Gio Reyes is the head of the Miami drug cartel, and the uncle of Pilar and Ernesto. Gio is in charge of shipping a supply of ephedrine for Bo, who is interested in taking over the meth business. When Bo started shaking Gio down he approached Sheriff Hunter to imprison Bo and run the drugs through Harlan at a fraction of the price. That worked until Hunter was caught and Gio was forced to reopen negotiations with Bo. Gio was also Tommy Bucks' boss, the gangster that was shot and killed by Raylan Givens in the pilot episode "Fire in the Hole".
Although not seen until near the end of the first season he repeatedly sends various hitmen to locations involving Raylan. The first time happened in "Long in the Tooth" when a pair of hitmen named Frank and Joe were sent to kill Roland Pike after he is discovered to be in Los Angeles who later try to kill Raylan but end up killed by Raylan. A third hitman who is a sniper managed to kill Roland before he could be compelled to testify. After that he set his sights on Raylan in "Blind Spot" and sent a hitman from Texas named Mr. Duke to kill him and had Hunter Mosley get a spotter for him named Red. This however backfired as Mr. Duke ended up killed by Hunter after Gio gave him clearance to clean up any loose ends and Hunter and Red ended up arrested thereby ending their smooth operation in Harlan forcing Gio to go back into business with Bo.
In "Fathers and Sons", Bo meets up with him in order to make a business transaction: Gio will have Ernesto and Pilar deliver a $2 million supply of ephedrine to Bo and Bo cook the ephedrine into meth and sell it and pay back Gio's $2 million over a period of six months. Gio then threatens Bo with the consequences if he fails, to which Bo rebukes and says he already knows the consequences about what will happen and feels insulted that Gio would ask that. Gio comments to Bo about how Raylan Givens has eliminated Hunter, Mr. Duke, Frank, Joe, and Tommy Bucks and wonders if he could do the same to him. Bo assures him that he can "swallow that asshole with a short glass of water".
In "The Moonshine War", Raylan visits him in Miami after delivering a badly injured Pilar to him. A tense confrontation begins between the two, with Raylan wanting Gio to end the hit called on him, due to innocent people Raylan cares about being caught in the crossfire. Raylan orders Gio to give him his word in 10 seconds or he shoots him in the head. Before Raylan can act, Dan Grant calls and orders Raylan not to try anything. Grant orders the two men to discuss it further outside. Grant tells Gio that if he comes after Raylan again and harms him in any way, that Grant will kill Gio himself.
- Tommy Bucks: Captain, deceased
- Frank: Buttonman, deceased
- Joe: Buttonman, deceased
- Mr. Duke: Buttonman, deceased
- Roland Pike: Business associate, deceased
- Hunter Mosley: Business partner
- Bo Crowder: Business partner, deceased
- Raylan Givens: Deputy U.S. Marshal, target
|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|