Jack Welker is the leader of a White Supremacist gang. His nephew Todd Alquist is an associate of drug distributor Walter White. Jack serves as one of the main antagonist of the second half of season 5 of Breaking Bad.
He was portrayed by Michael Bowen.
Jack first appears when Walt requests he arrange the murder of ten prison inmates, who are witnesses to Walt's involvement with Gus Fring, within a 2 minute window spanning several different prisons. Despite Jack's original skepticism of the plans success, he accomplishes the task.
Later he personally takes part in the murder of current New Mexico meth kingpin, Declan and his associates, at the instruction of Lydia Rodarte-Quayle, so as to make his nephew Todd the sole meth cook and to take over Declan's territory.
He and his gang later get involved in a shootout with federal agents Steven Gomez and Hank Schrader, just as the two agents were about to arrest Walt for his crime, in the middle of the desert. The shootout results in Gomez's death and Hank badly wounded. Despite Walt's pleading for Hank's life Jack brutally executes him with a shot to the head and then proceeds to steal most of Walt's fortune, leaving him only a fraction of what he had accumulated through his vast drug empire. Jack and Todd also take Jesse Pinkman as a slave to cook their meth in their own private lab, they ensure his cooperating by Todd murdering Jesse's old girlfriend in front of him as well as threatening to do the same to her son should he not fully comply. Jack and Todd then threaten Walt's wife Skylar and their youngest child Holly, should she reveal any information about them or Lydia to the police.
Walt eventually emerges from hiding after being the subject of a nation wide manhunt. He contacts Todd and sets up a meeting with Jack and his gang seemingly to discuss business. Once Walt is cleared to drive up to their main clubhouse in their hidden compound, Jack greets him inside and reveals that he intends to kill Walt as he is too much of a liability and of no real use to them. Jack then has Todd bring Jesse into the room to show Walt what he has turned Jesse into, essentially a beaten and broken slave. However unbeknownst to Jack Walt had smuggled in a remote controlled M60 machine gun in the trunk of his car, Walt then proceeds to tackle Jesse to the floor and activated the weapon which quickly mows down Jack and all of his men, except Todd. Jack mortally wounded attempts to crawl away from the carnage, Walt picks up a a pistol from one of the fallen gangsters and aims it at the mortally wounded Jack. Jack attempts to persuade Walt to let him live so he can tell him the location of the rest of his money, but before he can finish his proposition Walt coldly shoots him in the head, executing him the same way he murdered his brother in-law Hank. An enraged Jesse then kills Todd for all the pain he has caused him, which effectively destroys Jack's gang and his whole operation.