As the debate over the Oscars' omission of Black performers and related boycotts grows in scope, we can't think of a more relevant #ThrowbackThursday than Sacheen Littlefeather's non-acceptance of Marlon Brando's Oscar in 1973.
Brando, who was recognized by the Academy for his iconic performance as "Vito Corleone" in "The Godfather," was involved with the American Indian Movement (AIM) at the time of the awards show. Instead of accepting the Oscar, he asked Sacheen Littlefeather, an Apache activist and actress who was involved in the 1969 occupation of Alcatraz, to accept the award on his behalf. Although Brando prepared a lengthy statement for Littlefeather to read, she instead delivered a concise and improvised speech rejecting the award on Brando's behalf in reaction to the racist treatment of Native Americans in Hollywood. Littlefeather also referenced the then-recent occupation of Wounded Knee, South Dakota by Oglala Lakota tribe members and AIM followers. 
Her speech, which you can see above, was met with a mix of boos and cheers. She later read Brando's full speech to the press.
The incident led the Academy to ban proxy recipients for awards, but maybe this method of protest will resurface this year?