Arturo Braga

Arturo Braga (also known as: Ramon Campos) is the main antagonist in Fast & Furious and appears as a supporting antagonist in Fast & Furious 6. He was a drug trafficker and the head of one of Mexico's biggest cartels known for running heroin across the Mexico-US border. He was also a friend and associate of Owen Shaw. He is portrayed by John Ortiz.

Fast & Furious
Braga is first seen when Dominic Toretto and Brian O'Conner are trying to secure a spot in Braga's driving team. Dom wins and joins Braga's team to race heroin into Mexico. After one of his drivers is arrested Brian joins his team. Brian and Dom never know the identity of Braga whilst they are working for him until they discover that Ramon Campos is actually Braga but he escapes to Mexico before they can apprehend him. He is later recaptured by Brian and Dom as they race back to the U.S via the tunnels. Brian's car crashes and he and Brian survive. His henchmen Fenix Calderon (who apparently murdered Letty Ortiz) is killed by Dominic. Braga is sentenced to life in prison.

Fast & Furious 6
It was revealed that Braga was working with Owen Shaw. Brian is smuggled into prison and asks Braga about Letty. He reveals that Letty survived the crash and explosion but suffered from memory loss. He sent Owen to finish the job but, because Letty had no memory, Owen recruited her. Braga and his men later attacked Brian but he managed to subdue them, with Brian stabbing Braga with a shank after.

Trivia

 * Although his right hand man, Fenix Calderon, drove the full plot of Fast & Furious 4 due to injuring key character Letty then faked her death but nearly killed her entirely, Braga is the true main villain because he had bigger plans than Fenix, treated him like his apprentice, used a fake Braga as a decoy and called himself Campos to hide his true identity and unknown motives.
 * Braga is one of the two only villains to be a recurring one alongside Deckard Shaw and coincidentally, they were both the main antagonist of the movies they first appeared in.