The Eppes Family
Donald "Don" Don Eppes
- Played by: Rob Morrow
Don's growth has him dealing with his choices and consequences, alongside his future plans and his occasional problems of commitment. One such incident was the end of season 2, where he went to some pretty big depths to solve the case and rescue Megan, but it lands him in trouble with his superiors and the rammifications are felt, even up to the Season 5. Additionally, he ends up having to go see a therapist to deal with his approach to violence.
The later seasons have him explore his family's Jewish roots and even going to temple (on some indirect advice from said therapist.) Additionally, he undergoes a midlife crisis as a result of a near-death experience He eventually takes on a higher position and finally proposes to his girlfriend, Robin, a prosecutor.
- Affectionate Nickname: Is often referred to as "Donnie" by Alan.
- Always Gets His Man
- Amicable Exes: With Liz Warner, after their relationship ends in season four.
- Big Brother Instinct: Don has always been protective of Charlie, even back when they weren't on the best terms as kids. As such, when antagonists in particular target his brother, he goes on the offensive.
- Big Brother Mentor: To his brother, Charlie, and to David, to a lesser extent.
- Brains and Brawn: He's the badass FBI agent to his math professor brother, what'd you expect?
- By-the-Book Cop/Cowboy Cop: He straddles the line between these two roles, which have consequences down the line though he himself admits that it's hard to tell because of different the cases are. On the one hand, he gets into some serious trouble by his superiors when he has a suspect physically beaten to get information out of it when his girlfriend kidnapped Megan in the Season 2 finale and Season 3 premiere. On the other hand, in Season 5 he also reports the veteran agent when he learns he lied and exaggerated about the figures and crime connections of their target in order to "get the job done" while also that it was personal, given said criminal targeted his sister. Despite the implications that said veteran may've used his influence and prestige to assist in Charlie being reinstated to get him to help. The one investigating him eventually asks him "what side of the line he's on," (referring to on the matters of following protocol vs doing what it takes to get the job done).Don: I wish I could tell you, if the line stopped moving around so much.
- Character Tics: Tends to check his watch from time to time when he feels particularly stressed.
- Chick Magnet: Seriously, the guy has had at least five girlfriends.
- Fair Cop: FBI and quite a looker.
- FBI Agent: Lead agent of the unit.
- Gracefully Demoted: In Don's backstory, he was the Special Agent in Charge of the FBI Field Office in Albuquerque but took a demotion when his mother got sick from cancer and returned to LA.
- Inspector Lestrade: Is this to some extent to Charlie.
- It's All My Fault: Has a tendency to feel this way, even when things are out of his control.
- Knight Templar Big Brother: When one guy went after Charlie, Don walked right into his office and told him right to his face that he would take him down hard for going after his brother.
- Ladykiller in Love: Is portrayed as this when he falls for Robin.
- The Leader: Head of the unit.
- On the Rebound: Did this with Liz after he and Robin broke up for a time.
- Oral Fixation: He has a tendency to chew gum when he is getting keyed up in the climax, like waiting for a suspect to show up.
- Papa Wolf: Threatening his family, team or associates is a good way to make Don pissed at you. Exploited in an episode. The Russian mob intentionally went after his brother and team as an elaborate distraction from their scam.
- Reasonable Authority Figure: Textbook example, as he will give a talking to his teammates if he thinks they need and he let Colby back when he turned out to be a Fake Defector. If he starts shutting down his team, it means he is in a bad place mentally.
- Sibling Team: The premise of the show is he's this with Charlie.
- Sibling Yin-Yang: He and his brother Charlie, referring to their approach in instinct and logic though it's a bit downplayed.
- Spiky Hair: Has variants of this throughout the series.
- Standard Cop Backstory: Notably averted. Charlie being a genius caused a few small issues, but he was always loved and cared for. There's a reason he's still so close to his family. He does have a few failed relationships, but it's implied to be mostly by choice.
- The Stoic: Don has a tendency to be a stone wall with his emotions. His girlfriend actually lampshades him doing this.
- Successful Sibling Syndrome: Felt this way with Charlie when they were kids, as Charlie was a child prodigy and graduated at the same time as he did. Still somewhat felt this at the beginning of the series, but it gradually goes away as they learn to work together.
- Team Dad: To be expected as the head of his unit. He looks out for them. And endangering them is a pretty good way to really piss him off. Also mildly deconstructed since this with his temper lands him in hot water regarding the use of questionable tactics to get information.
- The Un-Favourite: Not intentionally, but due to being a math child prodigy, Charlie required a lot more of their parents' attention when they grew up. Alan has some guilt about it and Don initially has some resentment, but they get over it.
- Working with the Ex:
- In the first season, he worked with Terry Lake, who he dated in their academy days.
- Spends part of Seasons 2-4 dating Liz Warner, before eventually parting ways.
Charlie Eppes
- Played by: David Krumholtz
The younger Eppes brother, he is considered something of a celebrity in the academic field for his impressive mathematical skills at a very young age, being a kid when he entered and graduated university. Now a celebrated professor, he ends up in a unique career spin when he becomes involved in the FBI with assisting his brother.
Charlie was arguably closer to his mother, as she was the one who went with him to university and he and the family work to handle their loss. Additionally, Charlie grows as he ends up in scuffles and having to define his life beyond the classroom. This includes moving on from his then magnum opus The Eppes Convergence, when his frenemy ends up pointing out the holes and becoming more used to the FBI life. He also deals with entering into a relationship with Anita along with the changes of his mentor, Larry. He goes to his next big study, in the emergance of cognition from brain development while also becoming a successful author in a book applying Game Theory to dating. However, he does up in serious trouble when an acquaintance of his gets involved in national security and the debacle has Charlie losing his FBI clearance though Don predicts it may have also been correlated to Don's own behavioral problems.
He ends up marrying Amita and the two of them eventually would take a teaching job in Cambridge.
- Absent-Minded Professor: Not to the extent of Larry, but he has his moments. Downplayed otherwise since he connects well with his students.
- Affectionate Nickname:
- Don refers to him as "Buddy" or "Chuck" from time to time, the latter of which he has some issue with.
- Colby often calls him "Whiz Kid".
- Annoying Younger Sibling: He is younger than Don by 5 years. Apparently, Charlie's gifted mind meant he required more attention and he and Don weren't that close as kids. Granted the only fight we know tht happened was when Don asked out Charlie's lab partner, whom the latter crushed on, to prom, which resulted in a wrestling match in the front lawn.
- Badass Bookworm: Post-Character Development. He has become better able to deal with hostile situations and learns how to shoot quite well in fact.
- Brains and Brawn: He's a college professor who works with his brother, the FBI agent.
- Brainy Brunette: Dark brown curly hair? Check. Mathematical genius, check.
- Child Prodigy: Was one, who graduated from Princeton when he was just 13.
- Defective Detective: Charlie, a mathematical genius who uses his talents to help his FBI agent brother solve crimes, has emotional difficulties to the point that he locks himself in the garage to work on unsolvable problems when he can't deal with life. However, he overcomes this early on.
- Embarrassing Nickname: Gets annoyed whenever Don calls him "Chuck".
- Expert Consultant: A math genius who consults for the FBI when they come across a difficult crime to solve.
- Geniuses Have Multiple PhDs: Charlie regularly proves he is an incredibly brilliant mathematician, so it's not a surprise when "Decoy Effect" mentions he is a multiple Ph.D.
- Gentleman and a Scholar: He's quite approachable and a gentleman, no doubt to being raised well by his parents.
- Good with Numbers: He went to university at 13 and mathematics remains to be his strongest passion.
- Insufferable Genius: He can be this at times, especially when confronted by a rival.
- Interdisciplinary Sleuth
- Jewish and Nerdy: Downplayed. While quite nerdy, he doesn't think much on his Jewish background. Becomes more noticeable when Don takes a greater interest in Judaism in later seasons.
- Nice Jewish Boy: He is still Jewish and quite a nice young man.
- More than Just a Teacher: Teaches math at the California Institute of Science, and is secretly a former CIA employee.
- Non-Action Guy: While he does later learn to shoot firearms, he is still primarily best when at the brains.
- The Professor: Professor Charles Eppes thank you very much.
- Quirky Curls: Amita certainly likes them.
- Reasonable Authority Figure:Is this to his students.
- Running Gag: He can't spell worth crap. This started with David Krumholtz accidentally writing "anomaly" with two "O"s in the pilot and became a recurring gag thereafter.
- Shorter Means Smarter
- The Scully: Reacts this way to psychics in contrast to the more open minded Larry.
- The Smart Guy: To pretty much the whole team in general.
- Smart People Play Chess: To the point that the only chance that most people have at beating him is for two people to play him at once while also distracting him.
- The Storyteller: Charlie teaches math with stories.
- The Strategist: Charlie would probably qualify with his ability to mathematically predict the moves of evildoers.
Alan Eppes
- Played by: Judd Hirsch
- Amazingly Embarrassing Parents: Tends to be this at times, although not as bad as some examples.
- The Everyman: His worldliness and status as just an everyday guy helps ground Don and Charlie's cases out of the realms of crime and academia and into everyday life. Some examples are relating how a friend of his died from organ failure while waiting for a donor, and identifying some random numbers as sports scores from the newspaper.
- Former Teen Rebel: Alan was a member of a radical anti-war student group in the 1960's.
- Good Parents: He does an admirable job in raising his sons to be honest and good men and he still looks out for them with advice and assistance. No wonder Charlie and Don turned up as well as they did.
- I Want Grandkids: Alan takes the proactive approach, giving solid relationship advice to Don and Charlie.
- Parental Substitute: Is this to Don's team and a big brother/mentor to Larry, giving out advice.
- Team Dad: Not just to his sons, but to their co-workers as well, serving as an impromptu father figure. He also serves something of an older brother figure to Charlie's mentor Larry.Alan: I'm going to give you the same advice I give to all the geniuses I know.Larry: And that is?Alan: Don't be an idiot.Larry: Ah. (nodding).
- This Looks Like a Job for Aquaman: Occasionally helps out on Don's cases when his past profession as a city planner becomes relevant.
Margaret Eppes
- Played by: JoBeth Williams ("''Hot Shot")
- Alliterative Name: Margaret Mann, her maiden name.
- Good Parents: Was this from the way the surviving Eppes family talks about her.
- Hidden Depths: Was a talented musician and composer, and could've gone to study in Vienna if she didn't have such a passion for the law. She kept that hidden from Alan because she didn't want him to know how much she gave up for him, but she still hoped that at least one of her sons would like music.
- The Lost Lenore: To Alan after she died of cancer.
- Missing Mom: Died before the series started.
- No Name Given: Wasn't named for two seasons, as she was only mentioned in passing due to her death.
Violent Crimes Squad
David Sinclair
- Played by: Alimi Ballard
- By-the-Book Cop: Don describes him as this in one episode, being too cautious to take initiative, and his own actions throughout the series generally support this assertion.
- Dark and Troubled Past: He grew in a rough neighborhood with troubled family members. He once described having to dodge gangs to graduate high school.
- FBI Agent: Don's second-in-command.
- Heterosexual Life-Partners: With Colby. The two are often seen side by side one another when investigating and David took it the hardest with Colby supposedly being a double agent, later revealed to be a triple agent.
- The Lancer: He's Don's right-hand man and the one people listen to when Don's not around. Fittingly, he takes Don's position when Don ends up moving on into a different role.
- Standard Cop Backstory: He grew up in a poor neighborhood "dodging gangs just to get [his] high school diploma". His father died when he was in his early teens, and one of his best friends was killed in a random act of violence (for which another close friend was unfairly blamed).
Colby Granger
- Played by: Dylan Bruno
- Badges and Dog Tags: Served in the Army as a CID investigator before joining the FBI.
- The Big Guy: Does the most physical activity on the show.
- Cold Sniper: Of course, all the FBI agents have to be this to a degree, but somehow Colby ends up having to shoot criminals more often than the others.
- Deadpan Snarker: Colby does has his moments.
- Fake Defector: Colby turns out to have been a triple agent for several years. This causes a fair bit of drama and angst, since the rest of the cast find out about the "defector" part well before they find out about the "fake".
- FBI Agent: Part of Don's unit.
- Heterosexual Life-Partners: With David.
- Hidden Depths: Is fluent in Spanish, which comes in handy when the team investigates the case of missing Spanish girls.
- I Just Want to Be Normal: After the Janus List incident, he expressed his desire to Don that he just wants to be a field agent, which he evenutally gets in the next episode.Colby: What I want is to go back and start over. Have a regular job at the bureau. No lying, no pretending.Don: Well, then the question is, can you be happy with a regular job at the bureau?'Colby: I mean, that's what I set out to do. If I wanted to be a spy, I would have applied somewhere else.
- The Mole: See "Fake Defector".
- Standard Cop Backstory: His father died in a single-car wreck when he was fifteen. There's no way to be sure, but Colby has always suspected it might have been a suicide. He also spent several years in the military, and was also involved in a Friendly Fire incident.
Megan Reeves
- Played by: Diane Farr
- Action Girl: The most frequent female team member we see in the action and she isn't afraid to kick ass when she needs to. She also teaches krav maga on the side.
- Deadpan Snarker: Likes to snark a lot, especially with Colby.
- FBI Agent: Part of Don's unit.
- Former Teen Rebel: As revealed when she was kidnapped, she used to be a fair bit wild when she was younger. It's implied this played a role in her choice to leave the FBI to counsel women in prison.
- Lady of War
- Nerds Are Sexy: Dates Larry, to everyone's surprise.
- Opposites Attract: Philosophical and dorky Larry is mutually attracted and has a relationship with practical and analytical profiler, Megan. Very much lampshaded how odd the couple are.
- Parental Issues: Has a serious problem with her dad that resurfaces every now and again.
- Probably why she was drawn in by someone like Larry, outside of him having some problems (albeit not to the same extent) with his own father.
- Put on a Bus: She ends up leaving the FBI to become a counselor to women in prison at the end of Season 4. Also has shades of Chuck Cunningham Syndrome since she and Larry talked about having a long distance relationship but she's never mentioned again while Larry occasionally dates other women.
- The Profiler: She is the one who psychoanalyzes their suspects and trying to figure out their motives.
- Standard Cop Backstory: She was wealthy, but her father always resented her because she was born a girl, and it's hinted (but never confirmed) that there's more to the story. Whatever did happen, it was bad enough that she didn't speak to him for over a decade.
- Why Couldn't You Be Different?: According to her, she was her father's "last attempt to get a son."
Liz Warner
- Played by: Aya Sumika
- Action Girl
- Amicable Exes: With Don, after their relationship ends.
- Dark and Troubled Past: Her early life is never discussed, but she does say that at one point that she had been pregnant in college and miscarried, and that her friends were so insensitive to her about it that she never spoke to them again.
- FBI Agent: Part of Don's unit from season two-four.
- Lady of War
- Working with the Ex: After she and Don break up.
Nikki Betancourt
- Played by: Sophina Brown
The "new girl" that joins the team in Season 5 fresh from Quantico after 4 years on the beat for LAPD.
- Action Girl: Takes Megan's role of this starting in Season 5, and is easily the most rough-and-tumble of the female leads, on account of her past in LAPD.
- Dark and Troubled Past: Her past is not really explored, but early in her career, she was dumped into undercover work unprepared and one of the targets tried to rape her. The way she plays it off as no big deal also suggests she might have more (ultimately unexplored) trauma in her past.
- Deadpan Snarker: Often manages to outsnark Colby with David being her usual target.
- FBI Agent: Part of Don's unit in season five-six.
Terry Lake
- Played by: Sabrina Lloyd
The team's profiler for season 1 before moving back to Washington in the interlude between season 1 and 2 to try again with her ex-husband.
- FBI Agent: Member of Don's unit in season one.
- The Profiler: She would often create a psychological profile of the criminals, most notably in the Pilot episode.
- Put on a Bus: Only appears in the first season. Her role as the team profiler was taken over by Megan during Seasons 2 through 4.
- Working with the Ex: She and Don dated during their academy days and work together during the first season.
California Institute of Science
Larry Fleinhardt (Peter MacNicol)
Charlie's best friend and colleague, Larry is an eccentric physics professor who often helps Charlie with his projects.
- Absent-Minded Professor: Oh yes. He's a very quirky person and has a tendency to be philosophical, which makes him amusing to the eyes of his students.
- Berserk Button: Somewhat downplayed; The episode "Atomic No.33" has the team deal with a cult; their regards to faith-healing and disregard to medicine and science makes him angry, albeit in a subdued manner. Still, this is probably one of the angriest we've seen him.
- Bunny-Ears Lawyer: A very bright and valuable man; he even went into space once. However, he also sold his home out of not wanting to constrain himself and once had a diet of only white foods, among other quirks, such as staying in bathtubs for a long time (which is related to the home thing).
- Cloud Cuckoolander: He comes off as this at times, due to his selling his home, that time he ate only white foods, long periods in bathtubs and his eccentric philsophical nature in general. Charlie and the others help keep him down to earth.
- The Gambling Addict: A former one, and his experience comes in handy when a prior colleague of his does the same scheme they did when they were younger — card-counting.
- Gentleman and a Scholar: While he be may an eccentric, he is still quite the gentleman and a very knowledgable physicist.
- The Lancer: To Charlie when it comes to the folks of CalSci.
- Like a Son to Me: It becomes increasingly evident that Larry views Charlie as this and when Larry went off on a sabbatical, he entrusted his work to Charlie in a way a father would to his son. Charlie in return very much looks up to Larry.
- Opposites Attract: Philosophical and dorky Larry is mutually attracted and has a relationship with practical and analytical profiler, Megan Reeves. Very much lampshaded how odd the couple are.
- Parental Issues: Not to the extent of Megan, but he had problems with his father wanting him to become an artist.
- Picky Eater: For awhile, he ate nothing but white food as part of an experiment.
- Put On A Space Shuttle/The Space Shuttle Came Back: Left in "Brutus" for doing research on the ISS. Landed safely in the "The Art of Reckoning".
- The Professor: A physics professor at CalSci and he was Charlie's professor back when he was a student.
- Sesquipedalian Loquaciousness: Part of what makes him come off as an eccentric professor, remiscent of the stereotypical kind.
- Smart People Play Chess: He often plays chess with Alan. He becomes much better at it when he returns from his sabbatical.
- The Spock: Downplayed. While Larry can show joy and sadness, he is often in a state of logical calmness and relies on logic and rationale. He's also not that good with dealing with passion and emotional uncertainty, which was examined in his budding relationship with Megan.
Amita Ramanujan (Navi Rawat)
A computer whiz at CalSci, Amita often helps Charlie in building computer programs to run his mathematical models.
- Arranged Marriage: Amita was in one and knew the guy as a good friend since she was young. Her parents invited him back to try and win Amita over and she does greet him warmly. When Charlie voices his concerns though, she explains that he is gay. However, when Charlie asks her if her parents knew he was gay, to which she replies in the negative, she realizes what her parents attempted to do.
- Bollywood Nerd: Of Indian descent and a computer genius.
- Brainy Brunette: Has long dark hair, and is very smart.
- Gamer Chick: As revealed in the episode "Primacy". Even when she was supposed to lose, her gaming reflexes kicked in and she won anyway.
- The Heart: Probably the most kind and feminine character in the show.
- Lady of War: Mostly "Primacy", but she shows elements of this in other episodes as well, most notably during her abduction in "Angels and Devils".
- Leet Speak: Is fluent in this, with her often decoding leet for the FBI team.
- Parental Abandonment: Not quite, but Amita's parents are always too busy to visit her.
Dr. Millie Finch (Kathy Najimy)
- Chuck Cunningham Syndrome: She's a prominent season 3 character but is only mentioned a few times afterwards.
Oswald Kittner (Jay Baruchel)
- You Are Better Than You Think You Are: He just sees himself as a small time operator and fantasy sports league player but Charlie and the others are really impressed by his math.
Ray Galuski (Chris Bauer)
- Genius Bruiser: A husky Cal-Scie professor and baseball fan whose a great mechanical engineer.
Otto Bahnhof (John Cariani)
Cal Sci's Plasma Physics and technology expert.- Affectionate Nickname: Ottobahn.
- Afraid of Blood: He's a bit squeamish with the cases he helps with.
- Endearingly Dorky: He's an excitable scientists who easily gets lost in his work.
- Jumped at the Call: He's happy to serve as Larry's assistant in the finale when he takes over for Charlie as main consultant.
Russell Lazlo (Tony Hale)
Calsci's geneticist.- The Friend Nobody Likes: Charlie finds him a bit overwhelming.
- Hidden Depths: Turns out he's also a motorcycle rider.
- Just Think of the Potential!: He's quite excited to be on a case which might involved the first human clone.
Federal Bureau of Investigations - Other Agents and employees
Walt Merrick (Anthony Heald)
Don's boss who appeared in the first episode.- One-Shot Character: Only appeared in the Pilot.
Ian Edgerton (Lou Diamond Phillips)
An FBI sniper who often assists the team in dealing with particularly dangerous criminals.- Anti-Hero: Out of the FBI, Ian's the one most willing to use extreme means to complete his task, most apparent during "Ultimatum", and shows no hesitation in killing. He's still an overall a good guy, though.
- Cold Sniper: You bet it! It sort of comes with being the fifth?.. Fourth?.. Third best sniper in the country. He lives up to the reputation, too. If he's in an episode, he'll usually end up being the one to take out the criminal of the week.
- Standard Cop Backstory: He has a military background but the rest of his backstory is a complete unknown.
Agent Billy Cooper (Max Martini)
An agent Don worked with when he was in fugitive recovery.
- Fair Cop: He's a somewhat handsome field agent.
- Reasonable Authority Figure: He's introduced as being used to his own methods and surprised by Charlie but there's no real conflict between them and he appreciates Charlie's information.
Agent Tim King (Chris Bruno)
Agent Roger Bloom (Henry Winkler)
- Caper Rationalization: He steals money to frame a man he wants the recourses to pursue more ruthlessly, but only hid the money to give back afterwards
- Knight Templar Big Brother: He goes out of his way to frame a man who cheated his sister of a small sum.
- Living Legend: He's a decades long agent whose worked some very big and important cases.
- Redemption Quest: His second and third episodes have him being an asset to the team after using them for a personal vendetta in his first.
Matt Li (Matthew Yang King)
One of the technicians.- Almighty Janitor: Mainly in the episode "Disturbed" where despite his technician status he's the first one to believe Charlie's theories about a serial killer not sticking to average methodologies (being aware of a past killer who did that) and giving Charlie information to help him
- Mauve Shirt: Matt appears across the series (from the second episode to the finale) but takes a while to be named and tends to only get two three minutes of screen time to an episode.
Dr. William Bradford (Wendell Pierce)
An FBI therapist who treats Don, beginning in season three after the Crystal Hoyle incident.- Hidden Depths: Don is initially dismissive of him about being all desk work and no field work, until Bradford reveals his own past in undercover narcotics.
- The Shrink: Bradford is a patient, insightful man who helps Don realize a lot about his own psyche.
Claudia Gomez (Lauren Velez)
—-- The Coroner who was a love interest for David.
Los Angeles Police Department & District Attorney's Office
Robin Brooks (Michelle Nolden)
An attorney who develops a relationship with Don.
- Hello, Attorney!: She's a smiling, attractive lawyer who wears business suits.
- Ivy League for Everyone: She attended Harvard Law.
Lt. Gary Walker (Will Patton)
- Defrosting the Ice Queen: There's some Inter-Service Rivalry with him and the team at first but he's a friend by his final appearance.
- A Father to His Men: He cares deeply about his subordinates and wants to avenge their murders and honor them afterwards.
- Serial Spouse: Has been married and divorced three times.
Civilians
Dr. Karen Fisher (Jennifer Westfeldt)
Simon Kraft (John Glover)
A supposed psychic Charlie butts heads with.- Maybe Magic, Maybe Mundane: Simon does have a talent for showing up at the right place or ferreting out information but there is a simple explanation for most of his stuff.
- Skewed Priorities: In his second episode he's filming a show about himself and cares more about getting footage than intervening with a crime, which leads to his Surprisingly Sudden Death.
Daniel Shay (Josh Eriksson)
A little boy who Don takes in after his mother is killed.Marshall Penfield (Colin Hanks)
- The Rival: He's a fellow talents prodigy with Charlie and they sometimes try to best each other.
Notable Criminals WARNING: UNMARKED SPOILERS AHEAD!!!
Season One:
Roland Haldane
- Played by William O'Leary
- Cold-Blooded Torture: Likes to brand his victims.
- Killed Off for Real: He is shot by Don when the attempted arrest turns violent.
- Serial Rapist: Rapes more than a dozen women before he's stopped.
- Serial Killer: He isn't technically one, since he only manages to kill two of his victims, but he was well on his way.
- Small Role, Big Impact: He's only in one episode, and has two or three lines of dialogue, but his crimes are what inspire Don and Charlie to begin teaming up on cases.
Dr. Clarence Weaver
- Played by: J. K. Simmons
- Well-Intentioned Extremist: He intentionally infected people with Spanish Flu to prove that the pharmaceutical companies chose the wrong (less virulent) strain to use in the development of vaccines and treatments, because he was convinced that a real epidemic was only a matter of time and so getting it right was literally a matter of life and death.
Paul Ballard
- Played by: Jamie McShane
Scott Reynolds
- Played by: Joseph Gordon-Levitt
McDowd
- Played by: Kevin Fry
Season Two:
Leonard Philbrick
- Played by: Ethan Phillips
- Gambling Ruins Lives: "Double Down" reveals that he did card counting with Larry when they were younger and he got caught up in it, which destroyed his promising academic career and his marriage, he ended up teaching at a high school. However, he wanted a second chance at proving himself with the casinos and he got several students to do card counting, which results in a couple of their deaths.
Season Three:
Crystal Hoyle
- Played by: Kim Dickens
Buck Winters
- Played by: David Gallagher
Dwayne Carter
- Played by: Shawn Hatosy
- Even Evil Has Loved Ones: He started being a spy to get money for his son and when he thinks Colby is another spy, he tries to keep his secret.
- The Mole: He's a hired spy for China.
- Villain's Dying Grace: He dies saving the life of his old friend Colby.
Abner Stone
- Played by: W. Earl Brown
- Dirty Coward: Abner gets his cult followers to commit suicide or surrender to him while surrendering himself.
- Dirty Old Man: A Cult leader whose taken eight wives and tries to take a teenager as his ninth.
- Klingon Promotion: He's suspected of killing the cults previous leader, his own brother.
Season Four
Mason Lancer
- Played by Val Kilmer
- Big Bad: appears in one episode but he becomes this when he tortures Colby.
- Character Death: Dies in Trust Metric by Carter in an effort to save Colby.
Season Five
Slobodan Radovic
- Played by Michael Khmurov
- Balkan Bastard: Not only did he stab Don, nearly killing him, he is also a war criminal for cleansing villages during the Balkan Wars and wiped out a village of some armed robbers, who began hitting houses in revenge.
- No Historical Figures Were Harmed: Radovic is an obvious stand-in for Slobodan Milosevic, the second to last president of Yugoslavia who was responsible for war crimes committed during the Yugoslav wars. It's practically spelled out by Radovic's nationality, Serbian, which is the same as Milosevic's.
Robert Posdner
- Played by Brian Howe
Other Love interests
Susan Berry (Sonya Walger)
Nadine Hodges (Sarah Carter)
- An attorney who appeared in season two.
- What Happened to the Mouse?: Appears in several episodes and was seen as a possible love interest for Don but she disappears and is never mentioned again.