Four Fast Guns (1960)

A gunslinger rides into the town of Purgatory and tells the townspeople he's the town tamer they've been expecting, knowing full well that he shot the man back in the desert. He agrees to their $500 fee, payable when the job is complete to the widow of another man he killed, and sets about freeing the town from it's wheelchair-bound criminal boss, who hires three killers in succession to rid the town of its new lawman.