Two Mules for Sister Sara is a 1970 American-Mexican Western film in Panavision directed by Don Siegel and starring Shirley MacLaine and Clint Eastwood set during the French intervention in Mexico (1861–1867). The film was to have been the first in a five-year exclusive association between Universal Pictures and Sanen Productions of Mexico. It was the second of five collaborations between Siegel and Eastwood, following Coogan's Bluff (1968). The collaboration continued with The Beguiled and Dirty Harry (both 1971) and finally Escape from Alcatraz (1979).

The plot follows an American mercenary who gets mixed up with a nun and aids a group of Juarista rebels during the puppet reign of Emperor Maximilian in Mexico. The film featured both American and Mexican actors and actresses, including being filmed in the picturesque countryside near Tlayacapan, Morelos. Ennio Morricone composed the film's music. Two Mules for Sister Sara was a moderate financial success and received a warm critical reception.