(also known by his clandestine alias

) is a fictional character and the main protagonist of

, portrayed by

. A graduate of the

, Walt was once a promising

who cofounded the company Gray Matter Technologies. He left Gray Matter abruptly, selling his shares for $5,000; soon afterward, the company made a fortune of roughly $2.16 billion, much of it from his research. Walt subsequently moved to

, where he became a high school chemistry teacher. After being diagnosed with Stage IIIA

, he resorts to manufacturing

and drug dealing to ensure his family's financial security after his death. Series creator

has described his goal with Walter White as "turning

into

", and deliberately made the character less sympathetic over the course of the series. Walt's transition from mild-mannered school teacher and family man to ruthless criminal mastermind and murderer is the show's central focus.