Cato Fong is Clouseau's Chinese manservant, trained to attack him regularly to keep him alert and skilled in martial arts. Cato and Clouseau have a love-hate relationship, with their fights being long and vicious, as well as destructive to the furniture, and always interrupted by the telephone ringing, at which point they will become civil again. Cato puts a lot of effort into taking his employer by surprise, and Clouseau never really feels safe as Cato will stop at nothing. A running gag is Cato attacking Clouseau during a romantic moment, or else Clouseau going away and Cato transforming the apartment. Clouseau usually batters Cato about quite a lot and calls him by derogatory names such as "my little yellow friend". His war cry is "Saaaaaaaaaah". Cato is played by Burt Kwouk.
In "A Shot in the Dark" Cato is introduced, going so far as to attack Clouseau when he is in bed with Maria. During the ensuing pillow fight, they fall through the floor, narrowly avoiding being killed by a bomb planted by Dreyfus. At the very end of the film, Cato attacks them again, and the three fall into a fountain.
In "Return of the Pink Panther" we see the first of the long and vicious fights we are familiar with.
In "The Pink Panther Strikes Again", Clouseau comes home and practically demolishes the entire apartment, trying to find Cato before he can attack him. Meanwhile, Dreyfus is trying to plant a bomb under the floor. After the lengthy battle, Clouseau's disguise that he is trying on inflates and carries him out of the window, leaving Cato to be wounded by the explosion. At the end of the film with the mission complete, Clouseau comes home to find his apartment transformed into a romantic setting with the girl waiting for him, but Cato attacks them in bed, the bed folds up into the wall and the three crash through the wall and into the water.
In "Revenge of the Pink Panther", Clouseau comes home in his latest disguise after a harrowing evening of attempted murder and creeps about the apartment yelling that Cato is to call off tonight's attack. Clouseau discovers the ninja sent to kill him, mistakes him for Cato, and smashes him through the floor before Cato actually attacks. Later on, when Clouseau is presumed dead, Cato seems to turn the apartment into a brothel, which infuriates Clouseau when he comes home. Cato later accompanies Clouseau to Hong Kong as a translator and is involved in the climactic chase scene.
In "Trail of the Pink Panther", when Clouseau is missing, reporter Marie comes to his empty apartment, only to be attacked by Cato. She quickly defeats him with a frying pan, apologizes, gives him an aspirin, and interviews him for some memories about Clouseau.
In "Curse of the Pink Panther" while Clouseau is still away Cato converts the apartment into a museum, displaying disguises of Clouseau's. When Sleigh comes to investigate, Cato mistakes him for an intruder but helps him when this is cleared up. In "Son of the Pink Panther" Cato does the same for Clouseau's son.
In the modern films, Clouseau's first assistant is trained to attack him as well, but they never get into brutal fights.