Shane
Unforgiven
Josey Wales
Dances With Wolves
All Rooster Cogburn movies
Hostiles
Buster Scruggs
Lefty Brown
High Noon
3:10 to Yuma
Butch and Sundance
Lonesome Dove
Deadwood
The Quick and the Dead (NOT the Raimi movie. The Sam Elliot TV Movie from the L'amour novel)
Bone Tomahawk
El Dorado
Rio Bravo
Red River
Hateful Eight

I'm sure there are way more I can't think of. I really liked the first Horizon and can't wait for more. Westerns are hard to come by these days. Hostiles was one of the really good modern ones.