Anything late at night on GRIT TV. I've watched a metric shyte ton of old westerns on there, mostly cast with actors whose names few on this board would recognize.
I'm quoting myself to expand on some of these classic western actors. For you "less seasoned" folks on the board, these cats helped make Hollywood and "the movies" in general.
Marion Mitchell Morrison - Most know him as John Wayne
Randolph Scott - WWI veteran whose career spanned 5 decades
Gary Cooper - classic leading man
Robert Taylor - another great leading man
James Coburn - couldn't sing a lick in "Paint Your Wagon" with Clint Eastwood and Shirley Maclaine, but his characters were just that: characters
Gene Autrey - the original singing cowboy
Burt Lancaster - talented actor
Hugh O'Brian - fun fact: met him while serving as a chauffer for the "Freedom Train" when it came to Omaha in 1976. HS DECA project. No shit.
Jason Robards - booze got him at the end, but he was in a lot of great old westerns
Dale Robertson - "The Tales of Wells Fargo" leading man
Yul Brynner - more westerns than other genres, but mainly remembered for "The King and I". Etcetera, etcetera, etcetera ...
Lee Van Cleef - born to be "the bad guy", he had an amazing career until cancer took him. Fucking cigarettes,
Glenn Ford - another WWII vet that went on to have a great career in films
Gregory Peck - most know him from "To Kill a Mockingbird", but he was in a lot of westerns
Roy Rogers & his wife, Dale Evans - fun fact: my first dog was the grandson of Bullet, RR's on-screen dog
Audie Murphy - more than the most decorated WWII hero and owner of the Los Angeles Angels
Walter Brennan - rarely a leading man, but always an interesting screen presence
Forrest Tucker - like Walter Brennan above, rarely a leading man and usually in a US Army Calvary uniform, but he was in a ton of movies
Ben Johnson - you'll know him the second you see him
Jack Elam - made that wonky eye famous
Rory Calhoun - another B&W movie star
Eli Wallach - interesting career, but he's in a lot more old westerns than you think he would be
Charles Bronson - yes, he got his start in westerns
Jimmy Stewart - always one of the good guys
Omaha's own Henry Fonda - rarely played a good guy, but man he had presence on the screen. Steely blue eyes and a penchant for evil.
Anyways, by now you get the idea. Tons of great actors that either got their start in westerns or were made famous by the genre. And we haven't even touched on some of the famous women that appears in those shows (e.g. Claudia Cardinale ...).