Guy Mezger (born January 1, 1968) is an American martial artist, who competed in professional combat sports including full contact karate, kickboxing, and boxing, but is most recognized as a mixed martial arts (MMA) fighter. Mezger retired from professional competition on January 25, 2005. He is associated with Lion's Den and runs their school in Dallas. Mezger was a champion in mixed martial arts in two different promotions, the UFC and Pancrase. He holds wins over Tito Ortiz, Masakatsu Funaki, Yuki Kondo, Semmy Schilt, and Minoru Suzuki.