Late in Ms. Monroe’s life, Ms. Irvine was her go-to makeup artist in New York City. Earlier this month, she became a TikTok sensation.Marie Irvine was 99 years old when a chapter in her long-ago career became a TikTok sensation. During a crucial period late in Marilyn Monroe’s life, Ms. Irvine had been her makeup artist in New York City. When a TikTok star learned her story, it blew up the internet.In 1958, Life magazine commissioned Richard Avedon to reimagine Ms. Monroe as the screen and stage sirens Clara Bow, Marlene Dietrich, Theda Bara, Jean Harlow and Lillian Russell. It was Ms. Irvine who assisted with her makeup — turning her into Ms. Russell’s candy-box pinup, and Ms. Dietrich’s steamy Lola Lola from the film “The Blue Angel.”It ran in the Dec. 22 issue of the magazine, with a piece written by Ms. Monroe’s husband at the time, the playwright Arthur Miller, with the headline, “My Wife Marilyn.” He described the photos “as a kind of history of our mass fantasy, so far as seductresses are concerned.”And when Ms. Monroe, having been sewn into her skintight sequined gown, sang a breathless “Happy Birthday” to President John F. Kennedy at a Democratic fund-raiser at Madison Square Garden in May of 1962, it was Ms. Irvine who prepared her beforehand in Ms. Monroe’s apartment on East 57th Street, and then rushed to the Garden later with the star’s drop earrings, because she had left them behind.Erin Parsons, a 45-year-old makeup artist and TikTok star with a passion for vintage makeup and Ms. Monroe, had read of Ms. Irvine’s small part in these iconic moments, and she tracked her down to learn more. And when she posted about her search on Jan. 8, her video went viral.More than a million people have viewed it, and it has accrued more than 1,600 comments. One woman was particularly moved by the $125 fee Ms. Irvine had charged for her services on the night of the Garden event, the equivalent of more than $1,200 today. (Ms. Parsons had a photo of the bill, an artifact which sold at auction for $1,152, and showed it in her video.)“We stan a queen that knows what her skills were worth!” the commenter wrote. “I bow down.”Ms. Irvine circa 1967. She helped transform Marilyn Monroe into stars like Marlene Dietrich and Jean Harlow for Richard Avedon’s famous Life magazine shoot in 1958.Courtesy Horan family, via Charlotte BentleyMs. Irvine died a week after Ms. Parsons’ post, on Jan. 15, at a care facility in Sarasota, Fla. Her daughter, Jane Bentley Sullivan, announced her death.Ms. Irvine was not the architect of Ms. Monroe’s signature look. Her sleepy, bedroom gaze, articulated by the swoop of her liquid eyeliner; her bright red moue; and that beauty mark were the star’s own creations, conceived with her longtime West Coast-based makeup artist, Whitey Snyder. Her fans and fetishists, from Norman Mailer to Ms. Parsons’ audience, knew that she used a secret blend of three shades of lipstick and a gloss made with Vaseline. Mr. Mailer spends a page describing it in his 1973 biography, “Marilyn.”Ms. Irvine met Ms. Monroe because she was an on-call makeup artist to Mr. Avedon in the 1950s, and he hired Ms. Irvine to help with the Life magazine project. It took three months to complete, largely because of Ms. Monroe’s erratic schedule.“We could shoot it only when Marilyn felt like it,” Ms. Irvine told an interviewer in 2014. “Sometimes it was in the middle of the night with a short notice. One time it was such a short notice, that I couldn’t find a babysitter so Marilyn said, ‘Bring your baby to the set.’”(That was Ms. Sullivan, who was 9 months old at the time.)“So it was like a family atmosphere,” Ms. Irvine added. “She told me how much she wanted a baby.”Ms. Irvine was self-effacing and discreet. Her earliest clients were society figures, like Thelma Foy, the daughter of Walter Chrysler, the automobile magnate, a swan who often appeared in Vogue and on an annual list of the 10 best-dressed women in the United States. When Ms. Foy became ill with leukemia, Ms. Irvine’s role shifted from preparing her for photo shoots to helping her hide the ravages of cancer. Ms. Foy died of the disease in 1957, in her early 50s.Marie Irvine was born on Dec. 16, 1924, in Pawling, N.Y., in Dutchess County, the only child of William and Theresa (Brendlin) Irvine. She attended a one-room schoolhouse through grade school. She moved to New York City in her late teens and trained to be a secretary at the Katharine Gibbs School — otherwise known as Katie Gibbs to generations of white-gloved young women — but found the prospect of secretarial work too boring.She found a job at Elizabeth Arden, at the flagship salon with the distinctive red door at 691 Fifth Avenue that served the ladies of the carriage trade, where she became a beauty adviser and color specialist for the company.Toward the end of World War II, Ms. Irvine met a naval officer at Delmonico’s restaurant when he was on leave; they married in 1947. In addition to her daughter, Ms. Sullivan, Ms. Irvine is survived by a son, who requested anonymity for himself and his father, whose name he shares, and two grandchildren. Ms. Irvine’s husband died in 1994.When her daughter was born in 1957, Ms. Irvine left Elizabeth Arden and became a freelance makeup artist, working for photographers like Mr. Avedon, Irving Penn, John Rawlings and Harold Krieger. She did commercial work, too, notably coating the actors who played the Jolly Green Giant, the mascot created to sell canned vegetables, in layers of green greasepaint.In the late ’60s, Ms. Irvine and her family moved from Queens to Essex County, N.J. Her husband, general counsel for a security firm, did not want his wife to continue working, so she retired — and learned to drive at 44.Once she left the fashion world behind, she rarely spoke of it.Ms. Parsons, the TikTok star, had many questions for Ms. Irvine that she was unable to answer before her death. She hoped the former makeup artist could illuminate the histories of the sort of esoterica that transfix Monroe obsessives: For instance, did Robert Champion, a hairdresser who was at the Garden when Ms. Monroe sang, really touch up her makeup and blot her lips with a tissue (an artifact that belongs to the Ripley’s Believe It Or Not! Museum in Orlando, Fla.)? Did Ms. Irvine recognize a gold lipstick tube that once belonged to Ms. Monroe that Ms. Parsons had won at auction for $15,625?Ms. Irvine was pleased she’d had her own moment of fame, though she wished, as she told her daughter, that the attention came when she had more energy to pursue it.“I told her that the important thing was that it had happened at all,” Ms. Sullivan said. “She was an original and one of a kind laboring in obscurity to create many beautiful images with the pioneering photographers of the 20th century. After all, how many 99-year-olds who attended one-room schoolhouses go on to be TikTok stars?” More