Oscar award-winning actress Patty Duke has died, her agent confirms. She was 69.

The beloved actress won an Academy Award when she was just 16 years old and went on to play identical cousins in "The Patty Duke Show."

Actress Patty Duke attends a ceremony honoring her with a star on the Hollywood Walk of Fame August 17, 2004 in Hollywood, California. (Photo by Vince Bucci/Getty Images)

Duke's agent, Mitchell Stubbs, says the actress died early Tuesday morning of sepsis from a ruptured intestine.
Duke won an Academy Award in 1963 for her portrayal of Helen Keller in "The Miracle Worker," a role she also played to acclaim on Broadway.
She built on her success in teenhood by playing identical cousins on popular sitcom, "The Patty Duke Show," from 1963-1966.
She was also known for roles in "Valley of the Dolls," "My Sweet Charlie" and "Me, Natalie."