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 III-A 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 Hei