Clearly, to make it to the UFC in the first place you have to be a pretty tough nut.
Toughness comes in various different ways, of course. Sometimes it's about simply how many times you can get punched in the face. Other times it's about how far you're willing to push your own body. And other times it's about being an out and out badass.
Here, we've looked through the annuls of Ultimate Fighting Championship history to try and pinpoint the ten toughest fighters that the organisation has ever seen. As in, this is purely a UFC-based feature - so apologies to the Fedor Emelianenko fans out there!
But while renown tough guy Emelianenko and his ridiculous ability to absorb punishment isn't a part of this list, there are plenty of other fighters here who could give the legendary Fedor a run for his money in the toughness stakes. In fact, you could even argue that some of the names here are actually tougher than the Pride icon, although that's a debate for another day.
So without any further ado, here are the ten toughest bastards ever to step foot inside a UFC octagon.