Sheriff Ralph Lamb (Dennis Quaid)
- Aloof Big Brother: To Jack.
- Cowboy Cop: Literally.
- Good Is Not Nice: He's not hesitant about expressing his dislike for people or his refusal to suffer fools but he is most often the one who suggests doing the right thing.
- Grin of Audacity: Ralph's trademark grin in his job.
- Nice Hat: He, his brother, and his son all wear cowboy hats, fittingly enough.
- Overprotective Dad: To Dixon.
- The Sheriff
- Sibling Team: With Jack.
Deputy Jack Lamb (Jason O'Mara)
- Cool Uncle
- Dating Catwoman: Well, he would like to be dating Mia. Both Ralph and Mia are warning him of the potential repercussions.
- Dude, Where's My Respect?: Jack feels that Ralph is taking him for granted and not giving him the respect he deserves.
- Hired to Hunt Yourself: Played with. Jack, who killed Johnny Rizzo, volunteers to lead the investigation.
- The Lancer
- Nice Hat
- Parental Substitute: He raised Dixon when Ralph served as a military policeman.
- Sibling Team: With Ralph.
Deputy Dixon Lamb (Taylor Handley)
- Born Detective: Katherine notes that he's got a knack for detective work. He even impresses Savino in "Estinto".
- The Casanova: He is a big hit with the ladies and in his Establishing Character Moment he is trying to get away from an angry husband firing a shotgun.
- Dude, Where's My Respect?: See Jack's entry.
- Nice Hat
- Why Did It Have To Be Spiders?: He hates this. The other deputies tease him for it. Ralph tells Jack that he was really raised on a ranch.
Yvonne Sanchez (Aimee Garcia)
- Brainy Brunette
- Girl Friday: While she is the sheriff department's receptionist, she also helps out with investigations.
- Hypercompetent Sidekick
- Sexy Secretary
- Spicy Latina: Averted. She's too all-American to be one and she's not particularly Hot-Blooded.
- Sweater Girl
- Twofer Token Minority: Mexican and female.
Assistant District Attorney Katherine O'Connell (Carrie-Anne Moss)
- Brainy Brunette
- Childhood Friend: She grew up on the ranch next to the Lambs.
- Damsel out of Distress: She outwits a rapist long enough for The Cavalry to arrive in "Masquerade".
- Hello, Attorney!
- Nerves of Steel: In "Masquerade", Ralph notes that it's the first time he's ever seen her not in control.
- The Smart Girl
District Attorney Rich Reynolds (Michael Reilly Burke)
- Amoral Attorney
- Corrupt Politician: He's working with the mob and feeding them information about cases relevant to them, as well as selling out the previous sheriff.
Mayor Ted Bennett (Michael O'Neill)
Vincent Savino (Michael Chiklis)
- Affably Evil: Extremely polite to everyone, loves his family and friends, orders the car bombing of a snitch...
- Bald of Evil
- Benevolent Boss: Is friends with most of his men and gives advice to his casino employees on how to get better tips. He even allows some employees who were stealing money from the casino to leave without incident. However...
- Bad Boss: ...if a mobster or employee does something he really doesn't like (such as beat up an employee for information without orders to do so) and he may beat the crap out of them. And if they get arrested for murder and stealing money from his casino and threaten to turn information over to the DA? Then they are screwed.
- Even Evil Has Loved Ones: He cares a lot about his wife and daughters and gets very upset when Borelli is killed by a Milwaukee mob hitman.
- Even Evil Has Standards: He dislikes it when civilians get caught in the crossfire during mob confrontations, does not tolerate narcotic use in his operation, goes out of his way to get an innocent employee away from Rizzo's wrath, and "teaches some manners" to a group of young motorcycle punks that threaten a family who gave Vincent and his "associates" a ride when the trio was stranded.
- Nice Hat
- Nice to the Waiter: Very much so. He gives his workers pointers on how to get better tips and saves one poor waiter from a fellow mobster with a Hair-Trigger Temper. Vincent also went off his way to give to beatdown to Beansy after he witnesses him attacking a casino dealer after informing Vincent in locating the corrupt Clark County Sheriff since he didn't give the order to beat the dealer.
- Sympathetic P.O.V.
- Ugly Guy, Hot Wife: With Laura.
- Villainous Friendship: With Red, Mia, and Borelli. Not so much Beansy because he is a moron.
- Villain Protagonist
- Visionary Villain: He sees Las Vegas as the next big thing for the mob and is pushing his bosses hard for expansion of operations in the city.
Anthony "Red" Cervelli (James Russo)
Mia Rizzo (Sarah Jones)
- Affably Evil
- Defrosting Ice Queen: It's subtle, but she's slowly warming up to Jack.
- Daddy's Little Villain
- Dark Chick
- Emotionless Girl
- Evil Genius: She's the casino's count room manager and is responsible for the monetary take to give Savino's mob family in Chicago.
- Good with Numbers
- Missing Mom: There's no mention of Mia's mother and it's obvious that she's out of the picture since Mia's dad gets engaged to Diane.
- It's later revealed that Lena Rizzo is still alive and is trying to reconnect with her daughter.
- Nerves of Steel: She remains remarkably cool under pressure and has got a hell of a poker face.
- The Ugly Guy's Hot Daughter
- Villainous Friendship: With Vincent.
Nick "Beansy" Cota (Sonny Marinelli)
Vic Borelli (Joe Sabatino)
- Affably Evil: In "The Real Thing", he was polite enough to give a truck driver some money and tell him that he won't be killed to make sure he gets home to his family after hijacking his cargo truck.
- The Brute
- Killed Off for Real: By Jones in "Bad Seeds".
Laura Savino (Vinessa Shaw)
- Dark Mistress
- Exact Words: She tells ADA Katherine O'Connell that she will never tell Katherine anything that might incriminate her husband and his associates. The next time she talks to Katherine, she repeats this statement but omits the part about "his associates". Katherine quickly picks up on this omission and the two women reach an unspoken understanding.
- Hidden Depths: She's incredibly savvy when it comes to politics and has even worked for Kennedy's campaign. She puts these skills to use by helping turn Grady's campaign around in "The Real Thing" and "Bad Seeds".
- Ugly Guy, Hot Wife: With Vincent.
Angelo LaFratta (Jonathan Banks)
Johnny Rizzo (Michael Wiseman)
- The Don: After killing Angelo.
- The Dragon: To Angelo.
- Hair-Trigger Temper
- Killed Off for Real
- Parent with New Paramour: He gets engages to Diane in "Estinto". It didn't last very long.
- The Starscream: He gets permission to kill Angelo for getting too soft and takes over as the new head of the Family.