Walter "Walt" Hartwell White Sr., also known by his clandestine pseudonym "Heisenberg", was a chemist and a former chemistry teacher in Albuquerque, New Mexico, who, after being diagnosed with Stage 3A inoperable lung cancer, started manufacturing crystal methamphetamine to both pay for his treatments and provide for his family in the event of his passing. He is the central character of the series, and is portrayed as a protagonist, antagonist and antihero.