| Dominic West | Off. James 'Jimmy' McNulty |
| Chris Bauer | Frank Sobotka |
| Paul Ben-Victor | Spiros 'Vondas' Vondopoulos |
| John Doman | Col. William A. Rawls |
| Idris Elba | Russell 'Stringer' Bell |
| 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 |
| Amy Ryan | Off. Beatrice 'Beadie' Russell |
| Sonja Sohn | Det. Shakima 'Kima' Greggs |
| Seth Gilliam | Sgt. Ellis Carver |
| Domenick Lombardozzi | Det. Thomas 'Herc' Hauk |
| Jim True-Frost | Det. Roland 'Prez' Pryzbylewski |
| James Ransone | Chester 'Ziggy' Sobotka |
| Pablo Schreiber | Nick Sobotka |
| Callie Thorne | Elena McNulty |
| J.D. Williams | Preston 'Bodie' Broadus |
| Hassan Johnson | Roland 'Wee-Bey' Brice |
| Kristin Proctor | Aimee |
| Michael Hyatt | Brianna Barksdale |
| Robert F. Chew | Joseph 'Proposition Joe' Stewart |
| Maria Broom | Marla Daniels |
| Lance Irwin | Maui |
| Delaney Williams | Sgt. Jay Landsman |
| Shamyl Brown | Donette |
| Keith Flippen | Bruce DiBiago |
| Gary 'D. Reign' Senkus | Frog |
| Tray Chaney | Malik 'Poot' Carr |
| Luray Cooper | Nathaniel 'Nat' Coxson |
| Charley Scalies | Thomas 'Horseface' Pakusa |
| Stan Stewart | Big Charles |
| Stephanie Bamberger | Natasha |
| Chris Ashworth | Sergei 'Serge' Malatov |
| Randall Boffman | Bill Anderson - Port Admin. Port of Baltimore |
| Richard Burton | Sean 'Shamrock' McGinty |
| Kelvin Davis | La La |
| Jacques Derosena | Leech |
| Jeffrey Pratt Gordon | John 'Johnny Fifty' Spamanto |
| Donovan Hagins | Dancer |
| Curtis McClarin | Florist |
| Richard Pelzman | Little Big Roy |
| Duncan Smith | Shipping Agent |