How 'Cobra Kai' Star Xolo Maridueña Stays Fighting Fit Brett Williams, NASM Replay Video Cobra Kai is centered on old-school Karate Kid antagonist Johnny Lawrence (as played by William Zabka), the show would be nothing without its cast of young characters carrying the martial arts torch in the 21st century. Foremost of those is Miguel Diaz, played by actor Xolo Maridueña, who fills the role of the promising young student in a position similar to that of the original film's protagonist. He's the outcast who finds his way through karate and the tutelage of an older master—albeit one who guzzles Coors Banquet Beer as much as he drops knowledge about fighting and life.