So many fine ones already named.
A few I haven't seen here yet:
North to Alaska, A John Wayne Western featuring Ernie Kovacs as a slippery con man, and beautiful Capucine as a prostitute who looks as if she should be wearing a tiara. Played mostly for laughs, with loads of fistfights, claim-jumping, a lumberjack competition, the usual plethora of romantic misunderstandings. Final brawl in the mud where everybody gets dirty except Capucine.
"Rough Riders", a 4-hour made for TV effort about the Spanish-American War with Tom Berenger as Teddy Roosevelt. Good depiction of the unpredictability of combat and the fog of war. Even with 240 minutes, tries to do a bit too much, showing us a huge cast of characters, ranging from Teddy to Wm. Randolph Hearst, Stephen Crane, Frederick Remington, Wm. McKinkley, Col. Leonard Wood, and several of Roosevelt's High Society gentleman-soldier friends.
"The Honkers', James Coburn as a self-centered rodeo cowboy and Slim Pickens as a rodeo clown who's a better friend than Coburn's character deserves.
"The Wind and the Lion", not exactly a Western in the conventional sense, as most of the action takes place in Morocco. More a contrast of the American culture we know (or at least admire) so well from Westerns and Arabs and Europeans of the early 20th Century. Sean Connery as a heroic Berber chief (who mysteriously seems to have learned his English in Edinburgh); Brian Keith as his equally heroic, manly opponent: Teddy Roosevelt. Vladek Sheybal the unscrupulous Bashaw of Tangier; John Huston as Sec.of State John Hay; A large crowd of dirty, smelly, & untrustworthy looking Euros... and Candice Bergen, the spirited kidnapped American Woman who refuses to be a pawn in any of their games.
(Very loosely) Based on a real event. We seem to see it all through the eyes of Bergen's impressionable young son, a boy's memory of romance and high adventure. Great action scenes that begin almost with the very first frame. Written & directed by John Milius.
"The Spoilers", another Alaskan Gold Rush tale that ends with a knock-down-drag-out brawl between John Wayne, and one of the few actors who looks as if he just might be able to take him: Randolph Scott. Marlene Dietrich as a saloon girl/love interest. She doesn't wear her tuxedo or kiss any girls in this one, more's the pity!
Scott made some fine westerns in the 50's Tough and gritty, I particularly like "The Tall T" and "Ride Lonesome", which also features Pernell Roberts just before he began "Bonanza", & James Coburn in his very first film.
... and it might be a stretch, but there's always "My Little Chickadee"! As hilarious a send-up of the Western as any ever made. W.C. Fields is bumbling Cuthbert J. Twillie, Mae West is the "beautiful"
Flower Belle Lee, and Joseph Calleia as Jeff Badger (another great name!), aka "The Masked Bandit"