Jeanne Cooper, who played matriarch Katherine Chancellor on CBS’ hit soap The Young and the Restless, has died. She was 84.

Cooper, who has starred in the daytime series since its first year in 1973, had been in and out of a Los Angeles hospital recently due to an undisclosed illness. Her actor/son Corbin Bernsen had been informing fans of her condition via Facebook, where he confirmed her death today. “My mother passed away this morning just a short time ago, peaceful with my sister by her side, in her sleep. I was going to visit this afternoon, thought I had time. Reminder to self – time is a precious thing. I too am at peace however. I said my goodbyes several times over during the last few weeks.

“I’ll go one last time now for a gentle kiss a final farewell for this lifetime,” he continued. “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! And while her light finally gave into the wind that gives flight to all our journeys, there will always be a glimmer left behind by what she stood for. I will speak about that more in coming days, months I suppose. I will certainly dedicate what remains of my life to continue her purpose of honesty, equality, humility, empathy and love.”

No cause of death was revealed.

It’s unclear for now how the CBS soap will address Cooper’s passing. The series is currently six weeks ahead of schedule and her storyline recently involved her character successfully undergoing surgery for a brain tumor.

“Jeanne 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, CBS Entertainment, in a statement. “She was the longest-running cast member on daytime’s No. 1 show, bringing indelible charm, class and talent to every episode. On behalf of everyone at CBS, we send our condolences to Jeanne’s family, as well as the legions of fans she has amassed during her record 39 years on The Young and The Restless, and throughout her career.”

President Steve Mosko of Sony Pictures TV, which produces the soap for CBS, also released this statement: “Jeanne Cooper was a legend in daytime and a beloved member of our Y&R family. She touched the lives of millions, who watched her every day over the past 40 years. We send our sincerest condolences to her family as we also celebrate her wonderful life.”

A California native who was born with the name Wilma Jeanne, Cooper had a flourishing career as a journeyman TV actor — she made countless appearances in shows that varied from Playhouse 90 and Twilight Zone to Gunsmoke and L.A. Law — when she was approached about a role on a daytime drama that was in development at CBS.

“(My agent) said ‘I know you. You won’t like doing it,” Cooper told EW recently. “Even with the stage you don’t like doing it for six months. You will get very bored playing the same person.’ I said you’re right, so I just kept hiding on island after island in Hawaii. Finally (Producer) John Conboy said, we have to have her. I caught a red-eye out for the table read. William Gray Espy, the young lead who played Snapper, warned everybody that I was a tough lady who doesn’t put up with a lot of nonsense.

“I was going to give it my all for three years but all of a sudden, when you are creating another person who grows with you, Katherine grew with me. I grew with her.,” Cooper continued. “It was fascinating. Then, of course, I got a divorce and couldn’t afford to be too terribly hard ass about what I was and wasn’t going to do. You have to admit, to have a paycheck coming in weekly for 40 years is pretty great. I did not join this show when I was 21. I was 45. Everybody was shocked I would do this and stay with it. [Co-creator] Bill Bell gave me carte blanche to do what I wanted.”

Cooper’s fan base — not to mention her stardom — exploded when she allowed the soap to incorporate her real-life facelift into the storyline. Cameras were there when her Beverly Hills plastic surgeon took off the bandages to reveal the results of her surgery for the first time.

Cooper and the soap were also was lauded for shining a light on alcoholism. The actress told EW that she was routinely approached by recovering alcoholics, who thanked her for the storyline. They also offered up their AA sober chips.

The actress was nominated 10 times for a Daytime Emmy and two times for a Primetime Emmy. She won a Lifetime Achievement Award in 2004 and finally took the gold for playing Katherine Chancellor in 2008.

“You can have a life with this show,” Cooper said recently about her longtime gig on Young and the Restless. “Lots of actresses say they want to do movie but that’s for only three months. It all depends on where you want to hang your lights. If you want to be a movie star, then this is entirely different. I never wanted to be a movie star. I always wanted to be an actress, one of the best. And I am.”