The main cast of The Rookie 2018.
The oldest rookie at the Los Angeles Police Department Wilshire Division, John is an ex-construction worker who had a midlife crisis following a divorce, until he became a heroic bystander in the midst of a Pennsylvania bank robbery, consequently dropping everything to become a police officer. He's proven to be the most affable and bumbling of the rookies (and, of course, the force in general).
- Butt-Monkey: Enforced by Sergeant Grey, who states he'll do all he can to harass, harangue, humiliate and haze John until he quits.
- Desperately Looking for a Purpose in Life: Was this at the very beginning of the story; he seems to have found a meaning in being a cop.
- Drives Like Crazy: Not deliberately, but he has quite bad luck with his patrol cars.(on being presented with a Lamborghini)Nolan: Can I drive?Wolf: The motor pool has a picture of your face on a dartboard. What do you think?Nolan: Fair enough.
- The Heart: John has the largest belief that there is good in all people, not just from the suspects he confronts, but also the cynical mindset his fellow officers in the force have come to embody from their experiences on the street.
- Older and Wiser: Despite being the oldest rookie, John has an advantage of being able to see situations from a different perspective thanks to his age and life experience.
- Heroic BSoD: Jackson freezes on multiple occasions in the midst of gunfire.
- In-Series Nickname: "Extra Credit", a moniker given to him at the academy because he was most enthusiastic at learning to be a cop.
- Nepotism: Discussed after Lopez discovers Jackson's Heroic BSoD - as the son of a reputed police commander at internal affairs, were she to report his rookie mistake, Lopez herself would be called into question, making it much harder for her to climb the ranks.
- Straight Gay: He's revealed to be this in "Heartbreak".
A newly promoted training officer assigned to John, Talia is making her way to detective with a goal of becoming the chief of police.
- Awesomeness by Analysis: When trapped in an escape room with Nolan, she quickly figures out a cipher that gets them out.
- Consummate Professional: Arguably the most out of the three training officers, Talia is very no-nonsense. For example, in the annual competition where training officers see who can get the most arrests in a single shift, she refuses to play on the grounds that it is utterly pointless.
- Dark and Troubled Past: She grew up in an abusive foster home which turned her foster brother into a criminal. She deliberately omitted this from her application papers, which inevitably comes back to haunt her.
- Not So Above It All: She gets caught up in the celebratory spirit after she and Nolan solve an escape room, enough to almost high five the suspect they apprehended.
- Shipping Torpedo: Talia discovers John and Lucy are dating and warns both of them the dangers of such a relationship in their environment.
- Sink-or-Swim Mentor: She has her rookies act as the primary officer on all their calls from Day One, in contrast to Bradford and Lopez who wait until their rookies have more experience before letting them act as the primary. This actually works out to Nolan's advantage as he ends up ahead of his cohort when it comes time to check the rookies' progress.
- The Stoic: She is consistently professional in her work, showing very little emotion. Outside of her job, she is quite casual.
- Jerkass with a Heart of Gold: He's abrasive, blunt, and delights in giving Chen random, startling tests and then punishing her for not responding perfectly. However, he also checks in regularly on a man who he brought to the hospital a couple years ago after the man was a victim of a hate crime, and he still has an obvious soft spot for his ex-wife.
- Limited Advancement Opportunities: When Bradford finally comes around to admitting that he wants to advance his career, Sergeant Grey points out that opportunities to sit the sergeant's exam are few and far between.
- Everyone Has Standards: While a professional cop focused on the job, when faced with the possibility of arresting an escaped convict who was currently dancing with his daughter at her Quinceañera, Lopez decided to let him finish the dance before arresting him.
- Loophole Abuse: Lopez demonstrates a greater willingness to bend the rules for personal benefit without actually letting criminals get away with their actions, such as deliberately creating a situation where a man who intended to 'dine and dash' would be charged with an actual felony by ensuring that his 'crime' would have cost over $700.
- Out of Focus: Of the six main characters she is the one with the least focus.
- Brutally Honest: Grey won't hesitate at telling the rookies and training officers alike what they don't want to hear. It's this trait that John chooses him to be his companion officer after he kills an armed suspect, on the grounds that Grey will tell him the truth about whether what John did was Justified or not, whereas another officer will simply tell John something else to ease his discomfort.
- Henpecked Husband: Although he jokes about it, Grey is genuinely terrified of getting his wife angry.
- Not So Different: Like John, Grey is also a father, whose child is constantly worried about his safety, especially when Grey was previously wounded on the job.
- Authority Equals Asskicking: A former soldier who rapidly rose up the ranks in the LAPD, and still appreciates the chance to get into the field.
- Character Death: In "Greenlight".
- Dying Moment of Awesome: After being tied to chair and pushed into a pool, she dislocates her wrist to escape her handcuffs and caps two white supremacists before the third accidentally fatally wings her.
- Hidden Depths: An ex-United States Marine deployed to the Middle East with fluency in Farsi.
- Reasonable Authority Figure: Andersen is the only division captain in the LAPD willing to give John a chance, believing he has more life experience and a fresh perspective that most police rookies don't have.
Head of internal affairs in the Los Angeles Police Department, Commander West is the father to Jackson.
A former undercover narcotics officer for the LAPD, Isabel is Tim's ex-wife and a drug addict.
John's college roommate, Ben is the one who shares his luxurious Los Angeles home with him as a house guest.
John's son who's attending college.
- Anger Born of Worry: Lampshaded; Henry calls out his father when visiting Los Angeles that he didn't have to worry about John when he was a construction worker, but as a cop, he's constantly anxious the next phone call he receives is one about John getting wounded or possibly killed on the job.
- Something Only They Would Say: Invoked when John states they should have a code word so Henry will know his father's alright the next time he calls - Henry suggests the word "turducken".
Sergeant Grey's daughter, a senior in high school.