Ninja Assassin is a 2009 martial arts film directed by James McTeigue. The story was written by Matthew Sand, with a screenplay by J. Michael Straczynski. The film stars South Korean pop musician Rain as a disillusioned assassin looking for retribution against his former mentor, played by ninja film legend Sho Kosugi. Ninja Assassin explores political corruption, child endangerment and the impact of violence. The Wachowskis, Joel Silver, and Grant Hill produced the film for Legendary Pictures, Dark Castle Entertainment and Silver Pictures. It was distributed by Warner Bros. Pictures.

Ninja Assassin premiered in theaters across the United States on November 25, 2009 and received mixed reviews from critics. Its box office gross was $61,590,252, of which $38,122,883 was from North America. The film's budget was $40–50 million.