"Although 'mash-up' is a phrase that originally referred to unlikely or unexpected musical blends, it's a pretty useful term for anything that takes two elements and puts them together for the sheer pleasure of seeing them side by side. It can be a combination of genres, or of beloved characters, and it's hard to say which works best: the conjunction between things that always should have gone together (Doctor Who meets Sherlock, anyone?), or the delicious contrast of things that you never expected should (mmmm, peanut butter and lemon curd). Science fiction and fantasy are both areas in which the mash-up can be especially rewarding, and – as you'll see from the list – comic books have been doing it for longer than the term mash-up has been around. My novel Dragon Frontier shows how simple and effective the mash-up can be. I've always loved stories of the Wild West, and I've always loved mythical beasts. How much more fun would it be to have a story where those two things meet head on?"
Dan Abnett is a novelist and comic book writer. He has written more than 45 novels, including several Doctor Who adventures, and many epic Warhammer 40,000 tales. Dragon Frontier, published by Puffin, is his first novel specifically for younger readers.
1. Monsters Versus Aliens
The 2009 animated film from Dreamworks is a good example of how simple a mash-up can be... and how entertaining. The film is packed with references and in-jokes celebrating the classic monster movies of the fifties, and the long tradition of alien invaders flicks, two beloved sub-genres of sci-fi and fantasy that come together here.
2. Aliens Versus Predator
This wildly successful movie franchise is simply a mash-up of two other wildly successful movie franchises, and sprang originally from an inventive comic published by Dark Horse, who had the license for both properties, and who took their creative cue from a little in-joke nod to the Alien films that was made in the second Predator movie. The Alien and the Predator are both terrifyingly memorable movie monsters. Who wouldn't want to see what happened if they crossed paths?
3. Cowboys and Aliens
The adventurous setting of the Wild West invites all sorts of blending and combinations. This very entertaining movie mixed up two escapist genres, and also explored what it might be like if people on the 19th century American frontier had to deal with the culture shock of confronting technologically advanced extraterrestrials.
4. The Valley of Gwangi
A particular inspiration for Dragon Frontier was this 1969 movie, one of the lesser known films by stop-motion animator and genius Ray Harryhausen, who was famous for Jason and the Argonauts and One Million Years BC. I think it was my favourite film when I was growing up: cowboys come face-to-face with dinosaurs, including a pteranodon, and an Allosaurus, which runs amok when it is put on display in a circus rodeo.
5. Superman versus the Amazing Spider-Man
Mash-ups, crossovers and team-ups are now a staple part of comic books, with many wonderful (and unlikely) combinations, but this 1976 special was the first time the two big American comic publishers came together. Marvel's Spider-Man met arch-rival DC's Superman in what was dubbed "The Battle of the Century", and a comic industry tradition was born.
6. The Hitchhiker's Guide to the Galaxy by Douglas Adams
Comedy and science fiction? Would they be comfortable bedfellows? Surely humour would detract from the essential credibility of an SF story? Douglas Adams proved it could be done – and brilliantly so – by creating a series that worked on the radio, on TV, in books and in the cinema, and which managed to be engrossingly credible and really, really funny.
7. The Harry Potter series by JK Rowling
You can love the Harry Potter books (and movies) for many, many reasons, but their greatest appeal is probably that, at the very heart of it, Harry Potter is a simple and brilliant mash-up of magical, sorcerous tradition that has been a mainstay of children's books for a very long time, and the very British and very appealing institution of the schooldays or boarding school story, the other great mainstay of children's literature.
8. Pirates of the Caribbean
Like the Wild West, there's something inherently adventurous about the swashbuckling world of pirates, so it's only a small leap of the imagination to make it even more rambunctious by adding the supernatural to it. These films did it with verve, and owed (literally, as it turn out by the third of them), a great deal to Tim Powers's marvellous pirates-and-supernatural-monsters novel On Stranger Tides.
9. Avengers Assemble
As a Marvel comic, The Avengers was always a mash-up, in that it brought together in one team (and one comic book) all of the most popular heroes Marvel published as a company. Last year's exhilarating movie took it one step further – each of the main heroes had featured in his own movie first (two, in the case of Iron Man), and those movies had laid the groundwork of continuity and backstory for how they could be brought together in one extravaganza. Audacious long-term planning on behalf of the movie makers, driven simply by the inherent thrill and appeal of the mash-up: to see these great characters actually side-by-side in the same room (or helicarrier).
10. Judge Dredd
Judge Dredd has now been turned into a movie twice, the most recent version being this year's very grown-up action thriller. But the character has been the mainstay and star of Britain's 2000AD comic since 1977 (appearing in 2000AD every week, as well as in the companion Judge Dredd Megazine). A tough, uniformed cop in an ultra-violent future America, Dredd patrols Mega City One, and the stories, a splendid conceptual mash-up of police procedural and sci-fi, often turn a very darkly humorous and downright satirical eye on our own world and culture.