There are so many - have to break it down in categories.
I. westerns:
Stagecoach (John Wayne version)
The Searchers
The Long Riders
Josey Wales
The Magnificent seven
Tombstone
John Ford's Cavalry trilogy - Rio Grande, Fort Apache, She Wore a Yellow Ribbon
Anything with Jimmy Stewart or Gary Cooper (Esp. High Noon)
more later.

(How about the Coen brothers? especially Fargo, Raising Arizona and Oh Brother, Where Art Thou.)

O'Meara