Patty Duke Is Dead at 69

— -- Patty Duke, Oscar-winning actress and the star of an eponymous TV show, died this morning, ABC News has confirmed.

According to her rep, Mitchell Stubbs, the cause of death was sepsis from a ruptured intestine.

The actress, whose real name was Anna Pearce, was 69.

"She was a wife, a mother, a grandmother, a friend, a mental health advocate and a cultural icon," Stubbs added in a statement. "She will be greatly missed."

Duke became a star as a teenager when she appeared as Helen Keller in "The Miracle Worker" on Broadway alongside Anne Bancroft. The play was later turned into a film, for which Duke won the Best Supporting Actress Oscar in 1963.

However, off-screen, she was struggling. When she was 7, she said two managers, John and Ethel Ross, took over her career, and gave her her famous stage name, allegedly telling her, "Anna Marie is dead; you're Patty now." In her memoir, the actress also accused them of taking advantage of her, and squandering her earnings, according to a 1987 article in the Philadelphia Inquirer.

"I don't hate them," she wrote in her book. "[And] it's obvious to me that had they not crossed my path, the likelihood of my becoming an actress was slim, and the joy of that far outweighs any of the pain."

Around the time that she separated from them, Duke was given her own series, "The Patty Duke Show," in which played identical cousins, "Patty" and "Cathy." The show, which ran from 1963-1966, earned her an Emmy nomination.

After "The Patty Duke Show" was canceled, however, the actress sought out more adult roles. In 1967, she appeared as Neely O'Hara in "Valley of the Dolls," and in 1969, she starred in "Me, Natalie," for which she won a Golden Globe. An Emmy followed the year after, when Duke starred as a pregnant teenager in a made-for-TV movie, "My Sweet Charlie." (She also won Emmys in 1977 and 1980.) However, privately, Duke was battling bipolar disorder, for which she was diagnosed in 1982.

"It's not a giant thrill to hear someone give you the label manic-depressive, but to me I was so relieved," Duke told the Inquirer. "What I was suffering from had a name and could be treated."

Duke became a staunch advocate for mental health, while continuing her acting career. Duke primarily worked in television, most recently appearing in shows including "Glee," "Liv and Maddie" and "Hawaii Five-0."

Duke is survived by her husband of 30 years, Michael Pearce, three children, Sean and Mackenzie Astin and Kevin Peace, and grandchildren.