''The page is likely to contain spoilers. Readers, beware.''
!!Dr. Harding Hooten [-(Creator/AlfredMolina)-]
* AlliterativeName: Harding Hooten
* CatchPhrase: Or characteristic, rather. The way he pours a glass of water just before he starts ripping into someone.
* HiddenDepths: He plays the piano and likes classical music.
* InSeriesNickname: "Hardly Human"
* JerkassHasAPoint: He's hard on the doctors, but he has to keep them in line.
* JerkWithAHeartOfGold: He has a soft side in him, and it's actually not hidden ''too'' deep. He fights for his doctors and respects them. [[spoiler:His dealing with his ageing mentor is very respectful and kind, or when he had to tragically fire a doctor who made a preventable mistake and killed his patient, he actually tells him that he thinks he's an excellent doctor, but he had no choice. The sacked doctor agrees it's the only way.]]

!!Dr. Jorge Villanueva [-(Creator/VingRhames)-]
* BaldBlackLeaderGuy: He's the leader among the doctors who look up to him and seek support with him.
* BaldOfAwesome: Most definitely. He can pull baldness off and looks awesome.
* DrowningMySorrows: He goes to a bar regularly. Sometimes his colleagues join him for a couple of drinks.
* FriendToAllChildren: He's great with kids and young teens. These patients trust him immediately.
* InSeriesNickname: "El Gato" aka "Big Cat". Everybody in the hospital looks up to him.

!!Dr. Tyler Wilson [-(Creator/JamieBamber)-]
* TheAce: He's a brilliant and cocky neurosurgeon. However, first episode crushes him and he becomes a downplayed BrokenAce instead.
* DarkAndTroubledPast: Implied, when his patient's death triggers a flashback to his brother's death. It's possible this is the reason he became a doctor.
* HeroicBSOD: His young patient -- a small boy -- dies on him. When it's revealed that he messed up and didn't check all relevant medical history, he breaks down. It has to be a short-lived Heroic Blue Screen of Death, because "Gato" needs him in ER. However, the event haunts him and his Heroic [=BSOD=] is on-and-off.
* HospitalHottie: A handsome manly man in blue scrubs and white coat. Ladies must be crazy about him -- one hot colleague fancies him, and one male patient calls him a baby face.
* MrFanservice: He has one shower scene and sometimes his mornings are shown...
* PermaStubble: Rugged manly man, unshaven look is awesome on Dr. Wilson.
* TooCleverByHalf: He has nearly all traits of this archetypal character. He's an extremely smart and brilliant neurosurgeon with magical hands. He knows it, and doctor Hooten often calls him on his medical arrogance, especially his failure or reluctance to consult with his colleagues who as as brilliant as himself. [[note]]Seriously, what a hospital! Apparently, they have at least four neurosurgeons who are all the world class top.[[/note]] However, he has sweet bedside manners and he's also very nice to his colleagues, which makes him popular.

!!Dr. Tina Ridgeway [-(Jennifer Finnigan)-]
* MyBiologicalClockIsTicking: There are hints that she would like to have family but she's too devoted to her job.
* HeterosexualLifePartners: She's best friends with Dr. Sydney Napur.
* HospitalHottie: She's a hot lady doctor.
* MsFanservice: She has a shower scene.
* YourCheatingHeart: [[spoiler:Her marriage is a mess, and she cheats on her husband. When she tells her husband, he files for divorce and blames her for destroying their relationship. And he blames Tina's lover even more and sues ''him''.]]

!! Dr. Buck Tierney [-(Bill Irwin)-]
* DoctorJerk: His set-up presents him as Dr. Jerk who is an ass hole and only good at his job, but it gets {{Subverted}}. He actually cares about lots of things and his boss tells him he's a good man.
* DudeWheresMyRespect: He thinks people should appreciate his commitment to the transplantation programme. Most of the time things go well and the procedure requires many steps with lots of bureaucratic B.S. He thinks he deserves some respect, and is insulted that people see him as a vulture or predator. He still considers himself an asshole. Conflicted guy, this doctor.
* CharacterTic: Dr Buck Tierney has a habit of pulling himself up and down and making a squeaky sound with his shoes.
* JerkWithAHeartOfGold: He shows his jerk side more often though.

!!Dr. Sung Park [-(Keong Sim)-]
* AsianRudeness: He's extremely blunt and sometimes rude to his patients, and similarly to his colleagues.
* AsianSpeekeeEngrish: His English is broken and fits the description, but other than that, he's nothing like this stereotype and counts as a subversion. He's an extremely self-assured and brilliant neurosurgeon with blunt-to-rude bedside manners.
* BeneathTheMask: He has terrible bedside manners in general. [[spoiler:He felt genuinely sorry for letting a widow to decide whether to pull a plug. He went to apologize and cried. In the rain.]]
* BrutalHonesty: He has no problems telling people what their problem is. "Too fat."
* CatchPhrase: "No do -- dead" and variations.
* HiddenDepths: He has a perfect pitch and plays the violin very well. He loves music very much. Surprisingly, he can also recognise a brilliant literary mind by reading a couple of pages. Considering his English language skills, that's impressive. Despite the abovementioned terrible bedside manner, he's incredibly compassionate and reassuring with Wilson after Tina's surgery.
* YouNoTakeCandle: He-speak-broken-English. Interestingly, his wife is shown speaking English at home, and she has a clear, normal accent. One has to wonder where his language skills come from.

!!Dr. Sydney Napur [-(Sarayu Rao)-]
* BrutalHonesty: She cannot take bullshit from either patients or her colleagues. She's not afraid to speak her mind and sometimes can be a bit controversial.
* HeterosexualLifePartners: With Tina. She calls Tina her best friend several times.
* MarriedToTheJob: People say it to her very often. Variations include asking her if she ever stops obsessing about her job and stuff. She doesn't.
* MyBiologicalClockIsTicking: It's a source of angst for her that she doesn't have children, but she's too committed to her job. Gato also thinks it will happen when she meets the right guy.
* OfficeRomance: She and Dr. Lieberman are not from the same department, and the hospital doesn't seem to have a policy against doctors dating each other.
* PitbullDatesPuppy: Dr. Napur is very tough and Dr. Lieberman is a little scared of her. When El Gato suggests that they might not get on, she gets angry.

!!Dr. Michelle Robidaux [-(Emily Swallow)-]
* BrainyBrunette: Michelle has long straight hair. She's a pretty and clever woman.
* HospitalHottie: Michelle gets hit on by patients and is referred to as "the pretty brunette".
* TheIntern: She's a resident and the youngest and least experienced on the team. Still very capable and a competent doctor.
* {{UST}}: With Dr. Delany, a one-shot character.

!!Dr. John Lieberman ([-Jonathan Silverman-])
* {{Adorkable}}: Tina and Sydney discuss whether he's attractive or dorky. They settle on "dorky enough".
* LoveInterest: He asks Dr Napur out in the first episode. She kind of made him. Their relationship lasts with the inevitable ups and downs.
* OfficeRomance: He dates her colleague.
* PitbullDatesPuppy: He's the puppy. Dr. Napur is way tougher than he is.
%%!!Atty. Scott Henderson ([-Jason Gray-Stanford-])
%%!!Mitch Tompkins ([-Anthony Heald-])
%%!!Fran Horowitz [-(Valerie Mahaffey)-]
%%!!Mark Ridgeway [-()-]