Unless you've been renting out an apartment space in the Fortress of Solitude for the last decade or so, you're probably aware that superhero movies are pretty big right now. And by "pretty big," I mean that this sub-genre has emerged as an unconquerable goliath of the cinema scene. It's not just sweaty nerds who like comic book movies now: your little sister, your grandparents and your mailman are all totally into them, too. The strangest thing about this, of course, is that the majority of comic book movie converts don't actually read comic books. What it is about these movies that we're collectively tapping into, then? And why now? Why are these characters - some of them nearly a century old - succeeding in bringing in record amounts of movie-goers time and time again, despite the fact that only a small number have explored their worlds in original comic form? Ultimately, I think it comes down to a single notion that remains eternally appealing: the idea of one person - a vigilante - doing whatever it takes to protect and defend humanity. It's a fantasy that we've all likely imagined for ourselves at some point. It wasn't really until The Dark Knight that comic books movies found themselves associated with the levels of idolisation that they are today, though. So what happened? Put it down to the realism that Christopher Nolan evoked with his second Batman movie: the director made a conscious choice to ground the character in a more familiar reality, one free of "corny" comic book aesthetics. The response to this approach was overwhelming, presumably because the "vigilante concept" becomes even more attractive when it feels genuinely possible. The big question - "what would happen if a superhero existed in real life?" - has been explored in a number of movies before, and ever since. Here are 10 of the most essential, all of which deal with the idea of a people living in familiar realities to our own and opting to become superheroes...