How To Steal A Million (1966)
Audrey Hepburn as Nichole
Hubert de Givenchy

Audrey Hepburn became the long time muse for Hubert de Givenchy after he allowed her to use some of his last season gowns and clothing in the movie Sabrina.  He went on to design her wardrobe for almost all of her films as well as much of her publicity and person clothing.