I'm going with Clint Eastwood.
There's nobody on earth that could've pulled off his cowboy characters better than he did. You can actually see someone try, in once upon a time in the West. I like Bronson but that role would've been so much better if Clint was willing to do it.
The squint, the jawline, the tall slender frame, Clint was born to be the perfect cowboy badass.