3. The War Wagon (1967)

Teaming up with John Wayne, Douglas plays Lomax, a charming gunslinger hired to help steal a heavily armed stagecoach carrying gold. Their unlikely partnership brings humor and tension, with Douglas adding swagger and wit to the mix. The film’s action sequences and lighthearted camaraderie make it one of the most entertaining Westerns of the era, with Douglas and Wayne’s chemistry stealing the show.