Sacheen Littlefeather, famously known for rejecting Marlon Brando's Oscar, her cause of death is still uncertain; however, multiple media reports claimed it was due to breast cancer.
According to Washington Post, Calina Lawrence, her niece, and caregiver, also said her cause of death was breast cancer.
In 2018, Ms. Littlefeather was diagnosed with stage 4 breast cancer metastasized to her right lung, as per A. Frame, the digital magazine of the Academy.
The Academy announced the 75-year-old death on Twitter.
The Johnny Firecloud actor's death came at the heels of weeks ago when the Academy formally apologized to her for treatment during the Oscars.
Earlier, during an interview with The Hollywood Reporter, Ms. Littlefeather said she was "stunned" by the apology. "I never thought I'd live to see the day I would be hearing this, experiencing this," she said.
Last month, Ms. Littlefeather spoke at a program hosted by the Academy called "An Evening with Sacheen Littlefeather," recalling how she had stood up for justice in the arts.
"I didn't represent myself," she said. "I was representing all Indigenous voices out there, all Indigenous people, because we had never been heard in that way before."
And when she spoke those words, the audience erupted in applause.
"I had to pay the price of admission, and that was OK," she said. "Because those doors had to be open."
