No. 2 - Corey Hill Gruesomely Breaks His Leg
There's really not much needed to say about this. Just look at that horrific picture. Hill was fighting Dale Hartt and went for a low kick. When his shin connected with Hartt's it snapped like a twig. Hill went to take a step back but because his leg was fractured he fell to the mat. Announcer Joe Rogan quickly realized what happened and started screaming "Stop the fight!" Thankfully they did before more damage was done. Hill took more than a year to recover from the injury, but he did make it back to the ring.