Rachel Zoe is the hottest of the current crop of star stylists thanks to her successful transformations of Lohan and Richie. Under Zoe's hand, Lohan has morphed from an unremarkable teen with a penchant for ripped jeans and tartan skirts to a celebrated fashion icon and covergirl du jour who owns a wardrobe bursting with Gucci, Versace and Chanel.

Now that she looks the part in slinky jersey dresses with plunging necklines and flowing tresses, the 20-year-old star of teen movies such as Mean Girls and Herbie Fully Loaded has made the smooth transition into the adult Hollywood A-list. In her latest role she stars alongside Meryl Streep in A Prairie Home Companion, the new Robert Altman film.

Before Zoe came into her life, Richie was known for little more than being Paris Hilton's frumpy best friend-turned-ex-best-friend. Says Halfpenny: "When Nicole first met Rachel she was wearing velour tracksuits and pink ugh boots. Now she's an elegant clotheshorse, which has spring-boarded her career. She's an author now, a singer and she is in demand to kick on her TV career after she finishes The Simple Life."

Zoe's own career has undergone a similar transformation. "Five years ago she was just grabbing bags of clothes from shops around LA," Halfpenny says. "Now she's living the life of a star, she's photographed on the red carpet, she earns $US6000 ($7800) a day and the look she pioneered - the floor-length clingy dresses, oversized accessories, the skinny figure - is everywhere."

Zoe isn't the only star stylist making a name for herself. Duo Estee Stanley and Cristina Ehrlich are bringing classic Hollywood glamour - their signature - to stars such as Demi Moore and Penelope Cruz and have helped teens Mandy Moore and the Olsen twins manage their public transitions into adulthood.

The music world is being glammed up by star stylist Andrea Lieberman, who was responsible for the plunging, green Versace frock Jennifer Lopez wore to the Grammys in 2000. Lieberman's ethnic-inspired, rock-star boho look has also helped shaped Gwen Stefani's image.

"The power of these stylists lies in their connection to the celebrities," Vassallo says. "Designers understand the massive publicity and branding value of working with celebrities. And they know it's the stylists they have to get past first."