25-year-old Ronda "Rowdy" Rousey isn't just a pretty face - she's also a vicious fighter who is currently undefeated.  After she blasted her way onto the mainstream MMA scene by beating the crap out of every woman she faced off against in Strikeforce last year, she became an instant superstar.  Since she is the first woman to sign with Dana White's enormous UFC organization, she has automatically been crowned as the 135lb women's champion.  

It's rumored that she'll defend her title against the likes of possible opponents such as Miesha Tate, Sara McMann, or Cris Cyborg (who has been flagged for using steroids in the past).  She's gorgeous to look at but don't let her get ahold of your arm in a fight.  Whether she has you in a kimora, armbar, or any other submission move that involves applying pressure the the various joints in your arm, she's known for breaking them in half, literally.

Check out this highlight reel of the gorgeous Ronda Rousey in action above.