->'''Portrayed by:''' Angie Harmon
* ActionGirl: Rarely shies away from action. Even injured, she still wants to be the one to take people down.
* AdaptationalAttractiveness: In the books that the series is based on, Jane Rizzoli is consistently described as plain or average looking. This is a significant characteristic, as she tends to have an irrational jealousy and dislike of beautiful women. But here, she's being played by the gorgeous Angie Harmon (though Harmon has played Jane as a little more rough and tumble as time went on).
* AloofDarkHairedGirl: Rizzoli is a tall, mature, dark haired woman.
* AscendedExtra: Rizzoli is actually a secondary character in "The Surgeon", the first book in the series, and author Gerritsen had planned to kill her off before positive reader feedback changed her mind.
* BerserkButton: Harm or threaten her family or Maura and she will show you why she's the top homicide detective in Boston PD.
* BrainsAndBrawn: The Brawn to Maura's Brains.
* BrotherSisterTeam: With Frankie.
* CoolBigSis: To Frankie.
* DeadpanSnarker: Sometimes in spite of herself. Even when she's around people she'd be better off not pissing off, she still can't help but snark at or about them.
* EmbarrassingMiddleName: [[spoiler: Clementine.]]
* HeterosexualLifePartners: With Maura.
* HiddenDepths: Jane is actually rather good at ballet and chess.
* ImpaledPalm: Jane still bears the scars from when The Surgeon literally pinned her hands to the ground.
* InformedAttribute: Jane describes herself as strong and athletic even though Angie Harmon has the lithe, muscular frame of a toothpick. She might be telling the truth, but she sure doesn't look it.
* LovelyAngels: With Maura.
* MiddleChildSyndrome: She's usually overlooked by her mother in favour of older brother Tommy or little brother Frankie.
* ObfuscatingStupidity: It turns out she was accepted to BCU, but ended up not going because of her family situation. She also pretended not to know anything about chess when she was the one who taught Tommy how to play.
* OnlySaneWoman: Jane qualifies, given how often the expression on her face resembles that of someone in the process of herding cats.
* RomanticTwoGirlFriendship: With Maura.
* TomboyAndGirlyGirl: The Tomboy to Maura's Girly Girl.
* TheUnfavorite: Angela always seemed to favor her boys over Jane, and even more so in the books.
->'''Portrayed by:''' Sasha Alexander
* AdaptationalAttractiveness: It's not as extreme with Maura Isles, who is described as "attractive", but as played by Sasha Alexander, she's far more stunning than one would have imagined.
* AmbiguouslyBi: Even discounting the ton of LesYay she has with Jane, she's put an awful lot of thought into what kind of women she'd be into if she were a lesbian.
* AscendedExtra: Isles doesn't exist at all in "The Surgeon", but when she makes an appearance (in "The Apprentice"), she's a minor character until her role enlarges to be almost equal with Rizzoli in most books, or the primary character in several.
* BrainsAndBrawn: The Brains to Jane's Brawn.
* CannotTellALie: At least in normal circumstances.
* EmbarrassingMiddleName: [[spoiler:Dorothea]]
* GoodBadGirl: Bizarrely enough. See ReallyGetsAround.
* HeterosexualLifePartners: With Jane.
* InsufferableGenius: She doesn't do it on purpose, but it drives Jane batty nonetheless.
* IntelligenceEqualsIsolation: Maura reveals that her childhood wasn't exactly parties and ponies in "I'm Your Boogie Man." In her own words, "there was a lot of benign neglect" - her parents had their own lives to lead that frequently didn't involve the mundane details of parenthood, and they didn't much care what Maura did as long as she kept good grades. As a result, Maura buried herself in schoolwork, to the point that she gave them the brochures to send her away to boarding school. ''At ten years old''.
* LovelyAngels: With Jane.
* MoralityPet: A minor and not always effective one to [[spoiler:her biological father Paddy Doyle Jr, a reputed mobster and killer. Paddy does seem to think she is the only good thing he's ever done and when his father, Paddy Sn. ia getting ill, he asks Maura to help him get a compassionate release from prison and stay with Maura.]]
* TheNotLoveInterest: To Jane.
* [[HandsomeLech Pretty Lech]]
* ReallyGetsAround: She has had more partners than anyone else on the show, flirts with a man while examining a dead body, and pursued Giovanni solely to sleep with him.
* RomanticTwoGirlFriendship: With Jane.
* ScrewTheMoneyIHaveRules: Maura turning her back on the high society scene to work as a medical examiner. When Jane calls her out on her privileged background, she demonstrates quite convincingly that she "has [their] backs," using her connections to obtain several vital clues to the murder.
* TomboyAndGirlyGirl: The Girly Girl to Jane's Tomboy.
->'''Portrayed by:''' Jordan Bridges
* BigLittleBrother: Jordan Bridges is 6'1 to Angie Harmon's 5'9.
* BrotherSisterTeam: With Jane.
* EmbarrassingFirstName: [[spoiler: Francesco]]
* [[BigBrotherInstinct Little Brother Instinct]]: Towards Jane.
->'''Portrayed by:''' Bruce [=McGill=]
* AdaptationalAttractiveness: Hardly a male model in his TV incarnation, but still much better looking than he's described in the books.
* FriendToAllLivingThings: Korsak is constantly rescuing animals.
* [[LikeASonToMe Like A Daughter To Me]]: His relationship with Jane.
* ThemeNaming: He has dogs named Starsky, Hutch, and Kojak.
* TheMentor: To Jane.
* PapaWolf: Towards Jane.
->'''Portrayed by:''' Lee Thompson Young
* ActorExistenceFailure: The unfortunate suicide of Lee Thompson Young.
* BlackAndNerdy: Frost is well versed in computer technology, action figures, and [=MMORPG=]s.
* EmbarrassingFirstName: [[spoiler:Barold]].
* [[spoiler:HasTwoMommies: His mom and roommate come to town. The others figure out they are a couple, but are afraid to say anything.]] Turns out he knew all along, was just waiting for his mom to say something.
* RaceLift: Detective Frost is white in the books, African-American in the TV series.
* VomitingCop: He seems to be getting better about it, though.
->'''Portrayed by:''' Creator/LorraineBracco
* BigSecret: She was going around taking up any odd job she could find and acting funny any time money is mentioned.[[spoiler: Her husband cheated on their taxes and left her holding a $27,000 debt.]] She doesn't want to let Jane and Frankie know so she can keep him looking good for them, but they find it out.
* ParentalFavoritism: Jane is blatantly ignored in favor of her brothers, especially Frankie.
* ParentalSubstitute: To Maura.