Oscar and Emmy winner Patty Duke died on Tuesday at the age of 69.

"Anna 'Patty Duke' Pearce passed away this morning March 29, 2016 at 1:20 am," her rep, Mitchell Stubbs, told USA Today in a statement. "Her cause of death was sepsis from a ruptured intestine. She was a wife, a mother, a grandmother, a friend, a mental health advocate and a cultural icon. She will be missed."

Duke rose to fame after winning an Academy Award for Best Supporting Actress in 1963 for her performance as Helen Keller in The Miracle Worker. She was only 16 at the time, making her the third youngest Oscar winner after Tatum O'Neal and Anna Paquin.

She went on to play "identical cousins" in her Emmy-nominated sitcom, The Patty Duke Show, and starred as Neely O'Hara in Valley of the Dolls. She later won three Emmys for her performances in the TV movies My Sweet Charlie, Captains and the Kings and The Miracle Worker, in which she played Annie Sullivan. More recently, she guest-starred on Hawaii Five-0, Glee and Liv and Maddie.

In 1982, Duke was diagnosed with bipolar disorder, after which the actress dedicated much of her time to mental health advocacy.

Duke also served as president of the Screen Actors Guild from 1985 to 1988. In 2004, she received a star on the Hollywood Walk of Fame.

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Duke was married four times in her life: to director Harry Falk, rock promoter Michael Tell, actor John Astin and drill sergeant Michael Pearce, with whom she celebrated their 30th anniversary on March 15. She had three sons, actors Sean and Mackenzie Astin, and Kevin Pearce. Sean grew up believing John was his father, until Duke told him it was actually Desi Arnaz Jr. However, DNA testing later revealed Sean's father was actually Tell.

"This morning, our beloved wife, mother, matriarch and the exquisite artist, humanitarian, and champion for mental health, Anna PATTY DUKE Pearce, closed her eyes, quieted her pain and ascended to a beautiful place," her family said in a statement. "We celebrate the infinite love and compassion she shared through her work and throughout her life."

Watch Duke's Oscar acceptance speech below.