Her family announced the death in a statement, noting that she had breast cancer. Ms. Somers had battled the disease intermittently since 2000, after previously being treated for skin cancer, and revealed in an Instagram post in July that her breast cancer had returned.
Across a half-century in the public eye, Ms. Somers was an actress, model, author, poet, self-help guru, nightclub singer, sex symbol and pitchwoman, steering her fans toward alternative health treatments and anti-aging supplements long before the term “influencer” entered the digital lexicon. “If anything,” Ms. Somers told an interviewer who asked what she considered her main profession, “I’m a reinvention specialist.”
Starting out, she was known simply as “Blonde in T-Bird,” the mysterious woman who flirts with a recent high school graduate named Curt (played by Richard Dreyfuss) in George Lucas’s 1973 film “American Graffiti.” While waiting for a traffic light to change, she mouths the words “I love you” through her car window, then drives off into the night. It was only a few seconds of screen time, but enough to make an impression.
“I just saw a vision. I saw a goddess,” Curt says, calling Ms. Somers’s character “the most perfect, dazzling creature I’ve ever seen.”
Audiences seemed to agree. Ms. Somers began making regular appearances on “The Tonight Show Starring Johnny Carson,” leading to a successful audition for “Three’s Company,” which premiered on ABC in 1977 and became one of the most popular shows of its time. Based on a British sitcom called “Man About the House,” it followed the lives of two roommates, Chrissy Snow (Ms. Somers) and Janet Wood (Joyce DeWitt), who offer to let a bumbling bachelor named Jack Tripper (John Ritter) move into their apartment. To get around their landlord’s rules on mixed-gender housing, the trio pretend Jack is gay.
Propelled by its bawdy humor and slapstick comedy, the series ran for eight seasons and inspired two spinoffs, even as critics dismissed the show as tiresome and unimaginative. Ms. Somers’s character, who was often dressed in negligee, was frequently targeted for seeming to perpetuate the stereotype of the dumb blonde, although she said she sought to give the role “a moral code,” with a sense of outrage and propriety that evoked the matriarch Edith Bunker of “All in the Family.”
“I’ve been playing what I think is one of the best dumb blondes that’s ever been done, but I never got any credit,” she told the New York Times in 1980. “I did it so well that everyone thought I really was a dumb blonde.”
After appearing on 100 episodes, her time on the show ended abruptly in 1981 following a dispute over her salary. Ms. Somers made $30,000 an episode, or about $106,000 in today’s money, and said she sought a raise that would have paid her about the same as Ritter and other male TV stars, including Ed Asner of “Lou Grant” and Henry Winkler of “Happy Days.” By some accounts, she wanted $50,000 an episode, plus a piece of the show’s earnings; in interviews, she often said she sought $150,000 an episode.
The producers refused, and Ms. Somers was fired, while the show continued on for three more seasons. “I guess I was ahead of my time because I wanted the same money as the man,” she told the Tampa Tribune in 1998. “But when I stood up for my rights, I was booted off the show and blacklisted for a decade.” (Her relationship with her cast members also suffered: Ms. Somers said she didn’t speak to either of her co-stars for decades.)
Backed by her husband and manager, Canadian-born entertainer Alan Hamel, Ms. Somers decamped to Las Vegas, where she developed a one-woman act while performing in casinos and nightclubs. She later returned to TV in the sitcom “She’s the Sheriff” (1987-89), as a widow who takes over her husband’s law-enforcement job, and starred with Patrick Duffy in “Step by Step” (1991-98), a “Brady Bunch” clone about a blended family.
When she wasn’t acting, she wrote, publishing more than two dozen books on beauty, health, spirituality, menopause and her own life. Her first memoir, “Keeping Secrets” (1988), recounted her struggles with an alcoholic father whose violent rages led her to spend much of her childhood hiding in a closet. As a result, she said, she preferred small rooms as an adult.
Ms. Somers also appeared on ubiquitous infomercials for the ThighMaster, a supersized binder clip that became one of the biggest exercise fads of the 1990s and made her millions of dollars. She had less success promoting a bluntly named product called the ButtMaster — “There were certain religious groups that picketed stores objecting to the name,” she told Time magazine, explaining that “we had to repackage it as the Lower Body Exerciser” — but maintained a loyal following well into the 21st century.
Physicians and medical researchers criticized some of Ms. Somers’s recommendations, including bioidentical hormone replacement therapy, a controversial treatment that aims to replenish hormones like progesterone with plant-based alternatives. She dismissed those concerns, saying that she only promoted products that she used and believed in, and argued that readers could trust her because she had experienced many of the same issues they had.
“I don’t put myself up as perfect,” she told Publishers Weekly in 2004. “My life is an open book, and I’m a woman with problems, and I’ve found a happy life in spite of it. Women who come from violent abuse, or have weight problems, or have had problems blending families, or who have hormone problems — I’ve had it all. And somehow I still have a smile on my face.
“I think they think, ‘I’ll have what she’s having.’”
The third of four children, Suzanne Marie Mahoney was born in San Bruno, Calif., on Oct. 16, 1946. Her mother was a medical secretary, and her father was a gardener and brewery worker. Ms. Somers said she found a refuge from his violence through music, and performed in musicals at her parochial school before being kicked out for writing love letters to a boy.
After graduating from Capuchino High School in San Bruno in 1964, she enrolled at the San Francisco College for Women, also known as Lone Mountain. (The school became part of the University of San Francisco.) She dropped out the next year, after discovering she was pregnant, and married the father, Bruce Somers. They divorced about two years later, and Ms. Somers supported herself and her son with modeling jobs and small film roles, including uncredited appearances in “Bullitt” (1968), with Steve McQueen, and “Magnum Force” (1973), with Clint Eastwood.
Around that same time, she met Hamel while working on a TV show called “Anniversary Game.” “He was the game show host and I was the prize model,” she later told The Washington Post, “and I got fired after the first day because I kept looking at the wrong television camera.”
They married in 1977. In addition to her husband, survivors include her son, Bruce Somers Jr. Additional details on survivors were not immediately available.
With the success of “Three’s Company,” Ms. Somers starred as a Washington lawyer in the romantic comedy “Nothing Personal” (1980), with Donald Sutherland. The film was panned, as was her autobiographical Broadway show “The Blonde in the Thunderbird” (2005), which closed after one week.
But Ms. Somers kept working, championing weight-loss techniques and products on the Home Shopping Network while cultivating a sex-positive image through her books, interviews and social media posts. To commemorate her 73rd birthday, she posted a picture on Instagram that showed her crouching naked in a field. “A sexual person,” she explained to the Times, “is a healthy person.”