There was resistance to Deneuve by the agency that until 1968 had created the No.5 campaigns, since she was by no means a household name and didn't speak English very well. But Helleu's dream ultimately became reality, and the ads in which Deneuve speaks of her intimate relationship with the scent (she says she wears Chanel No.5 behind her knees, for instance) met with rave reviews. The campaign "completely revived Chanel No.5," said Helleu.

In the early days of Deneuve and No.5, celebrity advertising was in its nascent phase. But now it's all the rage. And yet, Chanel continues luring new and faithful clients via models chosen "for certain characteristics, be it beauty or style," said Helleu. "It frequently has happened that after [being in a Chanel No.5 campaign] they become stars."

Cases in point? MacGraw, who was shot while still an assistant to legendary fashion editor Diana Vreeland, and Bergen, before she made it big.

Kidman, however, was already a major star when she was signed on to feature in a mini-film directed by Luhrmann for Chanel No.5. It aired in 2004.

Among those considered the most creative Chanel No.5 campaigns was "Share the Fantasy." Kicked off in 1979 by Scott's "Pool" ad, a surreal spot involving a woman, a plane and a pool, "Share the Fantasy" is the dream-like, post-Deneuve advertising.

"It was rather extraordinary. There were so many accidents in that film," reminisced Helleu. For one, it was a fluke the plane's loops were in sync with the music. "That's what is interesting [in advertising]. You can't have rigidity, storyboards, control."

Indeed, it was this vision that made him unique to work with, collaborators said.

Rather than commanding too much control, which could easily squelch creativity, Helleu gave a few words to inspire a photographer, said Dominique Issermann, who began working with Helleu at Chanel with a fragrance ad featuring Carole Bouquet in 1997. Since then, Issermann has lensed numerous Chanel print campaigns, the most recent of which is the Coco Mademoiselle ad starring Knightley.

"He wanted me to understand what he meant with two or three words," she said. "He wanted you to collaborate with him.