Main •
Jennifer Lopez After getting arrested by the FBI in an anti-corruption investigation, she becomes a reluctant informant against Wozniak in exchange for immunity. She eventually sacrifices her career and freedom to bring down the corrupt Intelligence Unit, and is sent to prison for three years. •
Ray Liotta as Lieutenant Matt Wozniak, a corrupt NYPD Lieutenant who is the commander of the 64th Precinct's Street Crimes detective squad and the main target in an FBI anti-corruption investigation. He is a 25-year veteran of the force, and before that spent six years in the
United States Marine Corps. He is very close to Harlee, whom he considers a daughter, and Harlee's own daughter, Cristina; this stems from the guilt he feels over the death of his own daughter Anna-Kate, from a drug overdose at age 19. After Harlee sacrifices her career and freedom to bring down the corrupt Intelligence Unit, Wozniak drives her to prison and takes in Cristina per her wishes. •
Drea de Matteo as Detective Marcus Tufo, an NYPD Detective who fancies himself as a ladies' man, and often has to deal with his brother's shortcomings. He is reassigned to patrol as an officer in season 3 due to the fallout of the events of the previous season's finale but is promoted back to detective in the series finale. •
Vincent Laresca as Detective Carlos Espada, an NYPD Detective who operates as the muscle of Wozniak's squad. He and Tess have a brief affair during season 1, which is then followed by much sexual tension between them for the rest of the series. •
Sarah Jeffery as Cristina Santos, Harlee's 16-year-old daughter and a musical prodigy. She is often kept in the dark regarding her mother's corrupt activities, but soon comes to know and accept her as a good person. At the end of the series, after Harlee is sent to prison, she moves in with the Wozniaks, settling into their late daughter's old room and reading a letter left by her mother. •
Gino Anthony Pesi as James Nava (seasons 2–3; recurring season 1), the
Assistant District Attorney assigned to monitor the 64th Precinct and who becomes romantically involved with Harlee. He is murdered at the start of season 3 by the corrupt Intelligence Unit detectives after being entrusted with a suspect running from them, who is killed along with him.
Recurring •
Leslie Silva as Gail Baker, an FBI special agent in charge, and an old friend of Harlee's, who assigns her as the mole under Stahl's supervision. •
Santino Fontana as David Saperstein (season 1), a detective who is part of Wozniak's crew. Wozniak kills him after being led to believe that he is the FBI's mole. •
Michael Esper as Donnie Pomp (season 1), a corrupt lieutenant in Internal Affairs who uses his position to protect Wozniak and his crew. He is later killed by Loman in self-defense and his body is cremated by Wozniak. •
Lolita Davidovich (season 1) and
Margaret Colin (seasons 2–3) as Linda Wozniak, Matt's wife •
Annie Chang as Molly Chen (seasons 1–2), an FBI special agent and Stahl's partner. She later has herself reassigned after becoming very uncomfortable with Stahl's growing obsession with Harlee. •
Mark Deklin as Joe Nazario (season 1), Tess' husband, who eventually becomes divorced from her. •
Erica Ash as Erica (season 1), Loman's love interest •
Kathryn Kates as David's mother (season 1) •
Stephen Lang as Terrence Linklater (seasons 1–2), a corrupt DEA agent in league with Wozniak and Pomp to pull off an armored car heist, only to betray the team and steal most of the money before fleeing the country. He later returns and is captured by Harlee and Wozniak, who aim to use him as a bargaining chip to get out from under the FBI's thumb. However, Stahl instead prevents this by murdering Linklater in cold blood and his body is cremated by Harlee and Wozniak. • Antonio Jaramillo as Miguel Zepeda (season 1), Harlee's violently abusive ex-boyfriend and Cristina's father. Wozniak and Harlee conspired to frame him for murder in order to keep Harlee and Cristina safe. He is later released and tries to reconnect with his daughter but is repeatedly stalled by Harlee's attempts to keep Cristina away from him. Harlee eventually kills him in self-defense after he attempts to rape her at gunpoint. His disappearance becomes a focus point in season 2 as Stahl attempts to uncover the truth behind it. • Vanessa Vander Pluym as Gina Rodriguez (seasons 2–3), a prostitute that Stahl frequents due to her resemblance to Harlee (Pluym is also Jennifer Lopez's stunt double for the show). Gina was killed by Stahl in an attempt to bring down Harlee. •
Dov Davidoff as Tom Verco (seasons 2–3), a detective serving as an Internal Affairs investigator, who gradually becomes a reluctant ally of Wozniak and his crew. • Cameron Scoggins as Nate Wozniak (seasons 2–3), Matt and Linda's son, and the brother of Anna Kate. He beat up the drug dealer who sold Anna Kate the drugs she overdosed on and left him for dead, and would have ended up in jail had Julia Ayres not covered it up. •
Anna Gunn as Julia Ayres (season 2), a New York City councilwoman and mayoral candidate. She was a member of Wozniak's crew prior to her promotion to NYPD Captain. During season 2, she becomes the subject of an FBI investigation led by Stahl. She later commits suicide after a fallout between her and Wozniak threatens to put all of her misdeeds out in the open, just as she is elected Mayor of New York City. • Karsen Liotta as Anna Kate Wozniak (season 3), Matt and Linda's daughter. Karsen Liotta, the real-life daughter of Ray Liotta, plays his character's deceased daughter Anna Kate, who Matt sees visions of in season 3. •
Afton Williamson as Katie Myers (season 3), an FBI special agent assigned to search for Stahl after he becomes a fugitive, but is later revealed to be allied with him, due to Stahl having saved her life when the two were in Quantico. Stahl later kills her after their attempted frame job against Harlee comes apart and she refuses to help him again after discovering he'd been keeping certain secrets from her. •
Bruce McGill as Jordan Ramsey (season 3), the corrupt captain who heads the NYPD's Intelligence Unit. As of the most powerful men in the department, he is not afraid to flex his muscle at anyone whom he sees as a threat to his plans. In the series finale, after his corrupt activities are exposed by Harlee, who sacrifices everything to bring them to light, Ramsey is arrested, his assets are frozen and he is killed by an enraged Wozniak. •
Nick Wechsler as Anthony Cole (season 3), a lieutenant in the Intelligence Unit who turns against them after they orchestrate the death of his partner. Although he at first works with the 64th detectives to bring them down, he soon discovers how ruthless his corrupt colleagues are and leaves town during the series finale. • Victor Turpin as Enrique Ortiz (season 3), the spoiled son of a dangerous, powerful and wealthy Colombian drug lord. His family have minions in the police department, who make sure he gets liberated after being arrested by Santos. ==Episodes==