Marie Windsor took some warming up. I wasn't used to her rhythms when I saw The Killing, but after The Narrow Margin I agree. Gloria Grahame is a good choice too, with Oklahoma being a large exception.
I like Thomas Mitchell, who I don't remember in Gone With the Wind or High Noon, but won't forget after Mr. Smith Goes to Washington. My brain sometimes mixes him with Edmond O'Brien who left his mark on me with The Man Who Shot Liberty Valance.
Walter Brennan is a great pick. I underestimated him until I saw The Westerner and learned soon after he'd won 3 Oscars. I have similar regard for Walter Huston. I don't know if Huston is more of a leading actor, but I know him more from Treasure of the Sierra Madre and Yankee Doodle Dandy than Dodsworth.
That reminds me of another great that always gets me excited... Barry Fitzgerald. Ever since Going my Way I've been happy to see him in And Then There Were None (with Huston), The Naked City, The Long Voyage Home, The Sea Wolf, How Green Was My Valley, and of course, The Quiet Man.
You could sub-question this in regards to the John Ford players. Always enjoy seeing them, especially Hank Worden, whose never had more than a cameo except in The Searchers.