Little Bigman...and if you felt it was intended as historic realism, you missed the point
The Big Country
Ulzana's Raid (the absolute best depiction of war between the US Cavalry and the Apache)
The Hi-lo Country
Missouri Breaks(Brando's looney regulator versus Nicholson's likeable rustler)
Lonesome Dove
One-eyed Jacks
Brokeback Mountain
Lonely are the Brave
Shane
Dances w Wolves