)
Fredric Lehne
Reggie Flood (1 eps)
April Grace
Cynthia (1 eps)
Silas Weir Mitchell
Erik Sorenson (1 eps)
Kirk Trutner
Homeless Man (1 eps)
Dempsey Pappion
Young Greg Haymer (1 eps)
Lombardo Boyar
Eddie (1 eps)
Kristin Bauer van Straten
Prostitute (1 eps)
Joe Spano
Henry Stein (1 eps)
Paul Moyer
Paul Moyer (1 eps)
Neil Patrick Harris
Peter Corman (1 eps)
David Dunard
Irate Grandfather (1 eps)
Frank John Hughes
Officer Vincent Manzani (1 eps)
Patricia Wettig
Nora Jean Flannery (1 eps)
Beth Grant
Landlady (1 eps)
Gregg Henry
Robert Colson (1 eps)
Garikayi Mutambirwa
Friend #2 (1 eps)
Michael Dempsey
Recovering drunk (1 eps)
Bobby Hosea
Greg Haymer (1 eps)
Anthony Montgomery
Recruit Dwight Baker (1 eps)
Richard Erdman
Kevin's Dad (1 eps)
Christoph Krisea
Warden Frank Collins (1 eps)
David Burke
Jay Colson (1 eps)
Chris Mulkey
Kevin Van Horn (1 eps)
Cullen Douglas
Arnold Rabjohn (1 eps)
Dakota Floeter
Young Wally Pollard (1 eps)
Ray Laska
Edward Nelson (1 eps)
Mark Totty
Chip Pollard (1 eps)
Henry G. Sanders
Police Sergeant Miller (1 eps)
Annika Peterson
Katrina (1 eps)
Demetra Raven
Lara (1 eps)
Brian Sites
Taylor Gates (1 eps)
Salvator Xuereb
John McBride (1 eps)
Ryan Stockstad
Paramedic (uncredited) (1 eps)
Kim Rhodes
Julia Sloane (1 eps)
Gregory White
Judge Harold Denby (1 eps)