Now that HBO's new $100 million Westworld series has galloped out of the gates with its premiere episode Sunday night, this might be the perfect time to dig your heels into more cowboy movies that hung their creative hats in the science fiction realm.

Rip-roaring westerns might seem like unlikely territory for a mashup with the tried-and-true tropes of speculative fiction, but it turns out they pair up nicely together, and Hollywood has a long history of tossing aliens, spaceships, rayguns and robots into their dusty "Oaters."

So grab a plate of beans and bread and gather 'round this campfire collection of sci-fi westerns corralled from the last 60 years of cinema and tell us which ones make you hoot 'n holler for more!