'Breaking Bad': Walter White's evolution

Walter White (Bryan Cranston) teaches chemistry class in the pilot episode of "Breaking Bad."

Walter White (Bryan Cranston) launders money in the pilot episode of "Breaking Bad."

Walter White (Bryan Cranston) next to the Winnebago he uses as a mobile meth lab in the pilot episode of "Breaking Bad."

Walter White (Bryan Cranston) his wife Skyler White (Anna Gunn) Walt's chemotherapy treatment during the first season of "Breaking Bad."

Walter White (Bryan Cranston) sports a Bollman 1940s pork pie hat in a scene from the second season of "Breaking Bad."

Drug dealer Tuco Salamanca (Raymond Cruz), left, stares down Jesse Pinkman (Aaron Paul) while Walter White (Bryan Cranston) looks on during the second season of "Breaking Bad."

Jane Margolis (Krysten Ritter) and Jesse Pinkman (Aaron Paul) in a scene from season two of "Breaking Bad."

Walter White (Bryan Cranston) holds daughter Holly while hiding money behind insulation in a scene from season two of "Breaking Bad."

Tio Salamanca (Mark Margolis), from left, Daniel Moncada (Marco Salamanca) and Luis Moncada (Marco Salamanca) in a scene from the third season of "Breaking Bad."

Hank Schrader (Dean Norris), top, and Jesse Pinkman (Aaron Paul) in a scene from the third season of "Breaking Bad."

Walter White (Bryan Cranston), left, and drug kingpin Gus Fring (Giancarlo Esposito) in a scene from the third season of "Breaking Bad."

From left, Jesse Pinkman (Aaron Paul), Mike Ehrmantraut (Jonathan Banks), Walter White (Bryan Cranston) and Gustavo "Gus" Fring (Giancarlo Esposito) during season four of "Breaking Bad."

Jesse Pinkman (Aaron Paul), left, and Walter White (Bryan Cranston) cook meth during the fifth season of "Breaking Bad."

Todd Alquist (Jesse Plemons), left, and Jesse Pinkman (Aaron Paul) during a heist of meth from a freight train in a scene from the fifth season of "Breaking Bad."

Walter White (Bryan Cranston) points a gun at Mike Ehrmantraut (Jonathan Bank)s in a scene from the fifth season of "Breaking Bad."

Skyler White (Anna Gunn) looking over a stash of money with husband Walter White (Bryan Cranston) in season five of "Breaking Bad."

Walter White (Bryan Cranston) plans multiple murders with Uncle Jack (Michael Bowen) in a scene from season five of "Breaking Bad."

Declan (Louis Ferreira) is about to be shot by Uncle Jack (Michael Bowen) in a scene from the fifth season of "Breaking Bad."

Henchmen from Uncle Jack's as dig up barrels of cash in a scene from season five of "Breaking Bad."

Hank Schrader (Dean Norris) foreground and Steven Gomez (Steven Michael Quezada) in a scene from season five of "Breaking Bad."

Skyler White (Anna Gunn) reacts after her daughter Holly is abducted by husband Walter White in a scene from the fifth season of "Breaking Bad."

Walter White (Bryan Cranston) after he abducted his daughter Holly in a scene from season five of "Breaking Bad."

Ed, a fixer portrayed by Robert Forster, administers medicine to Walter White (Bryan Cranston) in a scene from the fifth season of "Breaking Bad."

Walter White (Bryan Cranston) hides out in the woods of New Hampshire in a scene from season five of "Breaking Bad."

Walter White (Bryan Cranston) in a scene from the series finale of "Breaking Bad."