Henry Fonda is terrifying

Great choice from Leone to make him the main villain.

I think that was the "Whoa!" effect that he wanted the audience to feel. When that camera pans up and we see the main baddie is the blue-eyed Henry Fonda, who up until that time was the classic amiable/honest everyman, that must've shook some people up.

James Stewart to my knowledge never became a villain, but after the war he started playing darker characters with morally questionable standings (the Anthony Mann westerns were some of his best imo). Tom Hanks kind of reminds me of those actors, and the closest he's gotten to a "villain" would probably be in Road to Perdition.

The Rock I could see jumping over to the baddie side quite easily. I'm not sure about Chris Pratt yet because I need to see more of his dramatic work. But that would be an interesting flip for him.

I disagree. To me he was like Clint Eastwood ultra lite.

The scene at the McBain ranch is great, but he never lived up to that level of villainy throughout the rest of the movie. He never came close to that level of evil until the harmonica flashback at the end. Between those scenes he didn't really seem evil at all.

Indeed.

...and Abe Lincoln and Tom Joad... who'd have thunk indeed.

Yeah he was incredible in this!

This was exactly the reaction they were going for.

He looked like a stone cold killer.

Kind of bad strategy for Harmonica to challenge him to a gunfight though.