Duffy previously worked as a middle man in the Dixie Mafia under Emmitt Arnett. Duffy has a sister who owns a construction company. He also runs a security system installation business, with most of his clients being very rich people. Duffy is a loan collector and will usually threaten or harm loved ones and friends of his clients if they intervene or as a way to get people to pay him quicker. Duffy is described as having a very "mercurial" personality, which is the main reason Arnett hired him as a middle man. A year before events portrayed in the first season there was a man who didn't pay his debts to Duffy and he and Billy Mac found the guy's brother, carved his face off and stitched it onto a soccer ball. When Tim, another marshal working out of the Lexington office, told Raylan of the soccer-ball incident he advised that it be taken with a grain of salt, saying "That's what I heard." Duffy is now a partner of Boyd Crowder in the heroin business. Duffy is noted for his use of one-liners and dark sense of humor.
Duffy's first appearance is in the first season episode "Blowback". Winona Hawkins walks into her kitchen to find him standing there. Duffy tells Winona that with one phone call he was able to discover that the deposition she was scheduled to take part in that afternoon had been cancelled, letting him know that she'd be home early and likely be home alone. Duffy then tells her that the police is only a "janitorial service" used to clean up your blood after you have been murdered. Duffy's implied threat is understood but Winona has no idea who he is. She talks to her husband Gary, who denies knowing Duffy.
In "Hatless", Raylan pays a visit to Duffy and his "muscle", a former professional boxer named Billy Mac. Raylan threatens him saying, "if either of you go near Gary or Winona, I'll come back here and upend your entire existence." Duffy sends Billy Mac to follow and kill Raylan. Gary and his friend Toby Griffin visit Duffy soon after Raylan, and the three have a discussion. Gary tells Duffy that he can double Emmitt Arnett's money in 24 months, while Toby threatens Duffy. Duffy gives Toby the chance to back out, but Toby refuses and threatens Duffy even further.
Duffy and Billy Mac later enter Toby's home and Billy Mac easily and brutally beats Toby to the ground. They next meet Gary in a parking lot where Billy Mac punches Gary and tosses Toby's Super Bowl ring at him, saying "next time it'll be your wife's [ring]." Duffy meets with Arnett, Billy Mac, and Arnett's bodyguard in his office at the end of the episode. Raylan and Gary arrive and Gary offers Arnett the deed to the supermall in place of the money he owes. Arnett accepts the deed reasoning that the land will be worth more than Gary owes eventually. Duffy is enraged and pulls a gun because he was expecting to be paid a portion of the recovered money. Shots are exchanged and Duffy, Billy Mac, and Arnett's bodyguard are hit. Gary takes the opportunity to tackle Duffy to the ground.
Duffy first appears in "Save My Love". Gary Hawkins visits Duffy, whose office is now in an RV ("motor coach") and he has also hired his own bodyguard, Mike Cosmatopolis. Duffy recalls their last meeting didn't go well, and that he suffered a bullet wound and lost 18 inches of intestine. Gary tells him that he has come across an "exciting investment opportunity". This is revealed to be a hit on Raylan in the next episode "Debts and Accounts". Raylan and Winona take refuge in a warehouse when Raylan's car is rammed off the road and they are shot at by the would be assassins. Raylan manages to kill both of Duffy's men in the warehouse.
In "Full Commitment", Gary reveals that he was behind the hit on Raylan. Gary didn't want Raylan and Winona to get together. Gary says that he tried to call off the hit. Raylan figures this out when he learns that the hitman spying on them at Winona and Gary's house works for Duffy's sister. Raylan, Gary, and the handcuffed hitman all go to Duffy's trailer. Duffy and Raylan trade barbs, and Raylan reveals to Gary that he has no intention of saving him from Duffy, causing Gary to flee. Raylan warns Duffy that the next time they have this conversation, it will be more than just a conversation.
Duffy's first appearance in the third season is in "The Gunfighter". Raylan and Tim Gutterson question Duffy about the security system his company installed in the home of murder victim Delmar Coates. Tim asks him if he has ever employed a criminal named Fletcher Nix (who installed the alarm). Duffy refuses to answer their questions. Duffy calls Emmitt Arnett soon after the Marshals leave, confused as to why Arnett would hire one of Duffy's men to kill one of his clients. Arnett tells Duffy that he didn't know Nix was still his man. Duffy warns him that the Marshals are coming to talk to him. Duffy appears at the end of the episode, meeting with Detroit crime boss Robert Quarles and Arnett. Quarles shoots Arnett and his secretary Yvette while a stunned Duffy watches. Quarles asks him, "You know me now?", to which a stunned Duffy can only reply "Yeah".
In "Harlan Roulette" Quarles meets with Duffy to discuss his plans: Quarles is going to forge IDs, medical records, MRIs, X-Rays in order to legitimize corrupt doctors. He plans to supply drug addicts in Harlan County with prescription drugs from mobile trailers using a rotation of doctors. The addicts will get half of the prescribed pills at regular price, while the other half goes to Detroit to be sold for ten times the price. Duffy, taking orders from Quarles, calls a hit on Raylan, which Glen Fogle sends Wade Messer to do. Raylan survives the attempt and comes to Duffy's trailer. Duffy is punched twice by Raylan, who puts his boot onto Duffy's throat, telling him he knows he called the hit on him. Raylan then throws a bullet onto Duffy's chest and threatens him saying, "The next one's coming faster."
In "When the Guns Come Out", Quarles orders him to find out everything he can about Raylan, knowing that Raylan has been asking about him at the Marshals office. Quarles says he wants to know exactly where to apply pressure, and Duffy simply goes "sure thing boss". Duffy goes to leave, but soon comes back in and overhears Quarles assaulting the same man that Duffy found tied to the bed earlier in the season, and appears significantly disturbed. Duffy later informs Quarles that Boyd's clinic was hit earlier that morning, and suspects his boss to be behind it, but his boss informs him that he wasn't. Duffy says it's a coincidence that a few hours after the hit, their Oxy clinic was shut down as well by Raylan. Quarles laughs and says that it is "awesome" that they lost a clinic but smoked out a dirty Marshal in the process. Quarles also informs Duffy that there is no way Raylan could have found out about their clinic without the help of an "inside source", and believes that Raylan is working for Boyd, and declares it a smart move on the latter's part. Duffy, however, informs Quarles that Raylan's father, Arlo, is a part of Boyd's crew.
In "The Man Behind The Curtain Wynn Duffy and Robert Quarles are discussing what to do with the money that was intended to bribe Givens. Quarles he will drive to Harlan and offer it to someone who will not refuse. "The boss's son is coming" Wynn warns. Quarles explains he was more or less adopted by the boss, Theo Tonin, but despises the man's son, Sammy. It is implied that Quarles was passed over as heir to the criminal crown because of unsavory predictions that Given mentioned. Quarles then grabs the briefcase of money. Wynn Duffy remains silent as Quarles welcomes Sammy at his temporary Kentucky Home. He suggests that Quarles is wasting his time with a bunch of hillbillies. Quarles counters that once the Oxy market is secured, it will bring $1 million a month. Sammy who occasionally stutters, warns Quarles that he is on his last chance after the incident with the "rent boy". Wynn raises an eyebrow but remains silent. Wynn later has some bad news: the wire transfer of the money from Sammy was cancelled. Quarles correctly guesses that Givens was involved so he heads out to see Sammy. He tells Duffy to paint the back room and Wynn replies "You can't paint over blood." Quarles stares at him and Wynn says he will take care of it. Robert Quarles is shown talking to a drunk Gary Hawkins in a bar. Mike shows up and Gary asks him "Don't I know you?" Wynn Duffy appears behind him and replies "Yes Gary, you do."
In "Watching the Detectives Quarles, Mike, and Wynn are driving back from Tulsa, Oklahoma. Tanner, who is secretly spying for Limehouse, calls Quarles and says "he wants meets up to explain" his actions. "Brave man" Duffy says quietly. They stop the car in front of Gary and Winona's house, where Gary is released from the from the trunk. Quarles tells the confused man that he needs him to deliver a message to Raylan Givens and shoots Gary in the chest with a silenced pistol and he collapses on the front lawn.
The trio returns to Quarles' suburban home to find Elstin Limehouse and a pair of men waiting on the side lawn. Limehouse introduces himself to Quarles and explains that Boyd Crowder is backing former police officer Shelby Parlow for Sheriff. Quarles pointedly asks why this would interest him. Limehouse replies "I likes to be on the winning side."
Meanwhile back in Duffy's trailer he notices Detective Dempsey in his suburban homeand Quarles then asks Wynn if he painted the room. Wynn replies "not yet" he and Wynn quickly rush to the house as Detective Dempsey is about to open the door where Quarles had the gagged man tied up to the bed and asks him if he could help him, Duffy tells Dempsey the door sticks. Quarles and Duffy are brought in for questioning and neither will confirm Given's "thrown bullet" scenario, Wynn explains that Givens came looking for Gary and when Wynn couldn't locate the real estate agent, he savagely beat him. Wynn and Quarles calmly construct a frame around the Deputy Marshal. Givens lets himself into Quarles's home to find Wynn painting the room where Quarles had a semi nude man tied and gagged. Givens warns Wynn that Quarles is going down and he better get out of the way.
In "Measures", Duffy worries about Quarles since he had threaten to murder Raylan and is now leaving town for a few hours. Duffy asks what if Raylan comes back looking for him, and Quarles says to simply tell Raylan to wait. Quarles says that he is disappointed in Duffy given his "wild man" reputation in Detroit and now he suddenly wants to bail out. Quarles basically tells Duffy to "man up" before he leaves. Later, Duffy meets up with Sarno and Partlow, the two gun thugs that were hired by Theo Tonin to kill Quarles at his mobile RV. Duffy had sent the two men to Lindsey Salazar's bar in order to buy time for his next move (Hoping either they shoot Raylan or die themselves, both situations being a plus for Duffy). Duffy suggests cutting a deal with the two men. Duffy soon calls Theo Tonin, asking if Tonin plans to send more men to Harlan after Quarles. Duffy also expresses his interest in taking over the Oxy business in Kentucky once Quarles is out of the picture. Tonin refuses, but offers a proposition to Duffy: If Duffy can deliver Quarles to him ($100,000 dead or $200,000 alive), he will consider allowing Duffy to take over. After Quarles is tasered unconscious after being led into a trap by Tillman Napier and Boyd, Boyd talks to him on the phone after overhearing the conversation about the bounty on Quarles's head. Duffy truthfully tells Boyd the prices, but Boyd is skeptic. Duffy thinks that it is better to kill Quarles, who is notoriously resourceful but Boyd believes the man cannot retaliate as he is unconscious and chained to a bed. Duffy simply tells him "Don't say I didn't warn you".
In "Coalition", Boyd Crowder heads to the brothel with Duffy where they learn that Quarles is missing. Wynn is panicked explaining that Theo Tonin will not be happy when he finds out that Quarles has escaped from a "disease ridden whore factory up in Inbred Holler." "I'm going to let that one go" replies Boyd, who not surprisingly has a back up plan. When Quarles comes to see his old pal Wynn, Boyd will plant a bomb in Quarles' car, then the bomb will go off at one end of town and every cop and Marshal in the county comes running at the other end of town, Boyd will rob the bank giving Wynn a cut. Wynn then warms the new plan. Quarles calls Wynn explaining they have a new lease on life. Wynn returns to his trailer to find Quarles waiting who is smoking and high as a bleach blonde kite. Limehouse calls telling Quarles that Boyd won't be robbing a bank after all but still must pay his intent to kill him to appropriate Limehouse from his money. Quarles agrees to go to Johnny's bar and kill Boyd, he struggles to get straight before exiting. Wynn's thug Mike pulls the cellphone triggering device from his pocket that will blow up the bomb that has been planted in Quarles's car but rather than detonate it, Wynn suggests that they might as well wait to see if Quarles can kill Boyd first. Quarles exits his car from Johnny's Bar and Wynn watching from a nearby car and seeing an opportunity to kill two adversaries with a one blast tells Mike to activate the device. Boyd who knows his explosive devices hears the tell tale sound of what is about to distance himself from "ground zero" as a shot is fired. Boyd is thrown against a wall and Quarles back is set briefly on fire as Wynn and Mike drive off.
In the season 3 finale, "Slaughterhouse", Boyd Crowder reveals to Raylan that he had hired Duffy to kill Quarles. Raylan tracks Duffy down and threatens him with a game of Harlan Roulette. Duffy admits that he was the one who set the bomb off and tells Raylan where he might be able to find Quarles.
In "Where's Waldo?", Duffy enters the bar with his men. "I have many men in my employ," Wynn says. "If one of them strayed, I apologize." It turns out that Danny was one of Duffy's many drug peddlers. Boyd proposes a partnership with Duffy, who obviously doesn't trust the man or his offer. Duffy pulls a gun and shoots Danny in the head. "Any dealer silly enough to poach your territory is not welcome in my crew," Wynn says. "Sorry about the mess." Before leaving, Duffy tells Boyd about Arlo murdering another prisoner, who happens to be a soldier for the Dixie Mafia.
In "Truth and Consequences", Johnny has shown up at Duffy's trailer, offering him a partnership behind Boyd's back. He notes to Duffy that if Boyd knew what he was doing, he would kill him. Wynn worries that it was Boyd who sent Johnny, who notes that it was Boyd who put him in a wheelchair. "I want to believe you," Wynn says. Johnny then offers to help Wynn kill Boyd.
In "Kin", he is visited by dirty FBI agent Jerry Barkley and Nick Augustine, Barkley's old friend and a henchman for Theo Tonin. Duffy sits on the couch while Barkley and Augustine bond. Augustine reveals his knowledge of the FBI losing the Drew Thompson case to the Marshals. Augustine shoots Barkley in the head, and informs Duffy that Theo would like him to find Drew. Duffy complies. Duffy meets Boyd at Johnny's bar, and pays him off to help find Drew. Later, Boyd calls Duffy and offers him a deal: In exchange for finding Drew, he is rewarded with half of the heroin business, which Duffy agrees to. Johnny, who is present in the room, protests to Boyd, believing their deal is off. Duffy reassures him that the deal to kill Boyd is still intact.
In "Outlaw", Duffy then pays Boyd a visit and shares bad news: the mob is getting nervous that Drew Thompson has not yet been found. "Theo has a guy on the way down who has killed more people than malaria," Duffy explains. Boyd says that he has narrowed the list down to two names, and maybe it's safer to kill both. Later, Johnny visits Duffy in his mobile home and explains to him that the two men were not Drew Thompson, but rather two people on Boyd's enemy list. Duffy delivers good news and bad news to Johnny: The good news is Johnny is going to get his wish as far as Boyd's death is concerned. The bad news is that now Johnny has to deliver Drew Thompson to Theo Tonin.
In "The Hatchet Tour", Raylan visits Duffy in his motorcoach with Hunter Mosley in tow. Raylan believes that Duffy used Hunter to initiate the hit on Arlo, but does inform Duffy that Hunter may be the only person alive who knows Drew Thompson, which interests him. Duffy denies any involvement in Arlo's death.
In "Get Drew", Johnny calls him to tell him that they have identified Shelby Parlow as Drew Thompson, but they don't know where he is at. Duffy orders Johnny to find Drew, or else the deal to kill Boyd is off. Later, he hears from Nick that the Marshals have located Shelby. Duffy decides that he has to flee rather than face the Tonins.
In "Ghosts", Duffy returns to Johnny's bar and informs Boyd of the news out of Detroit: Sammy Tonin is the new head of the Detroit mob and has made Duffy his man east of the Mississippi. Duffy then offers Boyd the chance to handle his heroin distribution in Kentucky, to which Boyd agrees.
Up in Detroit Boyd & Wynn are being checked over by the drug dealers before they're allowed upstairs. They send up their IDs in a bucket on a rope & Boyd asks why they won't text & the guy says NSA is watching them.
Wynn & Boyd trudge up flight after flight of stairs in a grungy tenement building until they find the guys they're looking for, they are frisked again for good measure after they hand over the gas & a bag of stuff they were told to bring up. Another guy grabs the gas can for his chainsaw & walks away. Picker comes in & asks if they bought the money but Boyd insists they talk to the big guy. Picker calls for Sammy Tonin-the big guy- & he finally comes out. He's actually a tiny guy. The chainsaw cranks up & we hear screams. Picker tells them the rabble rousers that tried to steal from them were acting on their own & tell Sammy to get the breifcase full of money when he walks over to Boyd & Wynn, Picker shoots him in the back of the head & then shoots the chainsaw torturer & torturer. Boyd & Wynn are flabbergasted. Picker makes a call & tells someone that Sammy, the chainsaw guy & the guy are all dead. Picker demands the money & when he comes to get it Boyd makes his move & turns the situation around, Picker explains that Sammy owed the Canadians a millon & he made a deal to pay him off to save his life. Boyd says they need to talk to the Canucks & orders Picker to pick up the money that spilled out when he cranked him over the head with the breifcase.
Wynn & Boyd meet with the Canadians at a donut shop. Picker is there but not happy. They tell him that the money was to save Picker's life & Boyd says he desen't care & he just wants the dope. The Canadians say they can havie it in a day or two & Boyd reluctantly hands over the briefcase. Eeveryone is pissing Boyd off by asking about his ear bandage. Boyd tells Picker to go but the guy makes a counter offer to set them up with a new pipeline through Mexico & Boyd & Wynn grudgingly agree to explore this option since the Canuck connection will be Kaput.
In "The Kids Aren't All Right" Wynn Duffy is shown at Boyd's Bar & try's to assure the dealers working for him & Boyd that the drugs are en route, however no one is listening & one of the dealers threaten Wynn just as Boyd Crowder shows up to win back over the moutnain crowd & offer them free booze & a promise that the dope will be there the day after tomorrow.
In "Good Intentions", Boyd calls Duffy and blames him for the sabotage of their shipment, although Duffy denies the accusations. Later that night, Raylan visits Duffy in his motorcoach and warns him that Charles Monroe is going to kill him (as Charles believes that Duffy stole his gold since Duffy was the one that installed the safe in his office). Duffy is surprised that Raylan would give him a heads up, and Raylan says that he had Charles believe that the safe was empty.
In "Shot All to Hell", Wynn is shown at a diner getting ready to order breakfast with Mike and Ethan Picker, when they are interrupted by Art Mullen, who says that he is on unofficial business and wants to take Picker on a walk so that they can talk. Before they can leave, Elias Marcos enters the diner. Art then threatens to shoot Elias if he does not collaborate in 10 seconds, while Duffy remains calm and tells Elias and Picker "FYI, that's kind of a thing with these Marshals".
In "Wrong Roads", Picker and Duffy are seen at a hotel room, where Picker voices his concerns over getting in the heroin business with the Crowe family. At the meeting with Daryl Crowe Jr., both Picker and Duffy refuse to let Daryl have 20% of the cut, only allowing 10% of it because othe cut would also be given to the other Crowe family members and that would be more than any of them would receive.
In "Weight", Duffy receives the call about the stolen heroin from Boyd and informs Picker. Picker believes that Boyd and the Crowes are a problem, telling Duffy that he doesn't understand his fascination with Boyd and that he needs to think about who he'd rather work with: Boyd, who will get him killed or Picker, who will get him rich. Duffy later meets with an associate, Katherine Hale, and needs her help with an assessment on the "Detroit rock and the shitkicker hard place".
In "The Toll", Duffy, Katherine, and Picker meet with Boyd, with Katherine telling him that Duffy wants a reason that he shouldn't kill him over the missing heroin before they are all detained by the US Marshals. Once the meeting is resumed, Boyd offers Duffy his half of the heroin shipment as compensation. While Katherine and Duffy talk in another room, Boyd pulls out a pack of cigarettes, tapping the side of the pack before throwing it to Picker. The cigarette pack detonates within seconds of Picker catching it, immediately killing him due to the pack containing emulex explosive. Boyd gut punches Mike and takes his gun and points it at Duffy and Katherine, claiming that his offer still stands before leaving out the door.
In "Starvation", Duffy meets with Alberto Ruiz in his motorcoach, where he lies and claims that he executed Boyd, but Alberto says that his boss, Yoon, is going to want Boyd's skin as proof. Duffy also offers to help them out by delivering Daryl. Raylan, Rachel Brooks and Tim then show up, hoping to get Duffy and Boyd's cooperation with catching Daryl. Boyd speaks on his and Duffy's behalf, saying that they refuse to help the Marshals, who in turn impound the motorcoach, leaving Duffy angered. Duffy and Boyd then go to the hotel room where Mike has been brutally beaten by Daryl and confesses that he told that Jimmy Tolan and Carl were in possession of the heroin. Boyd proposes to deal with the Daryl problem by having both the Marshals and the cartel go to the old barn in Loyal, allowing the two sides to fight over who wants Daryl more, to which Duffy agrees to.
In "Restitution", Boyd meets with Duffy and Katherine in his motorcoach, saying that he is out of the heroin business. Katherine reveals that while Boyd is sloppy at the heroin business, he is a skilled bank robber, possibly implying that both Duffy and Katherine want to use Boyd's skill set in other areas.
In "Cash Game", he is seen in the hotel room with Katherine as she chastises Boyd for not finding Calhoun Schrier's money but rather a ledger and documents, and accuses him of stealing the money himself. Boyd angrily tells her and Duffy that he would have ran with the money if he was planning to steal it and she assures him that Calhoun's money is there. After Boyd leaves, Duffy assures Katherine that he can handle the "hillbilly".
In "The Trash and the Snake", Boyd and Duffy go to visit Lewis Mago, a crackpot safecracker who is supposed to help them find a way to break into the bank vault located at The Portal. Duffy, along with Boyd, end up splattered in blood after Mago accidentally blows himself up when he forgets to remove his own cell phone while attempting to detonate the vault door. Actually the splattering of blood all over Duffy, as other people die around him, is a recurring motif in Justified and has happened on at least three occasions in other seasons.
In "Sounding", Duffy and Mike trail Albert Fekus to a hotel to interrogate him, hoping to find out what really happened with Albert's "crisis of conscience" but he does not give up any information despite being continuously shocked with a cattle prod. Duffy decides that Albert does not know anything and leaves, unaware that Rachel and Tim were watching the interrogation via a hidden camera inside of a smoke alarm.
In "Alive Day", Duffy suggests the possibility that Markham could be playing Katherine and could be the person that snitched on Hale and was asking her to take the target off his back and his sudden proposal adds to that. Katherine says that he will die slowly if she finds out she is being played.
In "Dark as a Dungeon", Duffy shows Katherine a file with evidence that points to Markham being the person that snitched on Grady explaining that Gordon Keith, a henchman of Markham's was picked up while shoplifting vodka and that his primary weapon of choice was a shotgun, which was used to kill Simon Poole and Keith made bail after Grady had been killed in prison.
In "Burned", Art and Raylan visit Duffy in his hotel room in order to talk him into being their second CI in the case against Boyd. Raylan shows Duffy case files which confirm that Duffy was the snitch against Grady and Raylan threatens to expose him to Katherine, causing Duffy to agree to help. Duffy then goes to see Boyd and informs him that Markham is going to move the money and the only chance they have to get it will be during his party but this is all just something that the Marshals wanted him to relay to Boyd. Raylan tells Duffy to tell Boyd that he wants to be a part of the heist and is seen with Boyd in the mine and later emerging from it coughing following the explosion.
In "Trust", Katherine calls Duffy ranting about Boyd's plan to blow up the floor under the bank vault while people were present during the party. Duffy admits that he gave Boyd the impression that Markham was moving the money as he began to get skeptic Katherine was getting second thoughts about the robbery due to Markham proposing to her, causing her to call Duffy a bastard. Duffy helps Boyd and Carl map out the location of where Markham will be taking his money, that way they can intercept and rob him. As Mike and Duffy sit and eat lunch in the motorcoach, Mike has pieced together that Duffy snitched on Grady, recalling from the earlier conversation when Mike had doubts about Duffy's decision to be a CI. Duffy asks Mike if he figured it out all by himself before Mike slams his boss's head onto the table and handcuffs him, removing his weapons and cell phone. Mike calls Katherine and leaves a message for her, preparing to out Duffy as the snitch.
In "Fugitive Number One", Mike sits in the motorcoach and listens to classical music as Duffy bargains with Mike to give him more rights in their partnership such as letting him pick out the music, what to watch on TV and offering to drive the motorcoach himself. Mike punches Duffy when he threatens him for not listening, saying that he admired and looked up to Duffy until finding out that he was a rat and now he has to be exterminated. Katherine goes to visit Duffy and Mike in the motorcoach, asking why he snitched on Grady. Duffy says that he killed Simon Poole because Simon was going to rat him out to Grady and wonders why she even cares what happened to Grady since she is in love with Markham. As she prepares to kill Duffy, Mike intervenes and says that they don't have to kill Duffy but announce that he is a rat and leave him to fend for himself and that if she kills Duffy, he will have to avenge his death because he is Mike's boss. Frustrated, Katherine shoots him and a struggle ensues between the two, resulting in Mike being shot five times throughout his body, but not before delivering a fatal blow to Katherine that crushes her windpipe. Duffy, screaming, witnesses the entire brawl as Mike drops the handcuff key onto Duffy's lap before collapsing to the floor and groaning in pain from the bullet shots, asking for Duffy to hold him as he gurgles his final breaths. After Mike dies, Duffy calls 911 and remarks that he isn't sure where to start when they ask what his emergency is.
In "Collateral", David Vasquez gives Duffy back all of his possessions as Duffy is no longer part of the CI deal and asks Duffy before he leaves if he was the one responsible for killing his former boss Poole, which Duffy responds that he doesn't know anything. Duffy then visits Lorna and pays for a new ID, two guns and a new vehicle, preferably a dog grooming van that he requests be delivered by the next day as he plans on getting out of the Kentucky.
In "The Promise", he appears in a fantasy standing by a car as Ava drives up and is revealed to be one of the three people on a list that Raylan and the Marshals went down as the possible accomplice who helped her flee from Kentucky as Duffy would likely have helped her escape in exchange for the missing $9 million of Markham's cash. Duffy is seen at a roadblock with his dog grooming van that he had requested from Lorna, implying that Duffy was indeed the one responsible for aiding Ava's escape. Raylan remarks that Duffy has since fallen off the Earth but is rumored to be living in Fiji.
- Unnamed Sister
- Emmitt Arnett: Frankfort boss (Seasons 1 - 3), deceased
- Robert Quarles: Frankfort boss (Season 3), dismembered
- Sammy Tonin: Tonin Crime family underboss, deceased
- Theo Tonin: Tonin Crime family boss, in custody
- Billy Mac: Enforcer, deceased
- Fletcher Nix: Enforcer
- Tanner Dodd: Enforcer, deceased
- Gus: Enforcer, deceased
- Teddy: Enforcer
- Mike Cosmatopolis: Bodyguard, deceased
- Sam Porter: Dixie Mafia soldier, deceased
- Delmar Coates: Former client, deceased
- Gary Hawkins: Business partner, deceased
- Doc Stern: Business associate, deceased
- Boyd Crowder: Business associate, friend
- Johnny Crowder: Former criminal associate, deceased
- Ethan Picker: Criminal associate, deceased
- Charles Monroe: Former client, would-be-assassin
- Jimmy: Criminal associate, deceased
- Carl: Criminal associate
- Yoon: Business associate
- Alberto Ruiz: Business associate, deceased
- Katherine Hale: Business advisor, deceased
- "The police are just a janitorial service used to clean up your blood after you've been murdered." (Duffy to Winona Hawkins in "Blowback")
- "Come on Emmitt! Come On! Show me the Benjamin's the homies are always rapping about!” (Duffy to Emmitt in Hatless)
- "It'd be so much easier to just beat a confession out of me, wouldn't it, Raylan?" (Duffy to Raylan Givens in "The Gunfighter")
- "Don't say I didn't warn you." (Duffy to Boyd Crowder after Boyd refuses to kill Quarles in “Measures")
- "Marshal, are you accusing me of being a fake blonde? Because if you need me to prove it to you, I may be inclined to break you over that step ladder, ride you down like a teaser pony, and paint this room a whole different color." (Duffy to Givens in "Watching the Detectives")
- "Are you smoking oxy in my motor coach?" (Duffy to Quarles disappointedly)
- "I'm Sorry but he escaped from a disease ridden whore factory up in Inbred Holler! (Duffy to Boyd Crowder after hearing that Quarles has escaped in "Coalition")
- "Jesus Christ!" (A frightened Wynn to Raylan as he plays a game of Harlan Roulette, demanding to know where Quarles is. "Slaughterhouse")
- "I hope he's not your interior decorator." (Duffy to Boyd Crowder after seeing Danny tied up in Where's Waldo?))
- "I'm Sorry about the Mess." ((Duffy to Boyd after shooting Danny in the head in Where's Waldo?))
- "But I don't even trust the way just now said I could trust you." (Duffy to Boyd Crowder in Where's Waldo?)
- "Do you see any cats?" (Duffy to Nick Augustine's bodyguard in "Kin")
- "I had a Yorkie growin up". (Wynn to Raylan in The Hatchet Tour)
- "My people know Harlan County about as well as they know Juneau, Alaska." (Wynn to Johnny Crowder in "Get Drew")
- "You can stay. I don't know how I'll survive without you, but I'll try to get by." (Wynn to Mike Cosmatopolis in "Get Drew"
- "I didn't take you for a tennis fan Mr. Crowder,But the only reason I could see you calling at this hour is discuss Azeranka's last match". (Duffy to Boyd Crowder on the phone in A Murder of Crowes)
- "Is that a bb gun? (Wynn to Jimmy in Good Intentions)
- "The more you pump the harder it shoots?" (Wynn Duffy to Jimmy in Good Intentions)
- "Ear". (Duffy to Cyrus while shooting at him with a bb gun in Good Intentions)
- “No I want you to get behind the wheel & see if we can outrun him.” (Duffy to Mike Cosmatopolis in Good Intentions)
- “Mikey's a stone killer why do you think I keep him around.” (Duffy to Raylan in Good Intentions)
- "Does anybody mind if I order?" (Duffy to Elias Marcos, Art Mullen and Picker in "Shot All to Hell")
- "FYI, That's kind of a thing with these marshall.” (Duffy to Elias Marcos & Picker in "Shot All to Hell)
- "Could you send up another pot of coffee, please? Because this one tastes like my ass on Sunday." (Duffy to room service in "Wrong Roads")
- "Swanky? Paris is swanky, Lexington's pig shit." (Duffy to Raylan in "Starvation")
- "It's Okay Mikey, I know you thought hard." (Duffy to a bruised up Mike Cosmatopolis in Starvation)
- "Be a Peach Mikey." (Duffy to Mike Cosmatopolis in Restitution)
- "Mikey once again, talking while I'm in here can lead to unevenness in my facial tone!” (Duffy to Mike in Noblesse Oblige while in a tanning bed)
- "I'm Rehydrating" (Duffy to Kathrine Hale in Noblesse Oblige)
- "So you're out right? Let's just set aside all this poetic, down home, hillbilly bullshit. Bottom line is you're backing down". (Wynn Duffy to Boyd Crowder in Noblesse Oblige)
- "Hence mercenaries guarding a pizza place full of dough. Did you see what I did there?" (Duffy to Boyd Crowder in The Trash and the Snake)
- "F.Y.I., my guy's a handful, irritating. His brain's fried from who knows what kind of drugs. You're gonna want to punch him, but he's very good. I'm saying... have fun with it." (Duffy to Boyd Crowder in The Trash and the Snake)
- "I'm pretty sure 'aplex' isn't a word, Mikey.." (Duffy to Mike in Sounding while playing Scrabble)
- "Raylan Givens, Boyd Crowder, and Avery Markham are soon to converge, Mr. Vasquez, like the aligning of the planets if those planets carried guns and hated my guts. I don't ever plan on returning to Kentucky." (Duffy to David Vasquez in "Collateral")
- Duffy was originally supposed to die in the first season episode "Hatless" by being shot in the head, but this was changed to him being shot in the stomach and Duffy stayed on in a recurring role throughout the series before being upgraded as a main cast member for the final two seasons. Duffy was supposed to die again in the episode "Full Commitment" but the script was changed because actor Timothy Olyphant did not like the scene so they changed it.
|Season one appearances|
|Fire in the Hole||Riverbrook||Fixer||Long in the Tooth||The Lord of War and Thunder|
|The Collection||Blind Spot||Blowback||Hatless||The Hammer|
|Veterans||Fathers and Sons||Bulletville|
|Season two appearances|
|The Moonshine War||The Life Inside||The I of the Storm||For Blood or Money||Cottonmouth|
|Blaze of Glory||Save My Love||The Spoil||Brother's Keeper||Debts and Accounts|
|Full Commitment||Reckoning||Bloody Harlan|
|Season three appearances|
|The Gunfighter||Cut Ties||Harlan Roulette||The Devil You Know||Thick as Mud|
|When the Guns Come Out||The Man Behind The Curtain||Watching the Detectives||Loose Ends||Guy Walks Into a Bar|
|Season four appearances|
|Hole in the Wall||Where's Waldo?||Truth and Consequences||This Bird Has Flown||Kin|
|Foot Chase||Money Trap||Outlaw||The Hatchet Tour||Get Drew|
|Decoy||Peace of Mind||Ghosts|
|Season five appearances|
|A Murder of Crowes||The Kids Aren't All Right||Good Intentions||Over the Mountain||Shot All to Hell|
|Kill the Messenger||Raw Deal||Whistle Past the Graveyard||Wrong Roads||Weight|
|Season six appearances|
|Fate's Right Hand||Cash Game||Noblesse Oblige||The Trash and the Snake||Sounding|
|Alive Day||The Hunt||Dark as a Dungeon||Burned||Trust|
|Fugitive Number One||Collateral||The Promise|