Where did the versus memes come from?

[Lark]

Where did the versus memes come from do you think? Aliens vs. Predator? Werewolves vs. vampires? Ninjas vs. pirates?

I've seen each of those in film, comics and other media and serious and frivolous or funny treatments of each of them but they seem to have always been there but why?

I'm interested in the whole thing as a phenomenon and any of the versus matches specifically too.

 

[Isis]

This explains the Pirates vs. Ninjas one.

http://knowyourmeme.com/memes/pirates-vs-ninjas