Christian Cyrus Leben (born July 21, 1980) is an American former mixed martial artist, referee, and current bare knuckle boxer.
A professional MMA competitor from 2002 until 2013, he most notably competed in the UFC in the Middleweight division, compiling a record of 12-10 in 22 appearances for the organization.
Leben first appeared in the inaugural season of The Ultimate Fighter reality series, and also fought in the now-defunct WEC.
He began his UFC career with five victories in a row before suffering a knockout loss to future UFC Middleweight Champion Anderson Silva, and was known for his toughness and powerful left hand.
Leben was the inaugural WEC Middleweight Champion.