- Rusty Beck (Graham Patrick Martin): Sharon Raydor's adoptive son, a former prostitute who witnessed Phillip Stroh committing murder. He has since started a investigative video blog called Identity.
- Robert Gossett (Assistant Chief Russell Taylor): Assistant Chief of Operations until Season 5 episode "White Lies, Part 1". He is Captain Raydor's immediate supervisor. The former commander of Robbery-Homicide Division, and later press liaison for Major Crimes, Taylor long felt passed over and unappreciated.
- Jon Tenney (Deputy Chief Fritz Howard): Fritz Howard was an special agent for the F.B.I. and the liaison officer to the LAPD (The Closer and Major Crimes, Seasons 1 and 2). Upon his retirement, he is recruited to head the LAPD's Special Operations Bureau, and assumes the rank of Deputy Chief (Major Crimes, Season 3 onward). He is currently the Acting Director of Operations until a replacement for Assistant Chief Taylor can be found.
- Mary McDonnell (Captain Sharon Raydor): The commanding officer of Major Crimes Division.
- GW Bailey (Lieutenant Louie Provenza): The division's senior member and Sharon's second-in-command. He is the immediate supervisor of the team in the field.
- Anthony Denison (Lieutenant Andy Flynn): Provenza's partner.
- Michael Paul Chan (Lieutenant Michael Tao): The squad's forensics and technology expert; Tao previously was assigned to the LAPD's Scientific Investigation Division (SID).
- Raymond Cruz (Detective Julio Sanchez): The squad's gang and weapons expert, experience gained from his days on the LAPD's gang intelligence unit.
- Kearran Giovanni (Detective Amy Sykes): Transferred from the Special Investigation Section of Robbery-Homicide, she is an expert on undercover operations. Sykes is a military veteran who served in Afghanistan.
- Daniel DiTomasso (Detective Wes Nolan): Det. Nolan was transferred to the division after ending his SIS undercover assignment.
- Phillip P. Keene (Civilian Surveillance Coordinator Buzz Watson): Buzz is the Scientific Investigation Division's civilian investigator assigned to the division. He is responsible for memorializing crime scenes, and managing technology in the field and in the squad's office. He also recently qualified as an LAPD reserve police officer.
- Jonathan Del Arco (Dr. Fernando Morales): A Los Angeles County Deputy Medical Examiner who coordinates with the team, conducting autopsies. Morales has a sharp medical mind and and equally sharp, sometimes sarcastic, wit. Morales is gay, and provides expertise on the gay community in Los Angeles.
- Ransford Doherty (Investigator Kendall): Kendall is responsible for examining the body at the crime scene and taking initial measurements, as well as preparing the body for transportation to the Los Angeles County Coroner's office.
- Kathe Mazur (Deputy District Attorney Andrea Hobbs): The DDA who works most frequently with Major Crimes, Hobbs is a team player.
- Nadine Velazquez (Deputy District Attorney Emma Rios): A new, inexperienced DDA under Hobbs' supervision, she is charged with preparing the case against Phillip Stroh (Season 2).
Recurring cast Edit
- Laurie Holden (Commander Ann McGinnis): Commander McGinnis is the second-in-command of the LAPD's Special Operations Bureau.
- Malcolm-Jamal Warner (Lieutenant Chuck Cooper): Lieutenant Cooper is the commanding officer of the Special Investigation Section (SIS) of the LAPD.
- Brandon Barash (Detective Robert Oderno): Robert Oderno is a detective in the LAPD's Missing Persons Unit.
- Rene Rosado (Gustavo Wallace): Gus Wallace is the older brother of murder victim Mariana Wallace. He is currently dating Rusty Beck.
- Camryn Manheim (Deputy Chief Winnie Davis): Chief Davis is a Deputy Chief of Operations for the LAPD and one of the candidates to replace Chief Taylor as the new Director of Operations (Season 5 winter episodes).