Billingsley, who played small parts in B movies and appeared on television before achieving sitcom immortality, died Saturday at her home in Santa Monica of the rheumatoid disorder polymyalgia, said publicist Judy Twersky.
The gentle-humored series, which viewed life from a kid's point of view and ran from 1957 to 1963 — on CBS before moving to ABC in the fall of '58 — featured Jerry Mathers as Theodore "Beaver" Cleaver and Tony Dow as his older brother, Wally.
As June Cleaver, Billingsley was the personification of an Eisenhower-era stay-at-home mom — at least one residing in fictional Mayfield, U.S.A.: a mild-mannered, perfectly coiffed housewife who typically wore dresses, high heels and a strand of white pearls even while vacuuming or baking cookies for her boys.
"She was the ideal mother," Billingsley said of her character in 1997 in TV Guide. "Some people think she was weakish, but I don't. She was the love in that family. She set a good example for what a wife could be. I had two boys at home when I did the show. I think the character became kind of like me and vice versa. I've never known where one started and where one stopped."
As for the idealized TV family on "Leave It to Beaver," which continues in reruns on cable more than half a century after its debut, Billingsley had her own explanation for the Cleavers' enduring appeal.
"Good grief," she told TV Guide, "I think everybody would like a family like that. Wouldn't it be nice if you came home from school and there was Mom standing there with her little apron and cookies waiting?"
Born Barbara Combes in Los Angeles on Dec. 22, 1915, she and her sister grew up in a single-parent household after her parents divorced when she was an infant.
She always wanted to be an actress. She was attending Los Angeles City College when she joined the cast of "Straw Hat," a comedy that went to Broadway in late 1937. The show closed after four performances, but she "decided New York was more fun than college" and found work as a $60-a-week fashion model. She later toured with Billie Burke in a production of "Accidentally Yours."
Her marriage in the early 1940s to restaurant operator Glenn Billingsley, nephew of Stork Club owner Sherman Billingsley, produced two sons and prompted her move back to Los Angeles, where her husband managed the Mocambo nightclub.
When the marriage ended in divorce in the late '40s, Barbara Billingsley already had begun playing uncredited bit parts and small roles in a string of B movies. That continued into the '50s, when she also began landing roles on "Four Star Playhouse" and other television anthology programs.
In 1955, she played co-star Stephen Dunne's wife on the short-lived situation comedy "Professional Father," and she portrayed Gale Gordon's girlfriend on several episodes of the situation comedy "The Brothers."
In 1953, Billingsley married director Roy Kellino, who died three years later of a heart attack at age 44.
"It's a terrible blow, but you can't wallow in your grief," Billingsley said in a 1993 interview with The Times. "When Roy died, my agent made me work all the time. And six months later, they called me to start the series."
"They" were Joe Connelly and Bob Mosher, the creators of "Leave It to Beaver," the first TV series to show life from a child's point of view.
"Joe Connelly had seven children, and Bob Mosher had two, and they had a lot of material right there," Billingsley told the Nashville Tennessean in 2003. "Every show was taken from some kernel of truth, something that had happened to their children or a relative."
As for her trademark white-pearl necklace, Billingsley said in 2003 in The Times that she wore it "because I have a big hollow in my neck" and the necklace covered the spot perfectly.
"So no matter what I was doing — cleaning, cooking or answering the phone — I had those darn pearls on," she said. And there was a practical reason she wore high heels on the show.
"In the beginning of the series I wore flat shoes, but then Wally and the Beaver began to get taller," she said. "That's why they put me in heels. The producers wanted me to be as tall or taller than the kids."
But even with heels, Billingsley said, "sometimes I would stand on the stairs for a scene so I could have some more height."
After "Leave It to Beaver" ended in 1963, Billingsley made occasional TV guest appearances. But she primarily maintained a low public profile with her third husband, Dr. William Mortensen, whom she had married in 1959. He died in 1981.
In 1980, Billingsley was firmly back in the public eye with her cameo in the disaster-movie spoof "Airplane!" — as the unlikely passenger who volunteers to translate the incomprehensible urban ghetto talk of an ailing black male passenger for the flustered flight attendant. ("Oh, stewardess, I speak 'jive.'")
In 1983, Billingsley returned as June Cleaver in "Still the Beaver," a made-for-television film that reassembled the old series' cast, with the notable exception of Beaumont, who died in 1982.
"No father on television was ever better than Hugh," Billingsley once said.
Beaumont's wise and caring father figure was there in spirit in the reunion film, however, as Billingsley's June would visit his grave and say, "Ward, what would you do?"
The success of the "Still the Beaver" TV movie led to the series "Still the Beaver" on the Disney Channel from 1984 to 1986, with Billingsley returning as June. Retitled "The New Leave It to Beaver" when it was picked up by the cable superstation WTBS in 1986, the series ran until 1989.
Billingsley, who provided the voice of Nanny on the animated "Muppet Babies" series that aired from 1984 to 1991, appeared on television only sporadically in the '90s. She also played a cameo — as Aunt Martha — in the 1997 feature film "Leave It to Beaver."
Billingsley is survived by sons Drew Billingsley of Granada Hills and Glenn Billingsley of Phillips Ranch; stepson William Mortensen Jr. of Pacific Palisades; 16 grandchildren; and 23 great-grandchildren.
Services will be private.