In 1973, Marlon Brando won the Oscar for Best Actor, for his role in The Godfather, but he did not accept the award. He did not even attend the Oscars. Instead he, sent someone else up in his place, and abruptly changed the tone of an event that had never really ventured into politics.
Sacheen Littlefeather's appearance at the Oscars created controversy where there wasn't one previously, but the lack of controversy was due to a lack of representation from minority groups in Hollywood in 1973. Littlefeather delivered her remarks as deferentially as possible and did so without anger on a note of unity.