Enter the Ninja is a 1981 American martial arts film directed by Menahem Golan and starring Franco Nero, Susan George, Sho Kosugi and Christopher George. The film is about a martial artist named Cole (Nero) who is visiting his friend Frank in the Philippines. On arrival, Cole learns that his friend is being harassed by the wealthy businessman Charles Venarius who wants Frank's land for the oil underneath. Frank and his wife are continuously thwarted by Cole who defends them with his martial arts skills. Learning of Cole's presence, Venarius hires his own ninja (Kosugi).

The film was originally intended to be directed by Emmett Alston and to star Mike Stone. Early in the production, Alston was replaced by Golan but stayed on as 2nd unit director, and Stone was replaced with Nero, but stayed on as fight double and fight/stunt coordinator. The film began a craze of ninja-themed Hollywood films during the early 1980s and was the first film in Cannon Films' Ninja Trilogy, an anthology series which includes Revenge of the Ninja (1983) and Ninja III: The Domination (1984). The film launched the career of Sho Kosugi, who went on to play the leading role in both the film's sequels, while also starring in other 1980s ninja-themed films and television shows such as The Master (1984).