Celebrities’ fascination with Halloween is well-documented, but their creative costumes wouldn’t be possible without a team behind the scenes. Stars aren’t heading over to Party City in search of a good get up, instead they’re enlisting the talents of designers who specialize in bringing their most elaborate requests to life. This year, designers Bryan Hearns, Alejandro Peraza of Alejandro Collection, and Laura Pulice of Vex Latex were responsible for several of the holiday’s most talked-about outfits. Whether they were transforming Kim Kardashian West into Tiger King star Carole Baskin or creating a 2020 version of the genie Christina Aguilera sang about, the group delivered surreal transformations and outside the box ideas.

Here, they guide Vogue through the thought process behind some of those impressive Halloween fashions.

Kim Kardashian West as Carole Baskin by Alejandro Couture

To Instagram viewers, Kim Kardashian West’s Carole Baskin costume looked straightforward, but for Alejandro Collection designer Alejandro Peraza, replicating Carole Baskin’s signature cat-themed look was a painstaking process. Intent on creating a chic outfit despite the source material, Peraza went the extra mile. “The creation of Kim K, Jonathan, and the kids’ costumes was tedious,” he admits. “We searched for the perfect fabrications, trims, and fur to create the elevated version of the Tiger King phenom.” Recreating Baskin’s flower crown required real blooms fresh from the florist, while her leopard spots and denim were updated with luxe fabrics and crystal detailing. “We draped the blouse perfectly in a beautiful satin charmeuse, but wanted to make it look casual and effortless,” says Peraza “The jeans were customized and embellished by hand to resemble Carole’s.”

No Tiger King tribute would be complete without big cats, and Kardashian West brought her children into the fun with costumes and face paint. North, Saint, and Chicago’s pint-sized playsuits were given a kid-friendly touch thanks to plush faux pelts. “We selected the perfect lightweight fur for the four kids to wear and play around in as we knew they would,” says Peraza. “We even stuffed the tails to give a realistic movement and flair.”

As Joe Exotic, Cheban transformed into the series’s titular antihero with a mullet wig and fake mustache. Exotic’s sequin- and pattern-heavy wardrobe is a far cry from Cheban’s usual attire, but Peraza created the illusion by using a tricky material to great effect. “We created a replica of the dress shirt in a beaded fabric that broke a dozen needles,” he admits. “But it was worth it in the end. The biggest surprise is that every project comes with a new process or obstacle to face,” says Peraza. “[We are] designing for clients who can have anything their hearts desire and we aim to outdo ourselves each time.”

Hailey Bieber as Nurse Dolly and Christina Aguilera as a Devil, Alien Serpent, and Genie, by Vex Latex

Hailey Bieber’s tribute to Netflix’s Ratched took a different tack. Rather than emulate Sarah Paulson’s villainous nurse, Bieber wanted to play Dolly, the series’s resident nymphomaniac who (spoiler alert) is involved in some grizzly goings-on at the Lucia State Hospital. This meant her costume needed to be spooky yet sultry to capture the character’s vibe. Vex’s Laura Pulice worked with stylist Maeve Rielly to get things just right. “They wanted a super sexy version of Nurse Dolly,” says Pulice, noting that the pastel tones of the retro costumes were tricky to replicate in the latex. “The uniforms on the show are vibrant blue, so we wanted as close of a match as possible.” The challenge of getting it just right was part of the fun. “Halloween costumes are always so much fun; you can be as off the wall crazy and creative as you want!,” says Police. “Nothing surprises me anymore! I’ve made some crazy things for people in the past that it’s tough to shock me!”

Pulice might be hard to shock, but Christina Aguilera’s devilish transformations almost did it. The pop star, who transformed her backyard into a scene straight out of Tim Burton’s A Nightmare Before Christmas ahead of the holiday, wanted not one but three separate outfits. “They wanted a devil, an alien serpent look, and a playful variation of a genie,” says Pulice. “ Her stylist had a pretty good idea of how they wanted her costumes to look [in order] to stay true to her overall aesthetic.” Still, differentiating the familiar concepts from what existed on the market required careful design choices and input from the star herself who immortalized them in a special photo shoot. “While these are go-to Halloween costumes for the masses, Christina is always wants to add her personal touch to how she looks, which definitely comes through here,” says Pulice. “ Leading up to the night, we weren’t sure which she would wear, but were pleasantly surprised that she made all three work! The photos were incredible and captured all the fun and wonder that Halloween brings.”

Kendall and Kylie Jenner as Kendall and Kylie Jenner by Brian Hearns.

Back in 2016, Brian Hearns created his now-infamous X-tina tribute look for Kylie Jenner. A daring version of the bikini and chaps that Christina Aguilera wore in her “Dirrty” video back in 2002, the nostalgic costume became a sensation online. Four years later, Hearns is still collaborating with Jenner, this time on an adult update to outfits she and sister Kendall wore as children. “I enjoy putting my fashion spin on a costume version. I love digging into costume history and see how I can elevate it,” says Hearns of his epic reimaginings. “When I created Kylie as Christina Aguilera, that was an epic favorite because it was a classic throwback, and everyone went crazy for the look!”

The considerably more covered-up outfits Hearns made this year resulted from collaboration with the Jenners’s stylist Jill Jacobs. The bob wigs, glittery skirts, and tall boots might seem grownup, but they were worn in homage to the outfits “We recreated these looks based on a family photo but then transformed it into a sexier version,” he says. “I’ve been pleasantly surprised by people still putting in a big effort to dress up, especially for this year. We’ve all had such a crazy year, and it makes me happy to see other people happy letting their hair down and celebrating!”