The genesis of the SW anti-hero:
A man with no name/goes by just one name/by nickname arrives at some semi-abandoned western town, he will carry some trademark accesorie: poncho, fancy cigars, black gloves, a hidden machine gun, a tomahawk, or a deck of cards that can be used as weapon. He will probably have either a badass scar, or something else that shows us that he has been around. The town is either controlled by a wealthy sadistic hacienda/mine owner, or in the middle of a war between several factions. Our hero arrives at the local saloon, shows briefly but effectively his almost super human skills, beats up some bandito, and gets hired by the bad guys, after all the SW anti-hero will always work for the right money, but he might also have a personal vendetta against one of the bad guys. He will trick the bad guys at first, working for them or promising a large sum of gold for them. At the same time he will be making deals with another faction of bad guys, or looking out for some information about some secret weapon/stash of gold hidden somewhere.
In the process he meets either a noble yet weak bartender/old guy who might help him, or just a good looking señorita, who will obviously fall for our hero at first sight, much to his indifference. Eventually the bad guys find out about his true intentions. They torture him, beat him to a pulp and cripple him in some way that affects his skills, they will left him for dead, but he will come back, either by his own hand or with somebody's help. The hero has to heal his wounds somehow, and recover his skills, meanwhile the odds stack against him. The final confrontation arrives and, despise being outnumber, with a combination of skill, brains and luck our hero will blast all the bad guys, and will either die in the process or just ride into the sunset, saying goodbye to the señorita, and with the vague promise that we might see him sometime in the future. Cue to badass main theme, the end.