Sure, you can pick a Kelly Wearstler–designed room out of a decorating lineup and could tell your friends if Estee Stanley, Miles Redd, or Mary McDonald would be their dream designer. But do you know the people who inspired them? These seven interiors icons are the most influential masters of the 20th century—the true founders of the profession today—and they’re the names every lover of design should know.

Elsie de Wolfe

Known as “America’s first decorator,” De Wolfe boasted a lifestyle as glamorous as her decor. Born in New York City in 1865, her history reads not just as one wild romance and adventure novel, but several different ones. In her youth, she was educated in Scotland and was presented at court to Queen Victoria, but soon after returned to the U.S. and became a professional actress. By around 1887 she shared a “Boston marriage” (a term for two single women living together, attributed to Henry James’s The Bostonians) with successful literary agent Elisabeth “Bessie” Marbury. And later in life, she even gained the title of Lady when she married British diplomat Sir Charles Mendl, at the age of 61.

But early on in De Wolfe’s life, it was her onstage style and wardrobe—couture ensembles from Paris—that caught people’s eyes more than her acting chops. She successfully restyled the house on Irving Place that she shared with Marbury, eschewing the stuffy Victorian decorating approach of her day by decluttering, simplifying, and warming up its gloomy and too-busy interiors. That led to a commission to decorate the Colony Club—the city’s first elite social club exclusively for women—which could list members with surnames like Whitney, Morgan, Harriman, and Astor. De Wolfe blazed a trail as she became the most popular decorator of her time, handing out business cards emblazoned with her signature wolf and nosegay motif.

De Wolfe went on to decorate a home she and Marbury bought in Versailles for social gatherings, and took on vast redecorating projects for clients including Condé Nast, the Fricks, and the Hewitts. Her pioneering anti-Victorian style of brighter, airier, and more streamlined and refined rooms than the era dictated is still celebrated today.

Jean-Michel Frank

Artists inevitably take inspiration from the world around them, and it’s hard to imagine a richer environment than Paris in the 1930s, when Jean-Michel Frank was the most celebrated decorator and designer of the era. His projects were often to decorate rooms with Picassos and Braques hanging on the walls, and his circles included everyone from Parisian artists to socialites, Man Ray to the Rockefellers.

But Frank’s style is hard to describe. He’s known as a minimalist, but it’s his layer of maximalism that makes his work so interesting and complex. He was understated and restrained in the shapes of furniture he designed, but often dressed them in opulent materials: ornate mica screens, bronze doors, lamps made of quartz, as well as the shagreen-covered vanity and cubic sheepskin club chair he created for Hermès. Frank’s favorite color was white, which he made appear both spare and rich. And he’s credited with designing one of the most iconic minimalist pieces of furniture in history—the Parsons table—but would often cover the tables with the most luxe finishes.

Despite his keen eye for design and quality, Frank found the elements of daily life key to any space, and believed “perfect taste” to be a recipe for a soulless room.

A distant cousin of the famed diarist Anne Frank, he fled France around 1940 to escape Nazi occupation, and worked and traveled in South America and the United States. Sadly, he committed suicide by jumping from a Manhattan building in 1941, at the age of 46. But his work is still celebrated in museums today, and you can buy reproductions of some of his most iconic furniture pieces designed for Hermès.

Albert Hadley

Marrying glamour and functionality can be a difficult task for any designer, but it’s a relationship that Albert Hadley mastered. “The dean of American decorators,” who died in 2012 at the age of 91, boasted high society names like Rockefeller, Astor, Getty, and Mellon on his client roster, but always honored a democratic decorating spirit: “Names really are not the point,” he told New York magazine in 2004. “It’s what you can achieve for the simplest person. Glamour is part of it, but glamour is not the essence. Design is about discipline and reality, not about fantasy beyond reality.”

Tennessee-born Hadley became known for his modern style, which deftly incorporated a mix of design styles thanks to his seemingly innate sense of balance and what worked together. “Never less, never more,” was his overarching design philosophy.

Hadley joined forces with Sister Parish in 1962. Parish-Hadley Associates styled the homes of America’s elite for decades, but is probably best known for redecorating the Kennedy White House, as well as the Kennedy family’s own homes. But Hadley didn’t slow down after Parish’s death, or with age. In honor of his 85th birthday, The New York Times interviewed one of his clients, Diana Quasha, about why she’d just chosen him for her project. “He’s still the hippest thing out there,” she said. “I don’t want it to be modern, and I don’t want it to be traditional. I want it to look interesting. Who else would I ask?”

Sister Parish

Well-heeled, well-connected Dorothy May Kinnicutt (the childhood nickname “Sister” eventually replaced her given name) was born in 1910 to parents with homes in Manhattan, New Jersey, Maine, and Paris. She attended the Chapin School in Manhattan, and married Henry Parish in 1930, in a wedding that The New York Times reported at the time boasted “a representative gathering of old New York families on hand.”

When in the Wall Street crash of 1929 both Parish’s stockbroker husband’s and father’s fortunes took hits, she opened her own interior design shop in Far Hills, New Jersey. Her style was a counterpoint to her antiques collector father’s heavy, dark, brown furniture—she favored ticking stripe, glazed chintz, quilts, hooked rugs, and overstuffed armchairs instead of formal antiques—and is credited with popularizing that American country aesthetic in the 1960s.

Her designs for clients such as Brooke Astor were romantic, warm, and elegant, but her tactics were precise and exacting: Her unforgiving assessment of a client’s space before she started any design project involved rolling a tea cart around the room, editing out any items that didn’t meet with her approval.

Parish’s design relationship with Albert Hadley lasted 30-plus years—until her death in 1994 at the age of 84—and is widely considered one of the most successful partnerships in the world of interiors.