Alonso is the godmother to Deacon's children. Openly bisexual, she enters a polyamorous relationship in Season 2, but breaks it off later.

She serves as the Squad’s sniper and becomes close friends with Street.

Lina Esco as Officer III Christina 'Chris' Alonso, a former canine officer and (originally) one of the two female cops assigned to S.W.A.T.

He has since earned his way back on the team. He initially has trouble adjusting to being part of the team due to his impulsiveness as well as having abandoned his duties to take care of his mother which eventually got him removed from SWAT. His mother Karen is in prison for murdering her abusive husband/Street's father she was arrested by former S.W.A.T Team Leader Buck Spivey.

Alex Russell as Officer III James 'Jim' Street, a new transfer from the Long Beach Police Department.

By the start of the third season, she has seemingly taken the assignment permanently, with the actress being confirmed as having exited the show. In the second-season finale, she accepts an offer for an FBI assignment and leaves the LAPD to go undercover. She is a respected officer who has plans to improve the relationship between the LAPD and the citizens of Los Angeles, despite some resistance from the rank and file.

Stephanie Sigman as Captain Jessica Cortez (seasons 1 & 2), Commanding Officer of the LAPD Metropolitan Division and Hondo's lover, and then former lover.

He was in a clandestine relationship with Jessica Cortez but they were ultimately forced to break it off to protect their careers despite both mutually expressing their love for each other. He knows everyone in the neighborhood and treats them with respect and they usually give him information pertinent to his cases.

As team leader his callsign was 20-David but has since changed to 27-David following his demotion. He was demoted at the end of season 4 after leaking information of racism in the LAPD to the press.

Shemar Moore as Sergeant II Daniel 'Hondo' Harrelson Jr., a Los Angeles native who was promoted to team leader in a blatant attempt to ease the tensions between the community and the LAPD.

Swat 4 guide