The Protector (Chinese: 威龍猛探; lit. 'Dragon Detective') is a 1985 buddy cop action film written and directed by James Glickenhaus. It stars Jackie Chan and Danny Aiello, along with Roy Chiao, Peter Yang, Moon Lee, and Bill Wallace. An international co-production between the United States and Hong Kong, this was Chan's second attempt at breaking into the American film market, after 1980’s The Big Brawl, which had moderate box office success but was considered a disappointment.

Conflicts between Glickenhaus and Chan during production led to two official versions of the film: Glickenhaus' original version for American audiences and a Hong Kong version re-shot and re-edited by Jackie Chan. The original Glickenhaus version was a box office failure in North America, while Chan's edited version was a moderate success in Asia; the film was also moderately successful in Europe.

Billy Wong is a Hong Kong-born officer with the New York Police Department. During a bar robbery gone awry, Billy kills the perpetrators but loses his partner Michael Alexander, drawing the ire of his superiors. Later, in the middle of a fashion show, masked gangsters storm in and kidnap Laura Shapiro, the daughter of known gangster Martin Shapiro. Crime boss Harold Ko and Martin Shapiro are suspected of smuggling drugs from Hong Kong to New York. A surveillance of Shapiro's bodyguard Benny Garucci indicates that Ko may have taken her to Hong Kong for ransom. Wong and his new partner Danny Garoni travel to the colony, where they encounter local contacts Stan Jones, Hing Lee, and Hing's daughter Siu Ling.

The officers evade Ko's attempts to have them killed at a massage parlor and again at their hotel, while Royal Hong Kong Police chief superintendent Whitehead is reluctant to provide assistance, insisting that Ko is an upstanding citizen. Garoni and Wong attend a charity function hosted by Ko and confront him publicly. The next day, Wong, Garoni, and Jones discover that Hing Lee has been murdered. Garoni follows Garruci to a shipyard where Ko's drug lab is located and Laura Shapiro is held. In a meeting between Ko and Garucci, it is revealed that Shapiro's daughter was kidnapped because her father did not pay for Ko's last shipment.

Wong, Garoni and Jones raid the drug lab, destroy it and save Laura in the process. Garoni, however, is shot by Garucci and held hostage unless Billy returns Laura to Ko. Wong decides to leave her with Superintendent Whitehead. Wong meets Ko and Garucci at the shipyard, and learns that Superintendent Whitehead—was on Ko's payroll the whole time—has delivered Laura to his boss. Wong fights Garucci and Ko's guards, killing the former. Stan Jones and Siu Ling arrive to help rescue Garoni and Laura. Ko escapes in a helicopter, but Wong commandeers a crane and drops its contents onto his helicopter. With Ko dead and Laura saved, Billy and Danny return home and are given a NYPD Medal of Honor.

Jackie Chan's domestic version, while tweaking or removing ancillary content from Glickenhaus' version, adds an entirely new subplot. The first involves a woman named May-Fong Ho, who now works as a dancer under the alias of Sally after Ko had her father, one of his business associates, murdered. She is the one who connects Wong with Hing Lee, her father's old partner. Unbeknownst to Sally and Wong, one of Ko's men overhears the conversation.

Later, Benny Garucci expresses his concern to Ko's bodyguard, Ho Dai-Wai, about Garoni and Wong's investigation. Ho offers to help. That night, Hing Lee meets with an informant named Wing who reveals to him where Laura is being held. They are suddenly attacked by Benny Garucci and several henchmen. Later, Wong and Siu Ling find Lee and Wing's dead bodies. Realizing that Sally may be in danger, Wong pays her a visit and discovers that Sally's substitute maid, who works for Ko, has planted a bomb under her bed. Wong defuses the bomb. The massage parlor manager shows up, and is revealed to be Sally's uncle. Having fallen out of favor with Ko after failing to kill Garoni and Wong, the uncle reveals where Laura is held. Before assaulting Ko's lair, Wong escorts Sally and her uncle to the airport so they can start a new life in the U.S.

An early incarnation of The Protector featured a different story written by veteran director Robert Clouse, and was going to be produced by Golden Harvest's go-to American partner Fred Weintraub, with a Christmas 1982 start date. However, that version was delayed after Project A went over schedule, then shelved. It would subsequently be repackaged as China O'Brien, an American launchpad for the studio's next contract star, Cynthia Rothrock. The film was rebooted when Golden Harvest's head of overseas production Tom Gray reached out to director James Glickenhaus based on the success of The Exterminator. The Exterminator had opened the same week as The Big Brawl, Golden Harvest's previous attempt at an American vehicle for Jackie Chan, and outgrossed it at the box office.