The Mercenary (Italian: Il mercenario), also known as A Professional Gun, is a 1968 spaghetti western film directed by Sergio Corbucci. The film stars Franco Nero, Jack Palance, Tony Musante and Giovanna Ralli, and features a musical score by Ennio Morricone and Bruno Nicolai. The film takes place during the Mexican Revolution and is a well-known example of the "Zapata Western" subgenre.
The Mercenary was released the same year as Corbucci's more popular western, The Great Silence (Il grande silenzio). The film is often compared to Corbucci's 1970 film, Compañeros (Vamos a matar, compañeros), which features Nero and Palance in similar roles, and Tomas Milian in a role similar to Musante's in The Mercenary. Both films also had Morricone as the composer, Alejandro Ulloa as the cinematographer and Eugenio Alabiso as the editor. The Mercenary's theme music L'arena was later used by Quentin Tarantino in the 2004 film Kill Bill: Volume 2.
Paco Roman (Musante), a Mexican peasant, rebels against his rich boss and humiliates him. He is later captured, but saved from a certain death by his friends. Meanwhile, Sergei Kowalski (Nero), a Polish mercenary, arrives in Mexico and makes a deal with two Garcia brothers to take their silver safely across the border. Curly (Palance) sees the three men talking and tracks down the brothers to find out what they hired Kowalski for, after which Curly kills the two.