With Colin Kaepernick refusing to stand for the national anthem in recent 49ers game, the debate about athletes and protesting is once again raging.

While you may not agree with what Colin’s doing, the simple fact as this: athletes have been using their fame and the platform that it affords them to protest all manner of things.

With that in mind, here 15 of the most controversial athlete protests of all time…

1. Muhammad Ali Won’t Go to War

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After being drafted into the Vietnam War, Muhammad Ali refused to go in protest of the conflict, landing in jail, losing four years of fighting, and all of his titles in the process. Controversial at the time, it’s now widely seen as a brave move.

2. Mahmoud Abdul-Rauf Won’t Stand

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In protest of the United States’ oppression of people of color, Mahmoud refused to stand for “The Star-Spangled Banner” during the 1996 NBA season. He was suspended for a game, and eventually settled on bowing his head for a Muslim prayer during the anthem instead.