Curse of the Undead 1959

"B-grade western with a twist: mysterious gunslinger-for-hire Drake Robey is really a vampire, and it's up to Preacher Dan to save the town and girlfriend Dolores Carter.

Wikipedia: "Curse of the Undead started as a gag idea by husband-and-wife team Edward and Mildred Dein called Eat Me Gently, described by Edward as "a Western horror story about a fag vampire running around the desert eating little boys". Universal-International producer Joseph Gershenson heard about the idea from his wife and quickly phoned Edward Dein: "Hey, smartass. The good stuff you don't give us. I want to make this picture." According to an early studio announcement the film was intended as a satire of the vampire theme set in the Old West, but the final version is fairly serious. Shooting was finished in only 18 days."