Action film is a film genre in which the protagonist is thrust into a series of events that typically involve violence and physical feats. The genre tends to feature a mostly resourceful hero struggling against incredible odds, which include life-threatening situations, a dangerous villain, or a pursuit which usually concludes in victory for the hero.

Advancements in computer-generated imagery (CGI) have made it cheaper and easier to create action sequences and other visual effects that required the efforts of professional stunt crews in the past. However, reactions to action films containing significant amounts of CGI have been mixed, as some films use CGI to create unrealistic, highly unbelievable events. While action has long been a recurring component in films, the "action film" genre began to develop in the 1970s along with the increase of stunts and special effects.

This genre is closely associated with the thriller and adventure genres and may also contain elements of drama and spy fiction. Screenwriter and scholar Eric R. Williams identifies action film as one of eleven super-genres in his screenwriters' taxonomy, claiming that all feature-length narrative films can be classified by these super-genres.  The other eleven super-genres are crime, fantasy, horror, romance, science fiction, slice of life, sports, thriller, war, western and vigilante.