| 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
(credit only) |
| Michael Kenneth Williams | Omar Little |
| Gbenga Akinnagbe | Chris Partlow
(credit only) |
| Jamie Hector | Marlo Stanfield
(credit only) |
| 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
(credit only) |
| Michelle Paress | Alma Gutierrez |
| Isiah Whitlock Jr. | State Sen. R. Clayton 'Clay' Davis |
| Peter Gerety | Judge Daniel Phelan |
| David Costabile | Managing Editor Thomas Klebanow |
| Sam Freed | Executive Editor James C. Whiting III |
| Delaney Williams | Sgt. Jay Landsman |
| Edward T. Norris | Det. Edward Norris
(as Ed Norris) |
| Gregory L. Williams | Det. Michael Crutchfield |
| Brian Anthony Wilson | Det. Vernon Holley |
| Kara Lee Duncan | Regional Affairs Editor Rebecca Corbett
(as Kara Quick) |
| Brandon Young | Mike Fletcher |
| William F. Zorzi | Bill Zorzi |
| Dion Graham | State's Attorney Rupert Bond |
| Bill Murphy | Bill Murphy |
| Donnell Rawlings | Damien 'Day-Day' Price |
| Richard Belzer | John Munch |
| Thomas J. McCarthy | State Editor Tim Phelps
(as Tom McCarthy) |
| Crissandra Spencer | Cassandra Spencer |
| Stanley Boyd | Cherry
(as Stanely Boyd) |
| Chris Clanton | Savino Bratton
(as Christopher J. Clanton) |
| Edward Bernard Green Jr. | Spider
(as Edward Green) |
| Kwame Patterson | 'Monk' Metcalf |
| Thuliso Dingwall | Kenard |
| Jaymes Jorsling | Vincent |
| Jay Landsman | Maj. Dennis Mello |
| Michael Salconi | Off. Michael 'Sanny' Santangelo |
| Curt Boushel | Andy
(as Curt Boushell) |
| David E. Goodman | Budget Director
(as David Goodman) |
| Dennis Hill | Det. Christeson |
| Elijah Grant Johnson | Elijah |
| Kim Tuvin | Judge Emily Johnson |
| Stuart Evered | Detective
(as Stu Evered) |
| Seymour Horowitz | Grieving Father |
| Rosemary Knower | Grieving Mother |
| Ken Ulman | Reporter
(as Ken Ullman) |
| Vickie Warehime | Patrol Sergeant |
| Michael Ahl | Detective
(uncredited) |
| Anthony Bosco | The Sun Copy Editor
(uncredited) |
| Larry Carter | Reporter
(uncredited) |
| Tom Cutler | Detective
(uncredited) |
| Dave Ehrman | Researcher
(uncredited) |
| Michael Stone Forrest | Det. Frank Barlow
(uncredited) |
| Art Hall | Reporter
(uncredited) |
| Derek Horton | Off. Brian Baker
(uncredited) |
| Aubrohn King | Reporter
(uncredited) |
| Todd Scofield | Jeff Price
(uncredited) |
| Kevyn Settle | Sun Paper Layout Editor
(uncredited) |
| Patrick Michael Strange | Reporter
(uncredited) |
| Tom Townsend | Grand Juror
(uncredited) |