Walter Hartwell "Walt" White Sr., also known by his clandestine alias Heisenberg, is a fictional character and the main protagonist of Breaking Bad. He is portrayed by Bryan Cranston. A chemistry honours graduate of the California Institute of Technology, Walt cofounded the company Gray Matter Technologies with his close friend Elliot Schwartz and his then-girlfriend Gretchen. He left Gray Matter abruptly, selling his shares for $5,000;[1][2] soon afterward, the company made a fortune, much of it from his research. Walt subsequently moved to Albuquerque, New Mexico, where he became a high school chemistry teacher. Breaking Bad begins on Walt's 50th birthday, when he is diagnosed with Stage IIIA lung cancer. After this discovery, he resorts to manufacturing methamphetamine and drug dealing to ensure his family's financial security after his death. He is pulled deeper into the illicit drug trade, becoming more and more ruthless as the series progresses, and later adopts the alias "Heisenberg", which becomes recognizable as the kingpin figure in the local drug trade. Series creator Vince Gilligan has described his goal with Walter White as "turning Mr. Chips into Scarface", and deliberately made the character less sympathetic over the course of the series. Walt's evolution from mild-mannered school teacher and family man to ruthless criminal mastermind and murderer is the show's central focus.
Background and personality

Walter White was an only child. Walt's father died of Huntington's disease when he was six years old. He studied chemistry at the California Institute of Technology, where he conducted research on proton radiography that helped a team win a Nobel Prize in Chemistry in 1985.[6][1] After graduate school, Walt founded the firm Gray Matter Technologies with Elliott Schwartz (Adam Godley), his former classmate and close friend.[7] Around this time, Walt dated his lab assistant, Gretchen (Jessica Hecht). He left both Gretchen and Gray Matter Technologies, selling his financial interest in the company for $5,000.[1][2] Gretchen and Elliott later married and made a fortune, much of it from Walt's research.[2][8] Though they remain friendly, Walt secretly resents both Gretchen and Elliott for profiting from his work.[8][9]

At the age of 50, Walt works as a high school chemistry teacher in Albuquerque, New Mexico, providing instruction to uninterested and disrespectful students.[6][10] The job pays so poorly that Walt is forced to take another job at a local car wash to supplement his income, which proves to be particularly humiliating when he has to clean the cars of his own students.[11] Walt and his wife Skyler (Anna Gunn) have a teenage son named Walter Jr. (RJ Mitte), who has cerebral palsy. Skyler is also pregnant with their second child, Holly, who is born at the end of season two.[12] Walt's other family includes Skyler's sister, Marie Schrader (Betsy Brandt); her husband, Hank (Dean Norris), who is a DEA agent; and his mother, who is never seen.[13]
Appearances
Season 1

On Walt's 50th birthday, during his surprise party, he watches a news report about Hank's arrest of some methamphetamine drug dealers. Walt is impressed by the monetary returns from the meth operation, and Hank offers to take him as a ride-along to a DEA bust. The next day, Walt faints at the car wash and is taken to a hospital; there, he is told he has inoperable lung cancer and will likely die in two years. During the ride-along, Hank busts a crystal meth ring; Walt sees one of his former students, Jesse Pinkman (Aaron Paul), fleeing the scene, and deduces that Jesse is part of the operation. Looking to secure his family's well-being by producing and selling meth, Walt tracks Jesse down and blackmails him into setting up an operation. Walt gives Jesse his life savings to buy an RV that they can use as a rolling meth lab.

Jesse brings in two associates, Domingo "Krazy-8" Molina (Max Arciniega) and Emilio Koyama (John Koyama), to distribute the meth, but they recognize Walt from Hank's bust and try to kill him. Walt improvises a batch of red phosphorus that kills Emilio and incapacitates Krazy-8. Walt and Jesse chain Krazy-8 up in Jesse's house, planning to kill him. Walt decides to let Krazy-8 go after getting to know him, but is ultimately forced to strangle him to death with a bike lock after discovering that Krazy-8 was planning to stab him with a broken piece of plate.

As they make larger batches of meth, Walt and Jesse start using unregulated chemicals including methylamine, which tints their meth blue, a signature of Walt's product. Walt eventually tells his family about his cancer diagnosis, and they urge him to undergo expensive chemotherapy using money offered by Gretchen and Elliot. Walt secretly refuses the money, using his drug earnings to pay for treatment. The chemotherapy causes him to lose his hair, and he shaves his head and adopts the street name "Heisenberg", based on the theoretical physicist Werner Heisenberg,[14] which he uses when he interacts with drug dealers. By the end of the season, Walt and Jesse go into business with local drug lord Tuco Salamanca (Raymond Cruz). The partnership is unstable, but after Walt and Jesse deliver their first batch of meth, Tuco intimidates the pair by senselessly beating one of his own men, No-Doze (played by Cesar Garcia), to death in front of them.
Season 2

Walt's "blue meth" becomes incredibly popular, to the point that Hank takes notice. Meanwhile, a paranoid Tuco kidnaps Walt and Jesse. They manage to escape, however, and Tuco is killed in a gunfight with Hank. Walt explains his disappearance by claiming that he had gone into a fugue state as a result of his cancer medication and simply wandered off.

Walt hires unscrupulous criminal attorney Saul Goodman (Bob Odenkirk) to cover his involvement in the drug trade and launder his drug money. At Saul's suggestion, Walt approaches meth kingpin Gus Fring (Giancarlo Esposito) and offers to work for him. Gus is reluctant after meeting Jesse, who is now using heroin with his girlfriend Jane Margolis (Krysten Ritter). Walt refuses to give Jesse his share of their drug money, but Jane blackmails him. After talking to a stranger at a bar about family – not knowing that the man is Jane's father Donald (John de Lancie) – Walt goes to Jesse's apartment and finds Jane and Jesse passed out in a heroin stupor. Walt accidentally turns Jane over and causes her to choke on her own vomit, but he does nothing to save her and watches her die. Walt has Saul clear any connection Jesse has to Jane's death, and convinces Jesse to enter rehab.

Meanwhile, with his cancer in remission, Walt undergoes an operation to remove the remaining cancerous growth. Walt's anesthesia-induced references to a "second cell phone" – the one he uses to deal drugs – makes Skyler suspicious, leading her to uncover many of his lies and leave with their children. Just after her departure, two passenger planes collide directly above Walt's house; the accident was caused by Donald, who works as an air traffic controller and was so overcome with grief that he was not paying attention to his work. Walt watches the accident in horror, unaware that he is indirectly responsible for it.
Season 3

When Skyler demands to know what Walt has been hiding, he admits that he has been cooking meth. Horrified, Skyler asks for a divorce in return for her silence, and demands that Walt move out. She ultimately comes to uneasily accept the situation and helps Walt launder his drug money, but refuses to have anything to do with him outside of business. The rift in their marriage worsens when Skyler sleeps with her boss, Ted Beneke (Christopher Cousins). Walt tries to get back at her by making a pass at the principal at his school, who puts him on indefinite suspension.

Needing money, Walt takes Gus up on an offer to produce meth in a state-of-the-art laboratory hidden under an industria