Cobra Kai
Cobra Kai is a spin-off of the movie The Karate Kid and its first two sequels. In it, Johnny Lawrence, who was the bully in the first movie is an adult and he hates the kid he bullied Daniel LaRusso who has now gotten rich from selling cars, so Johnny starts his own dojo called Cobra Kai based on the one where he learned karate to teach martial arts to a kid named Miguel Diaz so that he can fight back against his bullies. Daniel believes that Cobra Kai is evil because of what happened to him in The Karate Kid and The Karate Kid Part III. So Daniel and Johnny end up as enemies.