A "Weird Western" is what you call it when supernatural elements meet a Western setting. TV Tropes has a great explanation: https://tvtropes.org/pmwiki/pmwiki.php/Main/WeirdWest.
Tor.com also posted a "primer" article to introduce people to some of the material already out there: https://www.tor.com/2015/09/23/six-guns-and-strange-shooters-a-weird-west-primer/. The Dark Tower would be considered a Weird Western.
This anthology also includes "Space Western" stories: https://tvtropes.org/pmwiki/pmwiki.php/Main/SpaceWestern
"Cattlepunk" stories: https://tvtropes.org/pmwiki/pmwiki.php/Main/CattlePunk
"Alternate History" stories https://tvtropes.org/pmwiki/pmwiki.php/Main/AlternateHistory
"Time Travel" stories https://tvtropes.org/pmwiki/pmwiki.php/Main/TimeTravel.