The office of Harlan County Sheriff on Justified has been held by five different people throughought the course of the show, and has been used to further the interests of different criminals and their orginazations from time to time.
Hunter Mosley is the first Harlan sheriff in the show. He is first seen investigating the dispute between Arlo Givens and his tenant Stan Perkins. Stan Perkins is eventually arrested and Arlo is given fair warning. He is later seen investigating who shot up Ava Crowder's house and questions Johnny Crowder about the shooting. It is later revealed to be part of the shooting and kills Mr. Duke and kidnaps Raylan and Ava to please his friends in Miami. He is eventully caught and all his cases are reopened because of his corruption, and Bo Crowder is released due to this and Hunter remains incarcerated to this day
After the incarceration of Hunter Mosley following the events of "Blind Spot", Kelly Davis becomes the new Sheriff. She is seen outside the VFW bar where a young war Veteran named Lucky is inside with a grenade in his hand, along with Raylan Givens father, Arlo. Kelly is bitter towards Raylan for incarcerating Hunter, who she views as a good man despite being in the back pocket of the Miami cartel. Unlike the other four Harlan sheriffs Mosely, Shelby Parlow, Tillman Napier and Nick Mooney, she is the only one with no affiliation with a criminal organization.
Tillman Napier is the third Harlan sheriff in the show, and succeeds former Sheriff Kelly Davis. Tillman is bribed by Robert Quarles to look the other way when he makes a play to take over the Oxy business, and to also take care of Boyd Crowder. Tillman does this by having Tanner Dodd plant a bomb underneath his car, and detonate it when he leaves it to go back in his office. Boyd is framed and arrested for an attempt on the Sheriff's life. Tillman runs against Shelby Parlow, who is being backed up by the Crowder organization. Although Tillman wins re-election, the win is stripped from him by county clerk Harvey Jones, when it turns out that Hanna Napier, Tillman's sister, is on his payroll. After being threatened by Boyd, he helps lure Quarles into a trap at Audrey's, where Quarles is tased by Boyd and chained to the bed.
After losing his job as Sheriff, he begins to host swinger parties in Clover Hill. Boyd Crowder infiltrates one of the parties when Arnold (who is blackmailed by Ava Crowder) persuades Tillman to invite him and Ava. He re-appears in the episode "Money Trap" in the fourth season, where he exchanges barbs with Boyd, saying that he is as welcome to the party as a case of the clap.
Shelby Parlow is the fourth Harlan County Sheriff in Justified. Before his stint as a Sheriff, he was the security agent at Black Pike Mining. During a heist led by Kyle Easterly, the plan was to kill Shelby and make it seem like he had accidentally blew himself up in the mines while running off with the money robbed from the company. However, Boyd Crowder, one of the accomplices, learned he was supposed to be killed as well as turned the tables on Easterly, Marcus, and Pruitt (the other accomplices) by switching the charges out of the detonators.
Boyd backs Shelby for running in the election for Sheriff against Tillman Napier (who is backed by Robert Quarles). Shelby loses the election to Tillman, but his victory is short-lived when county clerk Harvey Jones reveals that Hanna Napier, Tillman's sister, is on his payroll and because of this, it nullifies his win. His first day as Sheriff, he warns Boyd that there is a warrant out for his arrest for the murder of Devil, and that Ava's house is surrounded by police officers. Shelby feels that warning Boyd makes them "square".
In Season 4, Shelby tries to sever all ties he has with Boyd so that he can be a more law-abiding Sheriff. However, much to his chagrin, Boyd asks him for several favors involving St. Cyr siblings Billy and Cassie. Shelby also saves Ellen May when she is going to be executed by Colton Rhodes, and hides her in his office for protection, asking for her assistance in bringing down Boyd.
Shelby is eventually arrested by the Marshalls and secure him a deal that protects him and Ellen May and is striped of his job as Sheriff.
Nick Mooney is the fifth Harlan County Sheriff in Justified, replacing Shelby Parlow as he is released into WitSec after it is revealed that he is notorious fugitive Drew Thompson. Mooney had also previously worked under Parlow, Tillman Napier, and former corrupt chief of police Doyle Bennett (who Mooney wanted to replace after the Bennetts sold out to Black Pike Mining). Mooney is also shown to be corrupt as well, as he helps Napier plant drugs in Shelby's truck to make him lose the upcoming election for Sheriff. Mooney has a strong resentment towards Boyd Crowder. In Season 5, Mooney tries to have Boyd arrested by having Mara Paxton identify Boyd as Lee's assailant, but she refuses to do so as she had been previously bribed by Boyd. Mooney receives orders to kill Boyd from Lee, but Boyd and Mara threaten him to tell Lee that Boyd is dead and in exchange, Boyd will give Mooney the money that was promised to Lee. Mooney conspires with Boyd, bringing Lee a severed hand with duplicated tattoos that resemble Boyd's. Mooney then calls Lee after an anonymous tip told them that they would find several dead bodies (Detroit representatives killed by Boyd) in one of Lee's funeral homes, and that they also said Lee was conspiring with a local criminal element. Mooney meets with Boyd and Mara in a diner, requesting his money. Boyd departs for the bathroom, and Hayes Workman enters the diner, shooting Mooney to death. It turns out earlier that Boyd had paid Workman off to kill Mooney with the money he was supposed to receive, as Workman was dying of black lung from his mining days and wanted inheritance to leave to his family. Mooney is the first Harlan sheriff to be killed in the series.