7. Sean Sherk
Sorry to fans of the Muscle Shark, but Sean Sherk is clearly one of the worst UFC Champions of all-time.
Sherk won the title at UFC 64 by defeating Kenny Florian. In his first title defense at UFC 73, he defeated Hermes Franca but would later fail a drug test. Sherk was stripped of the championship.
Sherk dropped a title fight to BJ Penn at UFC 84 and never would again challenge for the championship he had stripped from him in 2007.
