| Dominic West | Off. James 'Jimmy' McNulty |
| John Doman | Dep. Comm. for Operations William A. Rawls |
| Frankie Faison | Commissioner Ervin H. Burrell |
| Aidan Gillen | Councilman Thomas 'Tommy' Carcetti |
| Deirdre Lovejoy | Asst. State's Atty. Rhonda Pearlman
(credit only) |
| Clarke Peters | Det. Lester Freamon |
| Wendell Pierce | Det. William 'Bunk' Moreland |
| Lance Reddick | Maj. Cedric Daniels |
| Andre Royo | Reginald 'Bubbles' Cousins
(credit only) |
| Sonja Sohn | Det. Shakima 'Kima' Greggs |
| Jim True-Frost | Roland 'Prez' Pryzbylewski |
| Robert Wisdom | Howard 'Bunny' Colvin |
| Seth Gilliam | Sgt. Ellis Carver |
| Domenick Lombardozzi | Det. Thomas 'Herc' Hauk |
| Reg E. Cathey | Norman Wilson |
| Chad L. Coleman | Dennis 'Cutty' Wise
(credit only) |
| Jamie Hector | Marlo Stanfield |
| Glynn Turman | Mayor Clarence V. Royce |
| J.D. Williams | Preston 'Bodie' Broadus
(as JD Williams) |
| Michael Kenneth Williams | Omar Little
(as Michael K. Williams) |
| Corey Parker Robinson | Det. Leander Sydnor |
| Amy Ryan | Off. Beatrice 'Beadie' Russell |
| Jermaine Crawford | Duquan 'Dukie' Weems |
| Maestro Harrell | Randy Wagstaff |
| Julito McCullum | Namond Brice |
| Tristan Mack Wilds | Michael Lee
(as Tristan Wilds) |
| Gbenga Akinnagbe | Chris Partlow |
| Robert F. Chew | Joseph 'Proposition Joe' Stewart |
| Anwan Glover | Slim Charles |
| Melvin Williams | Deacon |
| Susan Duvall | Assistant Principal Marcia Donnelly
(as Tootsie Duvall) |
| Dravon James | Grace Sampson |
| Dan De Luca | David Parenti
(as Dan DeLuca) |
| Boris McGiver | Lt. Charles Marimow |
| Gene Terinoni | Lt. Jimmy Asher |
| Daniel Lee Robertson III | Shaun Williams |
| Maria Broom | Marla Daniels |
| Brandy Burre | Theresa D'Agostino |
| Cleo Reginald Pizana | Chief of Staff Coleman Parker |
| Frederick Strother | State Delegate Odell Watkins |
| Tiffani Holland | Chiquan
(as Tiffani Aisha Holland) |
| Alfonso Christian Lover | Old Face Andre |
| Charmaine McPhee | Laetitia |
| Ramon Rodriguez | Renaldo |
| Nitin Adsul | Indian Shop Owner
(uncredited) |
| Michael Ahl | Detective
(uncredited) |
| Tyrell Baker | Little Kevin
(uncredited) |
| Lloyd Booker | mayoral aide
(uncredited) |
| Keenon Brice | Aaron 'Bug' Manigault
(uncredited) |
| Ciera Nicole Butts | Student
(uncredited) |
| Tamieka Chavis | Royce's Assistant
(uncredited) |
| Vicki Jean Clark | High Roller
(uncredited) |
| Davon Cooper | Darnell Tyson
(uncredited) |
| Frank Hansen | Undercover Cop at Precinct
(uncredited) |
| Robert Lee Hardy | Brother
(uncredited) |
| Amsara Holly | Tote's Niece
(uncredited) |
| Destiny Jackson-Evans | Crystal Judkins
(uncredited) |
| Jeffrey Lorenzo | Karim Williams
(uncredited) |
| Sandi McCree | De'Londa Brice
(uncredited) |
| Ed Moran | House Detective
(uncredited) |
| Rakiya Orange | Charlene Young
(uncredited) |
| Felicia Pearson | Felicia 'Snoop' Pearson
(uncredited) |
| Duane Chandler Rawlings | Nathaniel 'Hungry Man' Manns
(uncredited) |
| Doug Roberts | State's Attorney Steven Demper
(uncredited) |
| Tamika Simpkins | Mother
(uncredited) |
| Darrell M. Smith | School Officer Turner
(uncredited) |
| Clay Steakley | Asst. Hotel Manager
(uncredited) |
| Thomas W. Stewart | High Roller
(uncredited) |
| Troj Strickland | Ricardo 'Fat Face Rick' Hendrix
(uncredited) |
| Jason Wharton | Albert Stokes
(uncredited) |
| Gregory L. Williams | Det. Michael Crutchfield
(uncredited) |