Billie Eilish, Sabato de Sarno, Jessica Chastain and More Toast Gucci’s Vegan Horsebit 1955 Bag

No chauffeur needed — Billie Eilish drove herself to the Gucci party in her honor Friday night in L.A., pulling up to the plant-based restaurant Nic’s on Beverly in her matte black Dodge Challenger.

A lifelong animal rights activist, Eilish is the face of Gucci’s new Horsebit 1955 bag made using Demetra, a vegan alternative to leather. She arrived proudly carrying the monogram version of the asymmetrical bag, pairing it with a sheer monogram top, Gucci headscarf, glasses, jeans and her vegan Air Force 1 sneakers by Nike, another brand she’s changing with her next-gen activism.

“It’s been a process and we’re really happy with the results. Leather is unnecessary,” she said of the milestone for the heritage leather goods brand’s sustainability efforts, given the carbon impact of animal products. Two years ago, Gucci introduced sneakers made of Demetra, and the brand turned to Eilish to front images and videos to unveil its first bag in the animal-free material.

“It’s amazing,” said Jessica Chastain, proffering her black Demetra bag for a pet (shiny and substantial, the material containing upward of 77 percent plant-based raw materials as well as bio-based polyurethane from renewable sources, does have a luxury feel).

The cocktail party was held on the eve of the Gucci-sponsored LACMA Art + Film gala, which will mark the Hollywood coming-out for Gucci’s new creative director Sabato De Sarno.

“It’s a big moment..No pressure!” he laughed when asked about the event, during which he will be debuting his first eveningwear on some of the world’s biggest stars.

De Sarno has spent the week getting to know some of them, including Miley Cyrus, hiking with her to the Hollywood sign to shoot the next Gucci fragrance campaign.

“My first time here with my husband about nine years ago, I hated L.A. because I was looking for a square, a center like a European city. But then I really fell in love. Now we love to do the touristy things. This morning I went to Venice and rented a bike. It was nice,” he said.

“He’s so talented,” said Julia Garner, mingling at the cocktail party with Maude and Iris Apatow, Elliot Page, Jodie Turner Smith, Daisy Edgar Jones, Gucci chief brand officer Alessio Vannetti and Gucci president and chief executive officer Jean-Francois Palus.

“Her look for the gala we knew at the show,” said stylist Elizabeth Saltzman, with her client Jodie Comer. “I didn’t know there was going to be a war, but the look is perfect. I just couldn’t go all out, you feel stupid,” she said of the tense and turbulent times against the backdrop of the Israel-Hamas war.

“I don’t think it’s about wearing black, that’s not going to solve anything. I just don’t think you want to post a thousand selfies out of respect. But this is an artists’ dinner and until we can’t, we will.”

The new Gucci campaign conceived by De Sarno and photographed by Tyrell Hampton features the song “What Was I Made For?” by Eilish, a vegan since she was 12 and a longtime advocate for animal protection, pushing for designers and brands to stop using leather and fur.

At the end of August in London, the singer spoke at the second edition of Overheated, a climate activism event presented by the nonprofit organization Support + Feed. She talked about her support for thrifting and other methods of sustainable shopping.

To further amplify its sustainability commitments, Gucci made an undisclosed donation to Support + Feed, which was founded in L.A. by Eilish’s mom, Maggie Baird, to create an equitable, plant-based food system and combat food insecurity.

The Oscar and Grammy-winning Eilish has represented Gucci on several red carpets, including wearing a Regency-inspired upcycled ivory and duchesse satin corseted dress to the Met Gala last year, and a monogrammed sleep mask and blanket to last year’s LACMA Art + Film Gala. She has also fronted a campaign promoting Gucci’s eyewear collections.