Sam Peckinpah - Sergio Leone, two directors, one book. The first directed fourteen films, six of which are westerns. The second directed seven films, five of which are westerns. Both are considered today as masters of the genre – "maestro" and "master" are the respective expressions in each of their native languages.

According to Jim Kitses, a film professor at the University of San Francisco and author of the now-classic Horizons West: The Western from John Ford to Clint Eastwood, they are two of the six most important creators of the genre – the other four being John Ford, Anthony Mann, Budd Boetticher, and Clint Eastwood, who have indelibly linked their names to it, perhaps more so than Howard Hawks, Raoul Walsh, Delmer Daves, or John Sturges.