When Mad Men returns Sunday, April 13, for the final season, you’ll have many reasons to tune in. Don Draper, Peggy, the music, the affairs, the mysterious Bob Benson, etc. But if you’re into fashion, you only need one reason to tune in and that reason is Joan Harris (yes, we know she’s technically Joan Holloway now but her husband’s a douche so whatever). Granted, all of the fashion on Mad Men is exciting to witness and many of the women are beautiful and beautifully dressed. We love Peggy, we love Megan, and we love Betty, but Joan’s body working its way through Sterling Cooper Draper Price in one of her many fabulous dresses is so distracting it really should be illegal. In Season Two, the men tried to categorize all of the secretaries as either Marilyn Monroes or Jackie Kennedys, but they stopped short when they got to Joan. As Kinsey put it, Marilyn’s really a Joan. Because even she couldn’t work a dress — or a room — quite like Joan. Yeah. We said it. And we offer up the following gallery as scientific proof. And these are 15 essential looks from the eternally flawless Joan Harris.