John Woo Yu-Sen is a Hong Kong filmmaker, known as a highly influential figure in the action film genre. He is a pioneer of heroic bloodshed films and the gun fu genre in Hong Kong action cinema, before working in Hollywood films. He is known for his highly chaotic "bullet ballet" action sequences, stylized imagery, Mexican standoffs, frequent use of slow motion and allusions to wuxia, film noir and Western cinema.

The action film is a film genre that predominantly features chase sequences, fights, shootouts, explosions, and stunt work. The specifics of what constitutes an action film has been in scholarly debate since the 1980s. While some scholars such as David Bordwell suggested they were films that favor spectacle to storytelling, others such as Goeff King stated they allow the scenes of spectacle to be attuned to story telling. Action films are often hybrid with other genres, mixing into various forms ranging to comedies, science fiction films, and horror films.