I believe you are talking about the theme to <i>The Good, The Bad, and The Ugly</i>, likely the Hugo Montegegro cover that hit #2 on the US charts in 1968. The original composer is Ennio Morricone, who wrote music for many so-called "spaghetti westerns" that were made in Italy.
<a href="http://www.allmusic.com/cg/amg.dll?p=amg&sql=11:qzapqj1yoj6a">Here's Morricone's allmusic.com page</a>.