Robert Mitchum as Sheriff J.P. Harrah James Caan as Alan Bourdillion Traherne, nicknamed "Mississippi" Charlene Holt as Maudie Paul Fix as Dr. Miller Arthur Hunnicutt as Bull Harris Michele Carey as Josephine "Joey" MacDonald R. G. Armstrong as Kevin MacDonald Ed Asner as Bart Jason Christopher George as Nelse McLeod Marina Ghane as Maria Robert Donner as Milt John Gabriel as Pedro Johnny Crawford as Luke MacDonald Adam Roarke as Matt MacDonald Jim Davis as Jim Purvis, Bart Jason's foreman Olaf Wieghorst as Swede Larsen, gunsmith John Mitchum as Elmer, Jason's bartender (uncredited) Chuck Roberson as Jason's gunman (uncredited) Don Collier as Deputy Joe Braddock (uncredited) Dean Smith as Charlie Hagan (uncredited) Wayne's horse was a six-year-old Appaloosa stallion named Zip. Production Leigh Brackett wrote the original script, which she described as "the best script I had ever done in my life. It wasn't tragic, but it was one of those things where Wayne died at the end." However, she said that as production neared, "the more we got into doing Rio Bravo over again the sicker I got, because I hate doing things over again. And I kept saying to Howard I did that, and he'd say it was okay, we could do it over again." Mitchum later said: "When Howard called me, I said, 'What's the story?' and he said, 'No story, just characters' and that's the way it was. Did one scene, put it away, did another, put it away." Cinematographer Harold Rosson had retired in 1958, but Hawks persuaded him to come back to work. After making the film, Rosson resumed his retirement permanently. El Dorado was shot in Technicolor at Old Tucson Studios just west of Tucson, Arizona as well as in and around Kanab, Utah from October 1965 to January 1966. The film was Wayne's 138th picture and was filmed before The War Wagon, but its release was delayed so that Paramount's Nevada Smith with Steve McQueen would not have to compete with a John Wayne film at the box office. El Dorado finally reached the theatres in June 1967, a month after The War Wagon had opened. The film was the only screen pairing between Wayne and Mitchum; though they both appear in The Longest Day, they share no scenes in that film. El Dorado is the second of three films directed by Hawks about a sheriff defending his office against belligerent outlaw