Peggy Olson

Peggy arrives at Sterling Cooper as Don Draper's new secretary, fresh out of Brooklyn, earnest and a little unpolished in a room built to overlook her. She takes notes, absorbs everything, and quietly wants more than the job she's been given, though she barely knows yet what that would look like.

The show trusts small gestures to carry enormous meaning, and Moss is a master of them — a swallowed reaction, a straightened spine, a smile that costs something. Watching Peggy learn to read the room, then learn to work it, gives Mad Men its clearest, least cynical engine: ambition finding its own language in real time.