11. Jack Johnson KO12 Stanley Ketchel, Oct. 16, 1909 – Johnson was the heavyweight champion and Ketchel the middleweight champion, but the knockout was one of the most brutal ever. First, the power-punching Ketchel, one of the great punchers in the sport&amp;#39;s history, decked Johnson in the 12th. When Johnson got up, he went hard after Ketchel. He landed a right uppercut that not only knocked Ketchel out, but also reportedly left a few of Ketchel&amp;#39;s teeth embedded in his glove. (Photo credit: AP)