| Dominic West | Det. James 'Jimmy' McNulty |
| John Doman | Dep. Comm. for Operations William A. Rawls |
| Idris Elba | Russell 'Stringer' Bell |
| Frankie Faison | Acting Commissioner Ervin H. Burrell |
| Aidan Gillen | Councilman Thomas 'Tommy' Carcetti |
| Wood Harris | Avon Barksdale |
| Deirdre Lovejoy | Asst. State's Atty. Rhonda Pearlman |
| Clarke Peters | Det. Lester Freamon |
| Wendell Pierce | Det. William 'Bunk' Moreland |
| Lance Reddick | Lt. Cedric Daniels |
| Andre Royo | Reginald 'Bubbles' Cousins |
| Sonja Sohn | Det. Shakima 'Kima' Greggs |
| Jim True-Frost | Det. Roland 'Prez' Pryzbylewski |
| Robert Wisdom | Maj. Howard 'Bunny' Colvin |
| Seth Gilliam | Sgt. Ellis Carver |
| Domenick Lombardozzi | Det. Thomas 'Herc' Hauk |
| J.D. Williams | Preston 'Bodie' Broadus |
| Michael Kenneth Williams | Omar Little |
| Corey Parker Robinson | Det. Leander Sydnor |
| Glynn Turman | Mayor Clarence V. Royce |
| Peter Gerety | Judge Daniel Phelan |
| Chad L. Coleman | Dennis 'Cutty' Wise |
| Anwan Glover | Slim Charles |
| Brandy Burre | Theresa D'Agostino |
| Leo Fitzpatrick | Johnny Weeks |
| Michael Potts | Brother Mouzone |
| Justin Burley | Justin |
| Robert F. Chew | Joseph 'Proposition Joe' Stewart |
| Michael Kostroff | Maurice 'Maury' Levy |
| Cleo Reginald Pizana | Chief of Staff Coleman Parker |
| Kurt L. Schmoke | Health Commissioner |
| Frederick Strother | State Delegate Odell Watkins |
| William Zielinski | Gene |
| R. Emery Bright | Community Relations Sgt. |
| Tony D. Head | Maj. Bobby Reed |
| Kay Lawal | Meeting Woman |
| Doug Olear | FBI Spec. Agent Terrance 'Fitz' Fitzhugh |
| Michael Willis | Andy Krawczyk |
| Derren Fuentes | Lt. Torret |
| Edward Bernard Green Jr. | Spider |
| Joilet Harris | Off. Caroline Massey |
| Dennis Lehane | Off. Sullivan |
| Dameion Leslie | Man |
| Bobby J. Brown | Off. Bobby Brown |
| Richard Burton | Sean 'Shamrock' McGinty |
| Alana Campbelle | Mayor's Secretary |
| Vicki Jean Clark | Courthouse Clerk |
| Gil Deeble | Hucklebuck |
| Kahil Dotay | Undercover Street Cop |
| Jay Landsman | Lt. Dennis Mello |
| Raw Leiba | Stringer's Bodyguard |
| Marty Lodge | Banisky |
| Michael Noel | Computer Technician |
| Thomas W. Stewart | Courthouse Clerk |