| Dominic West | Off. James 'Jimmy' McNulty |
| John Doman | Dep. Comm. for Operations William A. Rawls
(credit only) |
| Frankie Faison | Commissioner Ervin H. Burrell |
| Aidan Gillen | Mayor Thomas 'Tommy' Carcetti |
| Deirdre Lovejoy | Asst. State's Atty. Rhonda Pearlman
(credit only) |
| Clarke Peters | Det. Lester Freamon
(credit only) |
| Wendell Pierce | Det. William 'Bunk' Moreland |
| Lance Reddick | Col. Cedric Daniels |
| Andre Royo | Reginald 'Bubbles' Cousins |
| Sonja Sohn | Det. Shakima 'Kima' Greggs
(credit only) |
| Jim True-Frost | Roland 'Prez' Pryzbylewski |
| Robert Wisdom | Howard 'Bunny' Colvin |
| Seth Gilliam | Sgt. Ellis Carver |
| Domenick Lombardozzi | Sgt. 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
(credit only) |
| J.D. Williams | Preston 'Bodie' Broadus
(as JD Williams) |
| Michael Kenneth Williams | Omar Little
(as Michael K. Williams) |
| Corey Parker Robinson | Det. Leander Sydnor |
| Callie Thorne | Elena McNulty |
| Isiah Whitlock Jr. | State Sen. R. Clayton 'Clay' Davis |
| 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 |
| Anwan Glover | Slim Charles |
| Jonnie Brown | Off. Eddie Walker
(as Jonnie Louis Brown) |
| Tray Chaney | Malik 'Poot' Carr |
| Nathan Corbett | Donut |
| Davon Cooper | Darnell Tyson
(as Davone Cooper) |
| Thuliso Dingwall | Kenard |
| Taylor King | Zenobia Dawson |
| Shamika Cotton | Raylene Lee
(as Shakima Cotton) |
| Cyrus Farmer | Devar Manigault |
| Sandi McCree | De'Londa Brice |
| Dawn Ursula | Lolita Colvin |
| Marlyne Barrett | Council President Nerese Campbell
(as Marlyne Afflack) |
| Stacie Davis | Ms. Duquette |
| Dan De Luca | David Parenti
(as Dan DeLuca) |
| Susan Duvall | Assistant Principal Marcia Donnelly
(as Tootsie Duvall) |
| Dravon James | Grace Sampson |
| Sheila Cutchlow | Miss Sheperdson |
| Richard Hidlebird | Principal Claudell Withers |
| Jay Landsman | Lt. Dennis Mello |
| Ramon Rodriguez | Renaldo |
| Franklin Ojeda Smith | Minister |
| Tyrell Baker | Little Kevin |
| Michael Coley | Kwame |
| Na'Dria Jennings | Chandra Porter |
| Felicia Pearson | Felicia 'Snoop' Pearson |
| Katherine Schmoke | Miss Mason |
| Benjamin Busch | Off. Anthony Colicchio |
| Derek Horton | Off. Brian Baker |
| Boris McGiver | Lt. Charles Marimow |
| Rick Otto | Off. Kenneth Dozerman |
| Michael Salconi | Off. Michael 'Sanny' Santangelo |
| Sabrina Flores | Girl
(unconfirmed) |
| Michael Ahl | Detective
(uncredited) |
| DeJuan Anderson | Little Bunk
(uncredited) |
| Keenon Brice | Aaron 'Bug' Manigault
(uncredited) |
| Armando Cadogan Jr. | Bubbles' Tormentor
(uncredited) |
| Antonio Cordova | Michael McNulty
(uncredited) |
| Tony D. Head | Maj. Bobby Reed
(uncredited) |
| Destiny Jackson-Evans | Crystal Judkins
(uncredited) |
| Brandon Larkins | Uniformed Officer
(uncredited) |
| Jeffrey Lorenzo | Karim Williams
(uncredited) |
| Kwame Patterson | 'Monk' Metcalf
(uncredited) |
| Eric G. Ryan | Sean McNulty
(uncredited) |
| Ryan Sands | Off. Lloyd 'Truck' Garrick
(uncredited) |
| Darrell M. Smith | School Officer
(uncredited) |
| Diana Villamonte | Rachel Shapiro
(uncredited) |
| Jason Wharton | Albert Stokes
(uncredited) |