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

Graham Yost