José Mendoza (ホセ・メンドーサ, lit. Hose Mendōsa) is a semi-recurring character in Ashita no Joe and the main antagonist of the second half of the series.
He is the Mexican undisputed and undefeated bantamweight champion of the world that holds the WBA and WBC belts. He first comes to Joe's attention after defeating the then sixth ranked WBC contender, Carlos, after Joe's contested bout with the Venezuelan boxer.
Including his fight with Joe, he has defended his WBC bantamweight title a grand total of 17 times, all but one by way of KO.
He is the perfect champion who had never lost, fought beautifully and was admired by all. He takes great care of his health and family, and is constantly calm and confident, giving an aura of being truly unbeatable. A recurring theme is his immense physical strength, to the point of leaving big bruises on Joe's body by gripping him, easily forcing him into a handshake, and even bending coins with his fingers. However, Joe eventually discovers that José has one weakness; despite his speed, strength and stamina, he can't take hits nearly as well, and relies on avoiding getting hit as much as possible.
He begins to break down from this during the later stages of his fight with Joe, where he loses his cool and fears for his life against Joe's unrelenting spirit. Mendoza was knocked down for the first time in his career during the fight, and even fouled Joe violently in a moment of terror. He would win the decision, but the trauma his body suffers from the fight ages him prematurely.