| Dominic West | Det. James 'Jimmy' McNulty |
| Reg E. Cathey | Norman Wilson |
| John Doman | Acting Commissioner William A. Rawls |
| Aidan Gillen | Mayor Thomas 'Tommy' Carcetti |
| Clark Johnson | City Editor Augustus 'Gus' Haynes |
| Deirdre Lovejoy | Asst. State's Atty. Rhonda Pearlman |
| Tom McCarthy | Scott Templeton |
| Clarke Peters | Det. Lester Freamon |
| Wendell Pierce | Det. William 'Bunk' Moreland |
| Lance Reddick | Dep. Comm. for Operations Cedric Daniels |
| Andre Royo | Reginald 'Bubbles' Cousins |
| Sonja Sohn | Det. Shakima 'Kima' Greggs |
| Seth Gilliam | Sgt. Ellis Carver |
| Domenick Lombardozzi | Thomas 'Herc' Hauk |
| Michael Kenneth Williams | Omar Little
(credit only) |
| Gbenga Akinnagbe | Chris Partlow |
| Jamie Hector | Marlo Stanfield |
| Neal Huff | Chief of Staff Michael Steintorf |
| Jermaine Crawford | Duquan 'Dukie' Weems |
| Corey Parker Robinson | Det. Leander Sydnor |
| Tristan Mack Wilds | Michael Lee
(as Tristan Wilds) |
| Michael Kostroff | Maurice 'Maury' Levy |
| Michelle Paress | Alma Gutierrez |
| Isiah Whitlock Jr. | State Sen. R. Clayton 'Clay' Davis |
| Robert Wisdom | Howard 'Bunny' Colvin |
| Julito McCullum | Namond Brice |
| Felicia Pearson | Felicia 'Snoop' Pearson |
| Steve Earle | Walon |
| Method Man | Melvin 'Cheese' Wagstaff |
| Delaney Williams | Sgt. Jay Landsman |
| Marlyne Barrett | Council President Nerese Campbell
(as Marlyne Afflack) |
| David Costabile | Managing Editor Thomas Klebanow |
| Sam Freed | Executive Editor James C. Whiting III |
| Darrell Britt-Gibson | Darius 'O-Dog' Hill |
| Edward Bernard Green Jr. | Spider
(as Edward Green) |
| Kwame Patterson | 'Monk' Metcalf |
| Thomas J. McCarthy | State Editor Tim Phelps
(as Tom McCarthy) |
| Robert Poletick | Metro Editor Steven Luxenberg |
| William F. Zorzi | Bill Zorzi |
| Michael Mosley | Raymond Wiley |
| Donald Neal | Rewrite Man Jay Spry |
| Stephen Schnetzer | Robert Ruby |
| Brandon Young | Mike Fletcher |
| Keenon Brice | Aaron 'Bug' Manigault |
| Eisa Davis | Bubbles' Sister |
| Dawn Ursula | Lolita Colvin |
| Melvin Williams | Deacon |
| Nat Benchley | Det. Augustus Polk |
| Bobby J. Brown | Off. Bobby Brown
(as Bobby Brown) |
| Rick Otto | Off. Kenneth Dozerman |
| Ryan Sands | Off. Lloyd 'Truck' Garrick |
| Bryan Anderson | Marino |
| Reggie Alvin Green | Arabber
(as Reggie A. Green) |
| Kathy Lally | Kathy Lally |
| Pam Spiliadis | Pam Spiliadis
(as Pam Spilliadis) |
| Dennis Hill | Det. Christeson |
| Ayanna S. Flemings | Woman
(as Ayanna Fleming) |
| Jason Moffett | Off. Tony |
| Marybeth Wise | Off. Karen
(as Mary Beth Wise) |
| Kim Bogues | Woman |
| Jon Jolles | Sun Librarian |
| D.L. Hopkins | Driver |
| Charlie Limber | Man |
| Dimitros 'Jimmy' Stakias | Greek Deliveryman |
| Michael Ahl | Detective
(uncredited) |
| Anthony Bosco | The Sun Copy Editor
(uncredited) |
| Philip DePalo | Undercover Detective
(uncredited) |
| Art Hall | Reporter
(uncredited) |
| Marcus Nel-Jamal Hamm | Off. Marcus
(uncredited) |
| Gina Hernandez | On-Air Reporter
(uncredited) |
| Brian E. McLarney | Off. Brian McLarney
(uncredited) |
| Neal McNeil | Bartender
(uncredited) |
| Gabriel Pearson | Baltimore County Police Liason
(uncredited) |
| Gavin Peretti | Reporter
(uncredited) |
| Jennifer Rouse | Whiting's Secretary
(uncredited) |
| Todd Scofield | Jeff Price
(uncredited) |
| Ethan S. Smith | Jamie Jaworski
(archive footage) (uncredited) |
| Tom Townsend | Grand Juror
(uncredited) |