More than 40 years after he directed the classic first installment, it seems that Ridley Scott still can't seem to get enough of the Alien franchise. The long-running sci-fi series has suffered from some major ups and downs over the decades, and has never managed to reclaim the all-time great status that the first two outings deservedly gained, but with over $1.3 billion in box office takings, you can see why the Xenomorphs keep coming back to our screens.