If I had to pick one movie that captures the concept of Weird Western, that movie is the 1973 Clint Eastwood vehicle HIGH PLAINS DRIFTER. The plot is enigmatic enough, a stranger without a name rides into the town of Lago. He kills, he rapes, he turns the town on its head… and all seemingly without any motive.
Except the town folk were complicit in the murder of a federal marshal, having hired outlaws to beat him to death when he threatened to shut down the town’s primary source of income, a mine on federal land. The town folk than turned on the outlaws that murdered the marshal, and are now in fear of what will happen now that the outlaws are out of jail. And the three gunmen the stranger kills when he enters the town? Yeah, they were there to protect against the outlaws.
This movie also has one of the most iconic climaxes in movie history. The town is painted red, a sign declaring it Hell, the townsfolk cowering in the face of the outlaws they betrayed… and all for it to be set on fire at the end.
In many ways, this movie is one of the great vigilante movies. The Stranger acts as a force of divine retribution, sparing the few people he comes across who have nothing to do with the murder of the marshal (the Native American and his family, the Mexican laborers tasked with tearing down the barn to build Picnic tables, Mordecai), unflinching with his violence. The Stranger has no trouble extorting, killing, and raping the people of Lago.
The nature of the Stranger also lends credence to the idea that some questions are best left to the reader or viewer. Who is the Stranger? Is he the dead marshal’s brother? Is he a revenant? Or is he Death himself coming to Lago to deliver a final reckoning? Regardless of the answer, it’s definitely a worthwhile film to acquaint yourself with when it comes to the concept of the Weird Western.
 Yes, this does get referenced in Sandman Slim where zombies are frequently referred to as High Plains Drifters, or simply Drifters.