Marianne Faithfull's personal style is so venerated in insider fashion circles that it's said to be one of the primary inspirations behind Kate Moss' entire wardrobe—Faithfull is the OG '60s It Girl, who recorded some incredible songs, dated Mick Jagger and was even somewhat of a muse to the original Yves Saint Laurent. That blend of style and rock substance makes Faithfull the perfect frontwoman for one of Hedi Slimane's campaigns for Saint Laurent, who's past selects have included Curtis Harding, Marilyn Manson and Courtney Love and Christopher Owens. You can barely see what she's wearing in the ad, but that's not even the point: you just know a cool girl when you see one.