Casting is one of the least understood or appreciated behind-the-scenes processes in filmmaking. Indeed, casting decisions are made all the time that change the course of film history. How altered would the film landscape be if Inspector Harry Callahan in Dirty Harry (1971) had been played by John Wayne (1907–1979)? Or Frank Sinatra (1915–1998)? Or Steve McQueen (1930–1980), Walter Matthau (1920–2000), Paul Newman (b. 1925), or Robert Mitchum (1917–1997)? All were offered the role, and all turned it down. Dirty Harry made Clint Eastwood (b. 1930) into an American cultural icon and lightning rod. However, it is easy to imagine that the movie would have been dismissed as just another cop film with any of these actors in the title role.
Casting is usually characterized outside the film industry as something the director does. Director Elia Kazan (1909–2003) once said that three-fourths of directing is casting. However, no director alone can cast a film, television show, or stage play. The process is too time-consuming to be done by their directors amid many other preproduction duties. Furthermore, many maintain that casting involves as much creative collaboration as other aspects of filmmaking.