Possibly one of the most iconic exchanges of dialogue in the series, this scene was arguably among Walt's most important turning points as a character. Until this moment, Breaking Bad had been the story of Walt's almost-methodical and gradual slide into moral darkness; from this moment onward, though, it's clear he's running like a lunatic into depravity. "Let me clue you in. I am the danger, Skyler. A guy opens his door and gets shot, and you think that of me? No. I am the one who knocks" -- with these lines, Walt effectively completes his transformation into Heisenberg.