One of the best old-school examples of Western horror came with Rod Serling's classic series The Twilight Zone.
Cowboys were all the rage when the series first premiered, and multiple episodes used Western tropes as the jumping-off point for their various spooky premises. One of them -- Season 3, Episode 7, "The Grave" -- is as good as anything The Twilight Zone has ever produced. It perfectly demonstrates how well-suited the two genres can be with the right story.
https://www.cbr.com/64-years-later-this-twilight-zone-episode-is-still-1-of-the-best-horror-westerns-ever/
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