A street gang a street-oriented youth group whose own identity includes involvement in illegal activity.
- One-Niners - Major black gang featured on The Shield.
- Spookstreet Souljahs - made a deal with the Horde for protection, were caught on the garage sting tapes, there was also a CI of Danny Sofer's that was Spookstreet. Members of the gang included Harold Pinker
- E-Park Johnnies - Featured in one episode of Season 2. Had an April Fools' party where members played dominoes and killed people while saying, "Johnny says April Fools"
- Compton Crowns
- Byzantine Latinos aka "Byz Lats" - Members included Garza, Diagur Leyva and Juan Lozano (Aceveda's rapist).
- Los Magnificos aka "Los Mags" - Featured in Season 1. They were the gang Hector was in when Lem shot Chaco and then planted the gun on him, and Vic got the fake tat and shot up the evidence van to get it back. Lem had an affair with Tigre Orozco, sister of a reformed gang banger targeted by the Los Mags.
- The Toros A.K.A. Los Torrucos- Vic partnered with a Latino detective who used to be a Toro. A white guy who shot some Mexicans was captured by shop owners who grabbed him and gave him to the Toros. Later merged with the Los Mags under the command of Armadillo Quintero.
- Las Prophetas - The gang that Vic used to go after the escaped rapist in season 4. They also had beef with the One-Niners over a priest getting killed after a black guy was hung.
- Baja Diablo Cartel - a Mexican drug cartel based in Baja California, Mexico. Mentioned once by Vic in Season 2 Episode 13.
- There is an unnamed Salvadoran gang formerly headed by Guardo Lima. It was founded years ago, by a man who was sentenced to life in prison but was released because of a terminal disease. The gang runs a hand grenade factory infiltrated by Vic Mackey's CI, Emolia Melendez. ICE Agent Hernan has also infiltrated the Salvadoran gang, and is attempting to climb the gang leadership.
- Armenian Might - Ran the ports and other illegal operation. Laundered money using the Money Train
- The Horde - white biker gang similar to Hell's Angels. They collaborated with Spookstreet Souljahs in season 4 to do a robbery.
- Russian Mafia