A Fistfull Of Dollars (1964)
https://www3.zoechip.com/watch-movie/a-fistful-of-dollars-18777.5299048
Drifter gunman, Joe (Clint Eastwood), arrives in the Mexican village of San Miguel at the border of the United States of America, and befriends the owner of the local bar, Silvanito. Joe discovers that the town is dominated by two gangster lords: John Baxter (Wolfgang Lukschy) and the cruel Ramón Rojo (Gian Maria Volontè). When Joe kills four men of Baxter's gang, he is hired by Ramón's brother, Esteban Rojo (Sieghardt Rupp), to join their gang. However, Joe decides to work for both sides, playing one side against the other

From IMDB:

9/10
'The Man With No Name' rides into town for the first time...
Nazi_Fighter_David28 August 2005
Warning: Spoilers
Sergio Leone shared a rebellious desire to tumble the old values and present the audience with a new, more mystifying piece of storytelling... The violence, the speed of action in his film announced a totally new European style...

Leone placed the poncho on Eastwood's shoulders to give his character a veil of mystery... The cigar acted as a sort of pendant to those ice-cold eyes... He creates a quite unique character, with no name, no horse and no money, a cynical bounty hunter whose impassivity is his main attraction, an ultra-cool gunslinger who leaves us impressed by his exceptionally swift draw... He is a mysterious 'gunman with green eyes' who comes from nowhere and returns there, a cult hero (set against a dry and dead landscape) entering a noisy violent world where evil competes with evil...

"A Fistful of Dollars" is distinguished by Sergio Leone's visual gift, and convincing fashion in handling violence, rape and torture... He presents his sadistic killers, invariably unshaven, sweating and bleeding in frequent big close-ups... Both the real and the unreal invincibility of his 'Stranger' are never better illustrated than in the final scene when the trembling Ramon fills the gunfighter's heart with bullets...

Leone's very dark brand of humor stands out when Eastwood walks past a coffin-maker: "Gets three coffins ready" he orders... The town heavies make fun of him, asking where his old mule is... "You see, my mule don't like people laughing, gets the crazy idea you're laughing at him!" All four heavies get their just punishment for such mockery and as Eastwood returns past the old man, he corrects his miscalculations: "My mistake, four coffins."

The film is strong on passionate emotions, and bloody violence... This aspect is completely foreign to the American tradition based on John Ford concepts of honor, bravery and romantic adventure... Sergio Leone's film deeply influenced the future of the Western in general and the Italian 'spaghetti' Western in particular.