That scene from "Unforgiven" is one of the all-time greatest--bar none. I watch it at least every two weeks.

Here's a bit of unforgettable dialog from the end of that scene:
(Little Bill, wounded on the floor):"I don't deserve this--I was building a house."
(William Munney): "Deserve's got nothing to do with this."
(Littlel Bill): "I'll see you in hell, William Munney."
(Munney): "Yeah,..(bang!).