Native American actress and activist Sacheen Littlefeather, who declined Marlon Brando's best actor Oscar in 1973, has died at age 75.

The Academy announced Littlefeather's death on Sunday night through its Twitter account without sharing a cause of death.

Born on Nov. 14, 1946, Marie Louise Cruz changed her name as she explored her Native American roots and became an activist in her 20s.

Littlefeather represented Marlon Brando at the 45th Academy Awards on March 27, 1973, where she, on Brando's behalf, declined the Best Actor award that he won for his performance in The Godfather.

Brando boycotted the ceremony as a protest against Hollywood's portrayal of Native Americans. Her speech to decline the Oscar was met by a mixture of boos and cheers.