Donald Siegel (October 26, 1912 - April 20, 1991) was an American film director and producer. His name variously appeared in the credits of his films as both Don Siegel and Donald Siegel. He was best known for the original Invasion of the Body Snatchers (1956) and five films with Clint Eastwood, including Dirty Harry (1971) and Escape from Alcatraz (1979).

Born in Chicago, with Jewish origins, he attended schools in New York and later graduated from Jesus College, Cambridge in England. For a short time he studied at Beaux Arts in Paris, France, but left at age 20 and later made his way to Los Angeles.

Siegel found work in the Warner Bros. film library after meeting producer Hal Wallis, and later rose to head of the Montage Department, where he directed thousands of montages, including the opening montage for Casablanca. In 1945 two shorts he directed, Hitler Lives? and Star in the Night, won Academy Awards, which launched his career as a feature director.

He directed whatever material came his way, often transcending the limitations of budget and script to produce interesting and adept works. He made the original Invasion of the Body Snatchers in 1956. He directed two episodes of The Twilight Zone, "The Self-Improvement of Salvadore Ross" and "Uncle Simon". He worked with Elvis Presley and Dolores del Río in Flaming Star (1960), with Steve McQueen in Hell Is for Heroes and Lee Marvin in the influential The Killers (1964) before directing a series of five films with Clint Eastwood that were commercially successful in addition to being well received by critics. These included the policiers Coogan's Bluff and Dirty Harry, the Budd Boetticher-scripted Western Two Mules for Sister Sara, the cynical American Civil War melodrama The Beguiled and the prison-break picture Escape from Alcatraz. He was a considerable influence on Eastwood's own career as a director, and Eastwood's film Unforgiven is dedicated "for Don [Siegel] and Sergio [Leone]".