What do Margot Robbie, Michelle Williams, Natalie Portman, Rachel Weisz, Dakota Johnson, Selena Gomez and Sienna Miller have in common? Apart from stellar talent, stunning looks and stratospheric success, they also share stylist Kate Young, making her one of the most in-demand — and influential — celebrity stylists working today.

It’s an achievement Young couldn’t have foreseen back when working as an assistant at Vogue. “Celebrity styling wasn’t a big thing at that point,” says Young, who happened upon it by accident. “I would do these shoots and people would ask if they could borrow the clothes for a premiere or a press tour, and I’d just organize it.

“They kept calling me. At the time I don’t think anybody ever paid me. I didn’t think of it as a career, it was just a side thing. I liked doing it. I tend to like actresses a lot — for the most part, they’re interesting, complicated, smart people.”

The admiration is mutual. “Kate’s super smart and wickedly funny and understands my specific needs and changing body shape around pregnancy and its aftermath,” says Portman, who’s been working with Young for almost 17 years.

Says Weisz, a client of 10 years: “Kate has incredible intelligence and instinct. She takes her work incredibly seriously but she helps you navigate the red carpet with her own brand of humor and irreverence. Her taste is immaculate and a fitting with her is always a hoot.”

By 2010, when Young decided to make celebrity styling the “focus” of her career, her role — and impact — had noticeably shifted.

“People, meaning managers and agents, started to realize that actors who worked with me got big deals and made a lot of money, and Vogue wanted to shoot them,” says Young. “It changed the way people talked to me, from being an afterthought to being included in conversations, like, ‘We want to be strategic with this press tour, this is what we’re trying to achieve, these are our goals, we want you on board.’”

Fashion brands, too, took stock of her work.

“Most of my clients are ambassadors to somebody,” says Young modestly. Shortly after she started working with Gomez, engineering an evolution from Disney star to style muse, the actress/singer became a face of Louis Vuitton, followed by collaborations with Coach.

While still a relative newcomer in Hollywood, Robbie attracted the attention of Calvin Klein, and Johnson, Gucci. Portman has worked with Christian Dior for more than seven years, Williams is a longtime face of Louis Vuitton, while Weisz has fronted campaigns for Bulgari and Burberry.

“Working with Kate is so much fun,” says Robbie, describing how they pick a theme for press tours. “For press tours we usually pick a theme… recently we went with a ’90s theme where we incorporate vintage Versace looks. I wore a butterfly dress that was worn on the cover of Vogue decades ago and a Tiffany cross necklace that Liz Hurley wore in the ’90s. For the ‘I, Tonya’ press tour we’ve used hair accessories like scrunchies and ribbons and lots of sequins and sparkles. Styling always feels like a good time with Kate. She doesn’t take it too seriously, which is why I think a lot of the time her looks pay off.”

Though Young packs an impeccable fashion pedigree — she has her own line of eyewear, Kate Young for Tura; consults for brands including Rosetta Getty, Cushnie et Ochs and Mansur Gavriel; has styled covers for Porter, Glamour and InStyle, campaigns for Dior, Guerlain and Carolina Herrera, and runway shows for Jason Wu, Nina Ricci and Derek Lam; and authored a book, “Dressing for the Dark,” for Assouline — she credits her success to something far less tangible: instinct.

“I think about if I were this girl, in this moment, in her body, and I was wearing this dress, what shoes would I wear with it? How would I wear my hair, how would I stand, what jewelry would I wear? That’s entirely how I do all my work. I close my eyes and pretend I’m them.”

For this very reason, Young admits she often “blows” the first fitting with a new client. “I watched the Golden Globes and I was like, had one fitting with her, had one fitting with her, had one fitting with her,” she says, “because until I meet them and make them try on clothes with me and see the way they move in clothes, and get an empathy with them, I can’t do what I do.”

While empathy might seem a surprising choice of word for such a seemingly glamourous job, Young, a mom of two young boys, says that not all actors relish the red carpet.

“A lot of them really like acting and really hate doing press,” says Young, who’s often a “symbol of a press tour starting — whether they like it or not.” Adds the Brooklynite, “I hope that I make that easier for them — that the clothes make them feel protected, give them a little part to play, or a little suit of armor.”

To wit, Weisz notes, “The red carpet is a fantasy zone. It has nothing to do with your real life or your acting jobs; it’s a make believe zone that lasts a few moments in front of cameras. Kate understands that … and keeps it fun and fresh.”

Says Portman: “Kate has been wonderful in creating a cohesive style that fits my personality and lifestyle so I have more time to focus on other areas of my work.”
Being that “the clothes” remain Young’s core passion, it’s a sartorial win-win. “Coming back the first the week of January for the Golden Globes to an office full of couture and sparkly things makes everything worthwhile,” she says. “I know, I sound so vapid, but it’s true. Sparkly dresses make me happy.”