Soap opera veteran Leslie Charleson, best known for his role as Monica Quartermaine on “General Hospital,” has died. She was 79.

“General Hospital” executive producer Frank Valentini announced Charleson’s death in an Instagram post on Sunday. The actress died as a result of a long illness, a source familiar with the situation but not authorized to speak publicly confirmed to USA TODAY.

“It is with a heavy heart that I announce the passing of my dear friend and colleague Leslie Charleson,” Valentini wrote. “Her enduring legacy spans nearly 50 years on General Hospital alone, and just as Monica was the heart of the Quartermaines, Leslie was a beloved matriarch of the entire cast and crew.”