- "Don't skimp on family, that's what I always say."
- ―Jack negotiating with Walt
Jack Welker was the leader of a White Supremacist Gang. His nephew Todd Alquist was an associate of drug distributor Walter White. At Walt's behest, Jack arranged the murder of ten prison inmates, and later personally took part in the murder of Declan and his associates at the instruction of Lydia Rodarte-Quayle. His gang later shoots and kills Steven Gomez during an intense gunfight and minutes later Jack personally murders Hank Schrader with a gunshot to the head. He is ultimately killed in the same manner by Walt. Because of his actions later on in Season 5, he becomes the final antagonist of the series.
Jack is first mentioned following the death of Drew Sharp at Todd's hands. While defending his actions, Todd mentions that his uncle has "hookups in prison who I think could be a real help to us". Mike later confirms this to be true based on the background check he did on him, but mentions that it doesn't worry him and says that the kid is "just flexing".
Following Mike's death as well as Jesse's exit from the meth business, Todd brings Walter White to meet with Jack, his number two Kenny and Frankie in a motel room. White offers to pay Jack's gang to murder ten prison inmates who he fears might testify against him. Jack is skeptical of the parameters White gives him, believing that co-ordinating all ten murders across three facilities within a two minute window is too complicated. Walter insists on his requirements and Jack acquiesces. The murders go smoothly, with nine inmates shanked and one, Dennis Markowski, burnt alive in his cell. ("Gliding Over All").
Months later, Jack associates himself with Lydia Rodarte-Quayle in order to help recuperate his nephew's role as her main cook. After Declan, a drug kingpin in Arizona, refuses to hire Todd back on Lydia's suggestion, Jack, along with his men and Todd himself, ambush Declan and his men in a shootout. Jack shoots a wounded Declan in the head and then commands his men to take all of Declan's lab equipment. ("Buried").
After the successful heisting of the lab equipment and methylamine, Jack and Kenny listen to Todd's recounting of the train heist he participated in to get the methylamine. Afterwards, Jack and his crew drive the chemical back from Arizona into New Mexico. ("Confessions").
Jack is present when Todd makes his first solo cook and is nonplussed by Lydia's claims that the purity and blue need to be present in the meth. Later, when Walter White tries to put a hit on Jesse through Todd and Jack, Jack asks Walt for the particulars of the contract, and then agrees, but on the condition that Walt will cook for them. Despite his efforts to triple Jack's fee, Walt reluctantly agrees, when it becomes clear Jack is not interested in money.
Later, Walter is tricked by Jesse Pinkman into driving out the desert spot where he buried his money; seeing Jesse driving up, Walt calls Jack for help, saying that he needs Jack and his gang to save him if they want him around to cook for them. Upon seeing that Jesse is with Hank Schrader and Steven Gomez, Walt tells Jack not to come.
However, after Walter's arrest by Hank, Jack, Kenny, Todd and the rest of the gang arrive and get into a Mexican standoff with Hank and Gomez. Jack gives Kenny the nod and the gang opens fire on Hank and Gomez, who fire back. ("To'hajiilee")
Jack's gang ends up killing Gomez and shooting Hank in the leg, crippling him. Hank, his pistol empty, struggles to retrieve Gomez's dropped shotgun by crawling to it. Jack stops him and points a pistol at his head. Walt tries to save Hank's life by telling Jack that he can have the $80 million buried underground nearby. Hank, knowing he will be killed, bravely tells Jack to do what he's got to do and Jack murders Hank.
Jack instructs his gang to dig up the $80 million. He leaves Walt one barrel with about $11 million and takes the rest for himself. As they are about to leave, Walt spots Jesse underneath a car and tells Jack to fulfill his contract to kill Jesse. As Jack is about to pull the trigger of his pistol, Todd stops him, warning Jack that maybe they should try and get as much information out of Jesse as possible about the DEA investigation before finally killing him. Walt agrees and Jack's gang takes Jesse back to their hideout. ("Ozymandias")
Jack's men retrieve Jesse's confession video after breaking into Hank's home. After seeing that Jesse "ratted out" Todd about killing Drew Sharp, Jack goes to kill Jesse in rage. Todd convinces Jack that Jesse was worth more alive in order to produce better Meth for Lydia. Jack laughed this off as Todd having feelings for Lydia and obliged.
After a failed escape attempt and subsequent denial to cook anymore by Jesse, Jack, Todd, and Kenny drive to Andrea's home. Todd shoots Andrea in the back of the head while Jesse watched in the nearby vehicle. Jack told Jesse to calm down after he started to weep and yell, using Brock's continued safety as a tool to keep him cooking and quiet. ("Granite State")
Walter arrived to negotiate with Jack about his new formula to create Meth. Jack said that they could get more methylamine from Lydia now that Madrigal is no longer under investigation. Jack then ordered Kenny to take Walt outside to kill him. After Walt accuses Jack of partnering with Jesse, Jack takes it as an insult that he would partner with a 'rat.' Jack calls Jesse in to show Walt his broken down state and that he was more a slave than a partner.
After Walt's machine-gun trap, Jack was severely wounded and coughing up blood, but alive. Jack grabbed for his cigarette before asking Walt if he wanted his money, and was going to use the money to negotiate his life before Walt shot him in the head mid-sentence, killing him. ("Felina")
- Jack has several tattoos including:
- An SS logo on the right side of his neck
- A swastika with a four-pointed star in the center on the left side of his neck
- A swastika on the back of his right hand, near his thumb
- "SKIN" and "HEAD" on his knuckles
- Welker was the last name of Victor, father-in-law of Hal Wilkerson (who was played by Bryan Cranston) in Malcolm in the Middle.
Murders committed by Jack
- Eight of Declan's men: All shot to death by Jack, Todd and the white supremacist group. ("Buried")
- Declan's Cook: Shot by Jack, Todd and the white supremacist group. ("Buried")
- Declan: Shot in the head, to take over the operation and for refusing to let his nephew cook. ("Buried")
- Steven Gomez: Shot by Jack and the white supremacist group. ("Ozymandias")
- Hank Schrader: Shot in the head. ("Ozymandias")
Murders connected to Jack
- Dan Wachsberger: Stabbed to death by white supremacist group on Walt's orders. ("Gliding Over All")
- Jack McGann: Stabbed to death by white supremacist group on Walt's orders. ("Gliding Over All")
- Andrew Holt: Stabbed to death by white supremacist group on Walt's orders. ("Gliding Over All")
- Anthony Perez: Stabbed to death by white supremacist group on Walt's orders. ("Gliding Over All")
- Isaac Conley: Stabbed to death by white supremacist group on Walt's orders. ("Gliding Over All")
- William Moniz: Stabbed to death by white supremacist group on Walt's orders. ("Gliding Over All")
- Harris Boivin: Stabbed to death by white supremacist group on Walt's orders. ("Gliding Over All")
- Raymond Martinez: Bludgeoned to death by white supremacist group on Walt's orders. ("Gliding Over All")
- Ron Forenall: Stabbed to death by white supremacist group on Walt's orders. ("Gliding Over All")
- Dennis Markowski: Burned to death by white supremacist group on Walt's orders. ("Gliding Over All")
- Andrea Cantillo: Shot dead by Todd due to Jesse Pinkman's refusal to cook meth with him and his attempted escape from the white supremacist compound. ("Granite State")