In the 2nd round of his fight against Chris Weidman, Anderson Silva broke his leg while kicking the champion. The first round was dominated by Weidman by staying on top of Silva and controlling the round.
In the 2nd round, Silva threw a kick and snapped his leg right in half. If you want to see it and other GIFs from the fight, check them out after the jump.
H/T as always to @ZProphet_MMA