Not that there are a lot of cyclops in film to begin with, but it's hard to beat Ray Harryhausen's from 7th Voyage of Sindbad.
Of the genre combinations, this is not one that readily comes to mind (such as the ever popular Slasher/Romantic Comedy crossover). My favorite crossover might be Horror/Comedy with SF/Horror a close second, but some really great SF just happens to have Western themes. Check out my top ten. It was originally five, but then I remembered 5 more: 10. Westworld (movie) - About a theme park that uses A.I. androids to show guests "a good time" in different worlds created to simulate space travel, ancient Rome, the Age of Chivalry, and the wild west. Unfortunately, a good time means being massacred by androids. Some great moments in this flick and Yul Brynner is the baddest android gunslinger badass ever, but takes too long to get going. This could use a remake, but avoid the sequel like the Black Death if you know what's good for ya'. Look for the late Majel Barrett Roddenberry Roddenberry in one of her few non-Trek roles. 9. Star Trek: The Original Series "Sp