Il buono, il brutto, il cattivo (The Good, the Bad and the Ugly) influenced Kill Bill

Tarantino has never hidden this one and the film quotes it openly:

• Morricone is used directly on the soundtrack, not imitated
• The extreme close-up on eyes before a killing, held far past comfort
• A standoff staged in a cemetery, which is where Leone's ends
• Chapter headings and a revenge list, so the plot is a structure rather than a mystery

What Tarantino changes is the genre underneath: Leone's grammar applied to a Japanese sword film, which is itself where Leone got A Fistful of Dollars from.