© WENN / Jeanne Cooper

LOS ANGELES (AP) — Jeanne Cooper, the enduring soap opera star who played  grande dame Katherine Chancellor for nearly four decades on "The Young and the  Restless," has died. She was 84.

Cooper died Wednesday morning in her sleep, her son the actor Corbin Bernsen  wrote on Facebook. The family confirmed the death to CBS, according to a network  spokeswoman.

Cooper will be remembered "as a daytime television legend and as a friend who  will truly be missed by all of us here at the network," said Nina Tassler,  president of CBS Entertainment, adding that the actress brought "indelible  charm, class and talent to every episode."

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Bernsen tweeted April 12 that his mother faced an "uphill battle" for an  undisclosed illness. In subsequent days he wrote of her gradual improvement and  said that she'd been taken off breathing equipment.

In a Facebook posting April 17, Bernsen said his mother cursed several times,  "showing me that she's becoming her old self, not thrilled about the situation,  and ready to get out of the hospital and shake up the world."

On Wednesday he wrote that she remained a fighter until the end: "She has  been a blaze her entire life, that beacon, that boxer I spoke of earlier. She  went the full twelve rounds and by unanimous decision... won!"

Cooper joined the daytime serial six months after its March 1973 debut,  staking claim to the title of longest-tenured cast member. The role earned her  11 Daytime Emmy nominations and a trophy for best actress in a drama series in  2008.

"God knows it's claimed a big part of my life," she told The Associated Press  in March as CBS' "Young and the Restless" celebrated its milestone 40th  anniversary.

As the years passed, Cooper brushed aside thoughts of saying goodbye to the  show and its fictional Wisconsin town of Genoa City.

"What would I do? I'm no good at crocheting. My fingers would bleed," she  told the AP as she turned 83.

Cooper, born in the California town of Taft in 1928, attended the College of  the Pacific and performed in local theater productions before her professional  career began with the 1953 film "The Redhead from Wyoming" starring Maureen  O'Hara. Other film credits include 1968's "The Boston Strangler" with Tony  Curtis and 1967's "Tony Rome" with Frank Sinatra.

She had a parallel career in TV, with shows including "The Adventures of Kit  Carson" in 1953 and "The Pepsi-Cola Playhouse" in 1954 and "Bracken's World" in  1969-70.

In a recurring role on "L.A. Law," she played the mother to Bersen's  character, Arnie, and received a 1987 Emmy nomination for best guest actress in  a drama. Bernsen later joined his mother on her series, making several  appearances as a priest, Father Todd.

But it was her role on "The Young and the Restless" that made her a TV star  intimately familiar to viewers.

In 1984, Coooper's real-life facelift was televised on the show as her  character underwent the surgery at the same time, and had no regrets about  it.

"It opened up reconstructive surgery for so many people, youngsters getting  things done," she said. "To this day, people will come up to me and say, 'Thank  you so much for doing that. My mom or I had something done, and not just  cosmetic surgery.' That was an incredible experience in my life."

"The Young and the Restless" has topped the daytime serial ratings for more  than 24 years, in part because of the continuity provided by Cooper and its  other long-time stars including Eric Braeden. It held its ground as the genre  diminished in popularity and the majority of soaps vanished.

Cooper's 30-year marriage to Harry Bernsen ended in divorce. The couple have  three children, Corbin, Caren and Collin, and eight grandchildren.