Oscar- and Emmy-winning actress Patty Duke died Tuesday at the age of 69.
Her husband, Michael Pearce, said the cause was complications of a ruptured intestine that Duke suffered Thursday.
Duke earned an Academy Award when she was just 16 for playing Helen Keller in "The Miracle Worker" (1962). Diagnosed with bipolar disorder in 1982, Duke worked as an advocate for mental health issues.
In many ways, Duke destigmatized the label by discussing her personal struggles in her 1987 autobiography, "Call Me Anna", as well as 1992's "A Brilliant Madness".
"She was a wife, a mother, a grandmother, a friend, a mental health advocate and a cultural icon", Stubbs said in a statement on Tuesday.
"As Helen, little Miss Duke is altogether superb - a plain, sullen, explosive, miniature monster whose destructive behavior makes sympathy for her afflictions impossible, but whose independence and vitality are nevertheless admirable". She crossed the Nation speaking and campaigning and lobbying for mental health.
In the video Duke talked about how well she was surviving with a mental illness that she referred to as a "life-threatening disease".
Soon after she became a fixture in many American homes via TV as the star of a sitcom created and named for her, The Patty Duke Show, which ran on ABC-TV from 1963 to '65.
William Shatner was another star to pay his respects saying he was "very saddened" by the news that his "wonderful friend" has passed away. Duke played two "identical cousins" with contrasting personalities; Patty Lane, a good if slightly rebellious and sassy teen who lived in Brooklyn Heights, and "Cathy" Lane, her more prim and brainy visiting Scottish cousin.
On the big screen, she appeared in "Valley of the Dolls", the 1967 adaptation of Jacqueline Susann's novel, playing Neely O'Hara, a woman addicted to sex, drugs and alcohol. And she continued to find success on TV with a mixture of TV movies and guest appearances.
In addition to her acting, Duke became involved in union activities, eventually becoming president of the Screen Actors Guild from 1985-1988.
Actress Marlee Matlin called Duke "brave, outspoken & humanitarian".
Also at that age, Duke was the youngest at that time to have a TV series bearing her name.
Sean Astin is best known for his role in the "Lord of the Rings" trilogy.
A message posted early in the afternoon on her Facebook fan page featured a photo of the actress and the words, "Rest in Peace, Sweet Anna".