Dr. Jordan Cavanaugh
A forensic pathologist in the Boston Medical Examiner's Office who solves crimes during the course of investigations. Jordan is emotionally scarred by her mother's murder when she was a child, indicated by significant trust issues that, until recently, severely limited her relationships with men. She attended the University of Massachusetts Amherst and Tufts University School of Medicine.
- Aloof Dark-Haired Girl
- Brainy Brunette: Jordan is a brilliant medical examiner who's also very good at solving cases, and she has dark brown hair.
- Clear My Name: At the end of season 5 and beginning of season 6, Jordan is on the run after her J.D. Pollack is murdered.
- The Coroner
- Cowboy Cop: Constantly
- Deadpan Snarker
- The Hero
- Mistaken for Gay: A tabloid runs a picture of Jordan and a lesbian talk show host, and implied that they are lovers.
- Mommy Issues: due to her mom's murder
- Ms. Fanservice: in "The Dawn of the New Day" she's walking around the ME's office in her underwear and then winds up standing completely nude in front of Trey Sanders due to her being in the wrong locker room.
- No Social Skills
- Will They or Won't They?: With Woody. They do. Sort of. Eventually.
Dr. Garret Macy
The Chief Medical Examiner and Jordan's boss. Macy must deal with Jordan's erratic behavior as well as his confused family—he has a teenage daughter, Abby, but is divorced from his wife—and his own personal demons; he is a recovering alcoholic. Garret has an affinity for jazz. He has been known to have had romantic entanglements with grief counselor Lily Lebowski, ADA Renee Walcott, Charlie Davis, and his one-time wife, Maggie Warner. Garret admitted to his drinking problem after finding out his daughter, Abby, had become addicted to heroin upon dropping out of college and becoming involved with another heroin addict. He is also allergic to strawberries and peanuts.
- Da Chief: Chief Medical Examiner.
- Deadpan Snarker
- The Leader: The Chief M.E.
- Reasonable Authority Figure
- The Stoic: Has a very good poker face.
- Not So Stoic: He has his moments.
- Throwing Out the Script: In the first episode, Garret is supposed to do a presentation about coroners at a career day. He starts off with one that's fairly dry and unenthusiastic, which gradually becomes a rant that practically drives people away with the lurid descriptions of his work.
Dr. Mahesh "Bug" Vijayaraghavensatyanaryanamurthy
A brilliant but shy forensic entomologist of Indian ancestry from Liverpool. His nickname refers to his knowledge of insects.
- Affectionate Nickname: Bug.
- Berserk Button: Murders that appear to have racial motivation.
- Deadpan Snarker: Big time.
- Dogged Nice Guy: To Lily. They become an Official Couple by the end.
- Good with Numbers: He is an astute mathematician.
- Improbable Taxonomy Skills: ANY time there are entomological traces found, ONE look was all Bug needs to tell what it was and how incredibly few but oh so conveniently dark and abandoned places it could be found.
- The Lab Rat
- Sesquipedalian Smith: Inverted. Dr. Mahesh Vijayaraghavensatyanaryanamurthy. Even his name tag is shortened to Dr V.R.S.Murthy.
- The Smart Guy: Shares this role with Nigel.
Lily Lebowski
A sweet but eccentric grief counselor.
- All-Loving Hero: She constantly tries to see the best in everyone and goes the extra mile to help even the most stubborn people who are dealing with the loss of a loved one. It is her job to do that, but she's insistent on doing her job to the best of her ability, no matter what.
- Beware the Nice Ones: Lily is a kindhearted and compassionate person, but that doesn't mean she can't get angry. One notable instance of this is in the season 4 epiosde "Sanctuary," where after her mom gets killed by a woman furious at her for sleeping with her husband, Lily spends most of the episode hellbent on ensuring that she spend the maximum possible amount of time in jail. She mellows out at the end of the episode, realizing that vengeance only leads to more pain and is ultimately unnecessary, but her sheer anger at her mother's killer throughout the episode is still shocking from the normally sweet Lily.
- Consistent Clothing Style: In the first two seasons, she mainly wore all-black outfits, usually with mesh shoulders or sleeves, fitting with her Perky Goth sensibilities. In the seasons after that, her outfits are generally pastel cardigans with either solid colored blouses paired with a floral print skirt, or a floral print blouses with a solid color skirt.
- Even the Loving Hero Has Hated Ones: Even Lily despises Dr. Slokam, the ME who gets Dr. Macy suspended and takes his place as Chief M.E. in season 5.
- Foolish Sibling, Responsible Sibling: She's the Responsible Sibling to her brother's Foolish Sibling. Her brother tends to be a lazy slacker who is not above foisting his own problems and responsibilities onto Lily.
- Good Is Not Soft: She's usually pleasant and sweet, but that doesn't mean she's not willing to stand up for herself and particularly vulnerable people who she feels have been treated unfairly.
- The Heart: Lily is often the one who seeks to help out other members of the main cast with their emotional problems, as well as trying to resolve conflicts they might have with each other. She's also the one who most frequently implores her coworkers to do what's right, serving as a moral compass to the group. She inspires the other characters to do what they can to help others, as Jordan even points out in an episode:Jordan: Because, as you once told me, if you can help, it's your moral obligation to help.
- Innocent Blue Eyes: She has blue eyes that reflect her sweet and kindhearted personality.
- Nice Girl: She's among the nicest members of the main cast.
- Perky Goth: In the first two seasons. She mellows out from season 3 onward, but maintains some of her eccentricities.
- The Pollyanna: Lily constantly looks for the positives of any situation she's in, no matter how dreadful. Her optimistic attitude often contrasts nicely with Garrett's more cynical perspective whenever they're in a subplot together.
- Shipper on Deck: She's enthusiastic about Jordan's and Woody's relationship and tries to encourage them to get together officially at multiple points in the series.
- The Shrink: Played With in that she's not actually a shrink and anytime she is called one, she is quick to correct the mistake and reiterate that she's actually a grief counselor, but on occasion she acts like a shrink for some of the main cast. She's fairly effective at psychoanalyzing people.
- Wacky Parent, Serious Child: Lily is the Serious Child to her mother's Wacky Parent. Her mother was fairly hedonistic and slept around a lot, and Lily remarks at multiple points that she's always had to be the grown-up in her family.
- The Watson: As the only one with no scientific background among the members of the main cast who regularly work in the morgue, she is the one who asks clarifying questions about cases to the other characters, giving them the opportunity to give the audience exposition on what they found in their autopsies or blood tests.
Dr. Nigel Townsend
The morgue's resident lab rat, a wise-cracking British criminologist with an ambiguous personal life.
- Ambiguously Gay: An entire episode is devoted to this. It isn't until several seasons later that the question is finally answered. Ironically, he's not.
- Ascended Extra: He was just a background character for a handful of scenes in the first episodes, but the producers liked the way he demanded your attention on just those scenes, and turned him into a regular.
- Belligerent Sexual Tension: With Kate Switzer.
- Deadpan Snarker
- Enhance Button: Constantly.
- The Lab Rat: As an ME, he regularly performs scientific analyses on corpses. He's also fairly geeky.
- Omnidisciplinary Scientist
- Perky Goth: Before Abby Sciuto, there was this man.
- The Smart Guy: Shares this role with Bug.
Detective Woodrow "Woody" Hoyt
A police detective for Boston PD, originally from Wisconsin. Also Jordan's on/off love interest.
- Berserk Button: After accidentally overdosing on a heroin-laced sweater, he tells Macy, who is trying to convince him to go to a hospital, about his personal hatred of drugs.Woody: I hate drugs. I hate drugs. I've never taken so much as a... my brother had a problem. He's clean now, or he says, but watched what they did to him, watched what they turned him into.
- The Big Guy
- Drugs Are Bad: Woody firmly believes this, to such a point that Nigel considers some of his viewpoints "a tad dogmatic, wouldn't you think?"
- Fair Cop
- Foolish Sibling, Responsible Sibling: Woody is the Responsible Sibling to his brother's Foolish Sibling. He often laments that his brother never had to grow up and that Woody is constantly stuck picking up after his messes.
- Naïve Newcomer: In the first two seasons.