I’m not sure this thread is still alive, but I HAD to step in, even if this answer is lost in the wind.
I just couldn’t accept the idea that people would deal with violent SW without mentioning the magnificent Keoma !!
This movie has the graphic violence of a Chang Cheh movie (I exagerate a little bit maybe, but not much), it is clearly one of the best, most beautifull, darkest, most violent SW ever made, maybe the last of its kind.
I suppose the most violent good SW (as pointed out by someone) would be
Django Kill (go and see Death Laid An Egg, his strange giallo, and Arcana (if you can find it) if you liked Django Kill)
The Great Silence (the best Corbucci effort in “serious” western)
The 4 of the Apocalypse (even though it is a little frustrating)
Texas Addios (almost a twin of Fulci’s Tempo Di Massacro)
Tempo di Massacro (almost a twin of… okay, okay, I stop here)
Vengeance (late Ferdinando Baldi which was screened in 3D and was indeed violent)
Obviously, violence is an important side of SW, the moral violence as well as the graphic one. It is often what makes me prefer Italian efforts to the classic american ones, the crude violence, hopelessness, vengefull dark heroes. (It is the only problem I have with Fulci’s heroes, they often do not go far enough, Testi both in Marseilles connection and in the Four of the Apocalypse is reluctant to pull a real “die in pain, bastard” kind of revenge, and it is frustrating to me, especially in regard of the horror he and his close ones suffered because of the villain Millian (and Buffosi in the mafia movie) )
Ah, I forgot the 2nd (or 3rd) of the dollar trilogy, (for a few dollars more, maybe ? I’m not sure about the title but i do remember this excellent movie well), the one with Gian Maria Volonte as the cruelest villain ever and Lee Van Cleef as a good guy (and good ol’ Clint of course)
And to those who love Millian, go and see Sergio Sollima Cuchillo trilogy! Not the most violent SW, but they are among the bests.