Margaret "Peggy" Olson (born May 25, 1939) is a fictional character in the AMC television series Mad Men, and is portrayed by actress Elisabeth Moss. Initially, Peggy is secretary to Don Draper (Jon Hamm), creative director of the advertising agency Sterling Cooper. Later, she is promoted to copywriter, the first female writer at the firm since World War II. She later joins Draper when he leaves Sterling Cooper to become a founding member of Sterling Cooper Draper Pryce.