Boomtown

Donnie Wahlberg

Detective Joel Stevens

Neal McDonough

Assistant District Attorney David McNorris

Mykelti Williamson

Police Department Detective II Bobby 'Fearless' Smith

Gary Basaraba

Police Department Police Officer III Ray Hechler

Lana Parrilla

Teresa Ortiz, paramedic in season one, rookie police officer in season two

Jason Gedrick

Police Department Police Officer II Tom Turcotte

Nina Garbiras

Andrea Little, a reporter (season one)

Megan Ward

Kelly Stevens

Vanessa Williams

Detective Katherine Pierce

Dorian Harewood

Captain Ronald Hicks

Kelly Rowan

Marian McNorris

Rick Gomez

Detective Daniel Ramos

Chase Ellison

Willie Stevens

Kelly Hu

Rachel Durrel

Matt Craven

Dr. Michael Hirsch

Kim Murphy

Susan

David Proval

Paul Turcotte

Rino Romano

Paul Turcotte in 1976

J.C. Brandy

Chandler

Wendy Schaal

Darlene Beechem

Derek Hamilton

Jimmy Black

Alia Shawkat

Denise Stein

LeVar Burton

Marvin Lloyd

John Kapelos

Hugo Pinkston

Kathleen Wilhoite

Sally McBride

Daniel Zacapa

Carlos Ramirez

Stacy Keach

Jack 'Mac' McNorris

Nathan West

Zack Berman

Bob Clendenin

Doofus

Virginia Madsen

Erika Ashland

Cody Kasch

Trevor 'T.J.' Jankowski Jr.

Shannon Sturges

Cherie Hechler

Chris Gartin

Jonny Rand

Peter Trencher

Coroner

Beau Billingslea

Police Academy Commandant

Tyler Christopher

Holden McKay

Alimi Ballard

Young Marvin Lloyd

Jennifer Sky

Vanessa Griggs / Laura

Lisa Cerasoli

Mia Lang

Sheeri Rappaport

Janice Edwards

Arlen Escarpeta

Cantrel LaFontaine

Alexander Gould

Tom at 8

Christian Camargo

Bradley Dawson

Kate Flannery

Tracey

Larry Joshua

Chet

Miguel A. Núñez Jr.

Freaktown

Raja Fenske

Puppet

Rick Ravanello

Sean Dornan

Trent Cameron

Bernie Leonard

Howard Hesseman

Mel Castle

Kevin Dunn

Ron Berman

Erin Daniels

Officer Karen Crane

Stephen Macht

John Donadoni

Megan Henning

Emily

Wade Williams

Paul Barnes

Joe Penny

Les Van Buren

Ken Davitian

Jewelry Store Owner

Alex Meneses

Vicki Pineda

Tracey Walter

Dwayne

Michael Muhney

Chris Griggs

Katee Sackhoff

Holly

Ernie Grunwald

Charlie Graham

Jessica Lundy

Vivian Colson

Mimi Paley

Rachel Stein

Robert Wisdom

Chronic (Daryl C. Norcott)

Fran Bennett

Beatrice Rahming

Mark Moses

Don Schneider

Marquise Wilson

Friend #3

Gina Hecht

Doreen Stein

Michael Paul Chan

Lobo Chan

Dan Byrd

Eddie Colson

Ramón Franco

Luis Valdoriso

Rebecca Lowman

Lisa

Dayo Ade

Banger

Tommy Hinkley

Mr. Flannery

Jason George

Thomas Paltrow

Doug Hutchison

Wally Pollard

Christopher Gorham

Gordon Sinclair

Robert LaSardo

Pope

Nigel Gibbs

Alex Leonard

Ali Hillis

Melanie Stone

Loren Lester

Homeowner

Paige Hurd

Grace Adams

Fredric Lehne

Reggie Flood

April Grace

Cynthia

Silas Weir Mitchell

Erik Sorenson

Kirk Trutner

Homeless Man

Dempsey Pappion

Young Greg Haymer

Lombardo Boyar

Eddie

Kristin Bauer

Prostitute

Joe Spano

Henry Stein

Paul Moyer

Paul Moyer

Neil Patrick Harris

Peter Corman

David Dunard

Irate Grandfather

Frank John Hughes

Officer Vincent Manzani

Patricia Wettig

Nora Jean Flannery

Beth Grant

Landlady

Gregg Henry

Robert Colson

Garikayi Mutambirwa

Friend #2

Michael Dempsey

Recovering drunk

Bobby Hosea

Greg Haymer

Anthony Montgomery

Recruit Dwight Baker

Richard Erdman

Kevin's Dad

Christoph Krisea

Warden Frank Collins

David Burke

Jay Colson

Chris Mulkey

Kevin Van Horn

Cullen Douglas

Arnold Rabjohn

Dakota Floeter

Young Wally Pollard

Ray Laska

Edward Nelson

Mark Totty

Chip Pollard

Henry G. Sanders

Police Sergeant Miller

Annika Peterson

Katrina

Demetra Raven

Lara

Brian Sites

Taylor Gates

Salvator Xuereb

John McBride

Ryan Stockstad

Paramedic (uncredited)

Kim Rhodes

Julia Sloane