Walter White

Walter Hartwell "Walt" White Sr., also known by his clandestine pseudonym and business moniker Heisenberg, is a chemist and drug kingpin from Albuquerque, New Mexico. Walt is a former underachieving high school chemistry teacher at J. P. Wynne High School who, after being diagnosed with terminal lung cancer, started manufacturing chemically pure crystal methamphetamine to provide for his family (his wife Skyler, son Walt Jr., and infant daughter Holly) upon his death. Knowing nothing about the drug trade, Walt enlists the aid of his former student, Jesse Pinkman, to sell the meth he produces.
Walt's scientific knowledge and dedication to quality lead him to produce crystal meth that is purer and more potent than any competitors'. To avoid the tedious collection of pseudoephedrine required for production, Walt devises an alternative chemical process utilizing methylamine, giving his product a distinctive blue color. His crystal meth, which is given the street name "Blue Sky," dominates the market, leading to confrontations with established drug makers and dealers. Although Walt and Jesse began as amateur small-time meth cooks, manufacturing the drug out of an RV in the deserts of New Mexico, and being met with very limited success, Walt and Jesse soon climbed up the drug hierarchy, killing or systematically destroying anyone who impeded them.
While initially heavily reluctant to use violence, Walt gradually came to see it as a necessity, and eventually developed into a ruthless drug lord motivated largely by vanity, ego, and greed. He also comes to find his new status as a drug lord psychologically rewarding, leading him to become increasingly willing to resort to criminal acts such as theft, extortion, money laundering, depraved indifference, and murder. Walt's descent into the criminal underworld unearthed immense levels of deeply repressed ambition, rage, resentment, vanity, and an increasing ruthlessness. Walt adopted the moniker "Heisenberg" as an alias as he immersed himself in the drug trade and worked his way up to the international level, becoming a famous and feared drug kingpin, with Walt's drug empire ultimately becoming the largest meth operation in American history.