These aren't in any particular order.
Rio Bravo
Rooster Cogburn
The Cowboys
The Sons of Katie Elder (my fave John Wayne film with Rio Bravo a close 2nd)
The Searchers
True Grit
The Unforgiven (my fave Western of all time)
Hang Em High
The Good, The Bad, The Ugly
The Outlaw Josey Wales
High Plains Drifter
A Fistful of Dollars
For a few Dollars More
The Magnificent Seven
That's all at the moment that i can recall.